diff --git a/changelog/unreleased/2026-07-22-web-app.md b/changelog/unreleased/2026-07-22-web-app.md
index d2ec802..f033835 100644
--- a/changelog/unreleased/2026-07-22-web-app.md
+++ b/changelog/unreleased/2026-07-22-web-app.md
@@ -1,4 +1,6 @@
-# Web App: Workspace HTML previews open on a separate origin
+# Web App
+
+## Workspace HTML previews open on a separate origin
 
 "Open in new tab" for a Workspace html file used to serve the page from the app's own origin under a CSP sandbox without `allow-same-origin`. That kept Agent-generated markup away from the session cookie and the API, but it also put the document in an opaque origin, so `localStorage` and `document.cookie` threw `SecurityError` and any third-party embed on the page — analytics, chat widgets, maps — failed outright. The query-parameter URL had a second problem: a page's relative subresources resolved to `/api/sessions/<id>/files/<name>`, a route that does not exist, so multi-file generated apps could never load their own CSS or JS.
 
@@ -9,3 +11,47 @@ Because the origin is now the isolation boundary, the preview response no longer
 The preview URL takes its port from the server's own binding rather than the browser's current origin. Those differ in development — the SPA runs on Vite's port and only `/api` is proxied — so deriving it from the request would point at a port that does not serve `/preview` at all, and the tab would fail to connect. In production the two coincide. Only a loopback-name bind (`127.0.0.1` / `localhost`) offers a loopback preview; a wildcard bind (`0.0.0.0` / `::`) or a specific non-loopback address has no reachable counterpart — `localhost` may resolve to `::1`, which a `0.0.0.0` bind never serves — so those fall back and must set `PENGUIN_PREVIEW_ORIGIN`, rather than pointing somewhere dead while `/api/me` claims isolation.
 
 The link is a plain anchor with `rel="noopener noreferrer"` rather than a fetch followed by `window.open`: opening a tab after an await trips popup blockers, and a script-opened window keeps an `opener` handle back to the app — the exact reference the separate origin exists to deny. The server also binds the IPv6 loopback alongside IPv4, because `localhost` commonly resolves to `::1` first and every preview URL would otherwise refuse the connection.
+
+## Unified form controls, one notification rule, and deduplicated copy
+
+The form-control layer had grown five near-identical copies of the same scaffolding. A shared `Field` wrapper now owns the label / hint / error markup, and a shared `controlBase` class string owns the border, hover, focus-ring and dark-mode treatment, so `Input`, `Textarea`, `Select`, `OptionMenu` and `PasswordInput` all read from one source instead of each carrying their own. `Select` dropped its hand-rolled open/close/position effect and now reuses the same `usePortalPanel` hook `OptionMenu` already used, so both menus flip up-or-down, clamp to the viewport and close on scroll/Esc through one code path. The close button triplicated across `Modal` / `Drawer` / `Sheet` became a single `CloseButton`, and the chevron, checkmark and plus glyphs that were inlined at a dozen call sites became shared icon components. The Agent runtime tab's thinking-level and compaction-mode dropdowns dropped their separate "Reset to default" link (a `ResettableOptionMenu` wrapper) in favour of a plain `OptionMenu` — the link only rewound an in-session pick, which closing the dialog already does.
+
+Notifications now follow one rule. A normal result — a save, an "already up to date", a connection failure — surfaces as a toast that slides in from the top and disappears on its own; the toaster gained an `info` tone alongside success and error for neutral messages. A value error on a specific field no longer lands in a generic red line at the bottom of the form: the offending input turns red and its message sits directly beneath it, so on a failed submit the eye goes straight to the field to fix. Every create/settings form was moved onto this split — required-field, format and mismatch errors went inline, ad-hoc emerald "saved" banners and transient action failures became toasts — with page-load-failure states that pair with a Retry button left inline where a disappearing toast would be wrong.
+
+Review hardening on that rule: the inline error text is now announced to assistive tech — `FieldError` carries `role="alert"` and every shared control links its message via `aria-describedby`, wired once in the control layer so all forms inherit it. `Select` and `OptionMenu` gained the same `error` prop the text inputs have (red border + message below), so a failed dropdown participates too. And a server rejection now lands under the field its **error code** names — the change-password and create-user dialogs used to pin every rejection to one hardcoded field, so a too-short new password rendered under "Current password" / "Username".
+
+The i18n catalog was pruned and deduplicated: 41 dead keys removed, and roughly two dozen values that were identical in both languages (Name, Username, Role, Actions, Created, Cost, Time, …) folded into shared `common` keys so a label is defined once. Mid-sentence "Agent" in English copy was lowercased to "agent" — it is a common noun, capitalized only at the start of a label or a sentence — while the domain terms (Workspace, Token, Task, Session, Project, Trace) and proper names (Agent State, AgentHub) keep their capitals.
+
+## Confirm before a skill update overwrites installs
+
+Updating a skill install — the card's rotate button, or a per-agent "Update" in the manage-installs dialog — reinstalls the library copy over the agent's files. That overwrite silently dropped any local edits to the installed skill, with no confirmation and (unlike an Agent State import) no snapshot. It now opens a confirmation dialog first: it lists each affected agent with its `v_old → v_new`, warns that the overwrite loses local edits, and suggests exporting a backup if needed. A shared `ConfirmModal` (Cancel / Confirm footer, danger or primary tone) backs it and is reusable for future confirmations. Existing destructive actions already confirmed (deleting a user / agent / project / session / vault entry / schedule), and an Agent State import still auto-snapshots and additionally confirms on a version conflict — those are unchanged.
+
+## Localized error prompts, full error detail, and required-field markers
+
+The server's `{error:{code,message}}` message is English-only, so a Chinese-locale user saw untranslated text for anything the frontend didn't map — and only two codes were mapped. `apiErrorText` now localizes ~two dozen common codes (auth, permission, not-found, id-already-taken, file/path, task-in-progress, version-conflict, …) via a new `S.errors.byCode` table, falling back to the raw server message only for unmapped codes, and every error surface that previously showed the raw `e.message` now routes through it. (The stale comment claiming the server messages were Chinese is fixed — they're English.)
+
+The Cost Center's recent-errors table truncated each message to one line with the full text reachable only through a hover title, so a request failure showed just its head — e.g. `llm request error: 402 openai_error` — and cut the provider's actual reason. Each message still shows on **one line by default** (an error storm shouldn't fill the table), but **clicking it expands the full text in place** (click again to collapse); the full text stays in the hover title too. The server keeps up to 500 chars; the full stack stays in the logs.
+
+Required form fields now carry a red `*` after the label, so required vs. optional is visible at a glance. The mark is driven by a `required` prop on the shared field controls (`Input`/`Textarea`/`Select`/`OptionMenu`/`PasswordInput`), which also sets `aria-required` while deliberately not forwarding the native `required` attribute (the app validates on submit; browser bubbles would collide with the inline field errors).
+
+## Sidebar: the session list loads only active sessions; folders load on click and page on their own
+
+Subagent- and schedule-created Sessions already live in their own labelled, collapsed folders (Subagents / Scheduled), so the small source badge repeated next to each title was noise — it's gone.
+
+The list's fetching and its "More" affordance were also untangled. Server pagination used to be source-blind: a page of 20 could arrive full of subagent/scheduled/archived rows that all disappear into collapsed folders, so the visible active list stayed short while "More" kept showing (or — worse — active sessions parked behind such pages were unreachable, because a group whose first page held no active row never offered "More" at all). The session list endpoint now takes a `category` filter (`active` / `subagent` / `schedule` / `archived`, the same archived-wins precedence the sidebar renders by) plus an optional `counts=1` for per-category totals, and the sidebar keys everything off it:
+
+- The default load fetches **only the active** (user-created, non-archived) rows — 10 per page, "More" loading 10 at a time — plus the category totals; archived, scheduled and subagent Sessions are no longer loaded up front.
+- A group's "More" counts **only the outer active rows** (the collapsed folders never feed it), and since the pages it fetches are category-filtered, every click now grows the visible list by a full page.
+- A collapsed folder is labelled from the server totals and fetches its first page **when first opened**. Once open it pages independently with its own "More" row — each group and each folder advances alone, without dragging pages in for the others.
+- The counted response also breaks the totals down **by Workspace path**, and every group — workspace groups included — shows a folder only for its **own share**: exact label counts, and "More" only while that share isn't fully loaded. (Initially a workspace group inferred its folders from per-Agent totals, so an Agent's subagent/scheduled Sessions living in *other* Workspaces made unrelated groups grow an empty folder whose "More" click made the whole folder vanish.)
+- Review follow-ups: the paging cursor is each pair's **fetched-row count**, so a deep-linked row that `add()` slips into the list no longer makes the next page skip a server row; a clicked "More" disables and reads "loading…" while its fetch runs (in workspace mode a page can land entirely in other groups — the click still visibly does something); and the server locates each Session's earliest Trace shard in the **same single directory walk** discovery already does, so `counts=1` classification no longer re-walks the Traces tree once per Session.
+
+One consequence of not loading folder content up front: in workspace grouping, a Workspace whose loaded Sessions are all archived or automation-created no longer forms a group by itself (nothing visible remains to hang it on); its Sessions stay reachable through agent grouping's folders.
+
+The auto-opened "last conversation" follows one rule now too. Entering `/chat` without a Session used to take the flat list's literal first row (the first Agent's newest loaded row — not the Project's newest, and after a deep link possibly an archived or subagent row), and the collapsed rail's entry merely skipped archived rows. Both — plus the after-delete jump to a neighbouring Session — now pick the newest loaded **active or schedule** conversation: an archived row is hidden by choice and a subagent Session belongs to its parent conversation, so neither is ever auto-opened. When the auto-opened conversation is schedule-created, only its group's Scheduled folder expands and loads; the outer active list's "More" is untouched.
+
+## Every file-writing action confirms first; an empty save says so
+
+Actions that write files on the server used to be a mix: deletions confirmed, a skill *update* confirmed, but a settings save (AGENTS.md / system prompt, runtime params, tool overrides), a skill *uninstall* (which deletes the installed copy, local edits included) and a workspace upload landing on an existing name all executed on one click. They now all confirm first through the shared `ConfirmModal`, which also got a face-lift: a compact card with **no title bar** — just a tinted icon badge that sets the tone at a glance (red warning triangle for deletions, neutral pencil for saves/overwrites), the message beside it (each message carries its own subject and consequence), and a small Cancel/Confirm pair. The former titles still name the dialogs for assistive tech. Every existing confirmation (delete session/agent/project/schedule/vault entry, model dialog writes, import version conflict) was moved onto the same component, so confirmations look identical everywhere. Adding a vault variable under an already-configured name also confirms now (it overwrites an unrecoverable value); quick-set controls inside the chat (approval mode, thinking level) intentionally stay one-click.
+
+Clicking save with nothing changed used to do nothing silently (most forms skipped the request; the models dialog even reported "Saved"). Every save path now detects the no-op — the agent settings tabs, the schedule edit dialog and the model edit dialog — and shows an info toast: "No changes to save".
diff --git a/changelog/unreleased/2026-07-24-llm-request-errors.md b/changelog/unreleased/2026-07-24-llm-request-errors.md
new file mode 100644
index 0000000..d96da5c
--- /dev/null
+++ b/changelog/unreleased/2026-07-24-llm-request-errors.md
@@ -0,0 +1,5 @@
+# LLM request errors surface their underlying cause
+
+A failed LLM request used to record a bare, unactionable message like `terminated`. Node's `fetch` wraps the real transport failure as a `TypeError: terminated` and hangs the actual reason — a socket close, `ECONNRESET`, a provider aborting the stream — on the error's `cause`; taking only `.message` when building the request outcome threw that away.
+
+The outcome message now walks the `cause` chain and appends each level's message and error `code`, so the same failure surfaces as e.g. `terminated: other side closed (UND_ERR_SOCKET)`. This flows straight through to the abort reason (`llm request error: …`), the Cost Center's recent-errors table, and Traces. Segments are de-duplicated, a non-Error cause tail is kept, and the walk guards against a cyclic `cause` chain. Covered by a `describeError` unit test.
diff --git a/changelog/unreleased/README.md b/changelog/unreleased/README.md
index 4b1a710..572c9cc 100644
--- a/changelog/unreleased/README.md
+++ b/changelog/unreleased/README.md
@@ -2,4 +2,5 @@
 
 Changes since v0.1.1. The version number is assigned at release, when this folder is renamed.
 
-- [2026-07-22] Web App: Workspace HTML previews open on a separate origin with a signed token, so `localStorage`, cookies and third-party embeds work while Agent-generated pages still cannot reach the session cookie or the API. ([details](2026-07-22-web-app.md))
+- [2026-07-24] LLM request errors surface their underlying `cause` (e.g. `terminated: other side closed (UND_ERR_SOCKET)`) instead of a bare `terminated`, visible in the Cost Center and Traces. ([details](2026-07-24-llm-request-errors.md))
+- [2026-07-22] Web App: unified the form controls onto a shared Field/portal layer (now with required-field `*` markers), moved notifications to one rule (success/info → top toast, field errors inline with a red border; error prompts localized by code), generalized write confirmations (every file-writing save / uninstall / upload-overwrite now confirms via one polished dialog with tone icons — skill updates show each agent's `v_old → v_new` — and an unchanged save toasts "no changes to save"), made the Cost Center show the full error message, deduplicated the i18n copy (dead keys removed, shared `common` labels, lowercase "agent"), and reworked the sidebar session list onto category-filtered paging (default load = active rows only; the Subagents/Scheduled/Archived folders load on first open and page independently); plus the earlier separate-origin Workspace HTML previews. ([details](2026-07-22-web-app.md))
diff --git a/packages/core/src/llm/generative-model.ts b/packages/core/src/llm/generative-model.ts
index 0751f0c..d261f72 100644
--- a/packages/core/src/llm/generative-model.ts
+++ b/packages/core/src/llm/generative-model.ts
@@ -701,6 +701,35 @@ export function translateEvents(
 // Retry policy
 // ---------------------------------------------------------------------------
 
+/**
+ * A fuller error string than `err.message` for the LLM request outcome. Node's `fetch`
+ * wraps the real transport failure as `TypeError: terminated` and puts the actual reason
+ * on `err.cause` (a socket close, `ECONNRESET`, a provider stream abort, …); taking only
+ * `.message` throws that away and leaves a bare, unactionable "terminated". This walks the
+ * `cause` chain and appends each level's message and error `code`, so it surfaces as e.g.
+ * "terminated: other side closed (UND_ERR_SOCKET)". Segments are de-duplicated and the
+ * chain walk guards against cycles; a non-Error cause tail (string/number) is still kept.
+ */
+export function describeError(error: unknown): string {
+  if (!(error instanceof Error)) return String(error);
+  const parts: string[] = [];
+  const seen = new Set<unknown>();
+  let cur: unknown = error;
+  while (cur instanceof Error && !seen.has(cur)) {
+    seen.add(cur);
+    const code = (cur as { code?: unknown }).code;
+    let piece = cur.message || cur.name;
+    if (typeof code === "string" && code && !piece.includes(code)) piece = `${piece} (${code})`;
+    if (piece && !parts.includes(piece)) parts.push(piece);
+    cur = (cur as { cause?: unknown }).cause;
+  }
+  if (cur != null && !(cur instanceof Error)) {
+    const tail = String(cur);
+    if (tail && !parts.includes(tail)) parts.push(tail);
+  }
+  return parts.join(": ") || error.message || String(error);
+}
+
 /**
  * Determines whether an error is an AgentHub / Provider "response delivered but unusable"
  * parse or validation error. Two shapes (@prismshadow/agenthub 0.4.x):
@@ -906,7 +935,7 @@ export class GenerativeModel implements LLMInterface {
     } catch (err) {
       return {
         status: "failed",
-        message: err instanceof Error ? err.message : String(err),
+        message: describeError(err),
       };
     }
 
@@ -984,7 +1013,7 @@ export class GenerativeModel implements LLMInterface {
         // malformed to reconnect and retry — must not be classified as failed.
         outcome = {
           status: "malformed",
-          message: error instanceof Error ? error.message : String(error),
+          message: describeError(error),
         };
       } else if (isRetryableError(error)) {
         outcome = { status: "timeout" }; // Network drop/network error -> needs reconnection
@@ -993,7 +1022,7 @@ export class GenerativeModel implements LLMInterface {
       } else {
         outcome = {
           status: "failed",
-          message: error instanceof Error ? error.message : String(error),
+          message: describeError(error),
         };
       }
     } finally {
diff --git a/packages/core/src/state/model-catalog.ts b/packages/core/src/state/model-catalog.ts
index 7b2c630..35a3b63 100644
--- a/packages/core/src/state/model-catalog.ts
+++ b/packages/core/src/state/model-catalog.ts
@@ -18,9 +18,9 @@
  * Scope: excludes deepseek-chat / deepseek-reasoner legacy aliases that AgentHub cannot
  * auto-route (deprecated 2026-07-24), glm-5v-turbo (image input unsupported by AgentHub's GLM
  * client), non-chat models (embedding / image generation / TTS), and Bedrock. Direct-vendor
- * ids are auto-routed by AgentHub and leave client_type unset; gateway entries (OpenRouter /
- * SiliconFlow / Qwen Token Plan) can't be auto-routed, so they set `client_type: "openai"`
- * and inline their preset base URL.
+ * ids are auto-routed by AgentHub and leave client_type unset; the five gateway groups
+ * (OpenRouter, Fireworks AI, SiliconFlow, Qwen Token Plan, Qwen Pay-As-You-Go) can't be
+ * auto-routed, so they set `client_type: "openai"` and inline their preset base URL.
  *
  * This file imports no Node built-ins (type-only imports only), so it can be bundled directly
  * for the browser.
@@ -74,8 +74,9 @@ const FIREWORKS_BASE_URL = "https://api.fireworks.ai/inference/v1";
 
 /**
  * Provider list (web model page groups in this order): DeepSeek first (the default model's
- * provider), followed by the OpenRouter, SiliconFlow, and Qwen Token Plan gateways, then
- * Google Gemini before Anthropic; custom groups custom OpenAI-protocol models and comes last.
+ * provider), followed by the five gateways (OpenRouter, Fireworks AI, SiliconFlow, Qwen Token
+ * Plan, Qwen Pay-As-You-Go), then the first-party providers Google Gemini, Anthropic, OpenAI,
+ * Z.AI (GLM) and Moonshot (Kimi); custom groups custom OpenAI-protocol models and comes last.
  */
 export const MODEL_PROVIDERS: ModelProviderInfo[] = [
   {
diff --git a/packages/core/test/describe-error.test.ts b/packages/core/test/describe-error.test.ts
new file mode 100644
index 0000000..a14257b
--- /dev/null
+++ b/packages/core/test/describe-error.test.ts
@@ -0,0 +1,45 @@
+import { describe, expect, it } from "vitest";
+import { describeError } from "../src/llm/generative-model.js";
+
+describe("describeError", () => {
+  it("walks the cause chain, surfacing the real reason behind a wrapper like 'terminated'", () => {
+    // Node's fetch throws TypeError("terminated") with the actual transport failure on cause.
+    const cause = Object.assign(new Error("other side closed"), { code: "UND_ERR_SOCKET" });
+    const err = new TypeError("terminated", { cause });
+    expect(describeError(err)).toBe("terminated: other side closed (UND_ERR_SOCKET)");
+  });
+
+  it("appends a top-level error code when not already in the message", () => {
+    const err = Object.assign(new Error("connect failed"), { code: "ECONNREFUSED" });
+    expect(describeError(err)).toBe("connect failed (ECONNREFUSED)");
+  });
+
+  it("does not duplicate a code already present in the message", () => {
+    const err = Object.assign(new Error("connect ECONNREFUSED 1.2.3.4:443"), {
+      code: "ECONNREFUSED",
+    });
+    expect(describeError(err)).toBe("connect ECONNREFUSED 1.2.3.4:443");
+  });
+
+  it("returns a plain message unchanged and stringifies non-Errors", () => {
+    expect(describeError(new Error("boom"))).toBe("boom");
+    expect(describeError("nope")).toBe("nope");
+  });
+
+  it("keeps a non-Error cause tail and de-duplicates repeated segments", () => {
+    expect(describeError(new Error("outer", { cause: "inner reason" }))).toBe(
+      "outer: inner reason",
+    );
+    const a = new Error("same");
+    (a as { cause?: unknown }).cause = new Error("same"); // duplicate message, dropped
+    expect(describeError(a)).toBe("same");
+  });
+
+  it("guards against a cyclic cause chain", () => {
+    const a = new Error("a");
+    const b = new Error("b");
+    (a as { cause?: unknown }).cause = b;
+    (b as { cause?: unknown }).cause = a; // cycle
+    expect(describeError(a)).toBe("a: b");
+  });
+});
diff --git a/packages/server/src/api/types.ts b/packages/server/src/api/types.ts
index 87a8406..c0a37df 100644
--- a/packages/server/src/api/types.ts
+++ b/packages/server/src/api/types.ts
@@ -475,8 +475,27 @@ export interface SessionInfo {
   archived: boolean;
 }
 
+/**
+ * Session list category, the sidebar's four-way split applied server-side: archived wins
+ * regardless of origin (archiving is an explicit user action), then the origin's bucket,
+ * and a Session with no (or an unknown) source is `active` — user-created rows.
+ */
+export type SessionCategory = "active" | SessionSource | "archived";
+
+/** Per-category totals across an Agent's whole Session list (returned when the list is requested with counts). */
+export type SessionCategoryCounts = Record<SessionCategory, number>;
+
 export interface SessionsResponse {
   sessions: SessionInfo[];
+  /** Present when the request asked for counts (`counts=1`): totals per category over the full list, not just the returned page. */
+  counts?: SessionCategoryCounts;
+  /**
+   * Present with `counts`: the same totals broken down by Workspace path (only paths
+   * with at least one Session appear). The sidebar's workspace grouping decides each
+   * group's folders and "More" from its own share, so a group never advertises
+   * content that lives in other Workspaces.
+   */
+  workspaceCounts?: Record<string, SessionCategoryCounts>;
 }
 
 /** Server directory browsing (advanced new-Workspace picker): starts from the home directory by default, can navigate up to the root. */
diff --git a/packages/server/src/http/routes/sessions.ts b/packages/server/src/http/routes/sessions.ts
index f044d70..ecbbe94 100644
--- a/packages/server/src/http/routes/sessions.ts
+++ b/packages/server/src/http/routes/sessions.ts
@@ -17,6 +17,7 @@ import type {
   FilesStatResponse,
   MessagesResponse,
   ServerEvent,
+  SessionCategory,
   SessionCreateResponse,
   SessionResponse,
   SessionsResponse,
@@ -57,6 +58,14 @@ const APPROVAL_MODES: readonly ApprovalMode[] = [
   "always-ask",
 ];
 
+/** Accepted `category` query values of the list endpoint (SessionCategory, spelled out for validation). */
+const SESSION_CATEGORIES: readonly SessionCategory[] = [
+  "active",
+  "subagent",
+  "schedule",
+  "archived",
+];
+
 /** Validate Prompt input parts: text or image (data: / http(s) URL). */
 function parseTaskInput(body: Record<string, unknown>): OmniMessage[] {
   const input = body.input;
@@ -101,12 +110,28 @@ export function agentSessionsRoutes(deps: AppDeps): Hono<AppEnv> {
     // Optional paging (absent = full list, the pre-paging contract): the sidebar requests
     // limit+1 and shows limit, detecting "has more" without a response-envelope change.
     const paging = optionalPagingQuery(c);
-    const sessions = await deps.sessionService.listSessions(
+    // Optional category filter (paging then applies within the category) and per-category
+    // totals — the sidebar loads active rows only and labels the collapsed folders from counts.
+    const rawCategory = c.req.query("category");
+    if (rawCategory !== undefined && !SESSION_CATEGORIES.includes(rawCategory as SessionCategory)) {
+      throw badRequest(`category must be one of ${SESSION_CATEGORIES.join(" / ")}.`);
+    }
+    const rawCounts = c.req.query("counts");
+    if (rawCounts !== undefined && rawCounts !== "1") throw badRequest("counts only accepts 1.");
+    const { sessions, counts, workspaceCounts } = await deps.sessionService.listSessions(
       projectId,
       agentId,
-      ...(paging ? [paging] : []),
+      {
+        ...(paging ? { paging } : {}),
+        ...(rawCategory !== undefined ? { category: rawCategory as SessionCategory } : {}),
+        ...(rawCounts !== undefined ? { withCounts: true } : {}),
+      },
     );
-    return c.json({ sessions } satisfies SessionsResponse);
+    return c.json({
+      sessions,
+      ...(counts ? { counts } : {}),
+      ...(workspaceCounts ? { workspaceCounts } : {}),
+    } satisfies SessionsResponse);
   });
 
   app.post("/", async (c) => {
diff --git a/packages/server/src/services/session-service.ts b/packages/server/src/services/session-service.ts
index 6936d8e..d236635 100644
--- a/packages/server/src/services/session-service.ts
+++ b/packages/server/src/services/session-service.ts
@@ -13,15 +13,22 @@
  * added to session-manager's active table (state idle).
  */
 import path from "node:path";
-import { readdir } from "node:fs/promises";
+import { open, readdir } from "node:fs/promises";
 import {
   createAgent,
   isSessionMeta,
+  parseTraceLines,
   readTraceTolerant,
   tracesDir,
 } from "@prismshadow/penguin-core";
 import type { SessionMetaMessage } from "@prismshadow/penguin-core";
-import type { ApprovalMode, SessionInfo, SessionSource } from "../api/types.js";
+import type {
+  ApprovalMode,
+  SessionCategory,
+  SessionCategoryCounts,
+  SessionInfo,
+  SessionSource,
+} from "../api/types.js";
 import { HttpError, isMissingCredential, modelCredentialMissing } from "../http/errors.js";
 import { badRequest } from "../http/validate.js";
 import type { SessionRow, SessionsRepo } from "../db/repos/sessions.js";
@@ -33,6 +40,39 @@ import type { ProjectConfigService } from "./project-config-service.js";
 const TRACE_FILE_RE = /^(.+)_(\d{3})\.jsonl$/;
 const SESSION_ID_TS_RE = /^session-(\d{4})-(\d{2})-(\d{2})-(\d{2})-(\d{2})-(\d{2})-[0-9a-f]{8}$/;
 
+/** Head window for session_meta reads: generous for a long system prompt, far below a whole multi-MB shard. */
+const TRACE_HEAD_BYTES = 256 * 1024;
+
+/**
+ * Parse a Trace file's head window only. session_meta is the first line core writes to
+ * every shard, so a bounded read finds it without pulling the whole file into memory —
+ * category filtering / counts may need every Session's source in a single request.
+ * The window is cut at its last newline (the tail fragment is incomplete); a first line
+ * larger than the whole window falls back to the full tolerant read.
+ */
+async function readTraceHead(filePath: string) {
+  const fh = await open(filePath, "r");
+  let text: string;
+  let truncated: boolean;
+  try {
+    // allocUnsafe: only subarray(0, bytesRead) is ever read, so the uninitialized tail never leaks.
+    const { buffer, bytesRead } = await fh.read(
+      Buffer.allocUnsafe(TRACE_HEAD_BYTES),
+      0,
+      TRACE_HEAD_BYTES,
+      0,
+    );
+    text = buffer.subarray(0, bytesRead).toString("utf8");
+    truncated = bytesRead === TRACE_HEAD_BYTES;
+  } finally {
+    await fh.close();
+  }
+  if (!truncated) return parseTraceLines(text);
+  const nl = text.lastIndexOf("\n");
+  if (nl === -1) return readTraceTolerant(filePath);
+  return parseTraceLines(text.slice(0, nl + 1));
+}
+
 /** Derives creation time from the local timestamp embedded in session_id; returns null if it doesn't match. */
 export function sessionIdCreatedAt(sessionId: string): string | null {
   const m = SESSION_ID_TS_RE.exec(sessionId);
@@ -57,10 +97,15 @@ export class SessionService {
   /**
    * DB row -> SessionInfo (run status and pending approval count come from session-manager).
    * Async because `source` is derived from session_meta: a registry miss (Session predating
-   * this process) falls back to reading the Trace head once (see sourceOf).
+   * this process) falls back to reading the Trace head once (see sourceOf). `traces` is the
+   * list flow's one-walk discovery result; without it a miss locates the shard itself.
    */
-  async toInfo(row: SessionRow, hasTrace: boolean): Promise<SessionInfo> {
-    const source = await this.sourceOf(row, hasTrace);
+  async toInfo(
+    row: SessionRow,
+    hasTrace: boolean,
+    traces?: ReadonlyMap<string, TraceLocation>,
+  ): Promise<SessionInfo> {
+    const source = await this.sourceOf(row, hasTrace, traces);
     return {
       sessionId: row.sessionId,
       projectId: row.projectId,
@@ -86,11 +131,20 @@ export class SessionService {
    * session_meta is read once and cached. A Session with no Trace yet stays unknown and
    * is NOT cached negatively — its meta may appear with the first run.
    */
-  private async sourceOf(row: SessionRow, hasTrace: boolean): Promise<SessionSource | undefined> {
+  private async sourceOf(
+    row: SessionRow,
+    hasTrace: boolean,
+    traces?: ReadonlyMap<string, TraceLocation>,
+  ): Promise<SessionSource | undefined> {
     const known = this.deps.sources.get(row.sessionId);
     if (known !== undefined) return known ?? undefined;
     if (!hasTrace) return undefined;
-    const meta = await this.readTraceMeta(row.projectId, row.agentId, row.sessionId);
+    // Single-session paths carry no discovery map: locate this Session's earliest shard on demand.
+    const location =
+      traces?.get(row.sessionId) ??
+      (await this.discoverTraces(row.projectId, row.agentId)).get(row.sessionId);
+    if (!location) return undefined;
+    const meta = await this.readTraceMeta(location);
     if (!meta) return undefined; // Unreadable/corrupt Trace: stay unknown, retry on the next list.
     // On-disk values are untrusted: only the exact known origins pass, junk = user-created.
     const source = asSessionSource(meta.payload.source) ?? null;
@@ -100,8 +154,22 @@ export class SessionService {
 
   /** Whether this Session already has a Trace record (a Task has been run). */
   async hasTrace(row: SessionRow): Promise<boolean> {
-    const ids = await this.discoverTraceSessionIds(row.projectId, row.agentId);
-    return ids.has(row.sessionId);
+    return (await this.discoverTraces(row.projectId, row.agentId)).has(row.sessionId);
+  }
+
+  /**
+   * The list category of a row: archived wins (an explicit user action), then the
+   * origin's bucket, and no/unknown source is `active` — the same precedence the
+   * sidebar's partition applies to loaded rows, so server filtering and client
+   * rendering can never disagree.
+   */
+  private async categoryOf(
+    row: SessionRow,
+    hasTrace: boolean,
+    traces?: ReadonlyMap<string, TraceLocation>,
+  ): Promise<SessionCategory> {
+    if ((row.archivedAt ?? null) !== null) return "archived";
+    return (await this.sourceOf(row, hasTrace, traces)) ?? "active";
   }
 
   /**
@@ -110,29 +178,77 @@ export class SessionService {
    * more"); slicing happens before toInfo, so per-request source derivation (lazy
    * Trace-head reads) stays bounded by the page size. Discovery/adoption still scans
    * the whole directory — the union and global ordering need every id.
+   *
+   * `category` filters to one sidebar bucket **before** paging, so offset/limit page
+   * within the category. Filtering needs each walked row's category (a possible
+   * Trace-head read per row, cached in the sources registry); without `withCounts`
+   * the walk stops as soon as the requested page is complete. `withCounts` classifies
+   * every row and returns per-category totals over the whole list — plus the same
+   * totals broken down by Workspace path — so the sidebar can label the collapsed
+   * folders (and a workspace group can know its own share) without loading them.
    */
   async listSessions(
     projectId: string,
     agentId: string,
-    paging?: { offset: number; limit: number },
-  ): Promise<SessionInfo[]> {
-    const traceIds = await this.discoverTraceSessionIds(projectId, agentId);
+    opts: {
+      paging?: { offset: number; limit: number };
+      category?: SessionCategory;
+      withCounts?: boolean;
+    } = {},
+  ): Promise<{
+    sessions: SessionInfo[];
+    counts?: SessionCategoryCounts;
+    workspaceCounts?: Record<string, SessionCategoryCounts>;
+  }> {
+    const { paging, category, withCounts } = opts;
+    const traces = await this.discoverTraces(projectId, agentId);
     const rows = new Map(
       this.deps.sessions.listByAgent(projectId, agentId).map((r) => [r.sessionId, r]),
     );
 
     // Unmanaged Trace Sessions: backfill an index row by reading the first line's session_meta.
-    for (const sessionId of traceIds) {
+    for (const [sessionId, location] of traces) {
       if (rows.has(sessionId)) continue;
-      const discovered = await this.adoptTraceSession(projectId, agentId, sessionId);
+      const discovered = await this.adoptTraceSession(projectId, agentId, sessionId, location);
       if (discovered) rows.set(sessionId, discovered);
     }
 
     const sorted = [...rows.values()].sort(
       (a, b) => b.createdAt.localeCompare(a.createdAt) || b.sessionId.localeCompare(a.sessionId),
     );
-    const page = paging ? sorted.slice(paging.offset, paging.offset + paging.limit) : sorted;
-    return Promise.all(page.map((row) => this.toInfo(row, traceIds.has(row.sessionId))));
+    const toPage = (page: SessionRow[]) =>
+      Promise.all(page.map((row) => this.toInfo(row, traces.has(row.sessionId), traces)));
+
+    // No classification asked for: slice straight away (the pre-category behavior).
+    if (category === undefined && !withCounts) {
+      return {
+        sessions: await toPage(
+          paging ? sorted.slice(paging.offset, paging.offset + paging.limit) : sorted,
+        ),
+      };
+    }
+
+    const want = paging ? paging.offset + paging.limit : Infinity;
+    const counts: SessionCategoryCounts = { active: 0, subagent: 0, schedule: 0, archived: 0 };
+    const workspaceCounts: Record<string, SessionCategoryCounts> = {};
+    const matched: SessionRow[] = [];
+    for (const row of sorted) {
+      if (!withCounts && matched.length >= want) break;
+      const cat = await this.categoryOf(row, traces.has(row.sessionId), traces);
+      counts[cat] += 1;
+      if (withCounts) {
+        const ws = (workspaceCounts[row.workspace] ??= {
+          active: 0,
+          subagent: 0,
+          schedule: 0,
+          archived: 0,
+        });
+        ws[cat] += 1;
+      }
+      if ((category === undefined || cat === category) && matched.length < want) matched.push(row);
+    }
+    const sessions = await toPage(paging ? matched.slice(paging.offset, want) : matched);
+    return withCounts ? { sessions, counts, workspaceCounts } : { sessions };
   }
 
   /**
@@ -273,45 +389,41 @@ export class SessionService {
     return this.toInfo(row, false);
   }
 
-  /** Scans the Trace directory to get the set of session_ids with records. */
-  private async discoverTraceSessionIds(projectId: string, agentId: string): Promise<Set<string>> {
-    const dir = tracesDir(this.deps.root, projectId, agentId);
-    const ids = new Set<string>();
-    for (const dateDir of await listDirsSafe(dir)) {
-      for (const file of await listFilesSafe(path.join(dir, dateDir))) {
-        const match = TRACE_FILE_RE.exec(file);
-        if (match) ids.add(match[1]!);
-      }
-    }
-    return ids;
-  }
-
   /**
-   * session_meta from the earliest Trace shard of a Session (the shard whose head carries
-   * the original meta); null when there is no readable Trace or it has no meta. Shared by
-   * adoption backfill and lazy `source` resolution.
+   * One walk over the Trace directory: session_id → its **earliest** shard (the shard
+   * whose head carries the original session_meta). Discovery (which Sessions have
+   * records) and the meta-read location come out of a single pass, so classifying every
+   * row (`counts=1`) costs one directory walk total instead of one per Session.
    */
-  private async readTraceMeta(
+  private async discoverTraces(
     projectId: string,
     agentId: string,
-    sessionId: string,
-  ): Promise<SessionMetaMessage | null> {
+  ): Promise<Map<string, TraceLocation>> {
     const dir = tracesDir(this.deps.root, projectId, agentId);
-    let earliest: { path: string; index: number } | null = null;
+    const out = new Map<string, TraceLocation>();
     for (const dateDir of await listDirsSafe(dir)) {
       for (const file of await listFilesSafe(path.join(dir, dateDir))) {
         const match = TRACE_FILE_RE.exec(file);
-        if (!match || match[1] !== sessionId) continue;
+        if (!match) continue;
+        const sessionId = match[1]!;
         const index = Number(match[2]);
-        if (!earliest || index < earliest.index) {
-          earliest = { path: path.join(dir, dateDir, file), index };
+        const cur = out.get(sessionId);
+        if (!cur || index < cur.index) {
+          out.set(sessionId, { path: path.join(dir, dateDir, file), index });
         }
       }
     }
-    if (!earliest) return null;
+    return out;
+  }
+
+  /**
+   * session_meta from a located Trace shard head; null when unreadable or it has no
+   * meta. Shared by adoption backfill and lazy `source` resolution.
+   */
+  private async readTraceMeta(location: TraceLocation): Promise<SessionMetaMessage | null> {
     let messages;
     try {
-      messages = await readTraceTolerant(earliest.path);
+      messages = await readTraceHead(location.path);
     } catch {
       return null; // Corrupt file: skip (does not block the list)
     }
@@ -323,8 +435,9 @@ export class SessionService {
     projectId: string,
     agentId: string,
     sessionId: string,
+    location: TraceLocation,
   ): Promise<SessionRow | null> {
-    const meta = await this.readTraceMeta(projectId, agentId, sessionId);
+    const meta = await this.readTraceMeta(location);
     if (!meta) return null;
     // An older Trace version's session_meta lacks provider (the model reference
     // wasn't split into separate fields yet): no backward compat, skip adoption
@@ -352,6 +465,12 @@ export class SessionService {
   }
 }
 
