penguin-harness/packages/web/test/stream-model.test.ts

/**
 * stream-model.ts unit tests: partial aggregation, full-message
 * convergence/replacement, orphan delta handling, overlap dedup, origin nested routing,
 * approval/abort/compaction events, Task segmentation and stats triggering.
 */
import { describe, expect, it } from "vitest";
import {
  abortEvent,
  approvalDecision,
  assistantText,
  compactionBegin,
  compactionEnd,
  imageUrlMessage,
  partialText,
  partialThinking,
  partialToolCall,
  partialToolCallOutput,
  requestBegin,
  requestEnd,
  sessionMeta,
  thinkingMessage,
  tokenUsage,
  toolCall,
  toolCallOutput,
  userText,
  withOrigin,
} from "@prismshadow/penguin-core/omnimessage";
import type {
  OmniMessage,
  SessionMetaPayload,
  TokenCounts,
} from "@prismshadow/penguin-core/omnimessage";
import {
  approvalKey,
  buildDedupIndex,
  createStreamModel,
  discardFragmentFor,
  finalizeHistory,
  findToolCard,
  isDuplicate,
  isModelAuthDead,
  notifyTaskIdle,
  pushMessage,
  pushMessages,
  registerLocalDecision,
} from "../src/lib/omni/stream-model";
import type {
  AssistantTextItem,
  CompactionItem,
  ReconnectItem,
  StreamModel,
  SubagentItem,
  TaskStatsItem,
  ThinkingItem,
  ToolCallItem,
  UserSteeringItem,
  UserTextItem,
} from "../src/lib/omni/stream-model";

/** Override a message timestamp (constructor defaults to the current time). */
function at<M extends OmniMessage>(msg: M, ts: string): M {
  return { ...msg, timestamp: ts };
}

function counts(total: number): TokenCounts {
  return { cache_read: 0, cache_write: 0, output: 0, total };
}

/** Output-only counts (for output-TPS timing cases: request.output = total = n). */
function out(n: number): TokenCounts {
  return { cache_read: 0, cache_write: 0, output: n, total: n };
}

function meta(sessionId: string): OmniMessage<SessionMetaPayload> {
  return sessionMeta({
    session_id: sessionId,
    model_id: "m",
    provider: "custom",
    model_context_window: 200000,
    system_prompt: "",
    tools: [],
    agent_state: "/a",
    workspace: "/w",
  });
}

function items(model: StreamModel) {
  return model.items;
}

describe("partial aggregation and full-message convergence", () => {
  it("partial_text start/delta/stop accumulates into one streaming item; the full message replaces its content", () => {
    const m = createStreamModel();
    pushMessage(m, partialText("start"));
    pushMessage(m, partialText("delta", "Hel"));
    pushMessage(m, partialText("delta", "lo"));
    expect(items(m)).toHaveLength(1);
    const item = items(m)[0] as AssistantTextItem;
    expect(item.kind).toBe("assistant_text");
    expect(item.text).toBe("Hello");
    expect(item.streaming).toBe(true);

    pushMessage(m, partialText("stop"));
    expect(item.streaming).toBe(false);

    // The full message replaces the fragment content (deliberately different here to prove replacement).
    pushMessage(m, assistantText("Hello!"));
    expect(items(m)).toHaveLength(1);
    expect(item.text).toBe("Hello!");
  });

  it("partial_thinking works the same; stop_reason is recorded on the item", () => {
    const m = createStreamModel();
    pushMessage(m, partialThinking("start"));
    pushMessage(m, partialThinking("delta", "thinking"));
    pushMessage(m, partialThinking("stop", "", "aborted"));
    const item = items(m)[0] as ThinkingItem;
    expect(item.kind).toBe("thinking");
    expect(item.thinking).toBe("thinking");
    expect(item.stopReason).toBe("aborted");
    pushMessage(m, thinkingMessage("thinking (complete)", "aborted"));
    expect(items(m)).toHaveLength(1);
    expect(item.thinking).toBe("thinking (complete)");
  });

