Changelog, dev startup, README, AgentHub 0.4.0, model catalog, and landing site (#7)

Branch-length batch covering tooling, the model layer, the Web App and the public
surfaces. Highlights:

- Changelog: a per-release `changelog/<version>/` tree, grouped by the surface each
  change touches, with a root CHANGELOG.md holding one line per release.
- Dev startup: `scripts/dev-prebuild.mjs` serializes the skills+core prebuild behind a
  lock and keeps `pnpm install` current; `pnpm dev` runs server+web together.
- AgentHub 0.3.3 -> 0.4.0: OmniMessage complete payloads carry one opaque `fidelity`
  object in place of item-level `signature`/`phase`, threaded verbatim through Trace,
  replay and resume; malformed classification adapted to the new error types.
- Model layer: a model is always referenced by an explicit `(provider, model_id)` pair.
  The provider is never inferred, guessed or defaulted -- both the catalog inference and
  the unique-match config resolution are gone, and CLI, SDK, server routes and
  run_subagent all require the complete pair. Catalog gains the Qwen Token Plan, Qwen
  Pay-As-You-Go and Fireworks AI gateways, plus an expanded OpenRouter group.
- Web App: catalog preset sync and per-group speed test on the Models page, positional
  slash commands, a markdown renderer, skill-library update reminders, and a vertically
  centred draft page whose upward menus size themselves to the room available.
- Public surfaces: restructured READMEs, the penguin.ooo landing site and blog, refreshed
  benchmark results for both suites, and the demo videos playing on the landing page.

Includes the fixes from a full review of the branch: 23 confirmed findings, among them a
provider-inference bug that could send one vendor's API key to another vendor's endpoint,
and an Escape handler that destroyed the composer's contents unrecoverably.

Verified on the branch head: pnpm test (1127 passing, 7 packages), pnpm typecheck and
pnpm format:check clean, Playwright e2e 14/14.

packages/core/src/session.ts

@@ -65,15 +65,26 @@ export interface SessionConfig {
   inputImagesDir?: string;
 }
 
-/** Cap on captured title material (chars per side, matching buildTitlePrompt's truncation); stops accumulating once exceeded. */
-const TITLE_MATERIAL_LIMIT = 2000;
+/**
+ * Caps on captured title material (chars per side); accumulation stops once exceeded. The
+ * assistant body is capped tighter: a title only needs the opening of the answer, and hosts
+ * may start generating as soon as this much body text has streamed (see the Web server's
+ * early trigger) — a long answer would otherwise overrun the material.
+ */
+const TITLE_USER_MATERIAL_LIMIT = 2000;
+const TITLE_ASSISTANT_MATERIAL_LIMIT = 1000;
 
 /**
  * Accumulates title material: the body text of complete text messages from the main session
  * (no origin) — thinking and tool calls naturally don't count — and stops once the cap is hit.
  */
-function appendTitleText(base: string, msg: OmniMessage, role: "user" | "assistant"): string {
-  if (base.length >= TITLE_MATERIAL_LIMIT) return base;
+function appendTitleText(
+  base: string,
+  msg: OmniMessage,
+  role: "user" | "assistant",
+  limit: number,
+): string {
+  if (base.length >= limit) return base;
   if (msg.origin && msg.origin.length > 0) return base;
   const p = msg.payload as { type?: string; role?: string; text?: string };
   if (msg.type !== "model_msg" || p.type !== "text" || p.role !== role || !p.text) return base;
@@ -153,12 +164,22 @@ export class Session {
     const capture = !this.titleMaterialFrozen;
     if (capture) {
       for (const m of newMessages) {
-        this.titleUserText = appendTitleText(this.titleUserText, m, "user");
+        this.titleUserText = appendTitleText(
+          this.titleUserText,
+          m,
+          "user",
+          TITLE_USER_MATERIAL_LIMIT,
+        );
       }
     }
     for await (const msg of this.engine.run(newMessages, opts)) {
       if (capture) {
-        this.titleAssistantText = appendTitleText(this.titleAssistantText, msg, "assistant");
+        this.titleAssistantText = appendTitleText(
+          this.titleAssistantText,
+          msg,
+          "assistant",
+          TITLE_ASSISTANT_MATERIAL_LIMIT,
+        );
       }
       yield msg;
     }