+/** A located Trace shard of one Session: absolute path plus its shard index. */
+interface TraceLocation {
+  path: string;
+  index: number;
+}
+
 /** Local date as yyyy-mm-dd (matches the Trace date directory convention: core's internal formatLocalDate, not publicly exported). */
 function localDate(d: Date): string {
   const pad = (n: number) => (n < 10 ? `0${n}` : `${n}`);
diff --git a/packages/server/test/session-index.test.ts b/packages/server/test/session-index.test.ts
index b5fb289..7d242b2 100644
--- a/packages/server/test/session-index.test.ts
+++ b/packages/server/test/session-index.test.ts
@@ -237,6 +237,113 @@ describe("session-index", () => {
     expect((await api.get(`${base()}?limit=2&offset=-1`)).status).toBe(400);
   });
 
+  it("category filter: each sidebar bucket lists only its rows, paging applies within the category, counts return full totals", async () => {
+    await configureModels();
+    // Two active user Sessions + one archived (HTTP), two schedule-created (service, one
+    // then archived — archived must win over the origin), and one subagent Session whose
+    // source only exists in its Trace head (cold-registry derivation during the walk).
+    const mkUser = async () =>
+      ((await (await api.post(base(), {})).json()) as SessionCreateResponse).session.sessionId;
+    const activeA = await mkUser();
+    const activeB = await mkUser();
+    const archivedC = await mkUser();
+    expect((await api.patch(`/api/sessions/${archivedC}`, { archived: true })).status).toBe(200);
+    const mkSchedule = async () =>
+      (
+        await t.deps.sessionService.createSession({
+          projectId,
+          agentId: "default_agent",
+          source: "schedule",
+        })
+      ).sessionId;
+    const scheduleD = await mkSchedule();
+    const archivedScheduleF = await mkSchedule();
+    expect((await api.patch(`/api/sessions/${archivedScheduleF}`, { archived: true })).status).toBe(
+      200,
+    );
+    const subagentE = "session-2026-07-02-09-30-00-cafe0001";
+    t.deps.sessionsRepo.insert({
+      sessionId: subagentE,
+      projectId,
+      agentId: "default_agent",
+      provider: "custom",
+      modelId: "m-x",
+      workspace: "/tmp/w-sub",
+      approvalMode: "allow-all",
+      title: null,
+      createdAt: "2026-07-02T09:30:00.000Z",
+    });
+    await writeTraceFile(t.root, projectId, "default_agent", "2026-07-02", subagentE, 1, [
+      sessionMeta({
+        session_id: subagentE,
+        model_id: "m-x",
+        provider: "custom",
+        model_context_window: 1000,
+        system_prompt: "",
+        tools: [],
+        thinking_level: "default",
+        agent_state: "/tmp/a",
+        workspace: "/tmp/w-sub",
+        source: "subagent",
+      }),
+      userText("child work"),
+    ]);
+
+    const list = async (qs: string) => {
+      const res = await api.get(`${base()}${qs}`);
+      expect(res.status, qs).toBe(200);
+      return (await res.json()) as SessionsResponse;
+    };
+    const idSet = (body: SessionsResponse) => new Set(body.sessions.map((s) => s.sessionId));
+
+    expect(idSet(await list("?category=active"))).toEqual(new Set([activeA, activeB]));
+    expect(idSet(await list("?category=schedule"))).toEqual(new Set([scheduleD]));
+    expect(idSet(await list("?category=subagent"))).toEqual(new Set([subagentE]));
+    expect(idSet(await list("?category=archived"))).toEqual(
+      new Set([archivedC, archivedScheduleF]),
+    );
+
+    // Paging applies within the category: the two archived rows page one at a time.
+    const page1 = await list("?category=archived&limit=1&offset=0");
+    const page2 = await list("?category=archived&limit=1&offset=1");
+    expect(page1.sessions).toHaveLength(1);
+    expect(page2.sessions).toHaveLength(1);
+    expect(new Set([...idSet(page1), ...idSet(page2)])).toEqual(
+      new Set([archivedC, archivedScheduleF]),
+    );
+    expect((await list("?category=archived&limit=1&offset=2")).sessions).toEqual([]);
+
+    // counts=1 returns totals over the whole list, not the returned page — with or without a filter.
+    const counted = await list("?category=active&counts=1&limit=1");
+    expect(counted.sessions).toHaveLength(1);
+    expect(counted.counts).toEqual({ active: 2, subagent: 1, schedule: 1, archived: 2 });
+    const full = await list("?counts=1");
+    expect(full.sessions).toHaveLength(6);
+    expect(full.counts).toEqual({ active: 2, subagent: 1, schedule: 1, archived: 2 });
+    expect((await list("")).counts).toBeUndefined();
+    expect((await list("")).workspaceCounts).toBeUndefined();
+
+    // The per-Workspace breakdown accompanies the totals and sums back to them: the
+    // subagent Session sits alone in its path; every other row lives in its own auto
+    // temp directory.
+    const byWorkspace = full.workspaceCounts!;
+    expect(byWorkspace["/tmp/w-sub"]).toEqual({
+      active: 0,
+      subagent: 1,
+      schedule: 0,
+      archived: 0,
+    });
+    const summed = { active: 0, subagent: 0, schedule: 0, archived: 0 };
+    for (const ws of Object.values(byWorkspace)) {
+      for (const key of Object.keys(summed) as (keyof typeof summed)[]) summed[key] += ws[key];
+    }
+    expect(summed).toEqual(full.counts);
+
+    // Junk values are rejected, never silently unfiltered.
+    expect((await api.get(`${base()}?category=weird`)).status).toBe(400);
+    expect((await api.get(`${base()}?counts=yes`)).status).toBe(400);
+  });
+
   it("half a model reference is 400: the missing half is never inferred", async () => {
     await configureModels();
     // Only modelId: even though it names the one configured model, the provider is never
diff --git a/packages/web/src/api/endpoints.ts b/packages/web/src/api/endpoints.ts
index fadc40d..e179419 100644
--- a/packages/web/src/api/endpoints.ts
+++ b/packages/web/src/api/endpoints.ts
@@ -42,6 +42,7 @@ import type {
   ScheduleItem,
   SchedulesResponse,
   ScheduleUpsertRequest,
+  SessionCategory,
   SessionCreateRequest,
   SessionCreateResponse,
   SessionPatchRequest,
@@ -185,17 +186,25 @@ export const getAgentTraces = (projectId: string, agentId: string) =>
 
 // Session ---------------------------------------------------------------------
 
-/** Optional paging (both absent = full list): the store requests `limit+1` per page to detect "has more". */
+/**
+ * Optional paging (absent = full unfiltered list): the store requests `limit+1` per page to
+ * detect "has more". `category` filters server-side (paging applies within the category);
+ * `withCounts` asks for per-category totals over the whole list alongside the page.
+ */
 export const listSessions = (
   projectId: string,
   agentId: string,
-  paging?: { offset: number; limit: number },
-) =>
-  apiFetch<SessionsResponse>(
-    `/api/projects/${encodeURIComponent(projectId)}/agents/${encodeURIComponent(agentId)}/sessions${
-      paging ? `?limit=${paging.limit}&offset=${paging.offset}` : ""
-    }`,
+  opts?: { offset: number; limit: number; category?: SessionCategory; withCounts?: boolean },
+) => {
+  const qs = opts
+    ? `?limit=${opts.limit}&offset=${opts.offset}` +
+      (opts.category ? `&category=${opts.category}` : "") +
+      (opts.withCounts ? "&counts=1" : "")
+    : "";
+  return apiFetch<SessionsResponse>(
+    `/api/projects/${encodeURIComponent(projectId)}/agents/${encodeURIComponent(agentId)}/sessions${qs}`,
   );
+};
 
 /** Server directory browsing: `path` is an absolute path; empty means start from the server's home directory. */
 export const listDirs = (projectId: string, path = "") =>
diff --git a/packages/web/src/components/account/change-password-dialog.tsx b/packages/web/src/components/account/change-password-dialog.tsx
index 7a96644..74fb580 100644
--- a/packages/web/src/components/account/change-password-dialog.tsx
+++ b/packages/web/src/components/account/change-password-dialog.tsx
@@ -7,6 +7,7 @@ import { useEffect, useState } from "react";
 import * as api from "../../api/endpoints";
 import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useAuth } from "../../state/auth";
 import { Button } from "../ui/button";
 import { PasswordInput } from "../ui/password-input";
@@ -17,34 +18,42 @@ export function ChangePasswordDialog({ open, onClose }: { open: boolean; onClose
   const [oldPassword, setOldPassword] = useState("");
   const [newPassword, setNewPassword] = useState("");
   const [confirmPassword, setConfirmPassword] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  const [errors, setErrors] = useState<{ old?: string; new?: string; confirm?: string }>({});
   const [busy, setBusy] = useState(false);
+  const clearErrors = () => setErrors((p) => (p.old || p.new || p.confirm ? {} : p));
 
   useEffect(() => {
     if (!open) return;
     setOldPassword("");
     setNewPassword("");
     setConfirmPassword("");
-    setError(null);
+    setErrors({});
   }, [open]);
 
   const submit = async () => {
-    if (!oldPassword || !newPassword || !confirmPassword) {
-      setError(S.common.requiredField);
-      return;
-    }
-    if (newPassword !== confirmPassword) {
-      setError(S.account.passwordMismatch);
+    const next: { old?: string; new?: string; confirm?: string } = {};
+    if (!oldPassword) next.old = S.common.requiredField;
+    if (!newPassword) next.new = S.common.requiredField;
+    if (!confirmPassword) next.confirm = S.common.requiredField;
+    if (!next.confirm && newPassword !== confirmPassword) next.confirm = S.account.passwordMismatch;
+    if (next.old || next.new || next.confirm) {
+      setErrors(next);
       return;
     }
     setBusy(true);
-    setError(null);
+    setErrors({});
     try {
       await api.changePassword({ oldPassword, newPassword });
       await refresh();
       onClose();
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      // Route by error code: invalid_password is about the NEW password's strength;
+      // password_mismatch (and anything unrecognized) is about the current one.
+      if (e instanceof ApiError && e.code === "invalid_password") {
+        setErrors({ new: apiErrorText(e) });
+      } else {
+        setErrors({ old: apiErrorText(e) });
+      }
     } finally {
       setBusy(false);
     }
@@ -69,29 +78,43 @@ export function ChangePasswordDialog({ open, onClose }: { open: boolean; onClose
       <div className="space-y-3">
         <PasswordInput
           label={S.account.oldPassword}
+          required
           size="sm"
           value={oldPassword}
-          onChange={(e) => setOldPassword(e.target.value)}
+          onChange={(e) => {
+            setOldPassword(e.target.value);
+            clearErrors();
+          }}
+          error={errors.old}
           autoComplete="current-password"
           hint={S.account.oldPasswordHint}
           autoFocus
         />
         <PasswordInput
           label={S.account.newPassword}
+          required
           size="sm"
           value={newPassword}
-          onChange={(e) => setNewPassword(e.target.value)}
+          onChange={(e) => {
+            setNewPassword(e.target.value);
+            clearErrors();
+          }}
+          error={errors.new}
           autoComplete="new-password"
           hint={S.auth.passwordHint}
         />
         <PasswordInput
           label={S.account.confirmPassword}
+          required
           size="sm"
           value={confirmPassword}
-          onChange={(e) => setConfirmPassword(e.target.value)}
+          onChange={(e) => {
+            setConfirmPassword(e.target.value);
+            clearErrors();
+          }}
+          error={errors.confirm}
           autoComplete="new-password"
         />
-        {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
       </div>
     </Modal>
   );
diff --git a/packages/web/src/components/layout/app-layout.tsx b/packages/web/src/components/layout/app-layout.tsx
index 6b97032..8356d03 100644
--- a/packages/web/src/components/layout/app-layout.tsx
+++ b/packages/web/src/components/layout/app-layout.tsx
@@ -6,8 +6,8 @@
  */
 import { useMemo, useState } from "react";
 import { NavLink, Outlet, useMatch, useNavigate } from "react-router";
-import type { SessionInfo } from "@prismshadow/penguin-server/api";
 import { S } from "../../lib/strings";
+import { latestConversation } from "../../lib/session-grouping";
 import { useAuth } from "../../state/auth";
 import { useProject } from "../../state/project";
 import { useSessions } from "../../state/sessions";
@@ -43,16 +43,8 @@ function CollapsedRail({ onExpand }: { onExpand: () => void }) {
   /** On some conversation (any non-draft /chat/:id): the "you are here" state of the last-conversation entry. */
   const onConversation = activeSessionId !== null && activeSessionId !== DRAFT_SESSION_ID;
 
-  /** Newest non-archived Session across the current Project by createdAt (the flat list is only ordered per Agent). */
-  const lastSession = useMemo(
-    () =>
-      sessions.reduce<SessionInfo | null>(
-        (best, s) =>
-          !s.archived && (!best || Date.parse(s.createdAt) > Date.parse(best.createdAt)) ? s : best,
-        null,
-      ),
-    [sessions],
-  );
+  /** Newest loaded conversation across the current Project (active/schedule only — archived and subagent rows are never auto-opened; the flat list is only ordered per Agent). */
+  const lastSession = useMemo(() => latestConversation(sessions), [sessions]);
 
   /** Mirrors Sidebar.openSession: the current Agent follows the opened Session's Agent. */
   const openLastSession = () => {
diff --git a/packages/web/src/components/layout/project-dialogs.tsx b/packages/web/src/components/layout/project-dialogs.tsx
index dbe70d8..be99b96 100644
--- a/packages/web/src/components/layout/project-dialogs.tsx
+++ b/packages/web/src/components/layout/project-dialogs.tsx
@@ -5,8 +5,8 @@
 import { useEffect, useState } from "react";
 import type { MemberInfo } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import {
   PROJECT_ID_MAX_LENGTH,
   PROJECT_SUFFIX_PATTERN,
@@ -16,7 +16,10 @@ import { projectDisplayName, useProject } from "../../state/project";
 import { useAuth } from "../../state/auth";
 import { Button } from "../ui/button";
 import { Input } from "../ui/input";
+import { FieldError, FieldHint, FieldLabel } from "../ui/field";
+import { toastError } from "../ui/toast";
 import { Modal } from "../ui/modal";
+import { ConfirmModal } from "../ui/confirm-modal";
 import { Badge } from "../ui/badge";
 
 export function CreateProjectDialog({
@@ -33,7 +36,8 @@ export function CreateProjectDialog({
   const prefix = user && !user.isAdmin ? `${user.userId}-` : "";
   const [idInput, setIdInput] = useState("");
   const [name, setName] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  // The id is the only validated field; format problems and the server's rejection (e.g. duplicate id) both land beside it.
+  const [idError, setIdError] = useState<string | undefined>(undefined);
   const [busy, setBusy] = useState(false);
 
   // No draft is kept: the form starts empty every time it opens.
@@ -41,13 +45,13 @@ export function CreateProjectDialog({
     if (!open) return;
     setIdInput("");
     setName("");
-    setError(null);
+    setIdError(undefined);
   }, [open]);
 
   const submit = async () => {
     const id = prefix + idInput.trim();
     if (!idInput.trim()) {
-      setError(S.common.requiredField);
+      setIdError(S.common.requiredField);
       return;
     }
     // Non-admin: validate the suffix segment (the hyphen is a reserved separator, appearing only once at the prefix join); admin: validate the whole string.
@@ -55,11 +59,11 @@ export function CreateProjectDialog({
       ? PROJECT_SUFFIX_PATTERN.test(idInput.trim()) && id.length <= PROJECT_ID_MAX_LENGTH
       : SEMANTIC_ID_PATTERN.test(id);
     if (!valid) {
-      setError(prefix ? S.project.idPrefixHint : S.project.idHint);
+      setIdError(prefix ? S.project.idPrefixHint : S.project.idHint);
       return;
     }
     setBusy(true);
-    setError(null);
+    setIdError(undefined);
     try {
       const res = await api.createProject({
         projectId: id,
@@ -67,7 +71,7 @@ export function CreateProjectDialog({
       });
       onCreated(res.project.projectId);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setIdError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
@@ -90,9 +94,7 @@ export function CreateProjectDialog({
       <div className="space-y-3">
         {prefix ? (
           <div>
-            <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-              {S.project.id}
-            </span>
+            <FieldLabel required>{S.project.id}</FieldLabel>
             <div className="flex items-stretch">
               <span className="flex shrink-0 items-center rounded-l-md border border-r-0 border-gray-300 bg-gray-100 px-2 font-mono text-xs text-gray-500 dark:border-gray-700 dark:bg-gray-800 dark:text-gray-400">
                 {prefix}
@@ -101,20 +103,31 @@ export function CreateProjectDialog({
                 size="sm"
                 className="rounded-l-none"
                 value={idInput}
-                onChange={(e) => setIdInput(e.target.value)}
+                invalid={Boolean(idError)}
+                onChange={(e) => {
+                  setIdInput(e.target.value);
+                  setIdError(undefined);
+                }}
                 autoFocus
               />
             </div>
-            <span className="mt-1 block text-xs text-gray-500 dark:text-gray-500">
-              {S.project.idPrefixHint}
-            </span>
+            {idError ? (
+              <FieldError>{idError}</FieldError>
+            ) : (
+              <FieldHint>{S.project.idPrefixHint}</FieldHint>
+            )}
           </div>
         ) : (
           <Input
             label={S.project.id}
+            required
             size="sm"
             value={idInput}
-            onChange={(e) => setIdInput(e.target.value)}
+            error={idError}
+            onChange={(e) => {
+              setIdInput(e.target.value);
+              setIdError(undefined);
+            }}
             hint={S.project.idHint}
             autoFocus
           />
@@ -125,7 +138,6 @@ export function CreateProjectDialog({
           value={name}
           onChange={(e) => setName(e.target.value)}
         />
-        {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
       </div>
     </Modal>
   );
@@ -137,7 +149,8 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
   const { currentProject, setCurrentProjectId, projects, reloadProjects } = useProject();
   const [members, setMembers] = useState<MemberInfo[] | null>(null);
   const [newMemberId, setNewMemberId] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  // Only the initial member-list load shows inline (in place of the table); action failures pop a toast.
+  const [loadError, setLoadError] = useState<string | null>(null);
   const [confirmDelete, setConfirmDelete] = useState(false);
 
   const projectId = currentProject?.projectId;
@@ -146,42 +159,39 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
   useEffect(() => {
     if (!open || !projectId) return;
     setMembers(null);
-    setError(null);
+    setLoadError(null);
     setConfirmDelete(false);
     api
       .listMembers(projectId)
       .then((res) => setMembers(res.members))
-      .catch((e: unknown) => setError(e instanceof ApiError ? e.message : S.common.unknownError));
+      .catch((e: unknown) => setLoadError(apiErrorText(e)));
   }, [open, projectId]);
 
   if (!currentProject || !projectId) return null;
 
   const addMember = async () => {
     if (!newMemberId.trim()) return;
-    setError(null);
     try {
       await api.addMember(projectId, { userId: newMemberId.trim() });
       setNewMemberId("");
       const res = await api.listMembers(projectId);
       setMembers(res.members);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
     }
   };
 
   const doRemove = async (memberId: string) => {
-    setError(null);
     try {
       await api.removeMember(projectId, memberId);
       const res = await api.listMembers(projectId);
       setMembers(res.members);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
     }
   };
 
   const doDelete = async () => {
-    setError(null);
     try {
       await api.deleteProject(projectId);
       onClose();
@@ -189,7 +199,7 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
       await reloadProjects();
       if (next) setCurrentProjectId(next.projectId);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
     }
   };
 
@@ -206,7 +216,9 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
 
         <div>
           <p className="mb-2 text-xs font-medium text-gray-500">{S.project.members}</p>
-          {members === null ? (
+          {loadError ? (
+            <p className="text-xs text-red-600 dark:text-red-400">{loadError}</p>
+          ) : members === null ? (
             <p className="text-xs text-gray-400">{S.common.loading}</p>
           ) : (
             // Member permission table: username / role / actions; cells never wrap.
@@ -216,13 +228,11 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
                 <thead>
                   <tr className="border-b border-gray-100 bg-gray-50 text-left text-gray-500 dark:border-gray-800 dark:bg-gray-900/60 dark:text-gray-400">
                     <th className="whitespace-nowrap px-2.5 py-1.5 font-medium">
-                      {S.project.memberUsername}
-                    </th>
-                    <th className="whitespace-nowrap px-2.5 py-1.5 font-medium">
-                      {S.project.memberRole}
+                      {S.common.username}
                     </th>
+                    <th className="whitespace-nowrap px-2.5 py-1.5 font-medium">{S.common.role}</th>
                     <th className="w-20 whitespace-nowrap px-2.5 py-1.5 text-right font-medium">
-                      {S.project.memberActions}
+                      {S.common.actions}
                     </th>
                   </tr>
                 </thead>
@@ -246,7 +256,7 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
                     <tr>
                       <td className="px-2.5 py-1.5">
                         <Input
-                          placeholder={S.project.memberUsername}
+                          placeholder={S.common.username}
                           size="sm"
                           value={newMemberId}
                           onChange={(e) => setNewMemberId(e.target.value)}
@@ -283,18 +293,6 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
               // Last accessible Project: deleting it would leave the account with no Project to select
               // (the page would get stuck on the skeleton screen), so the frontend hides the entry point outright, matching the server's 409 rejection.
               <p className="text-xs text-gray-400">{S.project.deleteLastForbidden}</p>
-            ) : confirmDelete ? (
-              <div className="space-y-2">
-                <p className="text-xs text-red-600 dark:text-red-400">{S.project.deleteConfirm}</p>
-                <div className="flex gap-2">
-                  <Button size="sm" onClick={() => setConfirmDelete(false)}>
-                    {S.common.cancel}
-                  </Button>
-                  <Button size="sm" variant="danger" onClick={() => void doDelete()}>
-                    {S.common.confirm}
-                  </Button>
-                </div>
-              </div>
             ) : (
               <Button size="sm" variant="danger" onClick={() => setConfirmDelete(true)}>
                 {S.project.deleteProject}
@@ -302,9 +300,17 @@ export function ProjectSettingsDialog({ open, onClose }: { open: boolean; onClos
             )}
           </div>
         )}
-
-        {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
       </div>
+
+      {/* Delete confirmation (shared ConfirmModal, stacked above the settings dialog). */}
+      <ConfirmModal
+        open={confirmDelete}
+        title={S.project.deleteProject}
+        onClose={() => setConfirmDelete(false)}
+        onConfirm={() => void doDelete()}
+      >
+        <p className="text-sm text-gray-600 dark:text-gray-300">{S.project.deleteConfirm}</p>
+      </ConfirmModal>
     </Modal>
   );
 }
diff --git a/packages/web/src/components/layout/sidebar.tsx b/packages/web/src/components/layout/sidebar.tsx
index c1808f0..b468aeb 100644
--- a/packages/web/src/components/layout/sidebar.tsx
+++ b/packages/web/src/components/layout/sidebar.tsx
@@ -18,10 +18,14 @@
 import { useEffect, useMemo, useRef, useState } from "react";
 import type { ReactNode } from "react";
 import { NavLink, useMatch, useNavigate } from "react-router";
-import type { SessionInfo, SessionSource } from "@prismshadow/penguin-server/api";
+import type {
+  SessionCategory,
+  SessionCategoryCounts,
+  SessionInfo,
+} from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useAuth } from "../../state/auth";
 import { useLocale } from "../../state/locale";
 import type { LangPref } from "../../state/locale";
@@ -30,20 +34,25 @@ import type { Accent, Currency, FontScale, ThemeMode } from "../../state/theme";
 import { agentDisplayName, projectDisplayName, useProject } from "../../state/project";
 import { useSessions } from "../../state/sessions";
 import {
+  FOLDER_CATEGORIES,
   SIDEBAR_PAGE_SIZE,
-  groupAgentsWithMore,
+  aggregateWorkspaceCounts,
   groupSessionsByWorkspace,
   partitionSessions,
   pinnedFirst,
+  sessionCategory,
   workspaceGroupKey,
 } from "../../lib/session-grouping";
-import type { SessionPartition } from "../../lib/session-grouping";
+import type { FolderCategory, SessionPartition } from "../../lib/session-grouping";
 import { Dropdown } from "../ui/dropdown";
 import { AgentAvatar } from "../ui/agent-avatar";
 import { Chevron } from "../ui/chevron";
+import { ChevronDown } from "../ui/icons";
+import { toastError } from "../ui/toast";
 import { Truncated } from "../ui/truncated";
 import { Badge } from "../ui/badge";
 import { Modal } from "../ui/modal";
+import { ConfirmModal } from "../ui/confirm-modal";
 import { Button } from "../ui/button";
 import { Input } from "../ui/input";
 import { Segmented } from "../ui/segmented";
@@ -71,15 +80,6 @@ function Icon({ d, size = 16 }: { d: string; size?: number }) {
   );
 }
 
-/** Dropdown caret (used by the Project switcher; distinct from the collapse-indicator Chevron). */
-function DropdownCaret() {
-  return (
-    <svg width="12" height="12" viewBox="0 0 12 12" fill="none" stroke="currentColor" aria-hidden>
-      <path d="M3 4.5l3 3 3-3" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
-    </svg>
-  );
-}
-
 /** Page-nav glyphs (shared with the collapsed rail in app-layout.tsx). */
 export const NAV_ICONS = {
   agents: "M12 3v3m-6 4a6 6 0 0 1 12 0v5a3 3 0 0 1-3 3H9a3 3 0 0 1-3-3v-5zm3 3h.01M15 13h.01",
@@ -152,11 +152,11 @@ function saveGroupSet(storageKey: string | null, next: ReadonlySet<string>): voi
 }
 
 /**
- * Open-state key of a per-origin folder (subagent / scheduled) inside a group: each folder
- * has its own state. "\0" never appears in Agent ids or Workspace paths, so the composite
- * never collides across groups or with plain group keys.
+ * Open-state key of a collapsed folder (subagent / scheduled / archived) inside a group:
+ * each folder has its own state. "\0" never appears in Agent ids or Workspace paths, so
+ * the composite never collides across groups or with plain group keys.
  */
-const sourceFolderKey = (groupKey: string, source: SessionSource) => `${source}\0${groupKey}`;
+const folderKey = (groupKey: string, category: FolderCategory) => `${category}\0${groupKey}`;
 
 /** Session status dot: running pulses green, compacting shows an amber dot; idle shows nothing. */
 function StatusDot({ session }: { session: SessionInfo }) {
@@ -200,8 +200,18 @@ export function Sidebar({
     currentAgent,
     setCurrentAgentId,
   } = useProject();
-  const { sessions, byAgent, hasMoreByAgent, loadMoreFor, loading, remove, replace } =
-    useSessions();
+  const {
+    sessions,
+    byAgent,
+    countsByAgent,
+    workspaceCountsByAgent,
+    isLoadedFor,
+    hasMoreFor,
+    loadMoreFor,
+    loading,
+    remove,
+    replace,
+  } = useSessions();
   const chatMatch = useMatch("/chat/:sessionId");
   const activeSessionId = chatMatch?.params.sessionId ?? null;
 
@@ -228,16 +238,15 @@ export function Sidebar({
     setCollapsedGroups(loadGroupSet(collapseStoreKey));
     setPinnedGroups(loadGroupSet(pinStoreKey));
   }, [collapseStoreKey, pinStoreKey]);
-  /** Expanded "archived" groups (collapsed by default), keyed like collapsedGroups. */
-  const [openArchived, setOpenArchived] = useState<ReadonlySet<string>>(new Set());
-  /** Expanded per-origin folders (subagent / scheduled Sessions; collapsed by default), keyed by sourceFolderKey — each folder has its own open state. */
-  const [openSourceFolders, setOpenSourceFolders] = useState<ReadonlySet<string>>(new Set());
+  /** Expanded folders (subagent / scheduled / archived; collapsed by default), keyed by folderKey — each folder has its own open state. */
+  const [openFolders, setOpenFolders] = useState<ReadonlySet<string>>(new Set());
+  /** "More" rows with a fetch in flight, keyed `${category}\0${groupKey}` — the row disables and reads "loading" so a page that lands entirely in other groups still visibly did something. */
+  const [pendingLoads, setPendingLoads] = useState<ReadonlySet<string>>(new Set());
   /** Per-group display cap for active rows (keyed by group key; absent = SIDEBAR_PAGE_SIZE). "More" raises it a page at a time. */
   const [groupCaps, setGroupCaps] = useState<ReadonlyMap<string, number>>(new Map());
   /** Session pending delete confirmation (null = none). */
   const [deletingSession, setDeletingSession] = useState<SessionInfo | null>(null);
   const [deletingBusy, setDeletingBusy] = useState(false);
-  const [deleteError, setDeleteError] = useState<string | null>(null);
   /** Session currently being renamed (null = none) and the title being typed. */
   const [renamingSession, setRenamingSession] = useState<SessionInfo | null>(null);
   const [renameText, setRenameText] = useState("");
@@ -252,6 +261,12 @@ export function Sidebar({
   /** Workspace groups (workspace mode): computed from the flat list, temp directories merged last. */
   const workspaceGroups = useMemo(() => groupSessionsByWorkspace(sessions), [sessions]);
 
+  /** Workspace-mode per-group exact server totals (folded from the per-Agent per-Workspace counts). */
+  const workspaceGroupCounts = useMemo(
+    () => aggregateWorkspaceCounts(workspaceCountsByAgent),
+    [workspaceCountsByAgent],
+  );
+
   // Pinned groups first within each mode; inside each partition the existing order is kept
   // (recency for Workspace groups, the configured Agent order for Agents).
   const orderedAgents = useMemo(
@@ -286,22 +301,42 @@ export function Sidebar({
     saveGroupSet(pinStoreKey, next);
   };
 
-  const toggleArchivedGroup = (key: string) =>
-    setOpenArchived((prev) => {
-      const next = new Set(prev);
-      if (next.has(key)) next.delete(key);
-      else next.add(key);
-      return next;
-    });
+  /** In-flight key of one group's category "More" (folderKey shares the same composite for folder categories). */
+  const loadKey = (groupKey: string, category: SessionCategory) => `${category}\0${groupKey}`;
 
-  const toggleSourceFolder = (groupKey: string, source: SessionSource) =>
-    setOpenSourceFolders((prev) => {
-      const key = sourceFolderKey(groupKey, source);
+  /** loadMoreFor with an in-flight marker for the triggering "More" row (disable + loading text). */
+  const trackedLoadMore = (groupKey: string, category: SessionCategory, agentIds: string[]) => {
+    const key = loadKey(groupKey, category);
+    setPendingLoads((prev) => new Set(prev).add(key));
+    void loadMoreFor(agentIds, category).finally(() => {
+      setPendingLoads((prev) => {
+        const next = new Set(prev);
+        next.delete(key);
+        return next;
+      });
+    });
+  };
+
+  /**
+   * Open/close a group's folder. A folder's content is loaded on demand: the first
+   * expand fetches its category's first page for every contributing Agent that hasn't
+   * been asked yet (already-loaded rows stay put — re-expanding never refetches; the
+   * folder's own "More" row does the paging from there).
+   */
+  const toggleFolder = (groupKey: string, category: FolderCategory, agentIds: string[]) => {
+    const key = folderKey(groupKey, category);
+    const opening = !openFolders.has(key);
+    setOpenFolders((prev) => {
       const next = new Set(prev);
-      if (next.has(key)) next.delete(key);
-      else next.add(key);
+      if (opening) next.add(key);
+      else next.delete(key);
       return next;
     });
+    if (opening) {
+      const unloaded = agentIds.filter((id) => !isLoadedFor(id, category));
+      if (unloaded.length > 0) void loadMoreFor(unloaded, category);
+    }
+  };
 
   // The open chat is an automation-created Session: expand exactly its origin's folder in its
   // group, so the active row is never hidden inside a collapsed folder (mirrors the archived
@@ -315,20 +350,25 @@ export function Sidebar({
   useEffect(() => {
     if (!activeSessionId) return;
     const s = sessions.find((x) => x.sessionId === activeSessionId);
-    if (!s || !s.source || s.archived) return;
+    if (!s) return;
+    const category = sessionCategory(s);
+    if (category === "active" || category === "archived") return;
     const guard = `${groupMode}\0${activeSessionId}`;
     if (lastAutoExpandedRef.current === guard) return;
     lastAutoExpandedRef.current = guard;
     const groupKey = groupMode === "agent" ? s.agentId : workspaceGroupKey(s.workspace);
-    const key = sourceFolderKey(groupKey, s.source);
-    setOpenSourceFolders((prev) => (prev.has(key) ? prev : new Set(prev).add(key)));
-  }, [activeSessionId, sessions, groupMode]);
+    const key = folderKey(groupKey, category);
+    setOpenFolders((prev) => (prev.has(key) ? prev : new Set(prev).add(key)));
+    // Same on-demand load a click-expand does, for this Session's own Agent (siblings of
+    // other contributing Agents stay behind the folder's "More").
+    if (!isLoadedFor(s.agentId, category)) void loadMoreFor([s.agentId], category);
+  }, [activeSessionId, sessions, groupMode, isLoadedFor, loadMoreFor]);
 
   /** Archive / unarchive: persists immediately and updates in place (fails silently; the next list refresh self-corrects). */
   const toggleArchive = async (s: SessionInfo) => {
-    // Archiving the currently open chat: expand the "archived" group so it doesn't silently vanish from the sidebar with no way back.
+    // Archiving the currently open chat: expand the "archived" folder so it doesn't silently vanish from the sidebar with no way back.
     if (!s.archived && s.sessionId === activeSessionId) {
-      setOpenArchived((prev) => new Set(prev).add(sessionGroupKey(s)));
+      setOpenFolders((prev) => new Set(prev).add(folderKey(sessionGroupKey(s), "archived")));
     }
     try {
       const res = await api.patchSession(s.sessionId, { archived: !s.archived });
@@ -349,7 +389,7 @@ export function Sidebar({
       replace(res.session);
       setRenamingSession(null);
     } catch (e) {
-      setRenameError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setRenameError(apiErrorText(e));
     } finally {
       setRenameBusy(false);
     }
@@ -358,7 +398,6 @@ export function Sidebar({
   const confirmDeleteSession = async () => {
     if (!deletingSession) return;
     setDeletingBusy(true);
-    setDeleteError(null);
     const target = deletingSession;
     try {
       await api.deleteSession(target.sessionId);
@@ -366,17 +405,21 @@ export function Sidebar({
       // The session is gone, so clear its input draft too (no orphaned keys left in localStorage; keys are scoped per user, #68).
       if (user) clearDraft(sessionDraftKey(user.userId, target.sessionId));
       setDeletingSession(null);
-      // The deleted session was the one open: jump to another **unarchived** Session in the same
-      // group, otherwise fall back to the chat home page (never jump into an archived session —
-      // it's hidden by default, so landing there would look like the chat vanished into thin air).
+      // The deleted session was the one open: jump to this Agent's next conversation, otherwise
+      // fall back to the chat home page. Auto-opened conversations are never archived (hidden by
+      // default — landing there would look like the chat vanished into thin air) and never
+      // subagent children (they belong to some other conversation).
       if (activeSessionId === target.sessionId) {
-        const rest = (byAgent.get(target.agentId) ?? []).filter(
-          (s) => s.sessionId !== target.sessionId && !s.archived,
-        );
+        const rest = (byAgent.get(target.agentId) ?? []).filter((s) => {
+          const category = sessionCategory(s);
+          return (
+            s.sessionId !== target.sessionId && (category === "active" || category === "schedule")
+          );
+        });
         navigate(rest[0] ? `/chat/${rest[0].sessionId}` : "/chat");
       }
     } catch (e) {
-      setDeleteError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
     } finally {
       setDeletingBusy(false);
     }
@@ -440,10 +483,7 @@ export function Sidebar({
             setRenameText(x.title ?? "");
             setRenamingSession(x);
           }}
-          onDelete={(x) => {
-            setDeleteError(null);
-            setDeletingSession(x);
-          }}
+          onDelete={(x) => setDeletingSession(x)}
           onToggleArchive={(x) => void toggleArchive(x)}
         />
       ))}
@@ -453,65 +493,102 @@ export function Sidebar({
   const folderClass =
     "flex w-full items-center gap-1 rounded px-1.5 py-1 text-left text-[11px] font-medium text-gray-400 transition-colors duration-150 hover:bg-gray-200/50 dark:text-gray-500 dark:hover:bg-gray-800/50";
 