  it("orphan delta/stop (no start seen, joined mid-stream) is ignored; the subsequent full message appends directly", () => {
    const m = createStreamModel();
    pushMessage(m, partialText("delta", "halfway"));
    pushMessage(m, partialText("stop"));
    expect(items(m)).toHaveLength(0);
    pushMessage(m, assistantText("full text"));
    expect(items(m)).toHaveLength(1);
    expect((items(m)[0] as AssistantTextItem).text).toBe("full text");
  });

  it("tool cards: partial_tool_call attaches by tool_call_id; the full message replaces the arguments", () => {
    const m = createStreamModel();
    pushMessage(m, partialToolCall({ eventType: "start", name: "exec_command", toolCallId: "t1" }));
    pushMessage(
      m,
      partialToolCall({ eventType: "delta", name: "", arguments: '{"cmd":"ls', toolCallId: "t1" }),
    );
    pushMessage(m, partialToolCall({ eventType: "stop", name: "", toolCallId: "t1" }));
    const card = items(m)[0] as ToolCallItem;
    expect(card.kind).toBe("tool_call");
    expect(card.name).toBe("exec_command");
    expect(card.argumentsText).toBe('{"cmd":"ls');
    expect(card.callStreaming).toBe(false);

    pushMessage(m, toolCall({ name: "exec_command", arguments: '{"cmd":"ls"}', toolCallId: "t1" }));
    expect(items(m)).toHaveLength(1);
    expect(card.argumentsText).toBe('{"cmd":"ls"}');
    expect(card.callComplete).toBe(true);

    // Output is appended while streaming; the full output replaces it.
    pushMessage(m, partialToolCallOutput({ eventType: "start", toolCallId: "t1" }));
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "delta", output: "a.txt\n", toolCallId: "t1" }),
    );
    expect(card.output).toBe("a.txt\n");
    expect(card.outputStreaming).toBe(true);
    pushMessage(m, partialToolCallOutput({ eventType: "stop", toolCallId: "t1" }));
    pushMessage(m, toolCallOutput({ output: "a.txt\nb.txt\n", toolCallId: "t1" }));
    expect(card.output).toBe("a.txt\nb.txt\n");
    expect(card.outputComplete).toBe(true);
  });

  it("when the full tool_call arrives first (history), the late streaming copy is ignored", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "read_file", arguments: '{"path":"x"}', toolCallId: "t2" }));
    pushMessage(m, partialToolCall({ eventType: "start", name: "read_file", toolCallId: "t2" }));
    pushMessage(
      m,
      partialToolCall({ eventType: "delta", name: "", arguments: "duplicate", toolCallId: "t2" }),
    );
    const card = items(m)[0] as ToolCallItem;
    expect(items(m)).toHaveLength(1);
    expect(card.argumentsText).toBe('{"path":"x"}');
  });

  it("orphan output deltas without a call card are ignored; the full output creates the card", () => {
    const m = createStreamModel();
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "delta", output: "orphan", toolCallId: "t3" }),
    );
    expect(items(m)).toHaveLength(0);
    pushMessage(m, toolCallOutput({ output: "full output", toolCallId: "t3" }));
    expect(items(m)).toHaveLength(1);
    expect((items(m)[0] as ToolCallItem).output).toBe("full output");
  });

  it("tool-output images land on the tool card as soon as a streaming delta carries them whole; the full message converges again", () => {
    const dataUrl = "data:image/png;base64,AAAA";
    const m = createStreamModel();
    pushMessage(
      m,
      toolCall({ name: "read_image", arguments: '{"source":"a.png"}', toolCallId: "t4" }),
    );
    const card = items(m)[0] as ToolCallItem;
    expect(card.images).toBeUndefined();
    // Streaming: start → text delta → image delta (a single delta carries the whole image) → stop.
    pushMessage(m, partialToolCallOutput({ eventType: "start", toolCallId: "t4" }));
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "delta", output: "image/png, 4 B", toolCallId: "t4" }),
    );
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "delta", toolCallId: "t4", images: [dataUrl] }),
    );
    // The image becomes visible as soon as the streaming delta arrives, without waiting for the full message.
    expect(card.images).toEqual([dataUrl]);
    pushMessage(m, partialToolCallOutput({ eventType: "stop", toolCallId: "t4" }));
    // Full message converges: text is replaced, image is overwritten with the same value.
    pushMessage(
      m,
      toolCallOutput({ output: "image/png, 4 B", toolCallId: "t4", images: [dataUrl] }),
    );
    expect(card.output).toBe("image/png, 4 B");
    expect(card.images).toEqual([dataUrl]);
    expect(card.outputComplete).toBe(true);
  });
});

describe("live-tail synthetic starts (mid-stream join seeding)", () => {
  it("a text start carrying the accumulated prefix opens a streaming item on top of history; deltas continue and the full message replaces", () => {
    const m = createStreamModel();
    pushMessage(m, userText("question"));
    pushMessage(m, partialText("start", "Already streamed prefix"));
    const item = items(m)[1] as AssistantTextItem;
    expect(item.kind).toBe("assistant_text");
    expect(item.text).toBe("Already streamed prefix");
    expect(item.streaming).toBe(true);
    pushMessage(m, partialText("delta", " + live tail"));
    expect(item.text).toBe("Already streamed prefix + live tail");
    pushMessage(m, partialText("stop"));
    pushMessage(m, assistantText("Already streamed prefix + live tail."));
    expect(items(m).filter((i) => i.kind === "assistant_text")).toHaveLength(1);
    expect(item.text).toBe("Already streamed prefix + live tail.");
  });

  it("a thinking start carrying the accumulated prefix seeds a streaming thinking item with its start time", () => {
    const m = createStreamModel();
    pushMessage(m, at(partialThinking("start", "half a thought"), "2026-07-05T00:00:01.000Z"));
    const item = items(m)[0] as ThinkingItem;
    expect(item.thinking).toBe("half a thought");
    expect(item.streaming).toBe(true);
    expect(item.startedAtMs).toBe(Date.parse("2026-07-05T00:00:01.000Z"));
  });

  it("an output start seeds the prefix (and images) onto a call-complete card; a start on an outputComplete card is ignored", () => {
    const dataUrl = "data:image/png;base64,AAAA";
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "exec_command", arguments: '{"cmd":"x"}', toolCallId: "t1" }));
    const card = items(m)[0] as ToolCallItem;
    // Synthetic start carries the accumulated prefix + the whole image set.
    pushMessage(
      m,
      partialToolCallOutput({
        eventType: "start",
        output: "line 1\nline 2\n",
        toolCallId: "t1",
        images: [dataUrl],
      }),
    );
    expect(card.output).toBe("line 1\nline 2\n");
    expect(card.outputStreaming).toBe(true);
    expect(card.images).toEqual([dataUrl]);
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "delta", output: "line 3\n", toolCallId: "t1" }),
    );
    expect(card.output).toBe("line 1\nline 2\nline 3\n");
    // Once the output is complete, a stray synthetic start must not reopen or append.
    pushMessage(m, toolCallOutput({ output: "final", toolCallId: "t1" }));
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "start", output: "stale", toolCallId: "t1" }),
    );
    expect(card.output).toBe("final");
    expect(card.outputStreaming).toBe(false);
  });

  it("an arguments start for an id whose call is already complete is ignored (no duplicate card, no reset)", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "exec_command", arguments: '{"cmd":"x"}', toolCallId: "t1" }));
    pushMessage(
      m,
      partialToolCall({
        eventType: "start",
        name: "exec_command",
        arguments: '{"cmd":"x"}',
        toolCallId: "t1",
      }),
    );
    expect(items(m)).toHaveLength(1);
    expect((items(m)[0] as ToolCallItem).argumentsText).toBe('{"cmd":"x"}');
  });

  it("an arguments start carrying accumulated arguments seeds a card that the full message then completes", () => {
    const m = createStreamModel();
    pushMessage(
      m,
      partialToolCall({
        eventType: "start",
        name: "exec_command",
        arguments: '{"cmd":"seq 1',
        toolCallId: "t1",
      }),
    );
    const card = items(m)[0] as ToolCallItem;
    expect(card.argumentsText).toBe('{"cmd":"seq 1');
    expect(card.callStreaming).toBe(true);
    pushMessage(
      m,
      partialToolCall({ eventType: "delta", name: "", arguments: ' 40"}', toolCallId: "t1" }),
    );
    pushMessage(m, partialToolCall({ eventType: "stop", name: "", toolCallId: "t1" }));
    pushMessage(
      m,
      toolCall({ name: "exec_command", arguments: '{"cmd":"seq 1 40"}', toolCallId: "t1" }),
    );
    expect(items(m)).toHaveLength(1);
    expect(card.argumentsText).toBe('{"cmd":"seq 1 40"}');
    expect(card.callComplete).toBe(true);
  });
});