-  /** Collapsed-by-default per-origin folder (subagent / scheduled), parallel to the archived folder. */
-  const renderSourceFolder = (
+  /**
+   * Collapsed-by-default lazy folder (subagent / scheduled / archived): nothing is
+   * fetched until the first expand, and once open the folder pages independently with
+   * its own "More" row. Everything is driven by the group's **own** exact server share
+   * (`totals` — the Agent's counts in agent mode, the per-Workspace fold in workspace
+   * mode): the folder exists only while its share is non-zero, the label shows that
+   * share, and "More" shows only while loaded rows fall short of it — an Agent's
+   * content in *other* Workspaces can never surface a folder here.
+   */
+  const renderFolder = (
     groupKey: string,
-    source: SessionSource,
-    rows: SessionInfo[],
+    category: FolderCategory,
+    parts: SessionPartition,
     withAgentHint: boolean,
+    /** Agents that may hold this group's rows of this category (fetch fan-out set). */
+    agentIds: string[],
+    totals: SessionCategoryCounts | undefined,
   ) => {
-    if (rows.length === 0) return null;
-    const open = openSourceFolders.has(sourceFolderKey(groupKey, source));
+    const rows = parts[category];
+    // Loaded rows win a disagreement with the totals (counts refresh only on reload).
+    const total = Math.max(totals?.[category] ?? 0, rows.length);
+    if (total === 0) return null;
+    const open = openFolders.has(folderKey(groupKey, category));
+    // More while the group's share isn't fully loaded AND somewhere is left to fetch from
+    // (counts drifting above reality would otherwise leave a dead button until reload).
+    const more = rows.length < total && agentIds.some((id) => hasMoreFor(id, category));
+    const pending = pendingLoads.has(loadKey(groupKey, category));
     return (
-      <div className="mt-1">
+      <div key={category} className="mt-1">
         <button
           type="button"
-          onClick={() => toggleSourceFolder(groupKey, source)}
+          onClick={() => toggleFolder(groupKey, category, agentIds)}
           className={folderClass}
         >
           <Chevron open={open} size={12} />
-          {S.chat.sourceGroups[source](rows.length)}
+          {S.chat.folderGroups[category](total)}
         </button>
         {open && renderRows(rows, withAgentHint)}
+        {/* The folder's own paging, independent of the active list's "More". In workspace
+            mode a fetched page can land rows in other groups' folders too, so one click may
+            grow this folder by fewer than a full page — the row shows a loading state while
+            the fetch runs and stays until this group's share is fully loaded. */}
+        {open && more && (
+          <button
+            type="button"
+            aria-label={S.chat.loadMore}
+            disabled={pending}
+            onClick={() => trackedLoadMore(groupKey, category, agentIds)}
+            className={`${folderClass} disabled:opacity-60`}
+          >
+            <span className="w-3" aria-hidden />
+            {pending ? S.common.loading : S.chat.loadMore}
+          </button>
+        )}
       </div>
     );
   };
 
-  /** "More": reveal one more page of already-loaded active rows AND fetch the next server page for every contributing Agent that still has one. */
-  const showMore = (groupKey: string, moreAgents: string[]) => {
+  /** Active-list "More": reveal one more page of already-loaded active rows AND fetch the next active server page for every Agent that still has one. */
+  const showMore = (groupKey: string, agentIds: string[]) => {
     setGroupCaps((prev) => {
       const next = new Map(prev);
       next.set(groupKey, (prev.get(groupKey) ?? SIDEBAR_PAGE_SIZE) + SIDEBAR_PAGE_SIZE);
       return next;
     });
-    if (moreAgents.length > 0) void loadMoreFor(moreAgents);
+    if (agentIds.length > 0) trackedLoadMore(groupKey, "active", agentIds);
   };
 
   /**
-   * Expanded group body shared by both modes: user rows (display-capped; "More" reveals and
-   * loads further pages) + the collapsed-by-default subagent / scheduled / archived subgroups
-   * (keyed by the group key; rendered uncapped over loaded data — they are collapsed by
-   * default and only ever hold what the pages brought in).
+   * Expanded group body shared by both modes: active user rows (display-capped; "More"
+   * reveals and loads further **active-only** pages — the folders below never feed it) +
+   * the collapsed-by-default subagent / scheduled / archived folders, each loading on
+   * first expand and paging on its own. `totals` / `agentsFor` carry the group's exact
+   * server share and its fetch fan-out set per category.
    */
   const renderGroupBody = (
     groupKey: string,
     parts: SessionPartition,
     withAgentHint: boolean,
-    /** Agents contributing to this group that still have unfetched server pages. */
-    moreAgents: string[],
+    totals: SessionCategoryCounts | undefined,
+    agentsFor: (category: SessionCategory) => string[],
   ) => {
-    const archivedOpen = openArchived.has(groupKey);
     const cap = groupCaps.get(groupKey) ?? SIDEBAR_PAGE_SIZE;
     const shownActive = parts.active.slice(0, cap);
-    // "More" while hidden loaded rows exist OR any contributing Agent has server-side pages
-    // left; a fetched page can also land rows in the folders below, so one click may grow
-    // the visible list by fewer than a full page — the row simply stays until exhausted.
-    const hasMore = parts.active.length > cap || moreAgents.length > 0;
-    const empty =
-      parts.active.length === 0 &&
-      parts.subagent.length === 0 &&
-      parts.schedule.length === 0 &&
-      parts.archived.length === 0;
+    // Only the outer active rows drive the group's "More" — the folders never feed it:
+    // hidden loaded rows exist, or the group's own active share isn't fully loaded yet.
+    const activeAgents = agentsFor("active");
+    const activeTotal = Math.max(totals?.active ?? 0, parts.active.length);
+    const hasMore =
+      parts.active.length > cap ||
+      (parts.active.length < activeTotal && activeAgents.some((id) => hasMoreFor(id, "active")));
+    const folders = FOLDER_CATEGORIES.map((category) =>
+      renderFolder(groupKey, category, parts, withAgentHint, agentsFor(category), totals),
+    );
+    const empty = parts.active.length === 0 && folders.every((f) => f === null);
+    const activePending = pendingLoads.has(loadKey(groupKey, "active"));
     return (
       <>
         {empty ? (
@@ -527,33 +604,19 @@ export function Sidebar({
           <button
             type="button"
             aria-label={S.chat.loadMore}
-            onClick={() => showMore(groupKey, moreAgents)}
-            className={`${folderClass} mt-0.5`}
+            disabled={activePending}
+            onClick={() => showMore(groupKey, activeAgents)}
+            className={`${folderClass} mt-0.5 disabled:opacity-60`}
           >
             <span className="w-3" aria-hidden />
-            {S.chat.loadMore}
+            {activePending ? S.common.loading : S.chat.loadMore}
           </button>
         )}
 
-        {/* Per-origin folders (collapsed by default, above Archived): subagent first — spawned
-            from the conversations at hand — then scheduled background runs. */}
-        {renderSourceFolder(groupKey, "subagent", parts.subagent, withAgentHint)}
-        {renderSourceFolder(groupKey, "schedule", parts.schedule, withAgentHint)}
-
-        {/* Archived group (collapsed by default; archived wins over the per-origin folders) */}
-        {parts.archived.length > 0 && (
-          <div className="mt-1">
-            <button
-              type="button"
-              onClick={() => toggleArchivedGroup(groupKey)}
-              className={folderClass}
-            >
-              <Chevron open={archivedOpen} size={12} />
-              {S.chat.archivedGroup(parts.archived.length)}
-            </button>
-            {archivedOpen && renderRows(parts.archived, withAgentHint)}
-          </div>
-        )}
+        {/* Folders (collapsed by default): subagent first — spawned from the conversations
+            at hand — then scheduled background runs, then archived (archived wins over the
+            origin folders). */}
+        {folders}
       </>
     );
   };
@@ -617,7 +680,7 @@ export function Sidebar({
                 {currentProject ? projectDisplayName(currentProject) : S.common.loading}
               </span>
               <span className="text-gray-400">
-                <DropdownCaret />
+                <ChevronDown />
               </span>
             </button>
           }
@@ -803,7 +866,8 @@ export function Sidebar({
                         agent.agentId,
                         parts,
                         false,
-                        hasMoreByAgent.get(agent.agentId) === true ? [agent.agentId] : [],
+                        countsByAgent.get(agent.agentId),
+                        () => [agent.agentId],
                       )}
                 </div>
               );
@@ -820,6 +884,12 @@ export function Sidebar({
             const parts = partitionSessions(group.sessions);
             const collapsed = collapsedGroups.has(group.key);
             const pinned = pinnedGroups.has(group.key);
+            /** This group's exact server share (per-Workspace fold) and its per-category fetch fan-out. */
+            const counts = workspaceGroupCounts.get(group.key);
+            const contributingAgents = [...new Set(group.sessions.map((s) => s.agentId))];
+            const agentsFor = (category: SessionCategory) => [
+              ...new Set([...(counts?.agents[category] ?? []), ...contributingAgents]),
+            ];
             return (
               <div key={group.key} className="pt-2.5">
                 {/* Group header: collapse toggle (folder icon + directory basename + count, full path in the tooltip) + pin + new chat in this Workspace.
@@ -842,9 +912,10 @@ export function Sidebar({
                     <span className="min-w-0 truncate text-xs font-semibold text-gray-500 dark:text-gray-400">
                       {group.temp ? S.chat.tempWorkspaces : group.label}
                     </span>
-                    {/* Header count = non-archived Sessions (user + automation-created; unchanged semantics) */}
+                    {/* Header count = the group's active conversations only (exact server share;
+                        loaded rows win a disagreement) — the folders never feed it. */}
                     <span className="shrink-0 text-[11px] text-gray-400 dark:text-gray-500">
-                      {parts.active.length + parts.subagent.length + parts.schedule.length}
+                      {Math.max(counts?.totals.active ?? 0, parts.active.length)}
                     </span>
                     <Chevron open={!collapsed} size={12} className="text-gray-400" />
                     <span className="min-w-0 flex-1" />
@@ -862,15 +933,13 @@ export function Sidebar({
                   </button>
                 </div>
 
-                {/* A workspace group can span Agents: "More" fans out to every contributing Agent that still has pages. */}
+                {/* A workspace group can span Agents: the group body fans folder loads and "More"
+                    out per category to the Agents whose share of THIS group is non-zero (plus the
+                    Agents already contributing loaded rows) — the active list and each folder
+                    page independently. */}
                 {collapsed
                   ? null
-                  : renderGroupBody(
-                      group.key,
-                      parts,
-                      true,
-                      groupAgentsWithMore(group.sessions, hasMoreByAgent),
-                    )}
+                  : renderGroupBody(group.key, parts, true, counts?.totals, agentsFor)}
               </div>
             );
           })
@@ -1001,47 +1070,34 @@ export function Sidebar({
         <Input
           label={S.chat.renameSessionLabel}
           value={renameText}
+          error={renameError ?? undefined}
           autoFocus
           maxLength={120}
-          onChange={(e) => setRenameText(e.target.value)}
+          onChange={(e) => {
+            setRenameText(e.target.value);
+            if (renameError) setRenameError(null);
+          }}
           onKeyDown={(e) => {
             if (e.key === "Enter" && renameText.trim() && !renameBusy) void confirmRename();
           }}
         />
-        {renameError && (
-          <p className="mt-2 text-xs text-red-600 dark:text-red-400">{renameError}</p>
-        )}
       </Modal>
 
-      {/* Delete chat confirmation */}
-      <Modal
+      {/* Delete chat confirmation (shared ConfirmModal) */}
+      <ConfirmModal
         open={deletingSession !== null}
         title={S.chat.deleteSession}
+        confirmLabel={S.common.delete}
+        busy={deletingBusy}
         onClose={() => (deletingBusy ? undefined : setDeletingSession(null))}
-        footer={
-          <>
-            <Button onClick={() => setDeletingSession(null)} disabled={deletingBusy}>
-              {S.common.cancel}
-            </Button>
-            <Button
-              variant="danger"
-              disabled={deletingBusy}
-              onClick={() => void confirmDeleteSession()}
-            >
-              {S.common.delete}
-            </Button>
-          </>
-        }
+        onConfirm={() => void confirmDeleteSession()}
       >
         <p className="text-sm text-gray-600 dark:text-gray-300">
           {deletingSession
             ? S.chat.deleteSessionConfirm(deletingSession.title ?? S.chat.defaultSessionTitle)
             : ""}
         </p>
-        {deleteError && (
-          <p className="mt-2 text-xs text-red-600 dark:text-red-400">{deleteError}</p>
-        )}
-      </Modal>
+      </ConfirmModal>
     </div>
   );
 }
@@ -1129,8 +1185,7 @@ function SessionRow({
                   : "text-gray-700 dark:text-gray-300"
             }`}
           />
-          {/* Source badge: schedule / sub-session (user-created sessions have no source and show nothing). */}
-          {s.source && <Badge tone="gray">{S.chat.sourceNames[s.source] ?? s.source}</Badge>}
+          {/* No per-row source tag: subagent / scheduled Sessions live in their own labelled, collapsed folders, so a badge on the title would just repeat the folder. */}
           <StatusDot session={s} />
           {s.pendingApprovalCount > 0 && (
             <span title={S.chat.pendingApprovals(s.pendingApprovalCount)}>
diff --git a/packages/web/src/components/ui/confirm-modal.tsx b/packages/web/src/components/ui/confirm-modal.tsx
new file mode 100644
index 0000000..74737c8
--- /dev/null
+++ b/packages/web/src/components/ui/confirm-modal.tsx
@@ -0,0 +1,116 @@
+/**
+ * Confirmation dialog for destructive or overwriting actions (delete,
+ * overwrite-on-update, save-to-file, …), deliberately minimal: **no title bar** —
+ * just the tone icon, the message and a small Cancel / Confirm pair, so every
+ * confirmation in the app is one compact, identical card. `tone` picks the look —
+ * danger (red) for deletions, primary for saves and other overwrites. The message
+ * and any details (e.g. a version list) go in children; `title` only names the
+ * dialog for assistive tech (never rendered).
+ */
+import { useState } from "react";
+import type { ReactNode } from "react";
+import { Modal } from "./modal";
+import { Button } from "./button";
+import { S } from "../../lib/strings";
+
+/** Tinted icon badge per tone: warning triangle on red for danger, pencil-on-gray for confirmations that overwrite/save. */
+function ToneBadge({ tone }: { tone: "danger" | "primary" }) {
+  const glyph =
+    tone === "danger"
+      ? // Triangle alert (lucide): outline + exclamation.
+        "m21.73 18-8-14a2 2 0 0 0-3.48 0l-8 14A2 2 0 0 0 4 21h16a2 2 0 0 0 1.73-3zM12 9v4m0 4h.01"
+      : // Pencil-line (lucide): writing changes down.
+        "M12 20h9M16.5 3.5a2.1 2.1 0 0 1 3 3L7 19l-4 1 1-4L16.5 3.5z";
+  return (
+    <span
+      aria-hidden
+      className={`flex h-9 w-9 shrink-0 items-center justify-center rounded-full ${
+        tone === "danger"
+          ? "bg-red-100 text-red-600 dark:bg-red-950/60 dark:text-red-400"
+          : "bg-gray-100 text-gray-600 dark:bg-gray-800 dark:text-gray-300"
+      }`}
+    >
+      <svg
+        width="18"
+        height="18"
+        viewBox="0 0 24 24"
+        fill="none"
+        stroke="currentColor"
+        strokeWidth="1.7"
+        strokeLinecap="round"
+        strokeLinejoin="round"
+      >
+        <path d={glyph} />
+      </svg>
+    </span>
+  );
+}
+
+export function ConfirmModal({
+  open,
+  title,
+  onClose,
+  onConfirm,
+  confirmLabel,
+  tone = "danger",
+  busy = false,
+  children,
+}: {
+  open: boolean;
+  /** Accessible dialog name only — the compact card renders no title bar. */
+  title: string;
+  onClose: () => void;
+  onConfirm: () => void;
+  /** Confirm button text (defaults to the shared "Confirm"). */
+  confirmLabel?: string;
+  /** Confirm button variant: danger for deletions, primary for saves and other overwrites. */
+  tone?: "danger" | "primary";
+  busy?: boolean;
+  children: ReactNode;
+}) {
+  return (
+    <Modal open={open} title={title} onClose={onClose} headerless widthClass="sm:max-w-sm">
+      <div className="flex items-start gap-3">
+        <ToneBadge tone={tone} />
+        <div className="min-w-0 flex-1 pt-1.5">{children}</div>
+      </div>
+      <div className="mt-4 flex justify-end gap-2">
+        <Button size="sm" onClick={onClose} disabled={busy}>
+          {S.common.cancel}
+        </Button>
+        <Button size="sm" variant={tone} disabled={busy} onClick={onConfirm}>
+          {confirmLabel ?? S.common.confirm}
+        </Button>
+      </div>
+    </Modal>
+  );
+}
+
+/**
+ * Shared confirm-before-save flow for the settings forms: `requestSave(run)` opens a
+ * standard "save these changes?" dialog and Confirm executes `run`. The caller decides
+ * beforehand whether there is anything to save (no changes → an info toast, not a
+ * dialog). Render `element` once per surface.
+ */
+export function useSaveConfirm(): {
+  requestSave: (run: () => void) => void;
+  element: ReactNode;
+} {
+  const [pending, setPending] = useState<(() => void) | null>(null);
+  const element = (
+    <ConfirmModal
+      open={pending !== null}
+      title={S.common.confirmSaveTitle}
+      tone="primary"
+      confirmLabel={S.common.save}
+      onClose={() => setPending(null)}
+      onConfirm={() => {
+        pending?.();
+        setPending(null);
+      }}
+    >
+      <p className="text-sm text-gray-600 dark:text-gray-300">{S.common.confirmSaveBody}</p>
+    </ConfirmModal>
+  );
+  return { requestSave: (run: () => void) => setPending(() => run), element };
+}
diff --git a/packages/web/src/components/ui/drawer.tsx b/packages/web/src/components/ui/drawer.tsx
index 2aac7b0..e58b174 100644
--- a/packages/web/src/components/ui/drawer.tsx
+++ b/packages/web/src/components/ui/drawer.tsx
@@ -4,7 +4,7 @@
  */
 import { useEffect } from "react";
 import type { ReactNode } from "react";
-import { S } from "../../lib/strings";
+import { CloseButton } from "./icons";
 
 export interface DrawerProps {
   open: boolean;
@@ -39,16 +39,7 @@ export function Drawer({ open, side = "left", title, onClose, children, widthCla
       >
         <div className="flex shrink-0 items-center justify-between border-b border-gray-200 px-4 py-3 dark:border-gray-800">
           <span className="text-base font-semibold">{title ?? ""}</span>
-          <button
-            type="button"
-            aria-label={S.common.close}
-            onClick={onClose}
-            className="rounded-md p-1.5 text-gray-400 transition-colors duration-150 hover:bg-gray-100 hover:text-gray-600 dark:hover:bg-gray-800 dark:hover:text-gray-300"
-          >
-            <svg width="14" height="14" viewBox="0 0 14 14" fill="none" stroke="currentColor">
-              <path d="M2 2l10 10M12 2L2 12" strokeWidth="1.5" strokeLinecap="round" />
-            </svg>
-          </button>
+          <CloseButton onClose={onClose} />
         </div>
         <div className="min-h-0 flex-1 overflow-y-auto pb-[env(safe-area-inset-bottom)]">
           {children}
diff --git a/packages/web/src/components/ui/field.tsx b/packages/web/src/components/ui/field.tsx
new file mode 100644
index 0000000..d7d9ab0
--- /dev/null
+++ b/packages/web/src/components/ui/field.tsx
@@ -0,0 +1,92 @@
+/**
+ * Shared field scaffolding: the label / hint / error text and the wrapping
+ * <label>, plus the class strings for a control's "look" and a menu row. Every
+ * form control (Input, Textarea, Select, OptionMenu, PasswordInput) and every
+ * form that shows a field error builds on these, instead of the five-plus
+ * near-identical copies that used to live in each control and call site.
+ */
+import type { ReactNode } from "react";
+
+/**
+ * The control "look" shared by Input, Select and OptionMenu: rounded box, gray
+ * border that darkens on hover, brand focus ring, dark-mode variants. Excludes
+ * layout (width/flex), text size, placeholder and disabled styling — each
+ * control appends what it needs.
+ */
+export const controlBase =
+  "rounded-md border border-gray-300 bg-white text-gray-900 " +
+  "transition-[border-color,box-shadow] duration-200 " +
+  "hover:border-gray-400 focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400/30 " +
+  "dark:border-gray-700 dark:bg-gray-900 dark:text-gray-100 " +
+  "dark:hover:border-gray-600 dark:focus:border-gray-400 dark:focus:ring-gray-500/30";
+
+/** Base padding/alignment/transition for a menu row (Select, OptionMenu, and the chat composer menus); callers add flex/block and the hover/selected colors. */
+export const menuRowClass = "w-full px-3 py-1.5 text-left transition-colors duration-150";
+
+export function FieldLabel({ children, required }: { children: ReactNode; required?: boolean }) {
+  return (
+    <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
+      {children}
+      {required && (
+        <span className="ml-0.5 text-red-500 dark:text-red-400" aria-hidden>
+          *
+        </span>
+      )}
+    </span>
+  );
+}
+
+export function FieldHint({ children }: { children: ReactNode }) {
+  return <span className="mt-1 block text-xs text-gray-500 dark:text-gray-500">{children}</span>;
+}
+
+/**
+ * Field-level error text: placed directly below the offending input (the input itself
+ * is highlighted red via the control's error/invalid state). role="alert" announces the
+ * message to assistive tech the moment it appears; `id` is the anchor the control's
+ * aria-describedby points at, so AT users can also find *what* is wrong from the input.
+ */
+export function FieldError({ id, children }: { id?: string; children: ReactNode }) {
+  return (
+    <span id={id} role="alert" className="mt-1 block text-xs text-red-600 dark:text-red-400">
+      {children}
+    </span>
+  );
+}
+
+/**
+ * Standard vertical field layout: an optional bold label above the control, and
+ * below it a red error if present, otherwise a gray hint. Renders the bare
+ * control (no wrapper) when there's no label/hint/error, so a caller can drop it
+ * into a toolbar or table cell unchanged.
+ */
+export function Field({
+  label,
+  hint,
+  error,
+  errorId,
+  required,
+  children,
+}: {
+  label?: ReactNode;
+  hint?: ReactNode;
+  error?: ReactNode;
+  /** id for the error text — the control passes the same id in aria-describedby. */
+  errorId?: string;
+  /** Renders a red "*" after the label to mark the field as required. */
+  required?: boolean;
+  children: ReactNode;
+}) {
+  if (!label && !hint && !error) return <>{children}</>;
+  return (
+    <label className="block">
+      {label != null && label !== "" && <FieldLabel required={required}>{label}</FieldLabel>}
+      {children}
+      {error ? (
+        <FieldError id={errorId}>{error}</FieldError>
+      ) : hint ? (
+        <FieldHint>{hint}</FieldHint>
+      ) : null}
+    </label>
+  );
+}
diff --git a/packages/web/src/components/ui/icons.tsx b/packages/web/src/components/ui/icons.tsx
new file mode 100644
index 0000000..00167f3
--- /dev/null
+++ b/packages/web/src/components/ui/icons.tsx
@@ -0,0 +1,99 @@
+/**
+ * Shared single-path icons and the dialog close button, replacing SVGs that were
+ * inlined identically at many call sites. Note `chevron.tsx` is a *different*
+ * glyph (the rotating right-caret used by collapsibles) and stays separate.
+ */
+import type { ButtonHTMLAttributes } from "react";
+import { S } from "../../lib/strings";
+
+/** Downward caret on Select / OptionMenu / composer dropdown triggers. Color follows currentColor (callers add text-gray-400). */
+export function ChevronDown({ size = 12, className = "" }: { size?: number; className?: string }) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 12 12"
+      fill="none"
+      stroke="currentColor"
+      aria-hidden
+      className={`shrink-0 ${className}`}
+    >
+      <path d="M3 4.5l3 3 3-3" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
+    </svg>
+  );
+}
+
+/** Selected-row checkmark in the Select / OptionMenu menus. */
+export function CheckIcon({ size = 13, className = "" }: { size?: number; className?: string }) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      aria-hidden
+      className={`shrink-0 ${className}`}
+    >
+      <path d="M5 12l4 4L19 6" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" />
+    </svg>
+  );
+}
+
+/** "Add" plus glyph used by create buttons / new-row affordances. */
+export function PlusIcon({
+  size = 14,
+  strokeWidth = 1.7,
+  className = "",
+}: {
+  size?: number;
+  strokeWidth?: number;
+  className?: string;
+}) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      aria-hidden
+      className={`shrink-0 ${className}`}
+    >
+      <path
+        d="M12 5v14M5 12h14"
+        strokeWidth={strokeWidth}
+        strokeLinecap="round"
+        strokeLinejoin="round"
+      />
+    </svg>
+  );
+}
+
+/**
+ * The X close button shared by the Modal / Drawer / Sheet headers: same glyph,
+ * padding and hover treatment. Extra button props (e.g. Sheet's onPointerDown
+ * guard) pass through.
+ */
+export function CloseButton({
+  onClose,
+  className = "",
+  ...rest
+}: { onClose: () => void; className?: string } & Omit<
+  ButtonHTMLAttributes<HTMLButtonElement>,
+  "onClick"
+>) {
+  return (
+    <button
+      type="button"
+      aria-label={S.common.close}
+      onClick={onClose}
+      className={`rounded-md p-1.5 text-gray-400 transition-colors duration-150 hover:bg-gray-100 hover:text-gray-600 dark:hover:bg-gray-800 dark:hover:text-gray-300 ${className}`}
+      {...rest}
+    >
+      <svg width="14" height="14" viewBox="0 0 14 14" fill="none" stroke="currentColor" aria-hidden>
+        <path d="M2 2l10 10M12 2L2 12" strokeWidth="1.5" strokeLinecap="round" />
+      </svg>
+    </button>
+  );
+}
diff --git a/packages/web/src/components/ui/input.tsx b/packages/web/src/components/ui/input.tsx
index a14ca80..3e2a822 100644
--- a/packages/web/src/components/ui/input.tsx
+++ b/packages/web/src/components/ui/input.tsx
@@ -1,18 +1,17 @@
 /**
  * Text input component: optional label and hint/error text; rounded corners with
- * a hover border darken and brand focus-ring transition.
+ * a hover border darken and brand focus-ring transition. Shares the control look
+ * and the label/hint/error scaffolding with the other form controls via field.tsx.
  */
-import { forwardRef } from "react";
+import { forwardRef, useId } from "react";
 import type { InputHTMLAttributes, TextareaHTMLAttributes } from "react";
+import { Field, controlBase } from "./field";
 
-// Excludes font size and padding: each of Input/Textarea appends its own (see their size).
+// Adds width, placeholder and disabled styling on top of the shared control look; each of Input/Textarea appends its own font size and padding (see their size).
 const baseClass =
-  "w-full rounded-md border border-gray-300 bg-white text-gray-900 " +
-  "placeholder:text-gray-400 transition-[border-color,box-shadow] duration-200 " +
-  "hover:border-gray-400 focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400/30 " +
-  "disabled:cursor-not-allowed disabled:opacity-60 " +
-  "dark:border-gray-700 dark:bg-gray-900 dark:text-gray-100 dark:placeholder:text-gray-500 " +
-  "dark:hover:border-gray-600 dark:focus:border-gray-400 dark:focus:ring-gray-500/30";
+  `w-full ${controlBase} ` +
+  "placeholder:text-gray-400 disabled:cursor-not-allowed disabled:opacity-60 " +
+  "dark:placeholder:text-gray-500";
 
 /** Size tier: base (form default) / sm (compact contexts like filter bars, keeps the toolbar from growing taller). */
 export type ControlSize = "base" | "sm";
@@ -38,13 +37,14 @@ export interface InputProps extends Omit<InputHTMLAttributes<HTMLInputElement>,
 
 /**
  * Error state: red border + light red background (a failed field is visible at a
- * glance; the error text sits below the box).
+ * glance; the error text sits below the box). Shared with Select/OptionMenu so a
+ * failed dropdown reads exactly like a failed input.
  * Forced with `!` — baseClass's border-gray-300 / bg-white are the same kind of
  * border/background utility classes, and which one wins depends on the order the
  * CSS was generated in, not the order of classes in the string (without `!important`
  * this would get overridden).
  */
-const errorClass =
+export const errorClass =
   "!border-red-400 !bg-red-50 hover:!border-red-500 focus:!border-red-500 focus:!ring-red-400/30 " +
   "dark:!border-red-800 dark:!bg-red-950/40 dark:hover:!border-red-700 dark:focus:!border-red-600";
 
@@ -53,39 +53,35 @@ export function Input({
   hint,
   error,
   invalid,
+  required,
   size = "base",
   className,
   ...rest
 }: InputProps) {
   const bad = Boolean(error) || Boolean(invalid);
-  const control = (
-    <input
-      className={`${baseClass} ${sizeClass[size]} ${bad ? errorClass : ""} ${className ?? ""}`}
-      aria-invalid={bad ? true : undefined}
-      {...rest}
-    />
-  );
-  if (!label && !hint && !error) return control;
+  const errorId = useId();
+  // `required` drives the label's asterisk + aria-required only; the native `required`
+  // attribute is intentionally not forwarded (the app validates on submit, so browser
+  // validation bubbles would collide with the inline field errors).
   return (
-    <label className="block">
-      {label && (
-        <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-          {label}
-        </span>
-      )}
-      {control}
-      {error ? (
-        <span className="mt-1 block text-xs text-red-600 dark:text-red-400">{error}</span>
-      ) : hint ? (
-        <span className="mt-1 block text-xs text-gray-500 dark:text-gray-500">{hint}</span>
-      ) : null}
-    </label>
+    <Field label={label} hint={hint} error={error} errorId={errorId} required={required}>
+      <input
+        className={`${baseClass} ${sizeClass[size]} ${bad ? errorClass : ""} ${className ?? ""}`}
+        aria-invalid={bad ? true : undefined}
+        aria-required={required || undefined}
+        aria-describedby={error ? errorId : undefined}
+        {...rest}
+      />
+    </Field>
   );
 }
 
 export interface TextareaProps extends TextareaHTMLAttributes<HTMLTextAreaElement> {
   label?: string;
   hint?: string;
+  error?: string;
+  /** Marks the field red without rendering error text (see Input.invalid). */
+  invalid?: boolean;
   /** Monospace font (for editing Prompts/parameters). */
   mono?: boolean;
   /** Font size: base (default, matches body text) or sm (smaller, for editing long Prompts). */
@@ -93,26 +89,21 @@ export interface TextareaProps extends TextareaHTMLAttributes<HTMLTextAreaElemen
 }
 
 export const Textarea = forwardRef<HTMLTextAreaElement, TextareaProps>(function Textarea(
-  { label, hint, mono, size = "base", className, ...rest },
+  { label, hint, error, invalid, required, mono, size = "base", className, ...rest },
   ref,
 ) {
-  const control = (
-    <textarea
-      ref={ref}
-      className={`${baseClass} px-3 py-2 ${size === "sm" ? "text-xs leading-relaxed" : "text-base"} ${mono ? "font-mono" : ""} ${className ?? ""}`}
-      {...rest}
-    />
-  );
-  if (!label && !hint) return control;
+  const bad = Boolean(error) || Boolean(invalid);
+  const errorId = useId();
   return (
-    <label className="block">
-      {label && (
-        <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-          {label}
-        </span>
-      )}
-      {control}
-      {hint && <span className="mt-1 block text-xs text-gray-500 dark:text-gray-500">{hint}</span>}
-    </label>
+    <Field label={label} hint={hint} error={error} errorId={errorId} required={required}>
+      <textarea
+        ref={ref}
+        className={`${baseClass} px-3 py-2 ${size === "sm" ? "text-xs leading-relaxed" : "text-base"} ${mono ? "font-mono" : ""} ${bad ? errorClass : ""} ${className ?? ""}`}
+        aria-invalid={bad ? true : undefined}
+        aria-required={required || undefined}
+        aria-describedby={error ? errorId : undefined}
+        {...rest}
+      />
+    </Field>
   );
 });
diff --git a/packages/web/src/components/ui/modal.tsx b/packages/web/src/components/ui/modal.tsx
index 799ab7c..af6bb67 100644
--- a/packages/web/src/components/ui/modal.tsx
+++ b/packages/web/src/components/ui/modal.tsx
@@ -14,16 +14,19 @@
 import { useEffect } from "react";
 import { createPortal } from "react-dom";
 import type { ReactNode } from "react";
-import { S } from "../../lib/strings";
+import { CloseButton } from "./icons";
 
 export interface ModalProps {
   open: boolean;
+  /** Dialog name: rendered as the header bar, or (headerless) exposed as the panel's aria-label only. */
   title: string;
   onClose: () => void;
   children: ReactNode;
   footer?: ReactNode;
   /** Panel width class (defaults to sm:max-w-md). */
   widthClass?: string;
+  /** No header bar (no visible title, no close button): compact dialogs like confirmations — the title still names the dialog for assistive tech. */
+  headerless?: boolean;
 }
 
 /**
@@ -36,7 +39,15 @@ export interface ModalProps {
  */
 const modalStack: symbol[] = [];
 
-export function Modal({ open, title, onClose, children, footer, widthClass }: ModalProps) {
+export function Modal({
+  open,
+  title,
+  onClose,
+  children,
+  footer,
+  widthClass,
+  headerless,
+}: ModalProps) {
   useEffect(() => {
     if (!open) return;
     const id = Symbol("modal");
@@ -61,21 +72,15 @@ export function Modal({ open, title, onClose, children, footer, widthClass }: Mo
       }}
     >
       <div
+        {...(headerless ? { role: "dialog", "aria-label": title } : {})}
         className={`anim-pop w-full ${widthClass ?? "sm:max-w-md"} rounded-t-lg border border-gray-200 bg-white pb-[env(safe-area-inset-bottom)] shadow-xl sm:rounded-lg sm:pb-0 dark:border-gray-800 dark:bg-gray-900`}
       >
-        <div className="flex items-center justify-between border-b border-gray-200 px-4 py-3 dark:border-gray-800">
-          <h2 className="text-base font-semibold">{title}</h2>
-          <button
-            type="button"
-            aria-label={S.common.close}
-            onClick={onClose}
-            className="rounded-md p-1.5 text-gray-400 transition-colors duration-150 hover:bg-gray-100 hover:text-gray-600 dark:hover:bg-gray-800 dark:hover:text-gray-300"
-          >
-            <svg width="14" height="14" viewBox="0 0 14 14" fill="none" stroke="currentColor">
-              <path d="M2 2l10 10M12 2L2 12" strokeWidth="1.5" strokeLinecap="round" />
-            </svg>
-          </button>
-        </div>
+        {!headerless && (
+          <div className="flex items-center justify-between border-b border-gray-200 px-4 py-3 dark:border-gray-800">
+            <h2 className="text-base font-semibold">{title}</h2>
+            <CloseButton onClose={onClose} />
+          </div>
+        )}
         <div className="max-h-[70vh] overflow-y-auto px-4 py-4">{children}</div>
         {footer && (
           <div className="flex justify-end gap-2 border-t border-gray-200 px-4 py-3 dark:border-gray-800">
diff --git a/packages/web/src/components/ui/option-menu.tsx b/packages/web/src/components/ui/option-menu.tsx
index 8f81764..f900c8b 100644
--- a/packages/web/src/components/ui/option-menu.tsx
+++ b/packages/web/src/components/ui/option-menu.tsx
@@ -25,10 +25,12 @@
  * the root stacking context, and this component may also be used inside a Modal
  * form, where z-40 would get covered by the overlay.
  */
-import { useState } from "react";
+import { useId, useState } from "react";
 import { createPortal } from "react-dom";
-import { sizeClass } from "./input";
+import { errorClass, sizeClass } from "./input";
 import type { ControlSize } from "./input";
+import { Field, controlBase, menuRowClass } from "./field";
+import { CheckIcon, ChevronDown } from "./icons";
 import { usePortalPanel } from "./use-portal-panel";
 
 export interface OptionMenuChoice<T extends string> {
@@ -55,6 +57,8 @@ export function OptionMenu<T extends string>({
   placeholder,
   mono,
   label,
+  error,
+  required,
   fullWidth,
   size = "base",
   "aria-label": ariaLabel,
@@ -69,6 +73,10 @@ export function OptionMenu<T extends string>({
   mono?: boolean;
   /** Field title above the control (same typography as Input); omit to render a bare trigger button (e.g. for table cell usage). */
   label?: string;
+  /** Field-value error: red border + message below, exactly like Input. */
+  error?: string;
+  /** Renders a red "*" after the label to mark the field as required. */
+  required?: boolean;
   /** Stretch the trigger button to fill the container width, as a replacement for native Select in dense form areas. */
   fullWidth?: boolean;
   /** Same size tier as Input/Select (sizeClass), for pixel-perfect alignment when mixed together. */
@@ -84,6 +92,7 @@ export function OptionMenu<T extends string>({
     panelWidth: PANEL_WIDTH,
   });
   const current = value != null ? options.find((o) => o.value === value) : undefined;
+  const errorId = useId();
 
   const control = (
     <>
@@ -93,29 +102,19 @@ export function OptionMenu<T extends string>({
         aria-label={ariaLabel}
         aria-haspopup="listbox"
         aria-expanded={open}
+        aria-required={required || undefined}
+        aria-invalid={error ? true : undefined}
+        aria-describedby={error ? errorId : undefined}
         onClick={() => setOpen((v) => !v)}
         className={
-          "flex items-center gap-2 rounded-md border border-gray-300 bg-white text-gray-900 " +
-          "transition-[border-color,box-shadow] duration-200 hover:border-gray-400 " +
-          "focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400/30 " +
-          "dark:border-gray-700 dark:bg-gray-900 dark:text-gray-100 dark:hover:border-gray-600 " +
-          "dark:focus:border-gray-400 dark:focus:ring-gray-500/30 " +
-          sizeClass[size] +
+          `flex items-center gap-2 ${controlBase} ${sizeClass[size]} ${error ? errorClass : ""}` +
           (fullWidth ? " w-full justify-between" : "")
         }
       >
         <span className={`min-w-0 truncate ${mono ? "font-mono" : ""}`}>
           {current?.triggerLabel ?? placeholder ?? "—"}
         </span>
-        <svg
-          viewBox="0 0 12 12"
-          fill="none"
-          stroke="currentColor"
-          aria-hidden
-          className="size-3 shrink-0 text-gray-400"
-        >
-          <path d="M3 4.5l3 3 3-3" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
-        </svg>
+        <ChevronDown className="text-gray-400" />
       </button>
       {open &&
         position &&
@@ -142,7 +141,7 @@ export function OptionMenu<T extends string>({
                   onChange(opt.value);
                   setOpen(false);
                 }}
-                className={`block w-full px-3 py-1.5 text-left transition-colors duration-150 hover:bg-gray-100 dark:hover:bg-gray-800 ${
+                className={`block ${menuRowClass} hover:bg-gray-100 dark:hover:bg-gray-800 ${
                   opt.value === value ? "bg-gray-100 dark:bg-gray-800" : ""
                 }`}
               >
@@ -157,22 +156,7 @@ export function OptionMenu<T extends string>({
                     {opt.label}
                   </span>
                   {opt.value === value && (
-                    <svg
-                      width="13"
-                      height="13"
-                      viewBox="0 0 24 24"
-                      fill="none"
-                      stroke="currentColor"
-                      className="shrink-0 text-gray-500 dark:text-gray-400"
-                      aria-hidden
-                    >
-                      <path
-                        d="M5 12l4 4L19 6"
-                        strokeWidth="2"
-                        strokeLinecap="round"
-                        strokeLinejoin="round"
-                      />
-                    </svg>
+                    <CheckIcon className="text-gray-500 dark:text-gray-400" />
                   )}
                 </span>
                 <span
@@ -187,13 +171,9 @@ export function OptionMenu<T extends string>({
         )}
     </>
   );
-  if (!label) return control;
   return (
-    <label className="block">
-      <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-        {label}
-      </span>
+    <Field label={label} error={error} errorId={errorId} required={required}>
       {control}
-    </label>
+    </Field>
   );
 }
diff --git a/packages/web/src/components/ui/password-input.tsx b/packages/web/src/components/ui/password-input.tsx
index afb2dc8..dbf43bf 100644
--- a/packages/web/src/components/ui/password-input.tsx
+++ b/packages/web/src/components/ui/password-input.tsx
@@ -7,8 +7,9 @@
  * shift out of place. So error is only passed down as `invalid` (red border), and
  * the error text is rendered below the box by this component.
  */
-import { useState } from "react";
+import { useId, useState } from "react";
 import { Input, type InputProps } from "./input";
+import { Field } from "./field";
 import { S } from "../../lib/strings";
 
 /** Eye (click to show) and a crossed-out closed eye (click to hide). */
@@ -21,25 +22,27 @@ export function PasswordInput({
   hint,
   error,
   invalid,
+  required,
   size = "base",
   className,
   ...rest
 }: Omit<InputProps, "type">) {
   const [visible, setVisible] = useState(false);
   const toggleLabel = visible ? S.auth.hidePassword : S.auth.showPassword;
+  // The error text renders in THIS component's Field (see the header comment), so the
+  // association is wired here too: the inner Input only gets `invalid` and points its
+  // aria-describedby at the outer FieldError.
+  const errorId = useId();
   return (
-    <label className="block">
-      {label && (
-        <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-          {label}
-        </span>
-      )}
+    <Field label={label} hint={hint} error={error} errorId={errorId} required={required}>
       <div className="relative">
         <Input
           {...rest}
+          required={required}
           size={size}
           type={visible ? "text" : "password"}
           invalid={Boolean(error) || Boolean(invalid)}
+          aria-describedby={error ? errorId : undefined}
           className={`${size === "sm" ? "pr-8" : "pr-10"} ${className ?? ""}`}
         />
         <button
@@ -68,11 +71,6 @@ export function PasswordInput({
           </svg>
         </button>
       </div>
-      {error ? (
-        <span className="mt-1 block text-xs text-red-600 dark:text-red-400">{error}</span>
-      ) : hint ? (
-        <span className="mt-1 block text-xs text-gray-500 dark:text-gray-500">{hint}</span>
-      ) : null}
-    </label>
+    </Field>
   );
 }
diff --git a/packages/web/src/components/ui/select.tsx b/packages/web/src/components/ui/select.tsx
index f0f166a..4cdc395 100644
--- a/packages/web/src/components/ui/select.tsx
+++ b/packages/web/src/components/ui/select.tsx
@@ -2,19 +2,24 @@
  * Dropdown select component: **custom-drawn** (not the native browser select),
  * keeping the same API — parses `<option>` children and follows the
  * `value` / `onChange(e.target.value)` convention. The menu is rendered via
- * portal to body (fixed positioning, computed from the button's rect), so it
+ * portal to body (fixed positioning from the shared usePortalPanel hook), so it
  * is never clipped by a Modal or scroll container; it closes on outside click,
- * Esc, or scroll. Styling matches Input.
+ * Esc, scroll, or resize. Styling matches Input.
  */
-import { Children, isValidElement, useEffect, useLayoutEffect, useRef, useState } from "react";
+import { Children, isValidElement, useId, useState } from "react";
 import type { ChangeEvent, ReactNode, SelectHTMLAttributes } from "react";
 import { createPortal } from "react-dom";
-import { sizeClass } from "./input";
+import { errorClass, sizeClass } from "./input";
 import type { ControlSize } from "./input";
+import { Field, controlBase, menuRowClass } from "./field";
+import { CheckIcon, ChevronDown } from "./icons";
+import { usePortalPanel } from "./use-portal-panel";
 
 export interface SelectProps extends Omit<SelectHTMLAttributes<HTMLSelectElement>, "size"> {
   label?: string;
   hint?: string;
+  /** Field-value error: red border + message below, exactly like Input. */
+  error?: string;
   /** Same size tier as Input: sm is for filter bars, keeps the toolbar from growing taller. */
   size?: ControlSize;
 }
@@ -40,13 +45,7 @@ function parseOptions(children: ReactNode): Opt[] {
   return out;
 }
 
-const CONTROL_CLASS =
-  "flex w-full items-center gap-2 rounded-md border border-gray-300 bg-white text-left text-gray-900 " +
-  "transition-[border-color,box-shadow] duration-200 hover:border-gray-400 " +
-  "focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400/30 " +
-  "disabled:cursor-not-allowed disabled:opacity-60 " +
-  "dark:border-gray-700 dark:bg-gray-900 dark:text-gray-100 dark:hover:border-gray-600 " +
-  "dark:focus:border-gray-400 dark:focus:ring-gray-500/30";
+const CONTROL_CLASS = `flex w-full items-center gap-2 text-left ${controlBase} disabled:cursor-not-allowed disabled:opacity-60`;
 
 /** Menu-row text follows the control's size tier, so the dropdown reads exactly like an Input of the same tier (review: dropdown text = input text). */
 const menuTextClass: Record<ControlSize, string> = { base: "text-base", sm: "text-xs" };
@@ -54,6 +53,8 @@ const menuTextClass: Record<ControlSize, string> = { base: "text-base", sm: "tex
 export function Select({
   label,
   hint,
+  error,
+  required,
   size = "base",
   className,
   children,
@@ -64,158 +65,83 @@ export function Select({
   const options = parseOptions(children);
   const current = String(value ?? "");
   const selected = options.find((o) => o.value === current);
+  const errorId = useId();
 
-  const btnRef = useRef<HTMLButtonElement>(null);
   const [open, setOpen] = useState(false);
-  const [pos, setPos] = useState<{ left: number; top: number; width: number; up: boolean } | null>(
-    null,
-  );
-
-  const place = () => {
-    const el = btnRef.current;
-    if (!el) return;
-    const r = el.getBoundingClientRect();
-    const below = window.innerHeight - r.bottom;
-    const up = below < 240 && r.top > below; // Not enough room below and more room above -> open upward
-    setPos({ left: r.left, top: up ? r.top : r.bottom, width: r.width, up });
-  };
-
-  useLayoutEffect(() => {
-    if (open) place();
-  }, [open]);
-
-  useEffect(() => {
-    if (!open) return;
-    const onDocDown = (e: MouseEvent) => {
-      const t = e.target as Node;
-      if (btnRef.current?.contains(t)) return;
-      if ((t as HTMLElement).closest?.("[data-select-menu]")) return;
-      setOpen(false);
-    };
-    const onKey = (e: KeyboardEvent) => {
-      if (e.key === "Escape") setOpen(false);
-    };
-    // Page scroll closes the menu (a fixed-positioned menu doesn't scroll with the
-    // page, so leaving it in place would misalign it). But **the menu's own internal
-    // scroll** (when there are more options than max-h-60) doesn't count: a
-    // capture-phase listener would catch that too, and closing on it would mean the
-    // menu shuts the moment the user scrolls, so they can never reach options below.
-    const onScroll = (e: Event) => {
-      const t = e.target;
-      if (t instanceof Element && t.closest("[data-select-menu]")) return;
-      setOpen(false);
-    };
-    const onResize = () => setOpen(false);
-    document.addEventListener("mousedown", onDocDown);
-    window.addEventListener("keydown", onKey);
-    window.addEventListener("scroll", onScroll, true);
-    window.addEventListener("resize", onResize);
-    return () => {
-      document.removeEventListener("mousedown", onDocDown);
-      window.removeEventListener("keydown", onKey);
-      window.removeEventListener("scroll", onScroll, true);
-      window.removeEventListener("resize", onResize);
-    };
-  }, [open]);
+  const { triggerRef, panelRef, position } = usePortalPanel({
+    open,
+    onClose: () => setOpen(false),
+    // Row height is roughly 36px (px-3 py-1.5 + text) — only used to decide up vs down.
+    estimatedHeight: options.length * 36 + 8,
+  });
 
   const pick = (v: string) => {
     setOpen(false);
     // Synthesize a minimal event object, following the caller's onChange(e.target.value) convention.
     onChange?.({ target: { value: v } } as unknown as ChangeEvent<HTMLSelectElement>);
-    btnRef.current?.focus();
+    triggerRef.current?.focus();
   };
 
   const control = (
     <>
       <button
-        ref={btnRef}
+        ref={triggerRef}
         type="button"
         disabled={disabled}
         aria-haspopup="listbox"
         aria-expanded={open}
+        aria-required={required || undefined}
+        aria-invalid={error ? true : undefined}
+        aria-describedby={error ? errorId : undefined}
         onClick={() => setOpen((v) => !v)}
-        className={`${CONTROL_CLASS} ${sizeClass[size]} ${className ?? ""}`}
+        className={`${CONTROL_CLASS} ${sizeClass[size]} ${error ? errorClass : ""} ${className ?? ""}`}
       >
         <span className="min-w-0 flex-1 truncate">
           {selected?.label ?? options[0]?.label ?? ""}
         </span>
-        <svg
-          width="12"
-          height="12"
-          viewBox="0 0 12 12"
-          fill="none"
-          stroke="currentColor"
-          className="shrink-0 text-gray-400"
-          aria-hidden
-        >
-          <path d="M3 4.5l3 3 3-3" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
-        </svg>
+        <ChevronDown className="text-gray-400" />
       </button>
       {open &&
-        pos &&
+        position &&
         createPortal(
-          <ul
-            data-select-menu
+          <div
+            ref={panelRef}
             role="listbox"
             className="anim-pop fixed z-[60] max-h-60 overflow-y-auto rounded-md border border-gray-200 bg-white py-1 shadow-lg dark:border-gray-700 dark:bg-gray-900"
             style={{
-              left: pos.left,
-              width: pos.width,
-              ...(pos.up ? { bottom: window.innerHeight - pos.top + 4 } : { top: pos.top + 4 }),
+              left: position.left,
+              width: position.triggerWidth,
+              top: position.topPx,
+              bottom: position.bottomPx,
             }}
           >
             {options.map((o, i) => (
-              <li key={`${o.value}-${i}`}>
-                <button
-                  type="button"
-                  role="option"
-                  aria-selected={o.value === current}
-                  disabled={o.disabled}
-                  onClick={() => pick(o.value)}
-                  className={`flex w-full items-center px-3 py-1.5 text-left ${menuTextClass[size]} transition-colors duration-150 disabled:opacity-50 ${
-                    o.value === current
-                      ? "bg-gray-100 font-medium text-gray-900 dark:bg-gray-800 dark:text-gray-100"
-                      : "text-gray-700 hover:bg-gray-100 dark:text-gray-300 dark:hover:bg-gray-800"
-                  }`}
-                >
-                  <span className="min-w-0 flex-1 truncate">{o.label}</span>
-                  {o.value === current && (
-                    <svg
-                      width="13"
-                      height="13"
-                      viewBox="0 0 24 24"
-                      fill="none"
-                      stroke="currentColor"
-                      className="shrink-0 text-gray-500 dark:text-gray-400"
-                      aria-hidden
-                    >
-                      <path
-                        d="M5 12l4 4L19 6"
-                        strokeWidth="2"
-                        strokeLinecap="round"
-                        strokeLinejoin="round"
-                      />
-                    </svg>
-                  )}
-                </button>
-              </li>
+              <button
+                key={`${o.value}-${i}`}
+                type="button"
+                role="option"
+                aria-selected={o.value === current}
+                disabled={o.disabled}
+                onClick={() => pick(o.value)}
+                className={`flex items-center ${menuRowClass} ${menuTextClass[size]} disabled:opacity-50 ${
+                  o.value === current
+                    ? "bg-gray-100 font-medium text-gray-900 dark:bg-gray-800 dark:text-gray-100"
+                    : "text-gray-700 hover:bg-gray-100 dark:text-gray-300 dark:hover:bg-gray-800"
+                }`}
+              >
+                <span className="min-w-0 flex-1 truncate">{o.label}</span>
+                {o.value === current && <CheckIcon className="text-gray-500 dark:text-gray-400" />}
+              </button>
             ))}
-          </ul>,
+          </div>,
           document.body,
         )}
     </>
   );
 
-  if (!label && !hint) return control;
   return (
-    <label className="block">
-      {label && (
-        <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-          {label}
-        </span>
-      )}
+    <Field label={label} hint={hint} error={error} errorId={errorId} required={required}>
       {control}
-      {hint && <span className="mt-1 block text-xs text-gray-500 dark:text-gray-500">{hint}</span>}
-    </label>
+    </Field>
   );
 }
diff --git a/packages/web/src/components/ui/sheet.tsx b/packages/web/src/components/ui/sheet.tsx
index e3854aa..cc15046 100644
--- a/packages/web/src/components/ui/sheet.tsx
+++ b/packages/web/src/components/ui/sheet.tsx
@@ -26,7 +26,7 @@
  */
 import { useCallback, useEffect, useLayoutEffect, useRef, useState } from "react";
 import type { PointerEvent as ReactPointerEvent, ReactNode } from "react";
-import { S } from "../../lib/strings";
+import { CloseButton } from "./icons";
 import { SPRING_DEFAULT, SPRING_MOMENTUM, createSpringDriver } from "../../lib/spring";
 import type { SpringDriver } from "../../lib/spring";
 import { nearestSnap, project, rubberband } from "../../lib/sheet-physics";
@@ -301,17 +301,7 @@ export function Sheet({ open, snap, onSnapChange, onClose, title, children }: Sh
           <div className="mx-auto mt-2 h-1 w-9 rounded-full bg-gray-300 dark:bg-gray-600" />
           <div className="flex items-center justify-between px-4 pb-2 pt-1.5">
             <span className="text-base font-semibold">{title ?? ""}</span>
-            <button
-              type="button"
-              aria-label={S.common.close}
-              onClick={onClose}
-              onPointerDown={(e) => e.stopPropagation()}
-              className="rounded-md p-1.5 text-gray-400 transition-colors duration-150 hover:bg-gray-100 hover:text-gray-600 dark:hover:bg-gray-800 dark:hover:text-gray-300"
-            >
-              <svg width="14" height="14" viewBox="0 0 14 14" fill="none" stroke="currentColor">
-                <path d="M2 2l10 10M12 2L2 12" strokeWidth="1.5" strokeLinecap="round" />
-              </svg>
-            </button>
+            <CloseButton onClose={onClose} onPointerDown={(e) => e.stopPropagation()} />
           </div>
         </div>
         <div className="min-h-0 flex-1 overflow-y-auto overscroll-contain pb-[env(safe-area-inset-bottom)]">
diff --git a/packages/web/src/components/ui/toast.tsx b/packages/web/src/components/ui/toast.tsx
index 7f6f180..1066c47 100644
--- a/packages/web/src/components/ui/toast.tsx
+++ b/packages/web/src/components/ui/toast.tsx
@@ -8,14 +8,15 @@
  * intercept mouse events (pointer-events-none) — only the toast itself is
  * interactive (clicking it dismisses immediately).
  *
- * Usage: call `toastSuccess("Saved")` / `toastError("Connection failed: ...")`
- * from anywhere, no context needed — a module-level subscriber list plus a
- * single `<Toaster />` mounted at the app root is all it takes.
+ * Usage: call `toastSuccess("Saved")` / `toastInfo("Already up to date")` /
+ * `toastError("Connection failed: ...")` from anywhere, no context needed — a
+ * module-level subscriber list plus a single `<Toaster />` mounted at the app
+ * root is all it takes.
  */
 import { useEffect, useState } from "react";
 import { createPortal } from "react-dom";
 
-type ToastKind = "success" | "error";
+type ToastKind = "success" | "error" | "info";
 
 interface ToastItem {
   id: number;
@@ -25,8 +26,8 @@ interface ToastItem {
   leaving?: boolean;
 }
 
-/** Display duration: error messages are usually longer and more important to read, so give them more time. */
-const DURATION: Record<ToastKind, number> = { success: 2500, error: 6000 };
+/** Display duration: error messages are usually longer and more important to read, so give them more time; info sits in between. */
+const DURATION: Record<ToastKind, number> = { success: 2500, info: 4000, error: 6000 };
 
 let items: ToastItem[] = [];
 let nextId = 1;
@@ -61,12 +62,14 @@ function push(kind: ToastKind, text: string): void {
 
 export const toastSuccess = (text: string): void => push("success", text);
 export const toastError = (text: string): void => push("error", text);
+export const toastInfo = (text: string): void => push("info", text);
 
 const KIND_CLASS: Record<ToastKind, string> = {
   success:
     "border-emerald-200 bg-emerald-50 text-emerald-800 dark:border-emerald-900 dark:bg-emerald-950 dark:text-emerald-200",
   error:
     "border-red-200 bg-red-50 text-red-800 dark:border-red-900 dark:bg-red-950 dark:text-red-200",
+  info: "border-sky-200 bg-sky-50 text-sky-800 dark:border-sky-900 dark:bg-sky-950 dark:text-sky-200",
 };
 
 /** Toast container: mount once at the app root. */
diff --git a/packages/web/src/features/admin/admin-users-page.tsx b/packages/web/src/features/admin/admin-users-page.tsx
index 942bbea..5e1a1d1 100644
--- a/packages/web/src/features/admin/admin-users-page.tsx
+++ b/packages/web/src/features/admin/admin-users-page.tsx
@@ -10,6 +10,7 @@ import type { UserInfo } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
 import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { USERNAME_PATTERN } from "../../lib/semantic-id";
 import { formatDateTime } from "../../lib/format";
 import { useDocumentTitle } from "../../lib/use-document-title";
@@ -34,7 +35,7 @@ export function AdminUsersPage() {
       setUsers((await api.adminListUsers()).users);
       setListError(null);
     } catch (e) {
-      setListError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setListError(apiErrorText(e));
     }
   }, []);
 
@@ -62,11 +63,11 @@ export function AdminUsersPage() {
             <table className="w-full text-sm">
               <thead>
                 <tr className="border-b border-gray-100 bg-gray-50 text-left text-xs text-gray-500 dark:border-gray-800 dark:bg-gray-900/60 dark:text-gray-400">
-                  <th className="whitespace-nowrap px-3 py-2 font-medium">{S.admin.userId}</th>
-                  <th className="whitespace-nowrap px-3 py-2 font-medium">{S.admin.role}</th>
-                  <th className="whitespace-nowrap px-3 py-2 font-medium">{S.admin.createdAt}</th>
+                  <th className="whitespace-nowrap px-3 py-2 font-medium">{S.common.username}</th>
+                  <th className="whitespace-nowrap px-3 py-2 font-medium">{S.common.role}</th>
+                  <th className="whitespace-nowrap px-3 py-2 font-medium">{S.common.created}</th>
                   <th className="whitespace-nowrap px-3 py-2 text-right font-medium">
-                    {S.admin.actions}
+                    {S.common.actions}
                   </th>
                 </tr>
               </thead>
@@ -93,7 +94,7 @@ export function AdminUsersPage() {
                       </Button>
                       {!u.isAdmin && (
                         <Button size="sm" variant="ghost" onClick={() => setDeleting(u)}>
-                          {S.admin.deleteUser}
+                          {S.common.delete}
                         </Button>
                       )}
                     </td>
@@ -138,33 +139,40 @@ function CreateUserDialog({
 }) {
   const [userId, setUserId] = useState("");
   const [password, setPassword] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  const [errors, setErrors] = useState<{ userId?: string; password?: string }>({});
   const [busy, setBusy] = useState(false);
+  const clearErrors = () => setErrors((p) => (p.userId || p.password ? {} : p));
 
   useEffect(() => {
     if (!open) return;
     setUserId("");
     setPassword("");
-    setError(null);
+    setErrors({});
   }, [open]);
 
   const submit = async () => {
     const id = userId.trim();
-    if (!id || !password) {
-      setError(S.common.requiredField);
-      return;
-    }
-    if (!USERNAME_PATTERN.test(id)) {
-      setError(S.auth.usernameHint);
+    const next: { userId?: string; password?: string } = {};
+    if (!id) next.userId = S.common.requiredField;
+    else if (!USERNAME_PATTERN.test(id)) next.userId = S.auth.usernameHint;
+    if (!password) next.password = S.common.requiredField;
+    if (next.userId || next.password) {
+      setErrors(next);
       return;
     }
     setBusy(true);
-    setError(null);
+    setErrors({});
     try {
       await api.adminCreateUser({ userId: id, password });
       onDone();
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      // Route by error code: invalid_password is about the password's strength;
+      // user_exists (and anything unrecognized) is about the id.
+      if (e instanceof ApiError && e.code === "invalid_password") {
+        setErrors({ password: apiErrorText(e) });
+      } else {
+        setErrors({ userId: apiErrorText(e) });
+      }
     } finally {
       setBusy(false);
     }
@@ -188,18 +196,28 @@ function CreateUserDialog({
     >
       <div className="space-y-3">
         <Input
-          label={S.admin.userId}
+          label={S.common.username}
+          required
           size="sm"
           value={userId}
-          onChange={(e) => setUserId(e.target.value)}
+          onChange={(e) => {
+            setUserId(e.target.value);
+            clearErrors();
+          }}
+          error={errors.userId}
           hint={S.auth.usernameHint}
           autoFocus
         />
         <PasswordInput
           label={S.admin.initialPassword}
+          required
           size="sm"
           value={password}
-          onChange={(e) => setPassword(e.target.value)}
+          onChange={(e) => {
+            setPassword(e.target.value);
+            clearErrors();
+          }}
+          error={errors.password}
           autoComplete="new-password"
           hint={S.auth.passwordHint}
         />
@@ -208,7 +226,6 @@ function CreateUserDialog({
             {S.admin.defaultProjectNote(`${userId.trim()}-default_project`)}
           </p>
         )}
-        {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
       </div>
     </Modal>
   );
@@ -216,28 +233,28 @@ function CreateUserDialog({
 
 function ResetPasswordDialog({ user, onClose }: { user: UserInfo | null; onClose: () => void }) {
   const [password, setPassword] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  const [passwordError, setPasswordError] = useState<string | undefined>(undefined);
   const [busy, setBusy] = useState(false);
 
   useEffect(() => {
     if (!user) return;
     setPassword("");
-    setError(null);
+    setPasswordError(undefined);
   }, [user]);
 
   const submit = async () => {
     if (!user) return;
     if (!password) {
-      setError(S.common.requiredField);
+      setPasswordError(S.common.requiredField);
       return;
     }
     setBusy(true);
-    setError(null);
+    setPasswordError(undefined);
     try {
       await api.adminResetPassword(user.userId, { password });
       onClose();
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setPasswordError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
@@ -262,15 +279,19 @@ function ResetPasswordDialog({ user, onClose }: { user: UserInfo | null; onClose
       <div className="space-y-3">
         <PasswordInput
           label={S.admin.initialPassword}
+          required
           size="sm"
           value={password}
-          onChange={(e) => setPassword(e.target.value)}
+          onChange={(e) => {
+            setPassword(e.target.value);
+            setPasswordError(undefined);
+          }}
+          error={passwordError}
           autoComplete="new-password"
           hint={S.auth.passwordHint}
           autoFocus
         />
         <p className="text-xs text-gray-400 dark:text-gray-500">{S.admin.resetPasswordNote}</p>
-        {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
       </div>
     </Modal>
   );
@@ -303,7 +324,7 @@ function DeleteUserDialog({
       await api.adminDeleteUser(user.userId);
       onDone();
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
diff --git a/packages/web/src/features/agents/agent-settings-page.tsx b/packages/web/src/features/agents/agent-settings-page.tsx
index c7a6bf9..f2ec1e0 100644
--- a/packages/web/src/features/agents/agent-settings-page.tsx
+++ b/packages/web/src/features/agents/agent-settings-page.tsx
@@ -21,13 +21,15 @@ import type { ToolDefinitionConfig, ToolPermission } from "@prismshadow/penguin-
 import * as api from "../../api/endpoints";
 import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useDocumentTitle } from "../../lib/use-document-title";
 import { useProject } from "../../state/project";
 import { Tabs } from "../../components/ui/tabs";
 import { Button } from "../../components/ui/button";
+import { toastError, toastInfo, toastSuccess } from "../../components/ui/toast";
 import { Input, Textarea } from "../../components/ui/input";
 import { OptionMenu, type OptionMenuChoice } from "../../components/ui/option-menu";
-import { Modal } from "../../components/ui/modal";
+import { ConfirmModal, useSaveConfirm } from "../../components/ui/confirm-modal";
 import { Skeleton } from "../../components/ui/skeleton";
 import { VaultTab } from "./vault-tab";
 import { SchedulesTab } from "./schedules-tab";
@@ -56,50 +58,6 @@ export function optionRows(
     }));
 }
 
-/**
- * OptionMenu whose pick can be explicitly rewound: the runtime menus no longer offer an
- * inherit row, so without this an accidental pick could not be backed out before saving.
- * The reset link (top-right of the label line, visible only while a value is picked) sets
- * the LOCAL edit state back to "" — the save guard skips empty values, nothing is written.
- * The unset trigger shows the (default) placeholder, matching the tools-table permission menu.
- */
-function ResettableOptionMenu({
-  label,
-  value,
-  onChange,
-  options,
-}: {
-  label: string;
-  value: string;
-  onChange: (value: string) => void;
-  options: ReadonlyArray<OptionMenuChoice<string>>;
-}) {
-  return (
-    <div className="relative">
-      <OptionMenu
-        label={label}
-        fullWidth
-        size="sm"
-        placeholder={S.agent.defaultValue}
-        value={value}
-        onChange={onChange}
-        options={options}
-      />
-      {value !== "" && (
-        <button
-          type="button"
-          title={S.agent.resetToDefault}
-          aria-label={S.agent.resetToDefault}
-          onClick={() => onChange("")}
-          className="absolute right-0 top-0 text-xs text-gray-400 transition-colors duration-150 hover:text-gray-700 dark:hover:text-gray-300"
-        >
-          {S.agent.resetToDefault}
-        </button>
-      )}
-    </div>
-  );
-}
-
 /** Numeric input's string state → number (empty/invalid = undefined, meaning no change). */
 function parseNum(s: string): number | undefined {
   const trimmed = s.trim();
@@ -131,8 +89,8 @@ export function AgentSettingsPage() {
 
   const [data, setData] = useState<AgentConfigResponse | null>(null);
   const [tab, setTab] = useState<TabKey>("overview");
+  // Only the initial config load failure renders inline (the page can't show without it); saves/imports report via toast.
   const [error, setError] = useState<string | null>(null);
-  const [notice, setNotice] = useState<string | null>(null);
 
   const load = useCallback(() => {
     if (!projectId || !agentId) return;
@@ -141,7 +99,7 @@ export function AgentSettingsPage() {
     api
       .getAgentConfig(projectId, agentId)
       .then(setData)
-      .catch((e: unknown) => setError(e instanceof ApiError ? e.message : S.common.unknownError));
+      .catch((e: unknown) => setError(apiErrorText(e)));
   }, [projectId, agentId]);
 
   useEffect(() => {
@@ -151,7 +109,7 @@ export function AgentSettingsPage() {
   /** Snapshot import succeeded: show the new version and reload the whole config (import overwrites the entire Agent State, so every tab's data needs a refresh). */
   const onImported = useCallback(
     (version: number) => {
-      setNotice(S.agent.importDone(version));
+      toastSuccess(S.agent.importDone(version));
       load();
       void reloadAgents();
     },
@@ -161,18 +119,16 @@ export function AgentSettingsPage() {
   const save = useCallback(
     async (update: AgentConfigUpdateRequest) => {
       if (!projectId || !agentId) return;
-      setError(null);
-      setNotice(null);
       try {
         const res = await api.putAgentConfig(projectId, agentId, update);
         setData(res);
-        setNotice(S.common.saved);
+        toastSuccess(S.common.saved);
         // Name/description changes affect the breadcrumb and list display.
         if (update.config?.name !== undefined || update.config?.description !== undefined) {
           void reloadAgents();
         }
       } catch (e) {
-        setError(e instanceof ApiError ? e.message : S.common.unknownError);
+        toastError(apiErrorText(e));
       }
     },
     [projectId, agentId, reloadAgents],
@@ -229,8 +185,6 @@ export function AgentSettingsPage() {
           {tab === "vault" && <VaultTab agentId={agentId} />}
           {tab === "schedules" && <SchedulesTab agentId={agentId} />}
         </div>
-        {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
-        {notice && <p className="text-xs text-emerald-600 dark:text-emerald-400">{notice}</p>}
       </div>
     </div>
   );
@@ -265,6 +219,7 @@ function OverviewTab({
   const [importError, setImportError] = useState<string | null>(null);
   // base64 of the snapshot package pending confirmation for a version conflict (409 version_conflict); non-null shows the confirm modal.
   const [conflict, setConflict] = useState<string | null>(null);
+  const { requestSave, element: saveConfirm } = useSaveConfirm();
 
   const submit = () => {
     const config: NonNullable<AgentConfigUpdateRequest["config"]> = {};
@@ -272,8 +227,11 @@ function OverviewTab({
     if (description.trim() !== (data.config.description ?? "")) {
       config.description = description.trim();
     }
-    if (Object.keys(config).length === 0) return;
-    void onSave({ config });
+    if (Object.keys(config).length === 0) {
+      toastInfo(S.common.noChangesToSave);
+      return;
+    }
+    requestSave(() => void onSave({ config }));
   };
 
   const runImport = async (dataBase64: string, confirm: boolean) => {
@@ -292,7 +250,7 @@ function OverviewTab({
         setConflict(dataBase64); // resend with confirm: true after confirming
       } else {
         setConflict(null);
-        setImportError(e instanceof ApiError ? e.message : S.common.unknownError);
+        setImportError(apiErrorText(e));
       }
     } finally {
       setImporting(false);
@@ -317,7 +275,7 @@ function OverviewTab({
     <div className="space-y-4">
       <Input
         size="sm"
-        label={S.agent.name}
+        label={S.common.name}
         value={name}
         onChange={(e) => setName(e.target.value)}
       />
@@ -381,29 +339,20 @@ function OverviewTab({
       <Button size="sm" variant="primary" onClick={submit}>
         {S.common.save}
       </Button>
+      {saveConfirm}
 
       {/* Version conflict confirmation: resend the same package with confirm: true after confirming. */}
-      <Modal
+      <ConfirmModal
         open={conflict !== null}
         title={S.agent.importConflictTitle}
+        busy={importing}
         onClose={() => setConflict(null)}
-        footer={
-          <>
-            <Button onClick={() => setConflict(null)}>{S.common.cancel}</Button>
-            <Button
-              variant="danger"
-              disabled={importing}
-              onClick={() => {
-                if (conflict !== null) void runImport(conflict, true);
-              }}
-            >
-              {S.common.confirm}
-            </Button>
-          </>
-        }
+        onConfirm={() => {
+          if (conflict !== null) void runImport(conflict, true);
+        }}
       >
         <p className="text-sm text-gray-600 dark:text-gray-300">{S.agent.importConflictBody}</p>
-      </Modal>
+      </ConfirmModal>
     </div>
   );
 }
@@ -412,13 +361,17 @@ function PromptTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
   const [agentsMd, setAgentsMd] = useState(data.agentsMd);
   const [systemPrompt, setSystemPrompt] = useState(data.config.systemPrompt);
   const promptRef = useRef<HTMLTextAreaElement>(null);
+  const { requestSave, element: saveConfirm } = useSaveConfirm();
 
   const submit = () => {
     const update: AgentConfigUpdateRequest = {};
     if (agentsMd !== data.agentsMd) update.agentsMd = agentsMd;
     if (systemPrompt !== data.config.systemPrompt) update.config = { systemPrompt };
-    if (update.agentsMd === undefined && update.config === undefined) return;
-    void onSave(update);
+    if (update.agentsMd === undefined && update.config === undefined) {
+      toastInfo(S.common.noChangesToSave);
+      return;
+    }
+    requestSave(() => void onSave(update));
   };
 
   /**
@@ -487,6 +440,7 @@ function PromptTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
       <Button size="sm" variant="primary" onClick={submit}>
         {S.common.save}
       </Button>
+      {saveConfirm}
     </div>
   );
 }
@@ -503,16 +457,18 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
   const [maxSessionTurns, setMaxSessionTurns] = useState(numToStr(cfg.compaction?.maxSessionTurns));
   const [mode, setMode] = useState(cfg.compaction?.mode ?? "");
   const [prompt, setPrompt] = useState(cfg.compaction?.prompt ?? "");
-  const [localError, setLocalError] = useState<string | null>(null);
+  const [fieldErrors, setFieldErrors] = useState<{ maxTurns?: string; timeoutMs?: string }>({});
+  const clearFieldErrors = () => setFieldErrors((p) => (p.maxTurns || p.timeoutMs ? {} : p));
+  const { requestSave, element: saveConfirm } = useSaveConfirm();
 
   const submit = () => {
-    setLocalError(null);
+    setFieldErrors({});
     const config: NonNullable<AgentConfigUpdateRequest["config"]> = {};
 
     const mt = parseNum(maxTurns);
     if (mt !== undefined && mt !== cfg.maxTurns) {
       if (mt <= 0 && mt !== -1) {
-        setLocalError(S.agent.maxTurnsInvalid);
+        setFieldErrors({ maxTurns: S.agent.maxTurnsInvalid });
         return;
       }
       config.maxTurns = mt;
@@ -527,7 +483,7 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
     const tmo = parseNum(timeoutMs);
     if (tmo !== undefined && tmo !== cfg.model?.timeoutMs) {
       if (tmo <= 0 && tmo !== -1) {
-        setLocalError(S.agent.timeoutInvalid);
+        setFieldErrors({ timeoutMs: S.agent.timeoutInvalid });
         return;
       }
       model.timeoutMs = tmo;
@@ -549,8 +505,11 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
     if (prompt !== (cfg.compaction?.prompt ?? "")) compaction.prompt = prompt;
     if (Object.keys(compaction).length > 0) config.compaction = compaction;
 
-    if (Object.keys(config).length === 0) return;
-    void onSave({ config });
+    if (Object.keys(config).length === 0) {
+      toastInfo(S.common.noChangesToSave);
+      return;
+    }
+    requestSave(() => void onSave({ config }));
   };
 
   // S is reassigned on language switch (live binding), so read it during render rather than hoisting to a module-level constant.
@@ -576,7 +535,11 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
               label={S.agent.maxTurns}
               size="sm"
               value={maxTurns}
-              onChange={(e) => setMaxTurns(e.target.value)}
+              error={fieldErrors.maxTurns}
+              onChange={(e) => {
+                setMaxTurns(e.target.value);
+                clearFieldErrors();
+              }}
               inputMode="numeric"
               className="font-mono"
             />
@@ -588,8 +551,11 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
               inputMode="numeric"
               className="font-mono"
             />
-            <ResettableOptionMenu
+            <OptionMenu
               label={S.agent.thinkingLevel}
+              fullWidth
+              size="sm"
+              placeholder={S.agent.defaultValue}
               value={thinkingLevel}
               onChange={setThinkingLevel}
               options={thinkingLevelOptions}
@@ -599,7 +565,11 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
               hint={S.agent.timeoutMsHint}
               size="sm"
               value={timeoutMs}
-              onChange={(e) => setTimeoutMs(e.target.value)}
+              error={fieldErrors.timeoutMs}
+              onChange={(e) => {
+                setTimeoutMs(e.target.value);
+                clearFieldErrors();
+              }}
               inputMode="numeric"
               className="font-mono"
             />
@@ -629,8 +599,11 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
               inputMode="numeric"
               className="font-mono"
             />
-            <ResettableOptionMenu
+            <OptionMenu
               label={S.agent.compactionMode}
+              fullWidth
+              size="sm"
+              placeholder={S.agent.defaultValue}
               value={mode}
               onChange={setMode}
               options={compactionModeOptions}
@@ -653,10 +626,10 @@ function RuntimeTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveF
         </div>
       </div>
 