describe("approvals and events", () => {
  it("approval_decision annotates the matching tool card; locally registered ones are manual, the rest remote", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "a", arguments: "{}", toolCallId: "t1" }));
    pushMessage(m, toolCall({ name: "b", arguments: "{}", toolCallId: "t2" }));
    registerLocalDecision(m, "t1");
    pushMessage(m, approvalDecision("allow", "t1"));
    pushMessage(m, approvalDecision("deny", "t2"));
    const [c1, c2] = items(m) as [ToolCallItem, ToolCallItem];
    expect(c1.decision).toBe("allow");
    expect(c1.decisionSource).toBe("manual");
    expect(c2.decision).toBe("deny");
    expect(c2.decisionSource).toBe("remote");
  });

  it("approval decisions arriving before the card are backfilled when the card is created", () => {
    const m = createStreamModel();
    pushMessage(m, approvalDecision("allow", "t9"));
    pushMessage(m, toolCall({ name: "x", arguments: "{}", toolCallId: "t9" }));
    expect((items(m)[0] as ToolCallItem).decision).toBe("allow");
  });

  it("a main-session request_end(auth) records the failure timestamp; other aborts/events do not", () => {
    const m = createStreamModel();
    pushMessage(m, abortEvent("aborted by user"));
    expect(m.lastAuthFailureMs).toBeNull();
    const end = requestEnd("auth", "401 invalid x-api-key");
    pushMessage(m, end);
    // The recorded time is the event's envelope timestamp (so a reload can compare it
    // against the Project's credentials-updated time).
    expect(m.lastAuthFailureMs).toBe(Date.parse(end.timestamp));
    // The abort that follows still renders its line (the notice is additional).
    pushMessage(m, abortEvent("llm request error: 401 invalid x-api-key"));
    expect(items(m)[1]).toMatchObject({
      kind: "abort",
      reason: "llm request error: 401 invalid x-api-key",
    });
    // Unrelated later messages don't clear it: only a COMPLETED request does (below) —
    // request_begin alone proves nothing about the credential.
    pushMessage(m, userText("hello?"));
    pushMessage(m, requestBegin());
    expect(m.lastAuthFailureMs).not.toBeNull();
  });

  it("a later completed request clears the auth-dead state; a new auth failure re-arms it", () => {
    const m = createStreamModel();
    pushMessage(m, requestEnd("auth", "401"));
    expect(m.lastAuthFailureMs).not.toBeNull();
    // The key was fixed and a request succeeded: the state must not outlive the success.
    pushMessage(m, userText("again"));
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("completed"));
    expect(m.lastAuthFailureMs).toBeNull();
    // A fresh auth failure re-arms (e.g. the replacement key is wrong too).
    pushMessage(m, requestEnd("auth", "401"));
    expect(m.lastAuthFailureMs).not.toBeNull();
  });

  it("history replay: order decides — auth failure then completed request stays alive; the reverse stays dead", () => {
    // Replay of a Trace where the auth failure was followed by a successful request (the
    // user fixed the key and continued): reload must NOT resurrect the dead composer.
    const recovered = createStreamModel();
    pushMessages(recovered, [
      userText("go"),
      requestBegin(),
      requestEnd("auth", "401 invalid x-api-key"),
      abortEvent("llm request error: 401 invalid x-api-key"),
      userText("after fix"),
      requestBegin(),
      requestEnd("completed"),
    ]);
    finalizeHistory(recovered);
    expect(recovered.lastAuthFailureMs).toBeNull();