-      {localError && <p className="text-xs text-red-600 dark:text-red-400">{localError}</p>}
       <Button size="sm" variant="primary" onClick={submit}>
         {S.common.save}
       </Button>
+      {saveConfirm}
     </div>
   );
 }
@@ -691,17 +664,28 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
       maxOutputLength: numToStr(t.maxOutputLength),
     })),
   );
-  const [localError, setLocalError] = useState<string | null>(null);
+  // Per-cell validation errors, keyed `${rowIndex}-${column}`, shown red under the offending numeric input.
+  const [fieldErrors, setFieldErrors] = useState<Record<string, string>>({});
+  const { requestSave, element: saveConfirm } = useSaveConfirm();
 
   const update = (index: number, patch: Partial<ToolRowState>) => {
     setRows((prev) => prev.map((r, i) => (i === index ? { ...r, ...patch } : r)));
+    setFieldErrors((p) => {
+      const kt = `${index}-timeoutMs`;
+      const km = `${index}-maxOutputLength`;
+      if (!p[kt] && !p[km]) return p;
+      const next = { ...p };
+      delete next[kt];
+      delete next[km];
+      return next;
+    });
   };
 
   const submit = () => {
-    setLocalError(null);
     // toolsBuiltin is submitted as a full table: an empty string omits that key (revert to default); non-empty values are validated per the server's rules.
+    const errs: Record<string, string> = {};
     const tools: ToolDefinitionConfig[] = [];
-    for (const row of rows) {
+    for (const [i, row] of rows.entries()) {
       const tool: ToolDefinitionConfig = { ...row.base };
       delete tool.timeoutMs;
       delete tool.maxOutputLength;
@@ -709,23 +693,41 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
       if (timeout) {
         const n = Number(timeout);
         if (!Number.isInteger(n) || (n <= 0 && n !== -1)) {
-          setLocalError(S.agent.toolFieldInvalid(row.base.name, "timeoutMs"));
-          return;
-        }
-        tool.timeoutMs = n;
+          errs[`${i}-timeoutMs`] = S.agent.toolFieldInvalid(row.base.name, "timeoutMs");
+        } else tool.timeoutMs = n;
       }
       const maxOutput = row.maxOutputLength.trim();
       if (maxOutput) {
         const n = Number(maxOutput);
         if (!Number.isInteger(n) || (n <= 0 && n !== -1)) {
-          setLocalError(S.agent.toolFieldInvalid(row.base.name, "maxOutputLength"));
-          return;
-        }
-        tool.maxOutputLength = n;
+          errs[`${i}-maxOutputLength`] = S.agent.toolFieldInvalid(row.base.name, "maxOutputLength");
+        } else tool.maxOutputLength = n;
       }
       tools.push(tool);
     }
-    void onSave({ config: { toolsBuiltin: tools } });
+    if (Object.keys(errs).length > 0) {
+      setFieldErrors(errs);
+      return;
+    }
+    setFieldErrors({});
+    // The table is submitted whole, so compare the editable columns against the loaded
+    // config to detect a no-op save (row order is stable — both sides map the same list).
+    const orig = data.config.toolsBuiltin;
+    const dirty =
+      tools.length !== orig.length ||
+      tools.some((t, i) => {
+        const o = orig[i]!;
+        return (
+          t.permission !== o.permission ||
+          t.timeoutMs !== o.timeoutMs ||
+          t.maxOutputLength !== o.maxOutputLength
+        );
+      });
+    if (!dirty) {
+      toastInfo(S.common.noChangesToSave);
+      return;
+    }
+    requestSave(() => void onSave({ config: { toolsBuiltin: tools } }));
   };
 
   return (
@@ -734,7 +736,7 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
         <table className="w-full min-w-[520px] text-left text-sm">
           <thead>
             <tr className="border-b border-gray-200 bg-gray-50/80 text-xs text-gray-500 dark:border-gray-800 dark:bg-gray-900">
-              <th className="px-3 py-2">{S.agent.toolName}</th>
+              <th className="px-3 py-2">{S.common.name}</th>
               <th className="px-3 py-2">{S.agent.toolPermission}</th>
               <th className="px-3 py-2">{S.agent.toolTimeout}</th>
               <th className="px-3 py-2">{S.agent.toolMaxOutput}</th>
@@ -743,8 +745,8 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
           <tbody>
             {rows.map((row, i) => (
               <tr key={row.base.name} className="border-b border-gray-100 dark:border-gray-800/60">
-                <td className="px-3 py-2 font-mono text-xs">{row.base.name}</td>
-                <td className="px-3 py-2">
+                <td className="px-3 py-2 align-top font-mono text-xs">{row.base.name}</td>
+                <td className="px-3 py-2 align-top">
                   <OptionMenu
                     mono
                     size="sm"
@@ -755,19 +757,21 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
                     onChange={(v) => update(i, { base: { ...row.base, permission: v } })}
                   />
                 </td>
-                <td className="px-3 py-2">
+                <td className="px-3 py-2 align-top">
                   <Input
                     size="sm"
                     value={row.timeoutMs}
+                    error={fieldErrors[`${i}-timeoutMs`]}
                     inputMode="numeric"
                     className="font-mono"
                     onChange={(e) => update(i, { timeoutMs: e.target.value })}
                   />
                 </td>
-                <td className="px-3 py-2">
+                <td className="px-3 py-2 align-top">
                   <Input
                     size="sm"
                     value={row.maxOutputLength}
+                    error={fieldErrors[`${i}-maxOutputLength`]}
                     inputMode="numeric"
                     className="font-mono"
                     onChange={(e) => update(i, { maxOutputLength: e.target.value })}
@@ -779,8 +783,6 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
         </table>
       </div>
 
-      {localError && <p className="text-xs text-red-600 dark:text-red-400">{localError}</p>}
-
       <div>
         <p className="mb-1 text-xs font-medium text-gray-500">{S.agent.mcpServers}</p>
         <pre className="max-h-64 overflow-auto rounded-md border border-gray-200 bg-gray-50 p-3 text-xs dark:border-gray-800 dark:bg-gray-900">
@@ -791,6 +793,7 @@ function ToolsTab({ data, onSave }: { data: AgentConfigResponse; onSave: SaveFn
       <Button size="sm" variant="primary" onClick={submit}>
         {S.common.save}
       </Button>
+      {saveConfirm}
     </div>
   );
 }
diff --git a/packages/web/src/features/agents/agents-page.tsx b/packages/web/src/features/agents/agents-page.tsx
index 4b734cc..4047cd3 100644
--- a/packages/web/src/features/agents/agents-page.tsx
+++ b/packages/web/src/features/agents/agents-page.tsx
@@ -15,8 +15,8 @@
 import { useState } from "react";
 import { useNavigate } from "react-router";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { SEMANTIC_ID_PATTERN } from "../../lib/semantic-id";
 import { formatDateTime, formatRelativeDays } from "../../lib/format";
 import { useDocumentTitle } from "../../lib/use-document-title";
@@ -25,6 +25,7 @@ import { agentDisplayName, useProject } from "../../state/project";
 import { Button } from "../../components/ui/button";
 import { Input, Textarea } from "../../components/ui/input";
 import { Modal } from "../../components/ui/modal";
+import { ConfirmModal } from "../../components/ui/confirm-modal";
 import { Badge } from "../../components/ui/badge";
 import { Skeleton, SkeletonCard } from "../../components/ui/skeleton";
 import { EmptyState } from "../../components/ui/empty-state";
@@ -71,7 +72,8 @@ export function AgentsPage() {
   const [agentId, setAgentId] = useState("");
   const [name, setName] = useState("");
   const [description, setDescription] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  // The id is the only validated create field; format problems and the server's duplicate-id rejection land beside it.
+  const [idError, setIdError] = useState<string | undefined>(undefined);
   const [busy, setBusy] = useState(false);
 
   /** Open the create dialog: don't keep the previous draft, always start from an empty form. */
@@ -79,7 +81,7 @@ export function AgentsPage() {
     setAgentId("");
     setName("");
     setDescription("");
-    setError(null);
+    setIdError(undefined);
     setCreateOpen(true);
   };
   /** Agent pending delete confirmation (null = none). */
@@ -92,15 +94,15 @@ export function AgentsPage() {
     if (!projectId) return;
     const id = agentId.trim();
     if (!id) {
-      setError(S.common.requiredField);
+      setIdError(S.common.requiredField);
       return;
     }
     if (!SEMANTIC_ID_PATTERN.test(id)) {
-      setError(S.agent.idHint);
+      setIdError(S.agent.idHint);
       return;
     }
     setBusy(true);
-    setError(null);
+    setIdError(undefined);
     try {
       // Name defaults to the id (leave blank to let the server fill it in from the id).
       const body: { agentId: string; name?: string; description?: string } = { agentId: id };
@@ -112,7 +114,7 @@ export function AgentsPage() {
       setCurrentAgentId(res.agent.agentId);
       navigate(`/agents/${res.agent.agentId}`);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setIdError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
@@ -139,7 +141,7 @@ export function AgentsPage() {
       setDeleting(null);
       await reloadAgents();
     } catch (e) {
-      setDeleteError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setDeleteError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
@@ -370,14 +372,19 @@ export function AgentsPage() {
         <div className="space-y-3">
           <Input
             label={S.agent.id}
+            required
             size="sm"
             value={agentId}
-            onChange={(e) => setAgentId(e.target.value)}
+            onChange={(e) => {
+              setAgentId(e.target.value);
+              setIdError(undefined);
+            }}
+            error={idError}
             hint={S.agent.idHint}
             autoFocus
           />
           <Input
-            label={S.agent.name}
+            label={S.common.name}
             size="sm"
             value={name}
             onChange={(e) => setName(e.target.value)}
@@ -390,33 +397,19 @@ export function AgentsPage() {
             value={description}
             onChange={(e) => setDescription(e.target.value)}
           />
-          {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
         </div>
       </Modal>
 
-      {/* Delete confirmation */}
-      <Modal
+      {/* Delete confirmation (shared ConfirmModal) */}
+      <ConfirmModal
         open={deleting !== null}
         title={S.agent.deleteAgent}
+        busy={busy}
         onClose={() => {
           setDeleting(null);
           setDeleteError(null);
         }}
-        footer={
-          <>
-            <Button
-              onClick={() => {
-                setDeleting(null);
-                setDeleteError(null);
-              }}
-            >
-              {S.common.cancel}
-            </Button>
-            <Button variant="danger" disabled={busy} onClick={() => void doDelete()}>
-              {S.common.confirm}
-            </Button>
-          </>
-        }
+        onConfirm={() => void doDelete()}
       >
         <p className="text-sm text-gray-600 dark:text-gray-300">
           {deleting ? S.agent.deleteConfirm(deleting.name) : ""}
@@ -424,7 +417,7 @@ export function AgentsPage() {
         {deleteError && (
           <p className="mt-2 text-xs text-red-600 dark:text-red-400">{deleteError}</p>
         )}
-      </Modal>
+      </ConfirmModal>
     </div>
   );
 }
diff --git a/packages/web/src/features/agents/schedules-tab.tsx b/packages/web/src/features/agents/schedules-tab.tsx
index 8dd528a..020a242 100644
--- a/packages/web/src/features/agents/schedules-tab.tsx
+++ b/packages/web/src/features/agents/schedules-tab.tsx
@@ -19,8 +19,8 @@ import type {
   ScheduleUpsertRequest,
 } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { formatDateTime } from "../../lib/format";
 import { useProject } from "../../state/project";
 import { providerInfo } from "@prismshadow/penguin-core/model-catalog";
@@ -29,7 +29,9 @@ import { Button } from "../../components/ui/button";
 import { Input, Textarea } from "../../components/ui/input";
 import { Select } from "../../components/ui/select";
 import { Modal } from "../../components/ui/modal";
+import { ConfirmModal } from "../../components/ui/confirm-modal";
 import { SkeletonList } from "../../components/ui/skeleton";
+import { toastError, toastInfo, toastSuccess } from "../../components/ui/toast";
 
 /** Display status → badge tone. */
 const STATUS_TONE: Record<ScheduleStatus, BadgeTone> = {
@@ -117,11 +119,20 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
   const isOwner = currentProject?.role === "owner";
 
   const [data, setData] = useState<SchedulesResponse | null>(null);
+  // Tab-level error is only the initial list load failure; row/edit actions report via toast.
   const [error, setError] = useState<string | null>(null);
-  const [notice, setNotice] = useState<string | null>(null);
   const [busy, setBusy] = useState(false);
   // Modal form: non-null means open (EMPTY_FORM for create / prefilled row for edit).
   const [form, setForm] = useState<FormState | null>(null);
+  // The form as opened — an edit submit with nothing changed reports "no changes" instead of rewriting the file.
+  const [initialForm, setInitialForm] = useState<FormState | null>(null);
+  // Per-field required errors sit next to their input; formError holds a submit rejection that isn't attributable to one field.
+  const [fieldErrors, setFieldErrors] = useState<{
+    name?: string;
+    prompt?: string;
+    startAt?: string;
+    sessionId?: string;
+  }>({});
   const [formError, setFormError] = useState<string | null>(null);
   // Name of the task pending deletion confirmation (non-null shows the confirm modal).
   const [deleting, setDeleting] = useState<string | null>(null);
@@ -135,7 +146,7 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
     try {
       setData(await api.listSchedules(projectId, agentId));
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setError(apiErrorText(e));
     }
   }, [projectId, agentId]);
 
@@ -151,27 +162,39 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
       .catch(() => setModels([]));
   }, [projectId, isOwner]);
 
-  const set = (patch: Partial<FormState>) =>
+  const set = (patch: Partial<FormState>) => {
+    setFieldErrors((p) => (p.name || p.prompt || p.startAt || p.sessionId ? {} : p));
+    setFormError((p) => (p ? null : p));
     setForm((prev) => (prev === null ? prev : { ...prev, ...patch }));
+  };
 
   const openForm = (next: FormState) => {
+    setFieldErrors({});
     setFormError(null);
     setForm(next);
+    setInitialForm(next);
   };
 
   const submit = async () => {
     if (!projectId || form === null) return;
     setFormError(null);
-    setNotice(null);
     const name = form.editing ?? form.name.trim();
     // sessionId is required in bind-to-Session mode — leaving it blank would silently downgrade to "new Session", changing the user's intended choice.
-    if (
-      !name ||
-      !form.prompt.trim() ||
-      !form.startAt ||
-      (form.target === "session" && !form.sessionId.trim())
-    ) {
-      setFormError(S.common.requiredField);
+    const next: { name?: string; prompt?: string; startAt?: string; sessionId?: string } = {};
+    if (!name) next.name = S.common.requiredField;
+    if (!form.prompt.trim()) next.prompt = S.common.requiredField;
+    if (!form.startAt) next.startAt = S.common.requiredField;
+    if (form.target === "session" && !form.sessionId.trim())
+      next.sessionId = S.common.requiredField;
+    if (next.name || next.prompt || next.startAt || next.sessionId) {
+      setFieldErrors(next);
+      return;
+    }
+    setFieldErrors({});
+    // Editing with nothing changed: report it instead of rewriting the same file (both
+    // sides are FormState built by openForm, so a field-wise JSON compare is exact).
+    if (form.editing !== null && JSON.stringify(form) === JSON.stringify(initialForm)) {
+      toastInfo(S.common.noChangesToSave);
       return;
     }
     // Empty-string keys are always omitted; target is one of two choices — sessionId is
@@ -198,11 +221,11 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
       if (form.editing !== null) await api.updateSchedule(projectId, agentId, form.editing, body);
       else await api.createSchedule(projectId, agentId, { name, ...body });
       setForm(null);
-      setNotice(S.common.saved);
+      toastSuccess(S.common.saved);
       await load();
     } catch (e) {
-      // Errors like 400 (validated with the same rules as hand-written files) land under the modal form.
-      setFormError(e instanceof ApiError ? e.message : S.common.unknownError);
+      // A 400 (validated with the same rules as hand-written files) isn't tied to one field — show it under the modal form.
+      setFormError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
@@ -212,8 +235,6 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
   const toggle = async (item: ScheduleItem) => {
     if (!projectId) return;
     setBusy(true);
-    setError(null);
-    setNotice(null);
     const model = itemModelRef(item);
     try {
       await api.updateSchedule(projectId, agentId, item.name, {
@@ -227,10 +248,10 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
         // Model reference is resent as a whole pair or not at all — never half of one.
         ...(model ? { modelId: model.modelId, provider: model.provider } : {}),
       });
-      setNotice(S.common.saved);
+      toastSuccess(S.common.saved);
       await load();
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
     } finally {
       setBusy(false);
     }
@@ -257,14 +278,12 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
   const confirmRemove = async () => {
     if (!projectId || deleting === null) return;
     setBusy(true);
-    setError(null);
-    setNotice(null);
     try {
       await api.deleteSchedule(projectId, agentId, deleting);
       if (form?.editing === deleting) setForm(null);
       await load();
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
     } finally {
       setBusy(false);
       setDeleting(null);
@@ -295,7 +314,7 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
           <table className="w-full min-w-[640px] text-left text-sm">
             <thead>
               <tr className="border-b border-gray-200 bg-gray-50/80 text-xs text-gray-500 dark:border-gray-800 dark:bg-gray-900">
-                <th className="px-3 py-2.5">{S.schedule.colName}</th>
+                <th className="px-3 py-2.5">{S.common.name}</th>
                 <th className="px-3 py-2.5">{S.schedule.colStatus}</th>
                 <th className="px-3 py-2.5">{S.schedule.colPeriod}</th>
                 <th className="px-3 py-2.5">{S.schedule.colTarget}</th>
@@ -423,8 +442,10 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
             <div className="grid grid-cols-1 gap-3 md:grid-cols-2">
               <Input
                 size="sm"
-                label={S.schedule.name}
+                label={S.common.name}
+                required
                 hint={S.schedule.nameHint}
+                error={fieldErrors.name}
                 value={form.name}
                 disabled={form.editing !== null}
                 onChange={(e) => set({ name: e.target.value })}
@@ -444,7 +465,9 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
               <Input
                 size="sm"
                 label={S.schedule.startAt}
+                required
                 type="datetime-local"
+                error={fieldErrors.startAt}
                 value={form.startAt}
                 onChange={(e) => set({ startAt: e.target.value })}
                 className="font-mono"
@@ -470,6 +493,8 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
                 <Input
                   size="sm"
                   label={S.schedule.sessionId}
+                  required
+                  error={fieldErrors.sessionId}
                   value={form.sessionId}
                   onChange={(e) => set({ sessionId: e.target.value })}
                   className="font-mono"
@@ -518,8 +543,10 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
             </div>
             <Textarea
               label={S.schedule.prompt}
+              required
               size="sm"
               rows={4}
+              error={fieldErrors.prompt}
               value={form.prompt}
               onChange={(e) => set({ prompt: e.target.value })}
             />
@@ -536,27 +563,20 @@ export function SchedulesTab({ agentId }: { agentId: string }) {
         )}
       </Modal>
 
-      {/* Delete confirmation (same pattern as Vault / Agent deletion: Modal + cancel/danger-confirm). */}
-      <Modal
+      {/* Delete confirmation (shared ConfirmModal, same pattern as Vault / Agent deletion). */}
+      <ConfirmModal
         open={deleting !== null}
         title={S.schedule.deleteTitle}
+        busy={busy}
         onClose={() => setDeleting(null)}
-        footer={
-          <>
-            <Button onClick={() => setDeleting(null)}>{S.common.cancel}</Button>
-            <Button variant="danger" disabled={busy} onClick={() => void confirmRemove()}>
-              {S.common.confirm}
-            </Button>
-          </>
-        }
+        onConfirm={() => void confirmRemove()}
       >
         <p className="text-sm text-gray-600 dark:text-gray-300">
           {deleting !== null ? S.schedule.deleteConfirm(deleting) : ""}
         </p>
-      </Modal>
+      </ConfirmModal>
 
       {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
-      {notice && <p className="text-xs text-emerald-600 dark:text-emerald-400">{notice}</p>}
     </div>
   );
 }
diff --git a/packages/web/src/features/agents/vault-tab.tsx b/packages/web/src/features/agents/vault-tab.tsx
index 2a0ac3a..0964dcb 100644
--- a/packages/web/src/features/agents/vault-tab.tsx
+++ b/packages/web/src/features/agents/vault-tab.tsx
@@ -12,14 +12,16 @@
 import { useCallback, useEffect, useState } from "react";
 import type { VaultEntryInfo, VaultUpdateRequest } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useProject } from "../../state/project";
 import { Button } from "../../components/ui/button";
 import { Input } from "../../components/ui/input";
 import { PasswordInput } from "../../components/ui/password-input";
 import { Modal } from "../../components/ui/modal";
+import { ConfirmModal } from "../../components/ui/confirm-modal";
 import { SkeletonList } from "../../components/ui/skeleton";
+import { toastError, toastSuccess } from "../../components/ui/toast";
 
 /** Vault key naming rule (consistent with core/server): shell environment variable name. */
 const VAULT_KEY_PATTERN = /^[A-Za-z_][A-Za-z0-9_]*$/;
@@ -30,16 +32,19 @@ export function VaultTab({ agentId }: { agentId: string }) {
   const isOwner = currentProject?.role === "owner";
 
   const [entries, setEntries] = useState<VaultEntryInfo[] | null>(null);
+  // Tab-level error is only the initial load failure; saves/deletes report via toast.
   const [error, setError] = useState<string | null>(null);
-  const [notice, setNotice] = useState<string | null>(null);
   const [busy, setBusy] = useState(false);
-  // Add modal: both form state and errors travel with the modal (tab-level error would be hidden behind the modal).
+  // Add modal: form state and per-field errors travel with the modal (a tab-level error would be hidden behind it).
   const [adding, setAdding] = useState(false);
   const [keyInput, setKeyInput] = useState("");
   const [valueInput, setValueInput] = useState("");
-  const [addError, setAddError] = useState<string | null>(null);
+  const [addErrors, setAddErrors] = useState<{ key?: string; value?: string }>({});
+  const clearAddErrors = () => setAddErrors((p) => (p.key || p.value ? {} : p));
   // Key pending deletion confirmation (non-null shows the confirm modal).
   const [deleting, setDeleting] = useState<string | null>(null);
+  // Existing key pending overwrite confirmation (adding a key that's already configured replaces its value).
+  const [overwriting, setOverwriting] = useState<string | null>(null);
 
   const load = useCallback(async () => {
     if (!projectId || !agentId) return;
@@ -49,7 +54,7 @@ export function VaultTab({ agentId }: { agentId: string }) {
       const res = await api.getVault(projectId, agentId);
       setEntries(res.entries);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setError(apiErrorText(e));
     }
   }, [projectId, agentId]);
 
@@ -61,14 +66,13 @@ export function VaultTab({ agentId }: { agentId: string }) {
   const persist = async (body: VaultUpdateRequest): Promise<string | null> => {
     if (!projectId || !agentId) return S.common.unknownError;
     setBusy(true);
-    setNotice(null);
     try {
       const res = await api.putVault(projectId, agentId, body);
       setEntries(res.entries);
-      setNotice(S.common.saved);
+      toastSuccess(S.common.saved);
       return null;
     } catch (e) {
-      return e instanceof ApiError ? e.message : S.common.unknownError;
+      return apiErrorText(e);
     } finally {
       setBusy(false);
     }
@@ -84,40 +88,42 @@ export function VaultTab({ agentId }: { agentId: string }) {
   const openAdd = () => {
     setKeyInput("");
     setValueInput("");
-    setAddError(null);
+    setAddErrors({});
     setAdding(true);
   };
 
   const addEntry = async () => {
     const key = keyInput.trim();
-    if (!key) {
-      setAddError(S.common.requiredField);
+    const next: { key?: string; value?: string } = {};
+    if (!key) next.key = S.common.requiredField;
+    else if (!VAULT_KEY_PATTERN.test(key)) next.key = S.vault.keyInvalid;
+    if (!valueInput) next.value = S.vault.valueRequired;
+    if (next.key || next.value) {
+      setAddErrors(next);
       return;
     }
-    if (!VAULT_KEY_PATTERN.test(key)) {
-      setAddError(S.vault.keyInvalid);
+    setAddErrors({});
+    // Submitting an already-configured key overwrites its value (unrecoverable): confirm first.
+    if (overwriting !== key && (entries ?? []).some((e) => e.key === key)) {
+      setOverwriting(key);
       return;
     }
-    if (!valueInput) {
-      setAddError(S.vault.valueRequired);
-      return;
-    }
-    setAddError(null);
+    setOverwriting(null);
     // Upsert by same key name: don't resend the existing entry too, to avoid a 400 from PUT's duplicate-key validation.
     const err = await persist({ entries: [...keepEntries(key), { key, value: valueInput }] });
     if (err !== null) {
-      setAddError(err);
+      // Server rejection (e.g. duplicate key) — surface it on the key field.
+      setAddErrors({ key: err });
       return;
     }
     setAdding(false);
   };
 
-  /** Confirm modal's "Confirm": closes the modal after deletion (on failure, the error lands on the tab's error line). */
+  /** Confirm modal's "Confirm": closes the modal after deletion; a failure pops a toast. */
   const confirmRemove = async () => {
     if (deleting === null) return;
-    setError(null);
     const err = await persist({ entries: keepEntries(deleting) });
-    if (err !== null) setError(err);
+    if (err !== null) toastError(err);
     setDeleting(null);
   };
 
@@ -200,9 +206,14 @@ export function VaultTab({ agentId }: { agentId: string }) {
           <Input
             size="sm"
             label={S.vault.key}
+            required
             hint={S.vault.keyHint}
+            error={addErrors.key}
             value={keyInput}
-            onChange={(e) => setKeyInput(e.target.value)}
+            onChange={(e) => {
+              setKeyInput(e.target.value);
+              clearAddErrors();
+            }}
             className="font-mono"
             placeholder="OPENAI_API_KEY"
             autoComplete="off"
@@ -210,39 +221,51 @@ export function VaultTab({ agentId }: { agentId: string }) {
           <PasswordInput
             size="sm"
             label={S.vault.value}
+            required
+            error={addErrors.value}
             value={valueInput}
-            onChange={(e) => setValueInput(e.target.value)}
+            onChange={(e) => {
+              setValueInput(e.target.value);
+              clearAddErrors();
+            }}
             className="font-mono"
             autoComplete="off"
             onKeyDown={(e) => {
               if (e.key === "Enter" && !busy) void addEntry();
             }}
           />
-          {addError && <p className="text-xs text-red-600 dark:text-red-400">{addError}</p>}
         </div>
       </Modal>
 
-      {/* Delete confirmation (same pattern as Agent / Session deletion: Modal + cancel/danger-confirm). */}
-      <Modal
+      {/* Overwrite confirmation: the add modal stays underneath, so cancel returns to the form. */}
+      <ConfirmModal
+        open={overwriting !== null}
+        title={S.vault.overwriteTitle}
+        tone="primary"
+        confirmLabel={S.common.save}
+        busy={busy}
+        onClose={() => setOverwriting(null)}
+        onConfirm={() => void addEntry()}
+      >
+        <p className="text-sm text-gray-600 dark:text-gray-300">
+          {overwriting !== null ? S.vault.overwriteConfirm(overwriting) : ""}
+        </p>
+      </ConfirmModal>
+
+      {/* Delete confirmation (shared ConfirmModal, same pattern as Agent / Session deletion). */}
+      <ConfirmModal
         open={deleting !== null}
         title={S.vault.deleteTitle}
+        busy={busy}
         onClose={() => setDeleting(null)}
-        footer={
-          <>
-            <Button onClick={() => setDeleting(null)}>{S.common.cancel}</Button>
-            <Button variant="danger" disabled={busy} onClick={() => void confirmRemove()}>
-              {S.common.confirm}
-            </Button>
-          </>
-        }
+        onConfirm={() => void confirmRemove()}
       >
         <p className="text-sm text-gray-600 dark:text-gray-300">
           {deleting !== null ? S.vault.deleteConfirm(deleting) : ""}
         </p>
-      </Modal>
+      </ConfirmModal>
 
       {error && <p className="text-xs text-red-600 dark:text-red-400">{error}</p>}
-      {notice && <p className="text-xs text-emerald-600 dark:text-emerald-400">{notice}</p>}
     </div>
   );
 }
diff --git a/packages/web/src/features/benchmark/benchmark-page.tsx b/packages/web/src/features/benchmark/benchmark-page.tsx
index 947c3d6..0af4a0b 100644
--- a/packages/web/src/features/benchmark/benchmark-page.tsx
+++ b/packages/web/src/features/benchmark/benchmark-page.tsx
@@ -20,8 +20,8 @@ import type {
   BenchmarkSummary,
 } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useDocumentTitle } from "../../lib/use-document-title";
 import { formatDateTime, formatMoney, formatScore, humanizeDuration } from "../../lib/format";
 import { agentDisplayName, useProject } from "../../state/project";
@@ -75,7 +75,7 @@ function AgentNode({
     api
       .listBenchmarks(projectId, agentId)
       .then((data) => setBenchmarks(data.benchmarks))
-      .catch((e: unknown) => setError(e instanceof ApiError ? e.message : S.common.unknownError));
+      .catch((e: unknown) => setError(apiErrorText(e)));
   }, [open, benchmarks, projectId, agentId]);
 
   return (
@@ -147,7 +147,7 @@ function metricLabel(metric: BenchmarkMetric): string {
   return metric === "score"
     ? S.benchmark.colScore
     : metric === "cost"
-      ? S.benchmark.colCost
+      ? S.common.cost
       : S.benchmark.colDuration;
 }
 
@@ -399,7 +399,7 @@ function EvaluationRow({
                 <tr className="text-xs text-gray-500">
                   <th className="px-2 py-1 font-medium">{S.benchmark.colCase}</th>
                   <th className="px-2 py-1 font-medium">{S.benchmark.colScore}</th>
-                  <th className="px-2 py-1 font-medium">{S.benchmark.colCost}</th>
+                  <th className="px-2 py-1 font-medium">{S.common.cost}</th>
                   <th className="px-2 py-1 font-medium">{S.benchmark.colDuration}</th>
                   <th className="px-2 py-1 font-medium">{S.benchmark.colSession}</th>
                 </tr>
@@ -565,11 +565,11 @@ export function BenchmarkPage() {
                     <table className="w-full min-w-[600px] text-left text-sm">
                       <thead>
                         <tr className="border-b border-gray-200 bg-gray-50/80 text-xs text-gray-500 dark:border-gray-800 dark:bg-gray-900">
-                          <th className="px-3 py-2.5">{S.benchmark.colTime}</th>
+                          <th className="px-3 py-2.5">{S.common.time}</th>
                           <th className="px-3 py-2.5">{S.benchmark.colVersion}</th>
                           <th className="px-3 py-2.5">{S.benchmark.colModel}</th>
                           <th className="px-3 py-2.5">{S.benchmark.colScore}</th>
-                          <th className="px-3 py-2.5">{S.benchmark.colCost}</th>
+                          <th className="px-3 py-2.5">{S.common.cost}</th>
                           <th className="px-3 py-2.5">{S.benchmark.colDuration}</th>
                         </tr>
                       </thead>
diff --git a/packages/web/src/features/chat/chat-page.tsx b/packages/web/src/features/chat/chat-page.tsx
index 48d06d9..5e2b0e2 100644
--- a/packages/web/src/features/chat/chat-page.tsx
+++ b/packages/web/src/features/chat/chat-page.tsx
@@ -26,6 +26,7 @@ import { S } from "../../lib/strings";
 import { apiErrorText } from "../../lib/api-error";
 import { useDocumentTitle } from "../../lib/use-document-title";
 import { formatDateTime, formatMoney, humanizeDuration, humanizeTokens } from "../../lib/format";
+import { latestConversation } from "../../lib/session-grouping";
 import { approvalKey } from "../../lib/omni/stream-model";
 import { useTheme } from "../../state/theme";
 import { useProject } from "../../state/project";
@@ -203,14 +204,17 @@ export function ChatPage() {
     };
   }, [draft, routeSessionId, sessionsLoading, sessions, addSession]);
 
-  // Auto-select the most recent Session when the route doesn't select one; if there are none at all, fall back to draft state (instead of auto-creating one).
+  // Auto-select the most recent conversation when the route doesn't select one (newest loaded
+  // active/schedule Session — archived rows are hidden by choice and subagent Sessions belong
+  // to their parent, so neither is auto-opened); if there is none, fall back to draft state
+  // (instead of auto-creating one).
   useEffect(() => {
     if (sessionsLoading || draft) return;
     if (routeSessionId && sessions.some((s) => s.sessionId === routeSessionId)) return;
     // A routed id missing from the paged list isn't gone until the direct lookup fails.
     if (routeSessionId && probeFailedId !== routeSessionId) return;
-    const first = sessions[0];
-    navigate(first ? `/chat/${first.sessionId}` : `/chat/${DRAFT_SESSION_ID}`, { replace: true });
+    const last = latestConversation(sessions);
+    navigate(last ? `/chat/${last.sessionId}` : `/chat/${DRAFT_SESSION_ID}`, { replace: true });
   }, [sessionsLoading, draft, routeSessionId, probeFailedId, sessions, navigate]);
 
   // Sync task_state to the sidebar list badge.
@@ -574,7 +578,7 @@ export function ChatPage() {
               <StatChip
                 icon={STAT_ICONS.cost}
                 value={`${formatMoney(sessionCost, currency)}${costUncosted ? " *" : ""}`}
-                label={`${S.chat.statCost}（${currency}）${costUncosted ? ` · ${S.usage.uncostedNote}` : ""}`}
+                label={`${S.common.cost}（${currency}）${costUncosted ? ` · ${S.usage.uncostedNote}` : ""}`}
               />
             )}
             <StatChip
@@ -660,7 +664,7 @@ export function ChatPage() {
               </div>
               <div>
                 <p className="text-xs font-medium text-gray-500 dark:text-gray-400">
-                  {S.models.createdAt}
+                  {S.common.created}
                 </p>
                 <p className="font-mono text-xs">{formatDateTime(selected.createdAt)}</p>
               </div>
@@ -672,7 +676,7 @@ export function ChatPage() {
                 <p className="font-mono text-xs">
                   {S.chat.statTokens} {humanizeTokens(totalTokens)}
                   {sessionCost != null &&
-                    ` · ${S.chat.statCost} ${formatMoney(sessionCost, currency)}`}{" "}
+                    ` · ${S.common.cost} ${formatMoney(sessionCost, currency)}`}{" "}
                   · {S.chat.statElapsed} {humanizeDuration(stream.model.stats.sessionElapsedMs)}
                 </p>
               </div>
diff --git a/packages/web/src/features/chat/draft-view.tsx b/packages/web/src/features/chat/draft-view.tsx
index 332f4b9..7f7f04e 100644
--- a/packages/web/src/features/chat/draft-view.tsx
+++ b/packages/web/src/features/chat/draft-view.tsx
@@ -39,7 +39,6 @@ import type {
   TaskInputPart,
 } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
 import { apiErrorText } from "../../lib/api-error";
 import { useAuth } from "../../state/auth";
@@ -245,7 +244,7 @@ export function DraftView({
         })
         .catch((e: unknown) => {
           setThinkingLevel(rollback);
-          toastError(e instanceof ApiError ? e.message : S.common.unknownError);
+          toastError(apiErrorText(e));
         });
     },
     [projectId, agentId],
@@ -810,7 +809,7 @@ function WorkspaceSelect({
       api
         .listDirs(projectId, abs)
         .then(setDir)
-        .catch((e: unknown) => setError(e instanceof ApiError ? e.message : S.common.unknownError))
+        .catch((e: unknown) => setError(apiErrorText(e)))
         .finally(() => setLoading(false));
     },
     [projectId],
diff --git a/packages/web/src/features/chat/message-item.tsx b/packages/web/src/features/chat/message-item.tsx
index 2708720..b09afc9 100644
--- a/packages/web/src/features/chat/message-item.tsx
+++ b/packages/web/src/features/chat/message-item.tsx
@@ -69,7 +69,7 @@ function MessageMeta({
       {text !== undefined && (
         <button
           type="button"
-          title={copied ? S.chat.copied : S.chat.copyMessage}
+          title={copied ? S.common.copied : S.chat.copyMessage}
           aria-label={S.chat.copyMessage}
           onClick={copy}
           className="rounded p-0.5 text-gray-400 transition-colors hover:bg-gray-100 hover:text-gray-600 dark:hover:bg-gray-800 dark:hover:text-gray-300"
diff --git a/packages/web/src/features/chat/task-stats-line.tsx b/packages/web/src/features/chat/task-stats-line.tsx
index 9a21083..cb482c2 100644
--- a/packages/web/src/features/chat/task-stats-line.tsx
+++ b/packages/web/src/features/chat/task-stats-line.tsx
@@ -118,7 +118,7 @@ export function TaskStatsLine({
             <StatChip
               icon={STAT_ICONS.cost}
               value={formatMoney(cost, currency)}
-              label={`${S.chat.statCost}（${currency}）`}
+              label={`${S.common.cost}（${currency}）`}
             />
           )}
           <StatChip
@@ -130,7 +130,7 @@ export function TaskStatsLine({
       )}
       <button
         type="button"
-        title={copied ? S.chat.copied : S.chat.copyReply}
+        title={copied ? S.common.copied : S.chat.copyReply}
         aria-label={S.chat.copyReply}
         onClick={copy}
         className="flex h-5 w-5 items-center justify-center rounded transition-colors duration-150 hover:bg-gray-100 hover:text-gray-600 dark:hover:bg-gray-800 dark:hover:text-gray-300"
diff --git a/packages/web/src/features/chat/workspace-browser.tsx b/packages/web/src/features/chat/workspace-browser.tsx
index 8197fc5..d9ff830 100644
--- a/packages/web/src/features/chat/workspace-browser.tsx
+++ b/packages/web/src/features/chat/workspace-browser.tsx
@@ -21,8 +21,11 @@ import * as api from "../../api/endpoints";
 import { ApiError } from "../../api/client";
 import { useAuth } from "../../state/auth";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { formatBytes, formatDateTime } from "../../lib/format";
 import { Button } from "../../components/ui/button";
+import { ConfirmModal } from "../../components/ui/confirm-modal";
+import { toastError, toastSuccess } from "../../components/ui/toast";
 import { Dropdown } from "../../components/ui/dropdown";
 import { SkeletonList } from "../../components/ui/skeleton";
 import { CodeBlock } from "./code-block";
@@ -195,8 +198,11 @@ export function WorkspaceBrowser({
   const [data, setData] = useState<WorkspaceFilesResponse | null>(null);
   const [error, setError] = useState<string | null>(null);
   const [preview, setPreview] = useState<Preview | null>(null);
-  const [notice, setNotice] = useState<string | null>(null);
   const [uploading, setUploading] = useState(false);
+  /** Picked files whose names collide with the loaded listing (non-null shows the overwrite confirm). */
+  const [pendingUpload, setPendingUpload] = useState<{ files: File[]; clashes: string[] } | null>(
+    null,
+  );
   const [reloadTick, setReloadTick] = useState(0);
   const [showPath, setShowPath] = useState(false);
   /** HTML / Markdown preview: rendered view (HTML via sandboxed iframe, Markdown via md-body) / source toggle. */
@@ -223,7 +229,6 @@ export function WorkspaceBrowser({
     setPath("");
     setPreview(null);
     setData(null);
-    setNotice(null);
   }, [session.sessionId]);
 
   // Edge-triggered refresh on the panel's hidden -> visible transition (doesn't count the initial mount: mounting itself already fetches once).
@@ -307,11 +312,8 @@ export function WorkspaceBrowser({
     void previewPath(joinPath(path, name));
   };
 
-  const onUpload = (e: ChangeEvent<HTMLInputElement>) => {
-    const files = e.target.files;
-    if (!files || files.length === 0) return;
+  const doUpload = (files: File[]) => {
     setUploading(true);
-    setNotice(null);
     setError(null);
     void (async () => {
       try {
@@ -327,15 +329,26 @@ export function WorkspaceBrowser({
           });
           await api.uploadWorkspaceFile(session.sessionId, joinPath(path, file.name), b64);
         }
-        setNotice(S.files.uploaded);
+        toastSuccess(S.files.uploaded);
         setReloadTick((t) => t + 1);
       } catch (err) {
-        setError(err instanceof ApiError ? err.message : S.common.unknownError);
+        toastError(apiErrorText(err));
       } finally {
         setUploading(false);
       }
     })();
+  };
+
+  const onUpload = (e: ChangeEvent<HTMLInputElement>) => {
+    const files = e.target.files ? [...e.target.files] : [];
     e.target.value = "";
+    if (files.length === 0) return;
+    // Uploads overwrite same-name files: names already present in the loaded listing
+    // confirm first (the picker is stashed — confirm continues, cancel drops it).
+    const existing = new Set((data?.entries ?? []).map((entry) => entry.name));
+    const clashes = files.filter((f) => existing.has(f.name)).map((f) => f.name);
+    if (clashes.length > 0) setPendingUpload({ files, clashes });
+    else doUpload(files);
   };
 
   const crumbs = path === "" ? [] : path.split("/");
@@ -693,10 +706,33 @@ export function WorkspaceBrowser({
             ))}
           </ul>
         )}
-        {notice && (
-          <p className="px-3 py-2 text-xs text-emerald-600 dark:text-emerald-400">{notice}</p>
-        )}
       </div>
+
+      {/* Upload-overwrite confirmation: same-name files in this directory get replaced. */}
+      <ConfirmModal
+        open={pendingUpload !== null}
+        title={S.files.overwriteTitle}
+        tone="primary"
+        confirmLabel={S.files.upload}
+        onClose={() => setPendingUpload(null)}
+        onConfirm={() => {
+          if (pendingUpload) doUpload(pendingUpload.files);
+          setPendingUpload(null);
+        }}
+      >
+        <div className="space-y-2">
+          <p className="text-sm text-gray-600 dark:text-gray-300">
+            {S.files.overwriteConfirm(pendingUpload?.clashes.length ?? 0)}
+          </p>
+          <ul className="max-h-40 overflow-y-auto rounded-md border border-gray-200 px-3 py-1.5 dark:border-gray-800">
+            {(pendingUpload?.clashes ?? []).map((name) => (
+              <li key={name} className="truncate py-0.5 font-mono text-xs" title={name}>
+                {name}
+              </li>
+            ))}
+          </ul>
+        </div>
+      </ConfirmModal>
     </div>
   );
 }
diff --git a/packages/web/src/features/models/models-page.tsx b/packages/web/src/features/models/models-page.tsx
index 2eeacff..6d00b94 100644
--- a/packages/web/src/features/models/models-page.tsx
+++ b/packages/web/src/features/models/models-page.tsx
@@ -39,8 +39,8 @@ import type {
   ModelUpdateEntry,
 } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useDocumentTitle } from "../../lib/use-document-title";
 import { useProject } from "../../state/project";
 import { useAuth } from "../../state/auth";
@@ -48,11 +48,13 @@ import { USD_TO_CNY, useTheme } from "../../state/theme";
 import type { Currency } from "../../state/theme";
 import { Button } from "../../components/ui/button";
 import { Input } from "../../components/ui/input";
+import { FieldError, FieldLabel } from "../../components/ui/field";
 import { PasswordInput } from "../../components/ui/password-input";
 import { Modal } from "../../components/ui/modal";
+import { ConfirmModal } from "../../components/ui/confirm-modal";
 import { Select } from "../../components/ui/select";
 import { Switch } from "../../components/ui/switch";
-import { toastError, toastSuccess } from "../../components/ui/toast";
+import { toastError, toastInfo, toastSuccess } from "../../components/ui/toast";
 import { Badge } from "../../components/ui/badge";
 import { Chevron } from "../../components/ui/chevron";
 import { GlyphIcon } from "../../components/ui/glyph-icon";
@@ -233,11 +235,6 @@ export function nextPointers(args: {
   };
 }
 
-/** Field-level error text: placed directly below the offending input (the input itself is highlighted red via Input's invalid prop). */
-function FieldError({ text }: { text: string }) {
-  return <span className="mt-1 block text-xs text-red-600 dark:text-red-400">{text}</span>;
-}
-
 /** Fields in the config dialog that can be highlighted red on error (keys match RowState field names, so they can be cleared per edit action). */
 type FieldErrors = Partial<
   Record<
@@ -383,7 +380,7 @@ export function ModelsPage() {
       setDefaultModel(res.defaultModel);
       setVisionModel(res.visionModel);
     } catch (e) {
-      setLoadError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setLoadError(apiErrorText(e));
     }
   }, [projectId]);
 
@@ -431,7 +428,7 @@ export function ModelsPage() {
       setRows(nextRows);
       if (nextDefault !== undefined) setDefaultModel(nextDefault);
       if (effectiveVision !== undefined) setVisionModel(effectiveVision);
-      toastError(e instanceof ApiError ? e.message : S.common.unknownError);
+      toastError(apiErrorText(e));
       return false;
     } finally {
       setBusy(false);
@@ -449,7 +446,7 @@ export function ModelsPage() {
     if (!rows) return;
     const merged = syncRowsWithCatalog(rows);
     if (merged.added === 0 && merged.updated === 0) {
-      toastSuccess(S.models.syncUpToDate);
+      toastInfo(S.models.syncUpToDate);
       return;
     }
     await persist(
@@ -484,7 +481,7 @@ export function ModelsPage() {
           setSpeedResults((prev) =>
             new Map(prev).set(key, {
               ok: false,
-              message: e instanceof ApiError ? e.message : S.common.unknownError,
+              message: apiErrorText(e),
             }),
           );
         }
@@ -813,6 +810,7 @@ export function ModelsPage() {
             <Input
               size="sm"
               label={S.models.groupNameLabel}
+              required
               value={groupName}
               invalid={Boolean(groupNameError)}
               onChange={(e) => {
@@ -826,7 +824,7 @@ export function ModelsPage() {
               className="font-mono"
               autoFocus
             />
-            {groupNameError && <FieldError text={groupNameError} />}
+            {groupNameError && <FieldError>{groupNameError}</FieldError>}
           </label>
           <p className="mt-2 text-xs text-gray-500 dark:text-gray-400">{S.models.addGroupDesc}</p>
         </Modal>
@@ -1121,7 +1119,7 @@ function ModelDialog({
       if (res.ok) toastSuccess(S.models.testOk(res.latencyMs ?? 0));
       else toastError(S.models.testFailed(res.message ?? ""));
     } catch (e) {
-      toastError(S.models.testFailed(e instanceof ApiError ? e.message : S.common.unknownError));
+      toastError(S.models.testFailed(apiErrorText(e)));
     } finally {
       setTesting(false);
     }
@@ -1133,6 +1131,17 @@ function ModelDialog({
    * top-level banner: it's too far from the error site, and with three price fields it's
    * hard to tell which one is wrong).
    */
+  // base URL required-field policy: an OpenAI-protocol endpoint can't be
+  // inferred — required for custom / user-defined groups and entries with an explicit
+  // openai protocol (gateway groups already have it pre-filled); optional for entries
+  // auto-routed within a first-party vendor group (the client has its own official
+  // default endpoint). Shared by validation and the label's required "*" mark.
+  const openAiLike =
+    form.clientType.trim().toLowerCase().includes("openai") ||
+    form.provider === "custom" ||
+    providerInfo(form.provider) === undefined;
+  const baseUrlRequired = !preset && openAiLike;
+
   const validated = (): RowState | null => {
     const modelId = form.modelId.trim();
     const ref: ModelRefDto = { provider: form.provider, modelId };
@@ -1143,16 +1152,7 @@ function ModelDialog({
     else if (!sameModelRef(ref, form.original) && existingRefs.some((r) => sameModelRef(r, ref))) {
       errs.modelId = S.models.modelIdExists;
     }
-    // base URL required-field policy: an OpenAI-protocol endpoint can't be
-    // inferred — required for custom / user-defined groups and entries with an explicit
-    // openai protocol (gateway groups already have it pre-filled); optional for entries
-    // auto-routed within a first-party vendor group (the client has its own official
-    // default endpoint).
-    const openAiLike =
-      form.clientType.trim().toLowerCase().includes("openai") ||
-      form.provider === "custom" ||
-      providerInfo(form.provider) === undefined;
-    if (!preset && openAiLike && !baseUrl) errs.baseUrl = S.models.baseUrlRequired;
+    if (baseUrlRequired && !baseUrl) errs.baseUrl = S.models.baseUrlRequired;
 
     // Under PUT full-table replace semantics, omitting pricing means deleting it: all three
     // prices must be either all empty or all filled, to avoid a partial entry silently
@@ -1241,6 +1241,10 @@ function ModelDialog({
         <span className="mb-1 flex items-baseline justify-between gap-2">
           <span className="text-xs font-semibold text-gray-600 dark:text-gray-400">
             {S.models.modelId}
+            {/* Required mark, hand-placed: this label row is custom (link on the right), so FieldLabel's asterisk doesn't apply. */}
+            <span className="ml-0.5 text-red-500 dark:text-red-400" aria-hidden>
+              *
+            </span>
           </span>
           <span className="flex shrink-0 items-baseline gap-2.5">
             {/* The model-homepage entry lives in the dialog header (top-right button); only the "get model ids" provider link stays here. */}
@@ -1258,6 +1262,7 @@ function ModelDialog({
         </span>
         <Input
           size="sm"
+          required
           value={form.modelId}
           disabled={!canEdit}
           invalid={Boolean(fieldErrors.modelId)}
@@ -1266,7 +1271,7 @@ function ModelDialog({
           autoFocus={isNew}
           placeholder={S.models.modelIdHint}
         />
-        {fieldErrors.modelId && <FieldError text={fieldErrors.modelId} />}
+        {fieldErrors.modelId && <FieldError>{fieldErrors.modelId}</FieldError>}
         {/* Hint when auto-routing misses (first-party provider group, adding): warns without blocking. */}
         {autoRouteMiss && (
           <span className="mt-1 block text-xs text-amber-600 dark:text-amber-400">
@@ -1346,10 +1351,26 @@ function ModelDialog({
             <Button
               variant="primary"
               onClick={() => {
-                // Validate first: if validation fails, show it via the top-level hint right away without popping the confirm dialog.
+                // Validate first: if validation fails, the inline field errors show right away without popping the confirm dialog.
                 if (!validated()) return;
-                if (isNew) submit("save");
-                else setConfirming("save");
+                if (isNew || row === null) {
+                  submit("save");
+                  return;
+                }
+                // Nothing changed: report it instead of confirming a no-op write (the
+                // baseline is rebuilt exactly like the form's initial state, so a plain
+                // JSON compare is field-exact).
+                const initial: RowState = {
+                  ...row,
+                  cacheRead: usdToInput(row.cacheRead, currency),
+                  cacheWrite: usdToInput(row.cacheWrite, currency),
+                  output: usdToInput(row.output, currency),
+                };
+                if (JSON.stringify(form) === JSON.stringify(initial)) {
+                  toastInfo(S.common.noChangesToSave);
+                  return;
+                }
+                setConfirming("save");
               }}
             >
               {S.common.confirm}
@@ -1498,7 +1519,7 @@ function ModelDialog({
             <span className="font-mono">{form.credential.apiKeyMasked}</span>
             {form.credential.createdAt && (
               <span className="text-gray-400">
-                {S.models.createdAt} {formatDateTime(form.credential.createdAt)}
+                {S.common.created} {formatDateTime(form.credential.createdAt)}
               </span>
             )}
             {canEdit && (
@@ -1514,16 +1535,20 @@ function ModelDialog({
           </div>
         )}
 
-        {/* 2) base URL */}
+        {/* 2) base URL (required for custom / user-defined groups and explicit openai protocol — see
+            baseUrlRequired). Official-protocol entries (everything except the OpenAI-protocol path)
+            carry a caution: a custom endpoint must still speak the vendor's official protocol. */}
         <Input
           size="sm"
           label={S.models.baseUrl}
+          required={baseUrlRequired}
           value={form.baseUrl}
           disabled={!canEdit}
           onChange={(e) => set({ baseUrl: e.target.value })}
           className="font-mono"
           placeholder={preset ? S.models.baseUrlHint : "https://…"}
           {...(fieldErrors.baseUrl ? { error: fieldErrors.baseUrl } : {})}
+          {...(!openAiLike ? { hint: S.models.baseUrlOfficialNote } : {})}
         />
 
         {/* 3) Context window + max output tokens side by side (one row): the "Token" unit
@@ -1536,9 +1561,7 @@ function ModelDialog({
             model stay under its window). */}
         <div className="grid grid-cols-2 items-start gap-2">
           <label className="block">
-            <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-              {S.models.contextWindow}
-            </span>
+            <FieldLabel>{S.models.contextWindow}</FieldLabel>
             <span className="relative block">
               <Input
                 size="sm"
@@ -1564,12 +1587,10 @@ function ModelDialog({
                 {S.models.tokenUnit}
               </span>
             </span>
-            {fieldErrors.contextWindow && <FieldError text={fieldErrors.contextWindow} />}
+            {fieldErrors.contextWindow && <FieldError>{fieldErrors.contextWindow}</FieldError>}
           </label>
           <label className="block">
-            <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-              {S.models.maxTokens}
-            </span>
+            <FieldLabel>{S.models.maxTokens}</FieldLabel>
             <span className="relative block">
               <Input
                 size="sm"
@@ -1587,7 +1608,7 @@ function ModelDialog({
                 {S.models.tokenUnit}
               </span>
             </span>
-            {fieldErrors.maxTokens && <FieldError text={fieldErrors.maxTokens} />}
+            {fieldErrors.maxTokens && <FieldError>{fieldErrors.maxTokens}</FieldError>}
           </label>
         </div>
 
@@ -1604,9 +1625,7 @@ function ModelDialog({
             ] as Array<[keyof FieldErrors & keyof RowState, string, string]>
           ).map(([key, label, value]) => (
             <label key={key} className="block">
-              <span className="mb-1 block text-xs font-semibold text-gray-600 dark:text-gray-400">
-                {label}
-              </span>
+              <FieldLabel>{label}</FieldLabel>
               <span className="relative block">
                 <span className="pointer-events-none absolute inset-y-0 left-2 flex items-center text-xs text-gray-400">
                   {CURRENCY_SYMBOL[currency]}
@@ -1624,7 +1643,7 @@ function ModelDialog({
                   {S.models.priceUnitShort}
                 </span>
               </span>
-              {fieldErrors[key] && <FieldError text={fieldErrors[key]} />}
+              {fieldErrors[key] && <FieldError>{fieldErrors[key]}</FieldError>}
             </label>
           ))}
         </div>
@@ -1669,30 +1688,21 @@ function ModelDialog({
 
       {/* Confirmation before writing config (save / set default / set as vision proxy model / remove): stacked on top of the config dialog. */}
       {confirming && (
-        <Modal
+        <ConfirmModal
           open
           title={CONFIRM_TITLE[confirming]()}
+          tone={confirming === "remove" ? "danger" : "primary"}
           onClose={() => setConfirming(null)}
-          footer={
-            <>
-              <Button onClick={() => setConfirming(null)}>{S.common.cancel}</Button>
-              <Button
-                variant={confirming === "remove" ? "danger" : "primary"}
-                onClick={() => {
-                  const action = confirming;
-                  setConfirming(null);
-                  submit(action);
-                }}
-              >
-                {S.common.confirm}
-              </Button>
-            </>
-          }
+          onConfirm={() => {
+            const action = confirming;
+            setConfirming(null);
+            submit(action);
+          }}
         >
           <p className="text-sm text-gray-700 dark:text-gray-300">
             {CONFIRM_BODY[confirming](form.displayName ?? form.modelId)}
           </p>
-        </Modal>
+        </ConfirmModal>
       )}
     </Modal>
   );
@@ -1733,6 +1743,7 @@ function GroupKeyDialog({
         <Input
           size="sm"
           label={S.models.apiKey}
+          required
           type="password"
           value={key}
           onChange={(e) => setKey(e.target.value)}
diff --git a/packages/web/src/features/skills/skills-page.tsx b/packages/web/src/features/skills/skills-page.tsx
index 73d8d67..76c7e9b 100644
--- a/packages/web/src/features/skills/skills-page.tsx
+++ b/packages/web/src/features/skills/skills-page.tsx
@@ -17,10 +17,12 @@
  * localizedShortText), and groups have no description. Icon buttons for
  * actions (copy goes into aria-label and title) —
  * - Rotate "update installs" (shown only when some Agent's installed copy has
- *   a lower version than the library): one click reinstalls the current
- *   library copy on every outdated Agent (install-again-is-update semantics),
- *   with a single success toast; the manage-installs Modal marks outdated
- *   rows with an accent "更新"/"Update" button doing the same per Agent;
+ *   a lower version than the library): opens a confirm dialog (lists each
+ *   Agent's v_old → v_new and warns the overwriting reinstall drops local
+ *   edits), then reinstalls the current library copy on every outdated Agent
+ *   (install-again-is-update semantics), with a single success toast; the
+ *   manage-installs Modal marks outdated rows with an accent "更新"/"Update"
+ *   button doing the same per Agent (through the same confirm);
  * - Paper plane "quick invoke": enters /chat/new draft mode with default_agent,
  *   pre-selects the skill, and pre-fills the invocation text per UI language
  *   (zh "使用 X 技能" / en "use the X skill", overwriting any existing draft body);
@@ -47,6 +49,7 @@ import { Button } from "../../components/ui/button";
 import { Chevron } from "../../components/ui/chevron";
 import { GlyphIcon } from "../../components/ui/glyph-icon";
 import { Modal } from "../../components/ui/modal";
+import { ConfirmModal } from "../../components/ui/confirm-modal";
 import { Skeleton, SkeletonCard } from "../../components/ui/skeleton";
 import { toastError, toastSuccess } from "../../components/ui/toast";
 import { DRAFT_SESSION_ID } from "../chat/chat-page";
@@ -353,6 +356,25 @@ function SkillCard({
   const { locale } = useLocale();
   const { agents } = useProject();
   const [installOpen, setInstallOpen] = useState(false);
+  // Agents pending an update confirmation (null = none): an update is an overwriting reinstall, so it needs a confirm + a per-agent version list before it runs.
+  const [pendingUpdate, setPendingUpdate] = useState<string[] | null>(null);
+  const [updating, setUpdating] = useState(false);
+  // Agent pending an uninstall confirmation (null = none): uninstalling deletes the installed files, local edits included.
+  const [pendingUninstall, setPendingUninstall] = useState<string | null>(null);
+
+  const confirmUpdate = async () => {
+    if (!pendingUpdate) return;
+    setUpdating(true);
+    await onUpdateOutdated(skill.name, pendingUpdate);
+    setUpdating(false);
+    setPendingUpdate(null);
+  };
+
+  /** Display name of the Agent pending uninstall (falls back to the raw id below). */
+  const uninstallAgent =
+    pendingUninstall !== null ? agents.find((a) => a.agentId === pendingUninstall) : undefined;
+  const uninstallAgentName = uninstallAgent ? agentDisplayName(uninstallAgent) : undefined;
+
   let installedCount = 0;
   for (const m of installed.values()) if (m.has(skill.name)) installedCount += 1;
   const outdated = outdatedAgentIds(
@@ -416,7 +438,7 @@ function SkillCard({
             className="h-8 w-8 shrink-0 justify-center p-0"
             aria-label={`${S.skills.updateOutdated(outdated.length)} ${skill.name}`}
             title={S.skills.updateOutdated(outdated.length)}
-            onClick={() => void onUpdateOutdated(skill.name, outdated)}
+            onClick={() => setPendingUpdate(outdated)}
           >
             <GlyphIcon d={UPDATE_ICON} size={13} />
           </Button>
@@ -457,13 +479,71 @@ function SkillCard({
                 name={agentDisplayName(a)}
                 installed={installed.get(a.agentId)?.has(skill.name) ?? false}
                 outdated={outdated.includes(a.agentId)}
-                onToggle={(on) => void onToggleInstall(a.agentId, skill.name, on, skill.version)}
-                onUpdate={() => void onUpdateOutdated(skill.name, [a.agentId])}
+                onToggle={(on) => {
+                  // Install runs directly; uninstall deletes the installed files, so it confirms first.
+                  if (on) void onToggleInstall(a.agentId, skill.name, true, skill.version);
+                  else setPendingUninstall(a.agentId);
+                }}
+                onUpdate={() => setPendingUpdate([a.agentId])}
               />
             ))}
           </div>
         </Modal>
       )}
+      {pendingUpdate && (
+        <ConfirmModal
+          open
+          title={S.skills.updateConfirmTitle(skill.name)}
+          tone="primary"
+          confirmLabel={S.skills.updateAction}
+          busy={updating}
+          onClose={() => setPendingUpdate(null)}
+          onConfirm={() => void confirmUpdate()}
+        >
+          <div className="space-y-3">
+            <p className="text-sm text-gray-600 dark:text-gray-300">
+              {S.skills.updateConfirmWarning(skill.name)}
+            </p>
+            {/* Per-agent old → new version, so it's clear exactly which installs get overwritten. */}
+            <ul className="divide-y divide-gray-100 overflow-hidden rounded-md border border-gray-200 dark:divide-gray-800 dark:border-gray-800">
+              {pendingUpdate.map((agentId) => {
+                const oldVersion = installed.get(agentId)?.get(skill.name);
+                const target = agents.find((a) => a.agentId === agentId);
+                return (
+                  <li
+                    key={agentId}
+                    className="flex items-center justify-between gap-3 px-3 py-1.5 text-xs"
+                  >
+                    <span className="min-w-0 truncate">
+                      {target ? agentDisplayName(target) : agentId}
+                    </span>
+                    <span className="shrink-0 font-mono text-gray-500 dark:text-gray-400">
+                      v{oldVersion ?? "?"} → v{skill.version}
+                    </span>
+                  </li>
+                );
+              })}
+            </ul>
+          </div>
+        </ConfirmModal>
+      )}
+      {pendingUninstall !== null && (
+        <ConfirmModal
+          open
+          title={S.skills.uninstallConfirmTitle(skill.name)}
+          confirmLabel={S.skills.uninstall}
+          onClose={() => setPendingUninstall(null)}
+          onConfirm={() => {
+            const agentId = pendingUninstall;
+            setPendingUninstall(null);
+            void onToggleInstall(agentId, skill.name, false, skill.version);
+          }}
+        >
+          <p className="text-sm text-gray-600 dark:text-gray-300">
+            {S.skills.uninstallConfirmBody(skill.name, uninstallAgentName ?? pendingUninstall)}
+          </p>
+        </ConfirmModal>
+      )}
     </div>
   );
 }
diff --git a/packages/web/src/features/traces/trace-file-view.tsx b/packages/web/src/features/traces/trace-file-view.tsx
index a72eec1..7da3821 100644
--- a/packages/web/src/features/traces/trace-file-view.tsx
+++ b/packages/web/src/features/traces/trace-file-view.tsx
@@ -31,8 +31,8 @@ import type {
   TraceToolSpan,
 } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import {
   cacheHitRate,
   computeTps,
@@ -209,7 +209,7 @@ export function TraceFileView({
         setModels(m);
       })
       .catch((err: unknown) => {
-        if (!cancelled) setError(err instanceof ApiError ? err.message : S.common.unknownError);
+        if (!cancelled) setError(apiErrorText(err));
       });
     return () => {
       cancelled = true;
@@ -425,7 +425,7 @@ export function TraceFileView({
           {/* Duration · cost · TPS (cost above duration, same order as the conversation page's stats row). */}
           <div>
             <SummaryRow
-              label={S.chat.statCost}
+              label={S.common.cost}
               value={formatMoney(costOf(global.buckets), currency)}
             />
             <SummaryRow
@@ -497,7 +497,7 @@ export function TraceFileView({
                 <StatChip
                   icon={STAT_ICONS.cost}
                   value={formatMoney(costOf(tokens), currency)}
-                  label={`${S.chat.statCost}（${currency}）`}
+                  label={`${S.common.cost}（${currency}）`}
                 />
                 <StatChip
                   icon={STAT_ICONS.elapsed}
diff --git a/packages/web/src/features/traces/traces-page.tsx b/packages/web/src/features/traces/traces-page.tsx
index a01834a..3659b48 100644
--- a/packages/web/src/features/traces/traces-page.tsx
+++ b/packages/web/src/features/traces/traces-page.tsx
@@ -9,8 +9,8 @@ import { useEffect, useRef, useState } from "react";
 import { useSearchParams } from "react-router";
 import type { AgentTracesResponse } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useDocumentTitle } from "../../lib/use-document-title";
 import { formatBytes } from "../../lib/format";
 import { agentDisplayName, useProject } from "../../state/project";
@@ -91,7 +91,7 @@ function AgentNode({
     api
       .getAgentTraces(projectId, agentId)
       .then((data) => setGroups(flattenSessions(data)))
-      .catch((e: unknown) => setError(e instanceof ApiError ? e.message : S.common.unknownError));
+      .catch((e: unknown) => setError(apiErrorText(e)));
   }, [open, groups, projectId, agentId]);
 
   // The Session deep link is applied only once: it selects the target as
diff --git a/packages/web/src/features/usage/errors-panel.tsx b/packages/web/src/features/usage/errors-panel.tsx
index df91927..967bfe6 100644
--- a/packages/web/src/features/usage/errors-panel.tsx
+++ b/packages/web/src/features/usage/errors-panel.tsx
@@ -9,6 +9,7 @@
  * exceptions) is a prominent rose; expected (HttpError, business 4xx) recedes into gray.
  * The outer frame is provided by the caller's ChartCard (full width, below the four business charts).
  */
+import { useState } from "react";
 import type { UsageErrors } from "@prismshadow/penguin-server/api";
 import { S } from "../../lib/strings";
 import { formatDateTime } from "../../lib/format";
@@ -60,10 +61,23 @@ function Th({ children, className = "" }: { children: React.ReactNode; className
 
 /**
  * Error panel: stats + a recent-errors table (the server already takes the top N, newest first).
- * The table is table-fixed with in-cell truncation: a long message doesn't break the layout, and the full text goes into title.
+ * The message column shows **one line per error by default** (kept compact — an error storm can
+ * fill the table); clicking a message expands it in place to the full text (wrapping, newlines
+ * preserved — the upstream detail after the code, e.g. a provider's 402 body, is what matters),
+ * and clicking again collapses it. The full text is also in the hover title. Cells align to the
+ * top so an expanded multi-line message keeps the row tidy; the table scrolls past max height.
  */
 export function ErrorsPanel({ errors }: { errors: UsageErrors }) {
   const { total, unexpected, topCode, recent } = errors;
+  // Message rows expanded to their full text (index into `recent`); one line each by default.
+  const [expanded, setExpanded] = useState<ReadonlySet<number>>(new Set());
+  const toggle = (i: number) =>
+    setExpanded((prev) => {
+      const next = new Set(prev);
+      if (next.has(i)) next.delete(i);
+      else next.add(i);
+      return next;
+    });
 
   return (
     <div>
@@ -93,7 +107,7 @@ export function ErrorsPanel({ errors }: { errors: UsageErrors }) {
           <table className="w-full table-fixed text-xs">
             <thead className="sticky top-0 bg-white text-left text-gray-400 dark:bg-gray-900 dark:text-gray-500">
               <tr>
-                <Th className="w-32">{S.usage.errorsColTime}</Th>
+                <Th className="w-32">{S.common.time}</Th>
                 {/* Wide enough to fully fit the longest error code: a tool
                     failure's code carries the tool name (e.g. environment ·
                     tool_failed:exec_command), and truncating it would hide which tool failed. */}
@@ -110,21 +124,29 @@ export function ErrorsPanel({ errors }: { errors: UsageErrors }) {
                     key={`${e.ts}-${i}`}
                     className="border-t border-gray-100 dark:border-gray-800/60"
                   >
-                    <td className="py-1.5 pr-2 font-mono tabular-nums text-gray-400">
+                    <td className="py-1.5 pr-2 align-top font-mono tabular-nums text-gray-400">
                       {formatDateTime(e.ts)}
                     </td>
-                    <td className="py-1.5 pr-2 font-mono text-gray-500 dark:text-gray-400">
-                      <span className="block truncate" title={`${e.source} · ${e.code}`}>
+                    <td className="py-1.5 pr-2 align-top font-mono text-gray-500 dark:text-gray-400">
+                      <span className="block break-words">
                         {e.source} · {e.code}
                       </span>
                     </td>
-                    <td className="py-1.5 pr-2">
+                    <td className="py-1.5 pr-2 align-top">
                       <Badge tone={key === "unexpected" ? "red" : "gray"}>{kindLabel(key)}</Badge>
                     </td>
-                    <td className="py-1.5 text-gray-500 dark:text-gray-400">
-                      <span className="block truncate" title={e.message}>
+                    <td className="py-1.5 align-top text-gray-500 dark:text-gray-400">
+                      {/* One line by default; click to expand to the full message (wrapping), click again to collapse. */}
+                      <button
+                        type="button"
+                        title={e.message}
+                        onClick={() => toggle(i)}
+                        className={`block w-full cursor-pointer text-left transition-colors hover:text-gray-700 dark:hover:text-gray-300 ${
+                          expanded.has(i) ? "whitespace-pre-wrap break-words" : "truncate"
+                        }`}
+                      >
                         {e.message}
-                      </span>
+                      </button>
                     </td>
                   </tr>
                 );
diff --git a/packages/web/src/features/usage/usage-page.tsx b/packages/web/src/features/usage/usage-page.tsx
index 6e30806..a20a06f 100644
--- a/packages/web/src/features/usage/usage-page.tsx
+++ b/packages/web/src/features/usage/usage-page.tsx
@@ -16,8 +16,8 @@ import { useCallback, useEffect, useState } from "react";
 import { useSearchParams } from "react-router";
 import type { ModelRefDto, UsageBucket, UsageResponse } from "@prismshadow/penguin-server/api";
 import * as api from "../../api/endpoints";
-import { ApiError } from "../../api/client";
 import { S } from "../../lib/strings";
+import { apiErrorText } from "../../lib/api-error";
 import { useDocumentTitle } from "../../lib/use-document-title";
 import { formatMoney, humanizeTokens } from "../../lib/format";
 import { catalogEntryFor } from "@prismshadow/penguin-core/model-catalog";
@@ -81,7 +81,7 @@ function SummaryCard({
         <SummaryRow label={S.usage.requests} value={String(bucket.requests)} muted />
         {/* The unpriced-records asterisk sits on the word "cost" (superscript), keeping the number clean and readable; see the footer for the explanation */}
         <SummaryRow
-          label={S.usage.colCost}
+          label={S.common.cost}
           value={formatMoney(bucket.cost, currency)}
           sup={bucket.hasUncosted}
         />
@@ -159,7 +159,7 @@ export function UsagePage() {
       });
       setData(res);
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setError(apiErrorText(e));
     }
   }, [projectId, from, to, agentFilter, modelFilter?.provider, modelFilter?.modelId]);
 
diff --git a/packages/web/src/lib/api-error.ts b/packages/web/src/lib/api-error.ts
index 72a52e6..f8e65f1 100644
--- a/packages/web/src/lib/api-error.ts
+++ b/packages/web/src/lib/api-error.ts
@@ -1,8 +1,9 @@
 /**
- * API error → display text: the server's message is hardcoded in Chinese
- * (`{error:{code,message}}`), but the UI language may be English — so for any
- * error the user might actually hit, we derive localized text from **code**;
- * the server message is only a fallback for unknown codes.
+ * API error → display text: the server's `{error:{code,message}}` message is
+ * **English-only**, but the UI language may be Chinese — so for any error the
+ * user might actually hit, we derive localized text from the **code** (the two
+ * context-dependent cases below, then the S.errors.byCode table); the raw
+ * server message is only a fallback for codes we haven't mapped yet.
  */
 import { ApiError } from "../api/client";
 import { S } from "./strings";
@@ -14,12 +15,12 @@ import { S } from "./strings";
  */
 export function apiErrorText(err: unknown, ctx?: { modelId?: string }): string {
   if (!(err instanceof ApiError)) return S.common.unknownError;
-  switch (err.code) {
-    case "model_credential_missing":
-      return ctx?.modelId ? S.errors.modelCredentialMissing(ctx.modelId) : err.message;
-    case "no_default_model":
-      return S.errors.noDefaultModel;
-    default:
-      return err.message;
+  // These two need context the error body doesn't carry (the model id) / their own phrasing.
+  if (err.code === "model_credential_missing") {
+    return ctx?.modelId ? S.errors.modelCredentialMissing(ctx.modelId) : err.message;
   }
+  if (err.code === "no_default_model") return S.errors.noDefaultModel;
+  // Code → localized text; the map is a plain object, indexed by the runtime code string.
+  const byCode = S.errors.byCode as Record<string, string | undefined>;
+  return byCode[err.code] ?? err.message;
 }
diff --git a/packages/web/src/lib/session-grouping.ts b/packages/web/src/lib/session-grouping.ts
index 039bf1b..5a6c60d 100644
--- a/packages/web/src/lib/session-grouping.ts
+++ b/packages/web/src/lib/session-grouping.ts
@@ -9,7 +9,11 @@
  * those is single-use, so per-path groups would be one-session noise — they are all
  * merged into ONE trailing "temp workspaces" group instead.
  */
-import type { SessionInfo } from "@prismshadow/penguin-server/api";
+import type {
+  SessionCategory,
+  SessionCategoryCounts,
+  SessionInfo,
+} from "@prismshadow/penguin-server/api";
 
 /** Group key of the merged auto-temp group ("\0" can never appear in a filesystem path, so it never collides with a real Workspace). */
 export const TEMP_WORKSPACE_GROUP_KEY = "\0temp-workspaces";
@@ -42,11 +46,13 @@ export function workspaceLabel(workspace: string): string {
 }
 
 /**
- * Sidebar page size: sessions fetched per Agent per page, and the per-group display cap
- * step for active rows. Fetches use limit = SIDEBAR_PAGE_SIZE + 1 (see splitPage) so one
- * request both fills a page and answers "is there more" without a response-envelope change.
+ * Sidebar page size: sessions fetched per (Agent, category) per page, and the per-group
+ * display cap step for active rows — 10 conversations show by default and every "More"
+ * click reveals/loads 10 more. Fetches use limit = SIDEBAR_PAGE_SIZE + 1 (see splitPage)
+ * so one request both fills a page and answers "is there more" without a
+ * response-envelope change.
  */
-export const SIDEBAR_PAGE_SIZE = 20;
+export const SIDEBAR_PAGE_SIZE = 10;
 
 /**
  * Applies the limit+1 fetch trick: `fetched` came from a request with `limit = pageSize + 1`;
@@ -60,51 +66,103 @@ export function splitPage<T>(fetched: T[], pageSize: number): { items: T[]; hasM
 }
 