    // Replay where the auth failure is the LAST word: the dead state is rebuilt.
    const dead = createStreamModel();
    pushMessages(dead, [
      userText("go"),
      requestBegin(),
      requestEnd("completed"),
      userText("later"),
      requestBegin(),
      requestEnd("auth", "401 invalid x-api-key"),
      abortEvent("llm request error: 401 invalid x-api-key"),
    ]);
    finalizeHistory(dead);
    expect(dead.lastAuthFailureMs).not.toBeNull();
  });

  it("isModelAuthDead gates on the credentials-updated timestamp", () => {
    expect(isModelAuthDead(null, null)).toBe(false); // no auth failure on record
    expect(isModelAuthDead(1000, null)).toBe(true); // no update info -> nothing proves a fix
    expect(isModelAuthDead(1000, 2000)).toBe(false); // key updated after the failure -> alive
    expect(isModelAuthDead(3000, 2000)).toBe(true); // a fresh failure after the update re-arms
  });

  it("a subagent-origin auth failure does NOT kill the parent session's input", () => {
    const m = createStreamModel();
    pushMessage(m, withOrigin(requestEnd("auth", "401"), "child1"));
    // The failure belongs to the child session: its nested model carries the state, the
    // parent composer stays usable (the subagent simply surfaces as failed).
    expect(m.lastAuthFailureMs).toBeNull();
    expect(m.subagents.get("child1")!.lastAuthFailureMs).not.toBeNull();
  });

  it("abort events produce an abort marker item", () => {
    const m = createStreamModel();
    pushMessage(m, abortEvent("user abort"));
    expect(items(m)[0]).toMatchObject({ kind: "abort", reason: "user abort" });
  });

  it("compaction begin/end produce a banner item; tokens accounting for the completion row", () => {
    const m = createStreamModel();
    pushMessage(m, tokenUsage(counts(1000), counts(1000)));
    pushMessage(
      m,
      compactionBegin({ reason: "manual", mode: "summarize", context: 1000, turns: 3 }),
    );
    const banner = items(m)[0] as CompactionItem;
    expect(banner.kind).toBe("compaction");
    expect(banner.running).toBe(true);
    // Compaction request's own usage.
    pushMessage(m, tokenUsage(counts(1300), counts(300)));
    pushMessage(m, compactionEnd({ reason: "manual", mode: "summarize", status: "completed" }));
    expect(banner.running).toBe(false);
    expect(banner.status).toBe("completed");
    // The banner doesn't show Token: that usage already lands in this round's stats row
    // and cost (see the tokensDelta assertion below).
    expect(banner).not.toHaveProperty("tokens");
  });

  it("request_begin/end (normal final state) and main-session session_meta do not render", () => {
    const m = createStreamModel();
    pushMessage(m, meta("session-x"));
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("completed"));
    expect(items(m)).toHaveLength(0);
  });

  it("request_end final state timeout/malformed produces a retry notice item (with attempt number); request_begin marks it as resent", () => {
    const m = createStreamModel();
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("malformed"));
    const retry = items(m)[0] as ReconnectItem;
    expect(retry).toMatchObject({
      kind: "reconnect",
      status: "malformed",
      attempt: 1,
      retrying: false,
    });
    // Retry request sent: the notice is marked as retrying.
    pushMessage(m, requestBegin());
    expect(retry.retrying).toBe(true);
    // Retry fails again: a second notice, attempt count increments.
    pushMessage(m, requestEnd("timeout"));
    const retry2 = items(m)[1] as ReconnectItem;
    expect(retry2).toMatchObject({ kind: "reconnect", status: "timeout", attempt: 2 });
    // Retry succeeds: no new entry, the consecutive-failure count resets to 0 — the next round's failure starts back at 1.
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("completed"));
    expect(items(m)).toHaveLength(2);
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("timeout"));
    expect((items(m)[2] as ReconnectItem).attempt).toBe(1);
  });

  it("retries exhausted: an arriving abort marks the waiting retry notice gaveUp and resets the consecutive-failure count", () => {
    const m = createStreamModel();
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("timeout"));
    pushMessage(m, abortEvent("reconnect failed after 5 retries"));
    const retry = items(m)[0] as ReconnectItem;
    expect(retry).toMatchObject({
      kind: "reconnect",
      status: "timeout",
      retrying: false,
      gaveUp: true,
    });
    expect(items(m)[1]).toMatchObject({ kind: "abort" });
    // A new failure in the next run starts back at 1; a gaveUp notice isn't revived by request_begin.
    pushMessage(m, requestBegin());
    expect(retry.retrying).toBe(false);
    pushMessage(m, requestEnd("malformed"));
    expect((items(m)[2] as ReconnectItem).attempt).toBe(1);
  });

  it("request_end.retry_in_ms lands on the waiting item with the CLIENT arrival anchor (the countdown's inputs)", () => {
    const m = createStreamModel();
    pushMessage(m, requestBegin());
    // The engine announced a 4s backoff before retry #1; nowMs (the injected client clock)
    // is the countdown anchor — NOT the envelope timestamp, so server clock skew cannot
    // bend the ticker.
    pushMessage(m, requestEnd("timeout", "403 quota (insufficient_user_quota)", 4000), 111_000);
    const item = items(m)[0] as ReconnectItem;
    expect(item).toMatchObject({
      kind: "reconnect",
      status: "timeout",
      attempt: 1,
      retrying: false,
      plannedDelayMs: 4000,
      arrivedAtMs: 111_000,
    });
    // An event without the field (old Traces / final failures) leaves the fields unset —
    // the view keeps the plain waiting text.
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("timeout"));
    const plain = items(m)[1] as ReconnectItem;
    expect(plain.plannedDelayMs).toBeUndefined();
    expect(plain.arrivedAtMs).toBeUndefined();
  });

  it("history replay of a retried failure leaves no live countdown: the following request_begin/abort flips the state", () => {
    // Replay delivers the whole Trace back-to-back: the waiting state (the only state the
    // countdown and the retry-now/give-up controls render for) never persists.
    const retried = createStreamModel();
    pushMessages(retried, [
      userText("go"),
      requestBegin(),
      requestEnd("timeout", "quota", 30_000),
      requestBegin(), // the engine's retry — replayed immediately after
      requestEnd("completed"),
    ]);
    finalizeHistory(retried);
    const item = items(retried).find((i) => i.kind === "reconnect") as ReconnectItem;
    expect(item.retrying).toBe(true); // not waiting -> no countdown, no controls

    const aborted = createStreamModel();
    pushMessages(aborted, [
      userText("go"),
      requestBegin(),
      requestEnd("timeout", "quota", 30_000),
      abortEvent("aborted during reconnect backoff"), // the user gave up mid-wait
    ]);
    finalizeHistory(aborted);
    const gaveUp = items(aborted).find((i) => i.kind === "reconnect") as ReconnectItem;
    expect(gaveUp.gaveUp).toBe(true); // not waiting -> no countdown, no controls
  });

  it("a new Task closes the previous Task's dangling retry notice (server died in the backoff window, no abort in the Trace)", () => {
    const m = createStreamModel();
    pushMessage(m, userText("go"));
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("timeout")); // dangling at the tail: no abort, no retry begin
    const dangling = items(m).find((i) => i.kind === "reconnect") as ReconnectItem;
    expect(dangling.retrying).toBe(false);
    // New Task: the dangling item is marked gaveUp (the new request isn't its retry), count resets.
    pushMessage(m, userText("next"));
    pushMessage(m, requestBegin());
    expect(dangling.gaveUp).toBe(true);
    expect(dangling.retrying).toBe(false);
    pushMessage(m, requestEnd("timeout"));
    const fresh = items(m).filter((i) => i.kind === "reconnect")[1] as ReconnectItem;
    expect(fresh.attempt).toBe(1);
  });

  it("a tool_call closed non-completed (malformed closure) settles the card on arrival instead of showing as running", () => {
    const m = createStreamModel();
    pushMessage(
      m,
      toolCall({
        name: "exec_command",
        arguments: '{"cmd": "ec',
        toolCallId: "tc-broken",
        stopReason: "malformed",
      }),
    );
    const card = findToolCard(m, undefined, "tc-broken")!;
    expect(card.callComplete).toBe(true);
    // This call was never dispatched for execution and will never have output: close it
    // immediately with the close reason, so execution timing doesn't spin idle.
    expect(card.outputComplete).toBe(true);
    expect(card.outputStopReason).toBe("malformed");
  });