 /**
- * The distinct Agents contributing to a group that still have unfetched server pages —
- * a workspace-mode group can span Agents, so "load more" for the group fans out to every
- * contributing Agent with more (agent-mode groups are single-Agent and get 0..1 entries).
+ * The sidebar category a Session renders under — the same precedence the server's
+ * `category` list filter applies, so filtered fetching and client rendering can never
+ * disagree: archived wins regardless of `source` (archiving is an explicit user action,
+ * so the Archived folder must show everything the user put there); otherwise a Session
+ * goes to its origin's bucket, and no (or an unrecognized future) source falls through
+ * to the active user rows (visible) rather than vanishing into the wrong folder.
  */
-export function groupAgentsWithMore(
-  sessions: SessionInfo[],
-  hasMoreByAgent: ReadonlyMap<string, boolean>,
-): string[] {
-  const out: string[] = [];
-  for (const s of sessions) {
-    if (hasMoreByAgent.get(s.agentId) === true && !out.includes(s.agentId)) out.push(s.agentId);
+export function sessionCategory(s: SessionInfo): SessionCategory {
+  if (s.archived) return "archived";
+  return s.source === "subagent" || s.source === "schedule" ? s.source : "active";
+}
+
+/** The collapsed-folder categories of a group, in render order (below the active user rows). */
+export const FOLDER_CATEGORIES = ["subagent", "schedule", "archived"] as const;
+export type FolderCategory = (typeof FOLDER_CATEGORIES)[number];
+
+/**
+ * Four-way split of one sidebar group's Sessions by sessionCategory (rendered top to
+ * bottom in this order): active user rows in the group body, then the collapsed
+ * Subagents / Scheduled / Archived folders.
+ */
+export type SessionPartition = Record<SessionCategory, SessionInfo[]>;
+
+/** Partitions a group's Sessions for rendering. Input order is preserved within each part. */
+export function partitionSessions(sessions: SessionInfo[]): SessionPartition {
+  const parts: SessionPartition = { active: [], subagent: [], schedule: [], archived: [] };
+  for (const s of sessions) parts[sessionCategory(s)].push(s);
+  return parts;
+}
+
+const ALL_CATEGORIES: readonly SessionCategory[] = ["active", ...FOLDER_CATEGORIES];
+
+/** One workspace-mode group's aggregated server counts: exact totals plus which Agents hold rows of each category. */
+export interface GroupCounts {
+  totals: SessionCategoryCounts;
+  /** Per category, the Agents whose share of this group is non-zero — the fetch fan-out set for the group's folders and "More". */
+  agents: Record<SessionCategory, string[]>;
+}
+
+/**
+ * Folds the per-Agent per-Workspace-path category counts (SessionsResponse.workspaceCounts)
+ * into workspace-mode groups, keyed like groupSessionsByWorkspace (exact path; auto-temp
+ * paths merged into the temp group). The sidebar labels a group's folders and decides its
+ * "More" from its own share — never from an Agent's other Workspaces, which would
+ * advertise folders whose content lives in other groups.
+ */
+export function aggregateWorkspaceCounts(
+  byAgent: ReadonlyMap<string, Readonly<Record<string, SessionCategoryCounts>>>,
+): Map<string, GroupCounts> {
+  const out = new Map<string, GroupCounts>();
+  for (const [agentId, byWorkspace] of byAgent) {
+    for (const [workspace, counts] of Object.entries(byWorkspace)) {
+      const key = workspaceGroupKey(workspace);
+      let group = out.get(key);
+      if (!group) {
+        group = {
+          totals: { active: 0, subagent: 0, schedule: 0, archived: 0 },
+          agents: { active: [], subagent: [], schedule: [], archived: [] },
+        };
+        out.set(key, group);
+      }
+      for (const category of ALL_CATEGORIES) {
+        const n = counts[category];
+        // !(n > 0) rather than n <= 0: a missing key (undefined) must not slip through and poison the totals with NaN.
+        if (!(n > 0)) continue;
+        group.totals[category] += n;
+        // Several temp paths of one Agent fold into the temp group: dedupe.
+        if (!group.agents[category].includes(agentId)) group.agents[category].push(agentId);
+      }
+    }
   }
   return out;
 }
 
-/** Four-way split of one sidebar group's Sessions (rendered top to bottom in this order). */
-export interface SessionPartition {
-  /** User-created, not archived: rendered directly in the group body. */
-  active: SessionInfo[];
-  /** Subagent-created (`source === "subagent"`), not archived: the collapsed "Subagents" folder. */
-  subagent: SessionInfo[];
-  /** Schedule-created (`source === "schedule"`), not archived: the collapsed "Scheduled" folder. */
-  schedule: SessionInfo[];
-  /** Archived: the collapsed "Archived" folder. Archived wins — an archived Session with a `source` goes here only. */
-  archived: SessionInfo[];
-}
-
 /**
- * Partitions a group's Sessions for rendering. Classification precedence: archived wins
- * regardless of `source` (archiving is an explicit user action, so the Archived folder
- * must show everything the user put there); otherwise a Session goes to its origin's
- * bucket, and an unrecognized future source falls through to the user rows (visible,
- * with its badge) rather than vanishing into the wrong folder. The sidebar renders the
- * parts top to bottom in the interface's field order — user rows, Subagents folder,
- * Scheduled folder, Archived folder. Input order is preserved within each part.
+ * The Session the UI opens as "the last conversation" (the chat home's auto-select and
+ * the collapsed rail's entry): the newest loaded row that is a conversation of the
+ * user's own. Archived rows are hidden by choice and a subagent Session is a child of
+ * some other conversation, so neither is ever auto-opened; schedule-created runs are
+ * the user's conversations and qualify. Newest by createdAt (uniform ISO-8601 UTC, so
+ * string comparison is chronological), ties broken by sessionId — the list's ordering
+ * convention. Input order doesn't matter.
  */
-export function partitionSessions(sessions: SessionInfo[]): SessionPartition {
-  const parts: SessionPartition = { active: [], subagent: [], schedule: [], archived: [] };
+export function latestConversation(sessions: readonly SessionInfo[]): SessionInfo | null {
+  let best: SessionInfo | null = null;
   for (const s of sessions) {
-    if (s.archived) parts.archived.push(s);
-    else if (s.source === "subagent") parts.subagent.push(s);
-    else if (s.source === "schedule") parts.schedule.push(s);
-    else parts.active.push(s);
+    const category = sessionCategory(s);
+    if (category !== "active" && category !== "schedule") continue;
+    if (
+      !best ||
+      s.createdAt > best.createdAt ||
+      (s.createdAt === best.createdAt && s.sessionId > best.sessionId)
+    ) {
+      best = s;
+    }
   }
-  return parts;
+  return best;
 }
 
 export interface WorkspaceGroup {
diff --git a/packages/web/src/lib/strings-en.ts b/packages/web/src/lib/strings-en.ts
index 1d6e410..d78a659 100644
--- a/packages/web/src/lib/strings-en.ts
+++ b/packages/web/src/lib/strings-en.ts
@@ -1,7 +1,9 @@
 /**
  * English dictionary (constrained by the `Strings` type to the same shape as zh):
  * locale switching goes through state/locale.tsx.
- * Keep domain term capitalization consistent with zh — Agent, Workspace, Token, Task, etc.
+ * Keep domain terms capitalized — Workspace, Token, Task, Session, Project, Trace.
+ * "agent" is a common noun: lowercase mid-sentence, capitalized only at the start
+ * of a label/sentence or in a proper name (Agent State, AgentHub).
  */
 import type { Strings } from "./strings";
 
@@ -62,20 +64,29 @@ export const en: Strings = {
     confirm: "Confirm",
     close: "Close",
     loading: "Loading…",
-    loadMore: "Load more",
     saved: "Saved",
     saving: "Saving…",
+    /** Clicking save with nothing changed: an info toast instead of a silent no-op. */
+    noChangesToSave: "No changes to save",
+    /** Confirm-before-save dialog shared by the settings forms (writes go to server-side config files). */
+    confirmSaveTitle: "Save changes",
+    confirmSaveBody:
+      "Save these changes? They will be written to the configuration files on the server.",
     none: "(none)",
     retry: "Retry",
     unknownError: "Request failed, please try again later",
     requiredField: "This field is required",
     copied: "Copied",
-    ownerOnly: "Only the owner can modify this",
+    name: "Name",
+    username: "Username",
+    role: "Role",
+    actions: "Actions",
+    created: "Created",
+    cost: "Cost",
+    time: "Time",
   },
 
   auth: {
-    loginTitle: "Sign in to PenguinHarness",
-    username: "Username",
     usernameHint:
       "2–32 chars: starts with a lowercase letter; lowercase letters, digits and underscores only",
     password: "Password",
@@ -102,12 +113,8 @@ export const en: Strings = {
 
   admin: {
     users: "Users",
-    userId: "Username",
-    role: "Role",
     roleAdmin: "Admin",
     roleUser: "User",
-    createdAt: "Created",
-    actions: "Actions",
     createUser: "Add user",
     initialPassword: "Initial password",
     initialPasswordFlag: "initial password",
@@ -116,7 +123,6 @@ export const en: Strings = {
     resetPasswordTitle: (u: string): string => `Reset password for ${u}`,
     resetPasswordNote:
       "All sign-in sessions of this user will be revoked; they must sign in with the new password",
-    deleteUser: "Delete",
     deleteUserTitle: (u: string): string => `Delete user ${u}`,
     deleteUserConfirm: (u: string): string =>
       `This deletes user ${u} and every Project they own (including data directories). This cannot be undone.`,
@@ -136,12 +142,7 @@ export const en: Strings = {
     settingsTitle: "Project settings",
     members: "Members",
     addMember: "Add member",
-    memberUsername: "Username",
-    memberRole: "Role",
-    memberActions: "Actions",
     removeMember: "Remove",
-    owner: "owner",
-    member: "member",
     deleteProject: "Delete Project",
     deleteConfirm:
       "Delete this Project? Its directory will be removed recursively and cannot be recovered.",
@@ -158,13 +159,12 @@ export const en: Strings = {
 
   agent: {
     listTitle: "Agents",
-    create: "Create Agent",
-    createTitle: "Create Agent",
+    create: "Create agent",
+    createTitle: "Create agent",
     id: "Agent id",
     idHint:
       "2–64 chars: starts with a lowercase letter; lowercase letters, digits and underscores only. Cannot be changed later.",
-    name: "Name",
-    nameHint: "Leave empty to use the Agent id as the name",
+    nameHint: "Leave empty to use the agent id as the name",
     description: "Description",
     activeSessions: "Active Sessions",
     sessionCount: (n: number): string => `${n} session${n === 1 ? "" : "s"}`,
@@ -194,7 +194,7 @@ export const en: Strings = {
       ["{{OS_VERSION}}", "Operating system version"],
       ["{{DATE}}", "Current date"],
       ["{{CWD}}", "Absolute Workspace path"],
-      ["{{AGENT_ID}}", "Current Agent id"],
+      ["{{AGENT_ID}}", "Current agent id"],
       ["{{PROJECT_DIR}}", "Absolute Project directory (Agent State/scratchpad derive from it)"],
       ["{{SESSION_ID}}", "Current Session id"],
     ] as ReadonlyArray<readonly [string, string]>,
@@ -240,8 +240,6 @@ export const en: Strings = {
     timeoutInvalid: "timeoutMs must be > 0 or -1",
     toolFieldInvalid: (name: string, field: string) =>
       `${name}: ${field} must be a positive integer or -1`,
-    builtinTools: "Built-in tools",
-    toolName: "Name",
     toolPermission: "permission",
     permissionReadLabel: "Read-only",
     permissionReadDescription: "Only reads. Auto-approved when the approval mode is read-only.",
@@ -252,11 +250,10 @@ export const en: Strings = {
     toolMaxOutput: "maxOutputLength",
     mcpServers: "MCP Servers (read-only)",
     defaultValue: "(default)",
-    resetToDefault: "Reset to default",
-    deleteAgent: "Delete Agent",
-    builtinUndeletable: "Built-in Agents cannot be deleted",
+    deleteAgent: "Delete agent",
+    builtinUndeletable: "Built-in agents cannot be deleted",
     deleteConfirm: (name: string): string =>
-      `Delete Agent "${name}"? Its directory (including all Traces) will be removed recursively and cannot be recovered.`,
+      `Delete agent "${name}"? Its directory (including all Traces) will be removed recursively and cannot be recovered.`,
     stateVersion: "Agent State version",
     transferTitle: "Export / import",
     transferDesc:
@@ -276,11 +273,14 @@ export const en: Strings = {
     addToGroup: "Add model",
     editTitle: "Model settings",
     addTitle: "Add model (OpenAI protocol)",
-    addTitleVendor: "Add model (auto-routed by id)",
+    addTitleVendor: "Add model",
     addProtocolHint:
       "New models always use the OpenAI Chat Completions protocol (no auto-routing by model id); set the base URL to a compatible endpoint",
     addAutoRouteHint:
       "New models in this group are auto-routed by their upstream id to the vendor's official client: leave the base URL empty for the official endpoint, and an empty API key falls back to the resolved client's environment variable",
+    /** Caution beside the base URL when the entry uses a vendor's official protocol (everything except the OpenAI-protocol path). */
+    baseUrlOfficialNote:
+      "Note: this model uses the vendor's official protocol — a custom base URL must serve an endpoint compatible with it; it never switches the model to the OpenAI protocol",
     autoRouteNone:
       "AgentHub cannot auto-route this id: double-check it, or add the model under Custom / a user-defined group with the OpenAI protocol",
     addGroup: "Add group",
@@ -337,21 +337,15 @@ export const en: Strings = {
     testing: "Testing…",
     testOk: (ms: number): string => `Connected (${ms} ms)`,
     testFailed: (msg: string): string => `Failed: ${msg}`,
-    modelIdRenameHint: "Renaming migrates the existing config and API key",
     priceCacheRead: "Cache read price",
     priceCacheWrite: "Cache write price",
     priceOutput: "Output price",
-    priceUnit: "per 1M tokens",
     currency: "Currency",
     currencyUsd: "USD $",
     currencyCny: "CNY ¥",
-    currencyHint: "Prices convert at 1 USD ≈ 7 CNY; always stored in USD",
-    firstModelDefault: "Set as the default model",
-    credential: "Credential",
     apiKey: "API key",
     apiKeyKeepHint: "Leave empty to keep the current key",
     apiKeyEnvHint: (envKey: string): string => `Leave empty to use the ${envKey} env var`,
-    useEnvVar: (envKey: string): string => `env ${envKey}`,
     keyConfigured: "Key configured",
     clearApiKey: "Clear stored API key",
     baseUrl: "Custom base URL",
@@ -382,17 +376,14 @@ export const en: Strings = {
     confirmDefaultTitle: "Set as default model",
     confirmDefault: (name: string): string =>
       `Make "${name}" the default model? New sessions will use it by default.`,
-    createdAt: "Created",
     default: "Default",
     setDefault: "Set as default model",
     remove: "Delete model",
-    saveAll: "Save all",
     readOnlyHint: "Members have read-only access; only owners can change models and credentials",
     empty: "No models configured yet",
     noKey: "No key",
     showModelsWithoutKey: (n: number): string =>
       `Show model${n === 1 ? "" : "s"} without a key (${n})`,
-    pendingSave: "(pending save)",
     modelIdExists: "This model id already exists",
     pricingAllOrNone: "Fill all three prices",
     pricingInvalid: "Must be a number",
@@ -400,7 +391,7 @@ export const en: Strings = {
   },
 
   vault: {
-    desc: "Environment variables owned by this Agent (stored in agent_state/.vault.toml), injected into the environment of its shell commands (exec_command); key names are shared with the model, values never enter the model context. Subagents use their own vaults and do not inherit this one. Saved changes take effect from the next task (a task already running is unaffected).",
+    desc: "Environment variables owned by this agent (stored in agent_state/.vault.toml), injected into the environment of its shell commands (exec_command); key names are shared with the model, values never enter the model context. Subagents use their own vaults and do not inherit this one. Saved changes take effect from the next task (a task already running is unaffected).",
     key: "Name",
     value: "Value",
     valueMasked: "Value (masked)",
@@ -410,6 +401,9 @@ export const en: Strings = {
     deleteTitle: "Delete variable",
     deleteConfirm: (key: string): string =>
       `Delete variable "${key}"? Its value cannot be recovered.`,
+    overwriteTitle: "Overwrite existing variable",
+    overwriteConfirm: (key: string): string =>
+      `"${key}" already exists — saving will overwrite its value, which cannot be recovered.`,
     empty: "No variables configured yet",
     readOnlyHint: "Members are read-only; only the owner can edit the vault",
     keyHint: "Letters, digits and underscores; must not start with a digit",
@@ -420,7 +414,6 @@ export const en: Strings = {
   schedule: {
     desc: "Scheduled tasks (agent_state/schedule/*.toml): the prompt is sent to the target Session on schedule; files can also be edited by hand, and changes made here take effect immediately.",
     readOnlyHint: "Members are read-only; only the owner can modify schedules",
-    colName: "Name",
     colStatus: "Status",
     colPeriod: "Period",
     colTarget: "Target",
@@ -443,7 +436,6 @@ export const en: Strings = {
     disable: "Disable",
     addTitle: "New scheduled task",
     editTitle: (name: string): string => `Edit scheduled task "${name}"`,
-    name: "Name",
     nameHint: "The file name (without .toml); cannot be changed later",
     prompt: "Prompt",
     enabled: "Enabled",
@@ -476,12 +468,19 @@ export const en: Strings = {
     usedByAgents: (n: number): string =>
       n === 0 ? "not used yet" : n === 1 ? "used by 1 agent" : `used by ${n} agents`,
     installedToast: (skill: string, agent: string): string => `Installed ${skill} to ${agent}`,
-    updateOutdated: (n: number): string => `Update available: update ${n} Agent install(s)`,
+    updateOutdated: (n: number): string => `Update available: update ${n} agent install(s)`,
     updateAction: "Update",
+    updateConfirmTitle: (name: string): string => `Update ${name}`,
+    updateConfirmWarning: (name: string): string =>
+      `Updating ${name} reinstalls the library copy over each agent's installed files — any local edits to the installed skill are lost. Export a backup first if you need them.`,
     updatedToast: (skill: string, n: number): string =>
-      `Updated ${skill} to the latest version (${n} Agent(s))`,
+      `Updated ${skill} to the latest version (${n} agent(s))`,
     uninstalledToast: (skill: string, agent: string): string =>
       `Uninstalled ${skill} from ${agent}`,
+    /** Uninstall confirmation: removing the installed copy deletes its files (local edits included). */
+    uninstallConfirmTitle: (name: string): string => `Uninstall ${name}`,
+    uninstallConfirmBody: (skill: string, agent: string): string =>
+      `Uninstall ${skill} from ${agent}? Its installed files (local edits included) will be deleted.`,
   },
 
   chat: {
@@ -584,7 +583,6 @@ When done, open index.html in a browser and self-test once.`,
       "read-only": "Approve read-only (read-only)",
       "always-ask": "Ask every time (always-ask)",
     } as Record<string, string>,
-    statusIdle: "Idle",
     statusRunning: "Running",
     statusCompacting: "Compacting",
     pendingApprovals: (n: number) => `${n} pending approval${n > 1 ? "s" : ""}`,
@@ -593,7 +591,6 @@ When done, open index.html in a browser and self-test once.`,
     inputPlaceholderShort: "Type a message…",
     send: "Send",
     stop: "Stop",
-    compactingHint: "Compacting context, input is temporarily disabled",
     compact: "Compact context",
     approve: "Allow",
     deny: "Deny",
@@ -627,7 +624,6 @@ When done, open index.html in a browser and self-test once.`,
     infoPanel: "Session info",
     sessionStats: "Stats",
     statTokens: "Total Tokens",
-    statCost: "Cost",
     statElapsed: "Elapsed",
     statInput: "Input tokens",
     statCached: "cached",
@@ -639,7 +635,6 @@ When done, open index.html in a browser and self-test once.`,
     noSessions: "No Sessions yet",
     emptyStream: "Send a message to start the conversation",
     historyLoadFailed: "Failed to load history",
-    sessionHealed: "Session healed with a new id",
     statsLabel: "Stats",
     removeImage: "Remove image",
     openWorkspace: "Open workspace",
@@ -663,12 +658,6 @@ When done, open index.html in a browser and self-test once.`,
     handoffBack: (title?: string) =>
       title ? `Back to the original conversation: ${title}` : "Back to the original conversation",
     scheduledFrom: (name: string) => `Triggered by scheduled task "${name}"`,
-    /** Source badge on session list rows (user-created sessions have no source). */
-    sourceNames: {
-      schedule: "Scheduled",
-      subagent: "Sub",
-    } as Record<string, string>,
-    commandCompact: "/compact",
     emptyGreeting: "Start a new conversation",
     compactionRunning: (mode: string) => `Compaction in progress (${mode})…`,
     compactionDone: (mode: string) =>
@@ -678,17 +667,13 @@ When done, open index.html in a browser and self-test once.`,
     compactionFailed: (status: string) =>
       `[Compaction] ${status === "aborted" ? "aborted" : "failed"}, keeping current context`,
     unknownTool: "(unknown tool)",
-    toolCall: "Tool call",
-    workGroupTitle: "Reasoning & tools",
     workRunning: "Running",
     workDone: "Done",
     workGroupSteps: (n: number) => `${n} ${n === 1 ? "step" : "steps"}`,
     approvalWaiting: "awaiting approval",
     copyCode: "Copy code",
-    copyStats: "Copy stats",
     copyReply: "Copy reply",
     copyMessage: "Copy message",
-    copied: "Copied",
     deleteSession: "Delete chat",
     renameSession: "Rename chat",
     renameSessionLabel: "Title",
@@ -696,13 +681,13 @@ When done, open index.html in a browser and self-test once.`,
       `Delete "${title}"? Its messages and Trace will be removed permanently.`,
     archiveSession: "Archive",
     unarchiveSession: "Unarchive",
-    archivedGroup: (n: number) => `Archived (${n})`,
     /** Sidebar group "reveal/load next page" row (display cap + server paging). */
     loadMore: "More",
-    /** Sidebar folders for automation-created sessions (one per origin), parallel to Archived; wording matches the sourceNames badges. */
-    sourceGroups: {
+    /** Collapsed sidebar folders inside a group (lazy-loaded); the count is the group's exact server share. */
+    folderGroups: {
       subagent: (n: number) => `Subagents (${n})`,
       schedule: (n: number) => `Scheduled (${n})`,
+      archived: (n: number) => `Archived (${n})`,
     },
     skillsBanner: (names: string[]): string =>
       `Using skill${names.length === 1 ? "" : "s"}: ${names.join(", ")}`,
@@ -718,11 +703,12 @@ When done, open index.html in a browser and self-test once.`,
     refresh: "Refresh",
     root: "Workspace root",
     empty: "Empty directory",
-    name: "Name",
-    size: "Size",
-    modified: "Modified",
     previewUnsupported: "Preview not supported for this type; download instead",
     uploaded: "Uploaded",
+    /** Upload-overwrite confirmation: same-name files in the current directory will be replaced. */
+    overwriteTitle: "Overwrite existing files",
+    overwriteConfirm: (n: number): string =>
+      `The current directory already has ${n} file(s) with these names — uploading will overwrite:`,
     loadFailed: "Failed to load",
     previewTruncated: "File too large; preview truncated, download for the full file",
     details: "Details",
@@ -739,19 +725,16 @@ When done, open index.html in a browser and self-test once.`,
     last7d: "Last 7 days",
     total: "Total",
     tokens: "Tokens",
-    cost: "Cost",
     requests: "Requests",
     from: "From",
     to: "To",
     colCacheRead: "cache_read",
     colCacheWrite: "cache_write",
     colOutput: "output",
-    colCost: "Cost",
-    trendTitle: "30-day trend",
-    uncostedNote: "* Includes records without pricing; cost is a partial figure",
-    filterAllAgents: "All Agents",
+    uncostedNote: "* Only models with configured pricing count toward cost",
+    filterAllAgents: "All agents",
     filterAllModels: "All models",
-    chartAgentCalls: "Calls per Agent",
+    chartAgentCalls: "Calls per agent",
     chartSuccessRate: "Model success rate",
     chartTokenTrend: "Daily token trend",
     chartCostTrend: "Daily cost trend",
@@ -762,7 +745,6 @@ When done, open index.html in a browser and self-test once.`,
     errorsUnexpected: "Unexpected",
     errorsExpected: "Expected",
     errorsTopCode: "Most common",
-    errorsColTime: "Time",
     errorsColCode: "Source · code",
     errorsColKind: "Type",
     errorsColMessage: "Message",
@@ -771,15 +753,8 @@ When done, open index.html in a browser and self-test once.`,
 
   traces: {
     title: "Traces",
-    filterAll: "All",
-    filterModel: "model_msg",
-    filterEvent: "event_msg",
-    analysis: "Trajectory view",
     timeline: "Execution timeline",
     laneLLM: "Model",
-    laneTools: "Tools",
-    phaseApproval: "approval",
-    phaseExec: "exec",
     kindThinking: "thinking",
     kindModelReply: "model reply",
     kindToolGen: "tool call gen",
@@ -803,16 +778,9 @@ When done, open index.html in a browser and self-test once.`,
     taskOutput: "Output tokens this turn",
     cacheHit: "Cache hits",
     hitRate: "Hit rate",
-    toolFailRate: "failure rate",
     compactions: "compactions",
     compactionRound: "Compaction",
-    usageTrend: "Token usage trend",
-    selectFile: "Select a Trace file on the left",
-    empty: "No Traces for this Agent",
-    colTime: "Time",
-    colType: "Type",
-    colSummary: "Summary",
-    lines: (n: number) => `${n} lines`,
+    empty: "No Traces for this agent",
     inProgress: "in progress",
     systemPrompt: "System prompt",
     toolDefs: (n: number) => `Tool definitions (${n})`,
@@ -821,18 +789,16 @@ When done, open index.html in a browser and self-test once.`,
   benchmark: {
     title: "Evaluation Center",
     selectBenchmark: "Select a Benchmark on the left",
-    emptyAgent: "No Benchmarks for this Agent",
+    emptyAgent: "No Benchmarks for this agent",
     caseCount: (n: number): string => `${n} case${n === 1 ? "" : "s"}`,
     trendTitle: (metric: string): string => `${metric} over time`,
     evaluations: "Evaluations",
     noEvaluations: "No evaluations yet",
     summaryLabel: "Summary",
     legendUnlabeled: "unlabeled model",
-    colTime: "Time",
     colVersion: "Version",
     colModel: "Model",
     colScore: "Score",
-    colCost: "Cost",
     colDuration: "Duration",
     colCase: "Case",
     colRun: "Run",
@@ -840,10 +806,37 @@ When done, open index.html in a browser and self-test once.`,
   },
 
   errors: {
-    unauthorized: "Session expired, please sign in again",
     networkError: "Network error, please check your connection",
     modelCredentialMissing: (modelId: string) =>
       `Model ${modelId} has no API key yet — configure it on the Models page first`,
     noDefaultModel: "This project has no default model yet — add one on the Models page first",
+    /** Localized text for the common server error codes (server error messages are English-only); looked up by ApiError.code in apiErrorText, falling back to the raw message for unmapped codes. */
+    byCode: {
+      invalid_credentials: "Incorrect username or password.",
+      password_mismatch: "The current password is incorrect.",
+      invalid_password: "Password must be at least 8 characters.",
+      admin_required: "Only an admin can perform this operation.",
+      not_found: "This resource does not exist, or you do not have access.",
+      agent_not_found: "This agent no longer exists.",
+      agent_exists: "This agent id is already taken.",
+      project_exists: "This Project id is already taken.",
+      user_exists: "This username is already taken.",
+      user_not_found: "This user no longer exists.",
+      cannot_delete_admin: "The built-in admin cannot be deleted.",
+      member_not_found: "This user is not a member of the Project.",
+      schedule_exists: "A scheduled task with this name already exists.",
+      schedule_not_found: "This scheduled task no longer exists.",
+      unknown_skill: "This skill is not in the library.",
+      file_not_found: "This file no longer exists.",
+      file_too_large: "The file is too large.",
+      payload_too_large: "The request is too large.",
+      dir_not_absolute: "The directory must be an absolute path.",
+      not_a_dir: "That path is not a directory.",
+      path_not_found: "That path does not exist.",
+      workspace_missing: "This Session's Workspace no longer exists.",
+      task_in_progress: "This Session already has a task running.",
+      version_conflict: "The snapshot's version is not newer than the current one.",
+      invalid_title: "The title is invalid.",
+    },
   },
 };
diff --git a/packages/web/src/lib/strings.ts b/packages/web/src/lib/strings.ts
index e8c0306..5f0702f 100644
--- a/packages/web/src/lib/strings.ts
+++ b/packages/web/src/lib/strings.ts
@@ -5,7 +5,9 @@
  * state/locale.tsx, which calls `setActiveStrings` to switch and remounts the whole
  * tree keyed by locale, so `S.x` reads in components always reflect the current
  * language (module-level constants do not update on switch — keep reads inside components).
- * Keep domain terms capitalized in English — Agent, Workspace, Token, Task, etc.
+ * Keep domain terms capitalized in English — Workspace, Token, Task, Session, Project, Trace.
+ * "agent" is a common noun: lowercase mid-sentence, capitalized only at the start of a
+ * label/sentence or in a proper name (Agent State, AgentHub). zh keeps "Agent" as-is.
  */
 export const zh = {
   appName: "PenguinHarness",
@@ -63,20 +65,28 @@ export const zh = {
     confirm: "确认",
     close: "关闭",
     loading: "加载中…",
-    loadMore: "加载更多",
     saved: "已保存",
     saving: "保存中…",
+    /** Clicking save with nothing changed: an info toast instead of a silent no-op. */
+    noChangesToSave: "当前没有需要保存的修改",
+    /** Confirm-before-save dialog shared by the settings forms (writes go to server-side config files). */
+    confirmSaveTitle: "保存修改",
+    confirmSaveBody: "确定保存这些修改吗？修改将写入服务器上的配置文件。",
     none: "（无）",
     retry: "重试",
     unknownError: "请求失败，请稍后重试",
     requiredField: "此项必填",
     copied: "已复制",
-    ownerOnly: "仅 owner 可修改",
+    name: "名称",
+    username: "用户名",
+    role: "角色",
+    actions: "操作",
+    created: "创建时间",
+    cost: "成本",
+    time: "时间",
   },
 
   auth: {
-    loginTitle: "登录 PenguinHarness",
-    username: "用户名",
     usernameHint: "2~32 位：小写字母开头，仅小写字母、数字与下划线",
     password: "密码",
     passwordHint: "至少 8 个字符",
@@ -101,12 +111,8 @@ export const zh = {
 
   admin: {
     users: "用户管理",
-    userId: "用户名",
-    role: "角色",
     roleAdmin: "管理员",
     roleUser: "用户",
-    createdAt: "创建时间",
-    actions: "操作",
     createUser: "新增用户",
     initialPassword: "初始密码",
     initialPasswordFlag: "初始密码",
@@ -114,7 +120,6 @@ export const zh = {
     resetPassword: "重置密码",
     resetPasswordTitle: (u: string): string => `重置 ${u} 的密码`,
     resetPasswordNote: "重置后该用户的登录会话全部失效，需用新密码重新登录",
-    deleteUser: "删除",
     deleteUserTitle: (u: string): string => `删除用户 ${u}`,
     deleteUserConfirm: (u: string): string =>
       `将删除用户 ${u} 及其名下全部 Project（含数据目录），不可恢复。`,
@@ -132,12 +137,7 @@ export const zh = {
     settingsTitle: "Project 设置",
     members: "成员",
     addMember: "添加成员",
-    memberUsername: "用户名",
-    memberRole: "角色",
-    memberActions: "操作",
     removeMember: "移除",
-    owner: "owner",
-    member: "member",
     deleteProject: "删除 Project",
     deleteConfirm: "确认删除该 Project？项目目录将被递归删除，不可恢复。",
     deleteDefaultForbidden: "default_project 与 CLI 共用，不允许在 Web 端删除",
@@ -155,7 +155,6 @@ export const zh = {
     createTitle: "创建 Agent",
     id: "Agent id",
     idHint: "2~64 位：小写字母开头，仅小写字母、数字与下划线；创建后不可修改",
-    name: "名称",
     nameHint: "留空则使用 Agent id 作为名称",
     description: "描述",
     activeSessions: "活跃 Session",
@@ -220,8 +219,6 @@ export const zh = {
     maxTurnsInvalid: "max_turns 必须 > 0 或为 -1",
     timeoutInvalid: "timeoutMs 必须 > 0 或为 -1",
     toolFieldInvalid: (name: string, field: string) => `${name}: ${field} 必须是 > 0 的整数或 -1`,
-    builtinTools: "内置工具",
-    toolName: "名称",
     toolPermission: "permission",
     permissionReadLabel: "Read-only",
     permissionReadDescription: "仅读取。审批模式为 read-only 时自动放行，无需确认。",
@@ -232,7 +229,6 @@ export const zh = {
     mcpServers: "MCP Server（只读）",
     defaultValue: "（缺省）",
     /** Reset link next to the runtime dropdowns: rewinds the local pick back to "not overridden" (the menus offer no inherit row). */
-    resetToDefault: "恢复缺省",
     deleteAgent: "删除 Agent",
     builtinUndeletable: "内置 Agent 不可被删除",
     deleteConfirm: (name: string): string =>
@@ -254,11 +250,14 @@ export const zh = {
     addToGroup: "新增模型",
     editTitle: "模型配置",
     addTitle: "新增模型（OpenAI 协议）",
-    addTitleVendor: "新增模型（按 id 自动路由）",
+    addTitleVendor: "新增模型",
     addProtocolHint:
       "新增模型固定走 OpenAI Chat Completions 兼容协议（不按模型 id 自动路由），base URL 填其兼容端点",
     addAutoRouteHint:
       "该分组的新模型按上游 id 由 AgentHub 自动路由到厂商官方客户端：base URL 留空即官方端点，API key 留空按解析出的客户端读取环境变量",
+    /** Caution beside the base URL when the entry uses a vendor's official protocol (everything except the OpenAI-protocol path). */
+    baseUrlOfficialNote:
+      "注意：该模型走厂商官方协议——自定义 base URL 必须是兼容官方协议的端点，不会因此切换为 OpenAI 协议",
     autoRouteNone:
       "该 id 无法被 AgentHub 自动路由：请核对 id，或改在 Custom / 自建分组下以 OpenAI 协议接入",
     addGroup: "新增分组",
@@ -317,21 +316,15 @@ export const zh = {
     testing: "测试中…",
     testOk: (ms: number): string => `连通正常（${ms} ms）`,
     testFailed: (msg: string): string => `连通失败：${msg}`,
-    modelIdRenameHint: "改 id 后原配置与 API key 一并迁移",
     priceCacheRead: "缓存读取价格",
     priceCacheWrite: "缓存写入价格",
     priceOutput: "输出价格",
-    priceUnit: "每百万 Token",
     currency: "币种",
     currencyUsd: "美元 $",
     currencyCny: "人民币 ¥",
-    currencyHint: "价格按 1 美元 ≈ 7 人民币折算；存储始终为美元",
-    firstModelDefault: "已自动设为默认模型",
-    credential: "凭据",
     apiKey: "API key",
     apiKeyKeepHint: "留空保留现有 key",
     apiKeyEnvHint: (envKey: string): string => `留空则使用环境变量 ${envKey}`,
-    useEnvVar: (envKey: string): string => `环境变量 ${envKey}`,
     keyConfigured: "已配置 key",
     clearApiKey: "清除已存 API key",
     baseUrl: "自定义 base URL",
@@ -364,17 +357,14 @@ export const zh = {
     confirmDefaultTitle: "设为默认模型",
     confirmDefault: (name: string): string =>
       `确定把「${name}」设为默认模型？新建的 Session 将默认使用它。`,
-    createdAt: "创建时间",
     default: "默认",
     setDefault: "设为默认模型",
     remove: "删除模型",
-    saveAll: "保存全部",
     readOnlyHint: "member 只读；模型与 credential 修改仅 owner 可执行",
     empty: "尚未配置任何模型",
     noKey: "未配置 key",
     /** Chat model dropdown's bottom expander row: reveals the models hidden by the configured-key filter. */
     showModelsWithoutKey: (n: number): string => `显示未配置 key 的模型（${n} 个）`,
-    pendingSave: "（待保存）",
     modelIdExists: "该模型 id 已存在",
     pricingAllOrNone: "三项价格需一并填写",
     pricingInvalid: "必须为数字",
@@ -391,6 +381,8 @@ export const zh = {
     remove: "删除",
     deleteTitle: "删除环境变量",
     deleteConfirm: (key: string): string => `确认删除环境变量「${key}」？值不可恢复。`,
+    overwriteTitle: "覆盖已有环境变量",
+    overwriteConfirm: (key: string): string => `「${key}」已存在，保存将覆盖原值且不可恢复。`,
     empty: "尚未配置任何环境变量",
     readOnlyHint: "member 只读；Vault 修改仅 owner 可执行",
     keyHint: "字母、数字与下划线，不能以数字开头",
@@ -401,7 +393,6 @@ export const zh = {
   schedule: {
     desc: "定时任务（agent_state/schedule/*.toml）：到点自动向目标 Session 发送 prompt；文件亦可手工编辑，Web 端修改后即时生效。",
     readOnlyHint: "member 只读；定时任务修改仅 owner 可执行",
-    colName: "名称",
     colStatus: "状态",
     colPeriod: "周期",
     colTarget: "目标",
@@ -424,7 +415,6 @@ export const zh = {
     disable: "停用",
     addTitle: "新建定时任务",
     editTitle: (name: string): string => `编辑定时任务「${name}」`,
-    name: "名称",
     nameHint: "即文件名（不含 .toml），创建后不可改",
     prompt: "Prompt",
     enabled: "启用",
@@ -462,9 +452,16 @@ export const zh = {
     installedToast: (skill: string, agent: string): string => `已将 ${skill} 安装到 ${agent}`,
     updateOutdated: (n: number): string => `有新版本：更新 ${n} 个 Agent 的安装`,
     updateAction: "更新",
+    updateConfirmTitle: (name: string): string => `更新 ${name}`,
+    updateConfirmWarning: (name: string): string =>
+      `更新 ${name} 会把库内当前副本重装到各 Agent，覆盖其已安装的文件——对已装技能的本地改动会丢失，如有需要请先导出备份。`,
     updatedToast: (skill: string, n: number): string =>
       `已将 ${skill} 更新到最新版（${n} 个 Agent）`,
     uninstalledToast: (skill: string, agent: string): string => `已从 ${agent} 卸载 ${skill}`,
+    /** Uninstall confirmation: removing the installed copy deletes its files (local edits included). */
+    uninstallConfirmTitle: (name: string): string => `卸载 ${name}`,
+    uninstallConfirmBody: (skill: string, agent: string): string =>
+      `确定从 ${agent} 卸载 ${skill} 吗？已安装的技能文件（含本地改动）将被删除。`,
   },
 