  it("request events inside a compaction span produce no retry notice (history rebuild exposes only the event pair for compaction)", () => {
    const m = createStreamModel();
    pushMessage(m, compactionBegin({ reason: "context", mode: "summarize", context: 1, turns: 1 }));
    pushMessage(m, requestBegin());
    pushMessage(m, requestEnd("timeout"));
    pushMessage(m, compactionEnd({ reason: "context", mode: "summarize", status: "completed" }));
    expect(items(m).filter((i) => i.kind === "reconnect")).toHaveLength(0);
  });
});

describe("origin nested routing", () => {
  it("child session_meta binds to the nearest approved, unfinished run_subagent tool card and renders recursively inside it", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "run_subagent", arguments: "{}", toolCallId: "t1" }));
    pushMessage(m, approvalDecision("allow", "t1"));
    pushMessage(m, withOrigin(meta("child1"), "child1"));

    const card = items(m)[0] as ToolCallItem;
    expect(card.subagent).toBeDefined();
    expect(card.subagentSessionId).toBe("child1");

    // Child-session messages (after stripping the first hop) go into the card's nested model.
    pushMessage(m, withOrigin(userText("subtask"), "child1"));
    pushMessage(m, withOrigin(assistantText("child reply"), "child1"));
    const sub = card.subagent!;
    expect(sub.items).toHaveLength(2);
    expect(sub.items[0]).toMatchObject({ kind: "user_text", text: "subtask" });
    expect(sub.items[1]).toMatchObject({ kind: "assistant_text", text: "child reply" });
  });

  it("deeper origin chains route by stripping one hop per level (grandchild session)", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "run_subagent", arguments: "{}", toolCallId: "t1" }));
    pushMessage(m, approvalDecision("allow", "t1"));
    pushMessage(m, withOrigin(meta("child1"), "child1"));
    // Grandchild-session message: origin = [child1, child2].
    pushMessage(m, withOrigin(withOrigin(assistantText("grandchild reply"), "child2"), "child1"));

    const sub = (items(m)[0] as ToolCallItem).subagent!;
    // Within the child model, child2 has no run_subagent card to bind to -> standalone SubagentCard.
    const nested = sub.items.find((i) => i.kind === "subagent") as SubagentItem;
    expect(nested).toBeDefined();
    expect(nested.sessionId).toBe("child2");
    expect(nested.model.items[0]).toMatchObject({
      kind: "assistant_text",
      text: "grandchild reply",
    });
  });

  it("builds a standalone SubagentCard when no bindable card exists; denied cards do not bind", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "run_subagent", arguments: "{}", toolCallId: "t1" }));
    pushMessage(m, approvalDecision("deny", "t1"));
    pushMessage(m, withOrigin(meta("childX"), "childX"));
    const standalone = items(m).find((i) => i.kind === "subagent") as SubagentItem;
    expect(standalone).toBeDefined();
    expect(standalone.sessionId).toBe("childX");
    expect((items(m)[0] as ToolCallItem).subagent).toBeUndefined();
  });

  it("child-session token_usage counts toward parent stats (tokens include child sessions, context does not)", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("task"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(tokenUsage(counts(1000), counts(1000)), "2026-07-05T00:00:01.000Z"));
    pushMessage(
      m,
      at(withOrigin(tokenUsage(counts(400), counts(400)), "c1"), "2026-07-05T00:00:02.000Z"),
    );
    notifyTaskIdle(m, Date.now());
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(stats.stats!.tokens).toBe(1400);
    expect(stats.stats!.tokensDelta).toBe(1400);
    expect(stats.stats!.context).toBe(1000);
  });
});