   chat: {
@@ -494,7 +491,7 @@ export const zh = {
     draftSubtitle: "最擅长 AI 开发任务的自进化 Agent",
     /**
      * Example task cards on the draft screen: one click auto-submits the canned prompt (game
-     * card first, RAG card below/after it). These are the FULL working prompts — the README and
+     * card, then the LoL-player card, then the RAG card). These are the FULL working prompts — the README and
      * landing page show a condensed one-sentence version of the RAG example for reading, and
      * the cards' own desc lines stay short, but what actually gets submitted stays detailed:
      * build quality depends on it.
@@ -571,7 +568,6 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
       "read-only": "放行只读（read-only）",
       "always-ask": "总是询问（always-ask）",
     } as Record<string, string>,
-    statusIdle: "空闲",
     statusRunning: "运行中",
     statusCompacting: "压缩中",
     pendingApprovals: (n: number) => `${n} 个待审批`,
@@ -580,7 +576,6 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     inputPlaceholderShort: "输入消息…",
     send: "发送",
     stop: "停止",
-    compactingHint: "上下文压缩中，暂不接受新输入",
     compact: "压缩上下文",
     approve: "允许",
     deny: "拒绝",
@@ -613,7 +608,6 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     infoPanel: "Session 信息",
     sessionStats: "统计",
     statTokens: "Token 累计",
-    statCost: "成本",
     statElapsed: "用时",
     statInput: "输入 tokens",
     statCached: "已缓存",
@@ -625,7 +619,6 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     noSessions: "还没有 Session",
     emptyStream: "发送一条消息开始对话",
     historyLoadFailed: "历史消息加载失败",
-    sessionHealed: "Session 已自愈为新 id",
     statsLabel: "统计信息",
     removeImage: "移除图片",
     openWorkspace: "打开工作区",
@@ -650,12 +643,6 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     handoffFrom: (agent: string) => `由 ${agent} 的对话交接而来`,
     handoffBack: (title?: string) => (title ? `回到原对话：${title}` : "回到原对话"),
     scheduledFrom: (name: string) => `由定时任务「${name}」触发`,
-    /** Source badge on session list rows (user-created sessions have no source). */
-    sourceNames: {
-      schedule: "定时",
-      subagent: "子",
-    } as Record<string, string>,
-    commandCompact: "/compact",
     emptyGreeting: "开始一段新对话",
     compactionRunning: (mode: string) => `压缩进行中（${mode}）…`,
     compactionDone: (mode: string): string =>
@@ -663,17 +650,13 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     compactionFailed: (status: string) =>
       `[压缩] ${status === "aborted" ? "已中断" : "失败"}，保留当前上下文`,
     unknownTool: "（未知工具）",
-    toolCall: "工具调用",
-    workGroupTitle: "推理与工具",
     workRunning: "运行中",
     workDone: "运行完毕",
     workGroupSteps: (n: number) => `${n} 步`,
     approvalWaiting: "待审批",
     copyCode: "复制代码",
-    copyStats: "复制统计",
     copyReply: "复制回复",
     copyMessage: "复制消息",
-    copied: "已复制",
     deleteSession: "删除对话",
     renameSession: "重命名对话",
     renameSessionLabel: "标题",
@@ -681,13 +664,13 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
       `确定删除「${title}」？该对话的消息与 Trace 将被移除，且不可恢复。`,
     archiveSession: "归档",
     unarchiveSession: "取消归档",
-    archivedGroup: (n: number) => `已归档（${n}）`,
     /** Sidebar group "reveal/load next page" row (display cap + server paging). */
     loadMore: "更多",
-    /** Sidebar folders for automation-created sessions (one per origin), parallel to 已归档; wording matches the sourceNames badges. */
-    sourceGroups: {
+    /** Collapsed sidebar folders inside a group (lazy-loaded); the count is the group's exact server share. */
+    folderGroups: {
       subagent: (n: number) => `子智能体（${n}）`,
       schedule: (n: number) => `定时任务（${n}）`,
+      archived: (n: number) => `已归档（${n}）`,
     },
     skillsBanner: (names: string[]): string => `使用技能：${names.join("、")}`,
   },
@@ -702,11 +685,11 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     refresh: "刷新",
     root: "根目录",
     empty: "空目录",
-    name: "名称",
-    size: "大小",
-    modified: "修改时间",
     previewUnsupported: "该类型不支持预览，请下载查看",
     uploaded: "已上传",
+    /** Upload-overwrite confirmation: same-name files in the current directory will be replaced. */
+    overwriteTitle: "覆盖同名文件",
+    overwriteConfirm: (n: number): string => `当前目录已存在以下 ${n} 个同名文件，上传将覆盖：`,
     loadFailed: "加载失败",
     previewTruncated: "内容过大，预览已截断，请下载查看完整文件",
     details: "详情",
@@ -723,16 +706,13 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     last7d: "近 7 天",
     total: "累计",
     tokens: "Token",
-    cost: "成本",
     requests: "Requests",
     from: "起始日期",
     to: "结束日期",
     colCacheRead: "cache_read",
     colCacheWrite: "cache_write",
     colOutput: "output",
-    colCost: "成本",
-    trendTitle: "近 30 天趋势",
-    uncostedNote: "* 含未配置 pricing 的记录，成本为不完全统计",
+    uncostedNote: "* 只计入配置了价格的模型成本",
     filterAllAgents: "全部 Agent",
     filterAllModels: "全部模型",
     chartAgentCalls: "各 Agent 调用次数",
@@ -746,7 +726,6 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     errorsUnexpected: "未预期",
     errorsExpected: "预期内",
     errorsTopCode: "最常见",
-    errorsColTime: "时间",
     errorsColCode: "来源 · 错误码",
     errorsColKind: "类型",
     errorsColMessage: "消息",
@@ -755,15 +734,8 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
 
   traces: {
     title: "轨迹观测",
-    filterAll: "全部",
-    filterModel: "model_msg",
-    filterEvent: "event_msg",
-    analysis: "轨迹观测",
     timeline: "执行时间线",
     laneLLM: "模型",
-    laneTools: "工具",
-    phaseApproval: "审批",
-    phaseExec: "执行",
     kindThinking: "思考",
     kindModelReply: "模型回复",
     kindToolGen: "工具调用生成",
@@ -787,16 +759,9 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     taskOutput: "本轮输出 tokens",
     cacheHit: "命中缓存",
     hitRate: "命中率",
-    toolFailRate: "失败率",
     compactions: "压缩次数",
     compactionRound: "压缩",
-    usageTrend: "Token 用量趋势",
-    selectFile: "在左侧选择一个 Trace 文件",
     empty: "该 Agent 暂无 Trace",
-    colTime: "时间",
-    colType: "类型",
-    colSummary: "摘要",
-    lines: (n: number) => `${n} 行`,
     inProgress: "进行中",
     systemPrompt: "系统提示词",
     toolDefs: (n: number) => `工具定义（${n}）`,
@@ -815,11 +780,9 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
     summaryLabel: "评估说明",
     /** Chart legend: older evaluation records with no model label (gray series). */
     legendUnlabeled: "未标注模型",
-    colTime: "时间",
     colVersion: "版本",
     colModel: "模型",
     colScore: "总分",
-    colCost: "成本",
     colDuration: "耗时",
     colCase: "题目",
     colRun: "运行",
@@ -828,11 +791,38 @@ Penguin 视觉风格（见 web-design 技能），深色/浅色主题（<html da
 
   // Server error code → localized copy (the server's message is hardcoded Chinese; this is only a fallback for unknown codes).
   errors: {
-    unauthorized: "登录已过期，请重新登录",
     networkError: "网络错误，请检查连接",
     modelCredentialMissing: (modelId: string) =>
       `模型 ${modelId} 还没有可用的 API key，请先在「模型」页为它配置`,
     noDefaultModel: "该 Project 还没有默认模型，请先在「模型」页添加模型并设为默认",
+    /** Localized text for the common server error codes (server error messages are English-only); looked up by ApiError.code in apiErrorText, falling back to the raw message for unmapped codes. */
+    byCode: {
+      invalid_credentials: "用户名或密码错误。",
+      password_mismatch: "当前密码不正确。",
+      invalid_password: "密码至少 8 位。",
+      admin_required: "仅管理员可执行此操作。",
+      not_found: "资源不存在，或你没有访问权限。",
+      agent_not_found: "该 Agent 已不存在。",
+      agent_exists: "该 Agent id 已被占用。",
+      project_exists: "该 Project id 已被占用。",
+      user_exists: "该用户名已被占用。",
+      user_not_found: "该用户已不存在。",
+      cannot_delete_admin: "内置 admin 不可删除。",
+      member_not_found: "该用户不是本 Project 的成员。",
+      schedule_exists: "已存在同名定时任务。",
+      schedule_not_found: "该定时任务已不存在。",
+      unknown_skill: "该技能不在技能库中。",
+      file_not_found: "该文件已不存在。",
+      file_too_large: "文件过大。",
+      payload_too_large: "请求体过大。",
+      dir_not_absolute: "目录必须是绝对路径。",
+      not_a_dir: "该路径不是目录。",
+      path_not_found: "该路径不存在。",
+      workspace_missing: "该 Session 的 Workspace 已不存在。",
+      task_in_progress: "该 Session 已有任务在运行。",
+      version_conflict: "快照版本不高于当前版本。",
+      invalid_title: "标题无效。",
+    },
   },
 };
 
diff --git a/packages/web/src/pages/login.tsx b/packages/web/src/pages/login.tsx
index 3dfe425..81c9098 100644
--- a/packages/web/src/pages/login.tsx
+++ b/packages/web/src/pages/login.tsx
@@ -8,13 +8,13 @@
 import { useState } from "react";
 import { useNavigate } from "react-router";
 import { S } from "../lib/strings";
+import { apiErrorText } from "../lib/api-error";
 import { useDocumentTitle } from "../lib/use-document-title";
 import { useAuth } from "../state/auth";
 import { useLocale } from "../state/locale";
 import type { LangPref } from "../state/locale";
 import { useTheme } from "../state/theme";
 import type { ThemeMode } from "../state/theme";
-import { ApiError } from "../api/client";
 import { Button } from "../components/ui/button";
 import { Input } from "../components/ui/input";
 import { PasswordInput } from "../components/ui/password-input";
@@ -30,21 +30,26 @@ export function LoginPage() {
   const navigate = useNavigate();
   const [userId, setUserId] = useState("");
   const [password, setPassword] = useState("");
-  const [error, setError] = useState<string | null>(null);
+  // Per-field required errors sit next to their input; `form` holds the auth failure (wrong user/password), which isn't specific to one field.
+  const [errors, setErrors] = useState<{ userId?: string; password?: string; form?: string }>({});
   const [busy, setBusy] = useState(false);
+  const clearErrors = () => setErrors((p) => (p.userId || p.password || p.form ? {} : p));
 
   const submit = async () => {
-    if (!userId.trim() || !password) {
-      setError(S.common.requiredField);
+    const next: { userId?: string; password?: string } = {};
+    if (!userId.trim()) next.userId = S.common.requiredField;
+    if (!password) next.password = S.common.requiredField;
+    if (next.userId || next.password) {
+      setErrors(next);
       return;
     }
     setBusy(true);
-    setError(null);
+    setErrors({});
     try {
       await login(userId.trim(), password);
       navigate("/chat", { replace: true });
     } catch (e) {
-      setError(e instanceof ApiError ? e.message : S.common.unknownError);
+      setErrors({ form: apiErrorText(e) });
     } finally {
       setBusy(false);
     }
@@ -90,21 +95,31 @@ export function LoginPage() {
             }}
           >
             <Input
-              label={S.auth.username}
+              label={S.common.username}
+              required
               value={userId}
-              onChange={(e) => setUserId(e.target.value)}
+              onChange={(e) => {
+                setUserId(e.target.value);
+                clearErrors();
+              }}
+              error={errors.userId}
               autoComplete="username"
               autoFocus
             />
             <PasswordInput
               label={S.auth.password}
+              required
               value={password}
-              onChange={(e) => setPassword(e.target.value)}
+              onChange={(e) => {
+                setPassword(e.target.value);
+                clearErrors();
+              }}
+              error={errors.password}
               autoComplete="current-password"
             />
-            {error && (
+            {errors.form && (
               <p className="rounded-md border border-red-200 bg-red-50 px-3 py-2 text-xs text-red-700 dark:border-red-900 dark:bg-red-950/50 dark:text-red-300">
-                {error}
+                {errors.form}
               </p>
             )}
             <Button
diff --git a/packages/web/src/state/sessions.tsx b/packages/web/src/state/sessions.tsx
index 06ed495..1dae896 100644
--- a/packages/web/src/state/sessions.tsx
+++ b/packages/web/src/state/sessions.tsx
@@ -3,11 +3,15 @@
  * the sidebar groups by Agent, so all Agents' Sessions are loaded at once (fetched in parallel);
  * the chat page shares this same data for status sync / title events / self-healing reload.
  *
- * **Paged**: each Agent fetches SIDEBAR_PAGE_SIZE sessions per page (requesting one extra
- * to detect "has more" — see splitPage), so a Project with a long history doesn't pull
- * thousands of rows on every load; `loadMoreFor` appends the next page(s) on demand
- * (deduplicated by sessionId — new sessions shift server offsets). A reload resets every
- * Agent back to its first page.
+ * **Paged per (Agent, category)**: the default load fetches only the **active** category
+ * (user-created, non-archived) plus per-category totals — archived / subagent / schedule
+ * Sessions are not loaded until their collapsed folder is opened. Each pair fetches
+ * SIDEBAR_PAGE_SIZE sessions per page (requesting one extra to detect "has more" — see
+ * splitPage); `loadMoreFor` fetches a pair's first page when unloaded and the next page
+ * otherwise (deduplicated by sessionId — new sessions shift server offsets), so every
+ * category's paging is independent of the others. A reload resets each **loaded** pair
+ * back to its first page (an open folder must not blank on an event-triggered refresh)
+ * and leaves unopened folders unloaded.
  *
  * **Sessions are not auto-created here**: a new conversation starts as a draft (chat page `/chat/new`),
  * and the Session is only actually created when the first message is sent — after landing, the user
@@ -24,23 +28,39 @@ import {
   useState,
 } from "react";
 import type { ReactNode } from "react";
-import type { SessionInfo, SessionStatus } from "@prismshadow/penguin-server/api";
+import type {
+  SessionCategory,
+  SessionCategoryCounts,
+  SessionInfo,
+  SessionStatus,
+} from "@prismshadow/penguin-server/api";
 import * as api from "../api/endpoints";
 import { openUserEvents } from "../api/sse";
-import { SIDEBAR_PAGE_SIZE, splitPage } from "../lib/session-grouping";
+import {
+  FOLDER_CATEGORIES,
+  SIDEBAR_PAGE_SIZE,
+  sessionCategory,
+  splitPage,
+} from "../lib/session-grouping";
 import { useProject } from "./project";
 
 interface SessionsContextValue {
-  /** Loaded list (paged per Agent; each Agent's entries newest first). */
+  /** Loaded list (paged per Agent and category; each Agent's entries newest first). */
   sessions: SessionInfo[];
   /** agentId → that Agent's loaded Session list, newest first (empty array if none). */
   byAgent: ReadonlyMap<string, SessionInfo[]>;
-  /** agentId → whether the server has more (unfetched) sessions for that Agent. */
-  hasMoreByAgent: ReadonlyMap<string, boolean>;
+  /** agentId → per-category totals from the last list fetch (folder labels; kept in step locally on add / remove / archive toggles). */
+  countsByAgent: ReadonlyMap<string, SessionCategoryCounts>;
+  /** agentId → the same totals broken down by Workspace path (workspace-mode groups read their own share from it; maintained like countsByAgent). */
+  workspaceCountsByAgent: ReadonlyMap<string, Readonly<Record<string, SessionCategoryCounts>>>;
+  /** Whether a pair's first page has been fetched (false = the folder shows nothing because nothing was asked for yet). */
+  isLoadedFor: (agentId: string, category: SessionCategory) => boolean;
+  /** Whether the server still holds unfetched Sessions of a category for an Agent — an unloaded pair answers from the counts. */
+  hasMoreFor: (agentId: string, category: SessionCategory) => boolean;
   loading: boolean;
   reload: () => Promise<void>;
-  /** Fetches and appends the next page for each given Agent that still has more (no-op otherwise). */
-  loadMoreFor: (agentIds: string[]) => Promise<void>;
+  /** Fetches a category's first page for each given unloaded Agent and the next page for each loaded one with more (no-op otherwise). */
+  loadMoreFor: (agentIds: string[], category: SessionCategory) => Promise<void>;
   /** Prepend to the list on success (draft materialized by the first message, or explicit creation via dialog). */
   add: (session: SessionInfo) => void;
   /** Remove from the list in place after deletion. */
@@ -55,6 +75,22 @@ interface SessionsContextValue {
 
 const SessionsContext = createContext<SessionsContextValue | null>(null);
 
+/** Page-state key of one (Agent, category) pair ("\0" never appears in Agent ids). */
+const pageKey = (agentId: string, category: SessionCategory) => `${agentId}\0${category}`;
+
+/** One pair's paging cursor. */
+interface PagePosition {
+  /** Whether the server still has unfetched rows past `fetched`. */
+  hasMore: boolean;
+  /**
+   * Rows consumed from the server's category stream — the exact offset of the next
+   * page. Deliberately NOT derived from the loaded list: `add()` prepends rows that
+   * were never part of any page (deep-link self-heal), and counting those would skip
+   * a server row on the next fetch.
+   */
+  fetched: number;
+}
+
 export function SessionsProvider({ children }: { children: ReactNode }) {
   const { currentProject, agents } = useProject();
   const projectId = currentProject?.projectId ?? null;
@@ -63,7 +99,14 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
   const agentIdsKey = agents.map((a) => a.agentId).join(",");
 
   const [sessions, setSessions] = useState<SessionInfo[]>([]);
-  const [hasMoreByAgent, setHasMoreByAgent] = useState<ReadonlyMap<string, boolean>>(new Map());
+  /** pageKey → that pair's paging cursor; a key is present iff its first page has been fetched. */
+  const [pageState, setPageState] = useState<ReadonlyMap<string, PagePosition>>(new Map());
+  const [countsByAgent, setCountsByAgent] = useState<ReadonlyMap<string, SessionCategoryCounts>>(
+    new Map(),
+  );
+  const [workspaceCountsByAgent, setWorkspaceCountsByAgent] = useState<
+    ReadonlyMap<string, Readonly<Record<string, SessionCategoryCounts>>>
+  >(new Map());
   const [loading, setLoading] = useState(true);
   // Generation counter: invalidates any in-flight response once the Project/Agent set
   // changes or a reload happens.
@@ -71,8 +114,10 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
   // Current values for loadMoreFor (offsets are computed from what is actually loaded).
   const sessionsRef = useRef<SessionInfo[]>([]);
   sessionsRef.current = sessions;
-  const hasMoreRef = useRef<ReadonlyMap<string, boolean>>(hasMoreByAgent);
-  hasMoreRef.current = hasMoreByAgent;
+  const pageStateRef = useRef<ReadonlyMap<string, PagePosition>>(pageState);
+  pageStateRef.current = pageState;
+  const countsRef = useRef<ReadonlyMap<string, SessionCategoryCounts>>(countsByAgent);
+  countsRef.current = countsByAgent;
 
   const reload = useCallback(async () => {
     const agentIds = agentIdsKey === "" ? [] : agentIdsKey.split(",");
@@ -82,24 +127,66 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
     try {
       const results = await Promise.all(
         agentIds.map(async (agentId) => {
+          // Active first page (with per-category totals) always; plus the first page of
+          // every folder category already on screen — a reload triggered by a server
+          // event must refresh, not blank, an open folder.
+          const categories: SessionCategory[] = [
+            "active",
+            ...FOLDER_CATEGORIES.filter((cat) => pageStateRef.current.has(pageKey(agentId, cat))),
+          ];
           try {
-            // First page per Agent, requesting one extra row to learn whether more exist.
-            const fetched = (
-              await api.listSessions(projectId, agentId, {
-                offset: 0,
-                limit: SIDEBAR_PAGE_SIZE + 1,
-              })
-            ).sessions;
-            return { agentId, ...splitPage(fetched, SIDEBAR_PAGE_SIZE) };
+            const pages = await Promise.all(
+              categories.map(async (category) => {
+                const res = await api.listSessions(projectId, agentId, {
+                  offset: 0,
+                  limit: SIDEBAR_PAGE_SIZE + 1,
+                  category,
+                  ...(category === "active" ? { withCounts: true } : {}),
+                });
+                return {
+                  category,
+                  counts: res.counts,
+                  workspaceCounts: res.workspaceCounts,
+                  ...splitPage(res.sessions, SIDEBAR_PAGE_SIZE),
+                };
+              }),
+            );
+            return { agentId, pages };
           } catch {
             // A single Agent's fetch failure shouldn't bring down the whole batch (e.g. its directory was deleted externally).
-            return { agentId, items: [] as SessionInfo[], hasMore: false };
+            return { agentId, pages: [] };
           }
         }),
       );
       if (g !== gen.current) return;
-      setSessions(results.flatMap((r) => r.items));
-      setHasMoreByAgent(new Map(results.map((r) => [r.agentId, r.hasMore])));
+      const nextSessions: SessionInfo[] = [];
+      const seen = new Set<string>();
+      const nextPageState = new Map<string, PagePosition>();
+      const nextCounts = new Map<string, SessionCategoryCounts>();
+      const nextWorkspaceCounts = new Map<
+        string,
+        Readonly<Record<string, SessionCategoryCounts>>
+      >();
+      for (const r of results) {
+        for (const p of r.pages) {
+          nextPageState.set(pageKey(r.agentId, p.category), {
+            hasMore: p.hasMore,
+            fetched: p.items.length,
+          });
+          if (p.counts) nextCounts.set(r.agentId, p.counts);
+          if (p.workspaceCounts) nextWorkspaceCounts.set(r.agentId, p.workspaceCounts);
+          for (const s of p.items) {
+            if (!seen.has(s.sessionId)) {
+              seen.add(s.sessionId);
+              nextSessions.push(s);
+            }
+          }
+        }
+      }
+      setSessions(nextSessions);
+      setPageState(nextPageState);
+      setCountsByAgent(nextCounts);
+      setWorkspaceCountsByAgent(nextWorkspaceCounts);
     } finally {
       if (g === gen.current) setLoading(false);
     }
@@ -107,54 +194,117 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
 
   useEffect(() => {
     setSessions([]);
-    setHasMoreByAgent(new Map());
+    // reload() reads the ref synchronously to pick the categories to refetch — reset it
+    // in place so a Project switch can't carry folder page state across via shared Agent
+    // ids (default_agent exists in every Project).
+    pageStateRef.current = new Map();
+    setPageState(pageStateRef.current);
+    setCountsByAgent(new Map());
+    setWorkspaceCountsByAgent(new Map());
     void reload();
   }, [reload]);
 
   /**
-   * Next page for each given Agent that still has more. Offsets are the currently loaded
-   * per-Agent counts; a session created since the last page shifts server offsets, so
-   * appended rows are deduplicated by sessionId (a short page is fine — `hasMore` comes
-   * from the server response, and the next click continues from the new count).
+   * Category page fetch for each given Agent: the first page when the pair is unloaded
+   * (skipped unless the counts say the category holds anything), the next page when
+   * loaded with more. The offset is the pair's `fetched` cursor — rows actually
+   * consumed from the server's stream, never rows `add()` slipped in. A session
+   * created since the last page still shifts server offsets, so appended rows are
+   * deduplicated by sessionId (a short page is fine — `hasMore` comes from the server
+   * response, and the next click continues from the advanced cursor).
    */
   const loadMoreFor = useCallback(
-    async (agentIds: string[]) => {
+    async (agentIds: string[], category: SessionCategory) => {
       if (!projectId) return;
-      const targets = [...new Set(agentIds)].filter((id) => hasMoreRef.current.get(id) === true);
+      const targets = [...new Set(agentIds)].filter((agentId) => {
+        const position = pageStateRef.current.get(pageKey(agentId, category));
+        if (position === undefined) return (countsRef.current.get(agentId)?.[category] ?? 0) > 0;
+        return position.hasMore;
+      });
       if (targets.length === 0) return;
       const g = gen.current;
       const results = await Promise.all(
         targets.map(async (agentId) => {
-          const offset = sessionsRef.current.filter((s) => s.agentId === agentId).length;
+          const offset = pageStateRef.current.get(pageKey(agentId, category))?.fetched ?? 0;
           try {
             const fetched = (
               await api.listSessions(projectId, agentId, {
                 offset,
                 limit: SIDEBAR_PAGE_SIZE + 1,
+                category,
               })
             ).sessions;
             return { agentId, ...splitPage(fetched, SIDEBAR_PAGE_SIZE) };
           } catch {
-            // Transient failure: keep "has more" so the affordance stays and the user can retry.
-            return { agentId, items: [] as SessionInfo[], hasMore: true };
+            // Transient failure: leave the pair's state untouched (still unloaded / still
+            // has-more), so the affordance stays and the user can retry.
+            return null;
           }
         }),
       );
       if (g !== gen.current) return; // Project switch / reload raced this page: drop it.
+      const ok = results.filter((r) => r !== null);
       setSessions((prev) => {
         const seen = new Set(prev.map((s) => s.sessionId));
-        const appended = results.flatMap((r) => r.items.filter((s) => !seen.has(s.sessionId)));
+        const appended = ok.flatMap((r) => r.items.filter((s) => !seen.has(s.sessionId)));
         return appended.length > 0 ? [...prev, ...appended] : prev;
       });
-      setHasMoreByAgent((prev) => {
+      setPageState((prev) => {
         const next = new Map(prev);
-        for (const r of results) next.set(r.agentId, r.hasMore);
+        for (const r of ok) {
+          const key = pageKey(r.agentId, category);
+          next.set(key, {
+            hasMore: r.hasMore,
+            fetched: (prev.get(key)?.fetched ?? 0) + r.items.length,
+          });
+        }
         return next;
       });
     },
     [projectId],
   );
 
+  const isLoadedFor = useCallback(
+    (agentId: string, category: SessionCategory) => pageState.has(pageKey(agentId, category)),
+    [pageState],
+  );
+
+  const hasMoreFor = useCallback(
+    (agentId: string, category: SessionCategory) => {
+      const position = pageState.get(pageKey(agentId, category));
+      if (position !== undefined) return position.hasMore;
+      // Unloaded pair: anything the counts report is by definition still unfetched.
+      return (countsByAgent.get(agentId)?.[category] ?? 0) > 0;
+    },
+    [pageState, countsByAgent],
+  );
+
+  /** Keeps an Agent's category totals — overall and per Workspace — in step with a local list mutation of `session` (no-op while its counts are unknown). */
+  const adjustCount = useCallback(
+    (session: SessionInfo, category: SessionCategory, delta: number) => {
+      const { agentId, workspace } = session;
+      setCountsByAgent((prev) => {
+        const cur = prev.get(agentId);
+        if (!cur) return prev;
+        const next = new Map(prev);
+        next.set(agentId, { ...cur, [category]: Math.max(0, cur[category] + delta) });
+        return next;
+      });
+      setWorkspaceCountsByAgent((prev) => {
+        const cur = prev.get(agentId);
+        if (!cur) return prev;
+        const ws = cur[workspace] ?? { active: 0, subagent: 0, schedule: 0, archived: 0 };
+        const next = new Map(prev);
+        next.set(agentId, {
+          ...cur,
+          [workspace]: { ...ws, [category]: Math.max(0, ws[category] + delta) },
+        });
+        return next;
+      });
+    },
+    [],
+  );
+
   // User-level event stream (/api/events): a scheduled task firing may have created a new
   // Session (new-session mode); reload the list so it appears immediately. schedule_queued
   // doesn't change the list (the target Session already exists), so it's ignored.
@@ -176,21 +326,50 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
     return () => conn.close();
   }, []);
 
-  const add = useCallback((session: SessionInfo) => {
-    // Invalidate any in-flight reload: the newly created entry mustn't be wiped by a stale snapshot.
-    gen.current += 1;
-    setSessions((prev) => [session, ...prev.filter((s) => s.sessionId !== session.sessionId)]);
-  }, []);
+  const add = useCallback(
+    (session: SessionInfo) => {
+      // Invalidate any in-flight reload: the newly created entry mustn't be wiped by a stale snapshot.
+      gen.current += 1;
+      // Count the row only when the pair's fetched pages provably held its whole category
+      // (loaded, no more): the row is then genuinely new to the server totals. Otherwise
+      // (deep-link self-heal of an unfetched row) the counts already include it — a
+      // possible one-off drift self-heals on the next reload.
+      const existed = sessionsRef.current.some((s) => s.sessionId === session.sessionId);
+      if (
+        !existed &&
+        pageStateRef.current.get(pageKey(session.agentId, sessionCategory(session)))?.hasMore ===
+          false
+      ) {
+        adjustCount(session, sessionCategory(session), 1);
+      }
+      setSessions((prev) => [session, ...prev.filter((s) => s.sessionId !== session.sessionId)]);
+    },
+    [adjustCount],
+  );
 
-  const remove = useCallback((sessionId: string) => {
-    // Invalidate any in-flight reload: the deletion mustn't be undone by a stale snapshot.
-    gen.current += 1;
-    setSessions((prev) => prev.filter((s) => s.sessionId !== sessionId));
-  }, []);
+  const remove = useCallback(
+    (sessionId: string) => {
+      // Invalidate any in-flight reload: the deletion mustn't be undone by a stale snapshot.
+      gen.current += 1;
+      const row = sessionsRef.current.find((s) => s.sessionId === sessionId);
+      if (row) adjustCount(row, sessionCategory(row), -1);
+      setSessions((prev) => prev.filter((s) => s.sessionId !== sessionId));
+    },
+    [adjustCount],
+  );
 
-  const replace = useCallback((session: SessionInfo) => {
-    setSessions((prev) => prev.map((s) => (s.sessionId === session.sessionId ? session : s)));
-  }, []);
+  const replace = useCallback(
+    (session: SessionInfo) => {
+      // An archive toggle moves the row across categories: keep the folder totals in step.
+      const old = sessionsRef.current.find((s) => s.sessionId === session.sessionId);
+      if (old && sessionCategory(old) !== sessionCategory(session)) {
+        adjustCount(session, sessionCategory(old), -1);
+        adjustCount(session, sessionCategory(session), 1);
+      }
+      setSessions((prev) => prev.map((s) => (s.sessionId === session.sessionId ? session : s)));
+    },
+    [adjustCount],
+  );
 
   const setStatus = useCallback((sessionId: string, status: SessionStatus) => {
     setSessions((prev) => {
@@ -222,7 +401,10 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
     return {
       sessions,
       byAgent,
-      hasMoreByAgent,
+      countsByAgent,
+      workspaceCountsByAgent,
+      isLoadedFor,
+      hasMoreFor,
       loading,
       reload,
       loadMoreFor,
@@ -234,7 +416,10 @@ export function SessionsProvider({ children }: { children: ReactNode }) {
     };
   }, [
     sessions,
-    hasMoreByAgent,
+    countsByAgent,
+    workspaceCountsByAgent,
+    isLoadedFor,
+    hasMoreFor,
     loading,
     reload,
     loadMoreFor,
diff --git a/packages/web/test/session-grouping.test.ts b/packages/web/test/session-grouping.test.ts
index 52b5ee2..dfa7ecf 100644
--- a/packages/web/test/session-grouping.test.ts
+++ b/packages/web/test/session-grouping.test.ts
@@ -9,15 +9,17 @@
  *   concatenates per-Agent server responses, so its order isn't globally chronological.
  */
 import { describe, expect, it } from "vitest";
-import type { SessionInfo } from "@prismshadow/penguin-server/api";
+import type { SessionCategoryCounts, SessionInfo } from "@prismshadow/penguin-server/api";
 import {
   SIDEBAR_PAGE_SIZE,
   TEMP_WORKSPACE_GROUP_KEY,
-  groupAgentsWithMore,
+  aggregateWorkspaceCounts,
   groupSessionsByWorkspace,
   isTempWorkspace,
+  latestConversation,
   partitionSessions,
   pinnedFirst,
+  sessionCategory,
   splitPage,
   workspaceGroupKey,
   workspaceLabel,
@@ -148,6 +150,19 @@ describe("groupSessionsByWorkspace", () => {
   });
 });
 
+describe("sessionCategory (the bucket a Session renders under = the server's list filter)", () => {
+  it("archived wins over source; a source names its bucket; no source is active", () => {
+    const at = "2026-07-01T10:00:00.000Z";
+    expect(sessionCategory(session("/srv/a", at))).toBe("active");
+    expect(sessionCategory(session("/srv/a", at, { source: "subagent" }))).toBe("subagent");
+    expect(sessionCategory(session("/srv/a", at, { source: "schedule" }))).toBe("schedule");
+    expect(sessionCategory(session("/srv/a", at, { archived: true }))).toBe("archived");
+    expect(sessionCategory(session("/srv/a", at, { source: "subagent", archived: true }))).toBe(
+      "archived",
+    );
+  });
+});
+
 describe("partitionSessions (per-group user / subagent / scheduled / archived split)", () => {
   it("splits user rows and one bucket per origin, preserving order within each part", () => {
     const user1 = session("/srv/alpha", "2026-07-06T10:00:00.000Z");
@@ -189,6 +204,31 @@ describe("partitionSessions (per-group user / subagent / scheduled / archived sp
   });
 });
 
+describe("latestConversation (the auto-opened 'last conversation')", () => {
+  it("picks the newest active/schedule row regardless of input order; archived and subagent rows never win", () => {
+    const oldActive = session("/srv/a", "2026-07-01T10:00:00.000Z");
+    const newActive = session("/srv/a", "2026-07-03T10:00:00.000Z");
+    // Newer than every conversation, but never auto-opened:
+    const newerSub = session("/srv/a", "2026-07-08T10:00:00.000Z", { source: "subagent" });
+    const newerGone = session("/srv/a", "2026-07-09T10:00:00.000Z", { archived: true });
+    expect(latestConversation([newerSub, oldActive, newerGone, newActive])).toBe(newActive);
+
+    // A schedule-created run is the user's conversation: the newest one qualifies.
+    const newerSched = session("/srv/a", "2026-07-05T10:00:00.000Z", { source: "schedule" });
+    expect(latestConversation([newActive, newerSched, newerSub])).toBe(newerSched);
+  });
+
+  it("ties on createdAt break by sessionId, and no qualifying row yields null", () => {
+    const at = "2026-07-02T10:00:00.000Z";
+    const a = session("/srv/a", at, { sessionId: "session-a" });
+    const b = session("/srv/a", at, { sessionId: "session-b" });
+    expect(latestConversation([a, b])).toBe(b);
+    expect(latestConversation([b, a])).toBe(b);
+    expect(latestConversation([])).toBeNull();
+    expect(latestConversation([session("/srv/a", at, { source: "subagent" })])).toBeNull();
+  });
+});
+
 describe("splitPage (limit+1 fetch trick)", () => {
   it("an overflow row proves the server has more and is never shown", () => {
     const fetched = [1, 2, 3, 4];
@@ -202,21 +242,55 @@ describe("splitPage (limit+1 fetch trick)", () => {
   });
 });
 
-describe("groupAgentsWithMore (workspace groups span Agents)", () => {
-  it("returns each contributing Agent with unfetched pages once; others are skipped", () => {
-    const rows = [
-      session("/srv/alpha", "2026-07-03T10:00:00.000Z", { agentId: "agent_a" }),
-      session("/srv/alpha", "2026-07-02T10:00:00.000Z", { agentId: "agent_b" }),
-      session("/srv/alpha", "2026-07-01T10:00:00.000Z", { agentId: "agent_a" }),
-    ];
-    const hasMore = new Map([
-      ["agent_a", true],
-      ["agent_b", false],
-      ["agent_c", true], // not contributing to this group
+describe("aggregateWorkspaceCounts (per-group exact server share)", () => {
+  const zero = { active: 0, subagent: 0, schedule: 0, archived: 0 };
+
+  it("sums each Workspace path across Agents and records which Agents hold each category", () => {
+    const byAgent = new Map<string, Record<string, SessionCategoryCounts>>([
+      [
+        "agent_a",
+        {
+          "/srv/alpha": { ...zero, active: 2, subagent: 1 },
+          "/srv/beta": { ...zero, archived: 3 },
+        },
+      ],
+      ["agent_b", { "/srv/alpha": { ...zero, active: 1, schedule: 2 } }],
     ]);
-    expect(groupAgentsWithMore(rows, hasMore)).toEqual(["agent_a"]);
-    expect(groupAgentsWithMore(rows, new Map())).toEqual([]);
-    expect(groupAgentsWithMore([], hasMore)).toEqual([]);
+    const groups = aggregateWorkspaceCounts(byAgent);
+    expect(groups.get("/srv/alpha")).toEqual({
+      totals: { active: 3, subagent: 1, schedule: 2, archived: 0 },
+      agents: {
+        active: ["agent_a", "agent_b"],
+        subagent: ["agent_a"],
+        schedule: ["agent_b"],
+        archived: [],
+      },
+    });
+    expect(groups.get("/srv/beta")).toEqual({
+      totals: { ...zero, archived: 3 },
+      agents: { active: [], subagent: [], schedule: [], archived: ["agent_a"] },
+    });
+    // A group only in another Workspace never appears — its content can't surface elsewhere.
+    expect(groups.has("/srv/gamma")).toBe(false);
+    expect(aggregateWorkspaceCounts(new Map()).size).toBe(0);
+  });
+
+  it("folds every auto-temp path into the merged temp group, deduplicating agents", () => {
+    const byAgent = new Map([
+      [
+        "agent_a",
+        {
+          [TEMP_A]: { ...zero, active: 1 },
+          [TEMP_B]: { ...zero, active: 2, archived: 1 },
+        },
+      ],
+    ]);
+    const groups = aggregateWorkspaceCounts(byAgent);
+    expect(groups.size).toBe(1);
+    expect(groups.get(TEMP_WORKSPACE_GROUP_KEY)).toEqual({
+      totals: { ...zero, active: 3, archived: 1 },
+      agents: { active: ["agent_a"], subagent: [], schedule: [], archived: ["agent_a"] },
+    });
   });
 });