describe("message timestamps (footer hover display)", () => {
  it("user and assistant messages both carry atMs; streaming assistant uses start as a placeholder, switching to the completion time when the full message arrives", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("Q"), "2026-07-05T00:00:00.000Z"));
    // Streaming: the start timestamp is used as a placeholder first.
    pushMessage(m, at(partialText("start"), "2026-07-05T00:00:01.000Z"));
    pushMessage(m, at(partialText("delta", "A"), "2026-07-05T00:00:02.000Z"));
    const reply = items(m)[1] as AssistantTextItem;
    expect(reply.atMs).toBe(Date.parse("2026-07-05T00:00:01.000Z"));
    // Full message arrives -> switch to the **completion** timestamp (matches Trace's
    // convention: Trace records completion time).
    pushMessage(m, at(partialText("stop"), "2026-07-05T00:00:03.000Z"));
    pushMessage(m, at(assistantText("answer done"), "2026-07-05T00:00:04.000Z"));

    const user = items(m)[0] as UserTextItem;
    expect(user.atMs).toBe(Date.parse("2026-07-05T00:00:00.000Z"));
    expect(reply.atMs).toBe(Date.parse("2026-07-05T00:00:04.000Z"));
  });

  it("assistant messages from history rebuild (no streaming fragments) also carry atMs", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("Q"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(assistantText("A"), "2026-07-05T00:00:05.000Z"));
    expect((items(m)[1] as AssistantTextItem).atMs).toBe(Date.parse("2026-07-05T00:00:05.000Z"));
  });
});

describe("Task segmentation and stats triggering", () => {
  it("user text/image starts a new Task; the next Task's start backfills the previous Task's stats row (history accounting)", () => {
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("first question"), "2026-07-05T00:00:00.000Z"),
      at(assistantText("first answer"), "2026-07-05T00:00:03.000Z"),
      at(tokenUsage(counts(1000), counts(1000)), "2026-07-05T00:00:05.000Z"),
      at(userText("second question"), "2026-07-05T00:01:00.000Z"),
    ]);
    // Order: user1, text1, stats(task1), user2.
    expect(items(m).map((i) => i.kind)).toEqual([
      "user_text",
      "assistant_text",
      "task_stats",
      "user_text",
    ]);
    const stats = items(m)[2] as TaskStatsItem;
    expect(stats.stats!.context).toBe(1000);
    expect(stats.stats!.elapsedDeltaMs).toBe(5000); // time span from the first to the last message
  });

  it("stream end (finalizeHistory) closes the last Task; rounds without usage get no stats figures but still get a footer", () => {
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("with usage"), "2026-07-05T00:00:00.000Z"),
      at(tokenUsage(counts(500), counts(500)), "2026-07-05T00:00:01.000Z"),
      at(userText("no usage"), "2026-07-05T00:01:00.000Z"),
      at(assistantText("direct answer"), "2026-07-05T00:01:01.000Z"),
    ]);
    finalizeHistory(m);
    const statsItems = items(m).filter((i) => i.kind === "task_stats") as TaskStatsItem[];
    expect(statsItems).toHaveLength(2);
    expect(statsItems[0]!.stats).not.toBeNull(); // has token_usage -> has stats
    // No token_usage (e.g. the reply was aborted mid-stream) -> no stats to show, but this item
    // must still be produced: it doubles as this reply's footer (timestamp + copy). Otherwise an
    // aborted reply would have neither a timestamp nor a copy button.
    expect(statsItems[1]!.stats).toBeNull();
    expect(statsItems[1]!.assistantText).toBe("direct answer");
    expect(statsItems[1]!.atMs).toBe(Date.parse("2026-07-05T00:01:01.000Z"));
  });

  it("rounds with neither usage nor body text produce no items", () => {
    const m = createStreamModel();
    pushMessages(m, [at(userText("no-op"), "2026-07-05T00:00:00.000Z")]);
    finalizeHistory(m);
    expect(items(m).filter((i) => i.kind === "task_stats")).toHaveLength(0);
  });

  it("live streams close at task_state:idle, measuring the delta with the local clock", () => {
    const m = createStreamModel();
    pushMessage(m, userText("live question"), 10_000);
    pushMessage(m, tokenUsage(counts(800), counts(800)), 11_000);
    notifyTaskIdle(m, 15_100);
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(stats.stats!.elapsedDeltaMs).toBe(5100);
    expect(stats.stats!.tokens).toBe(800);
  });

  it("a full image_url message also starts a new Task", () => {
    const m = createStreamModel();
    pushMessage(m, tokenUsage(counts(100), counts(100))); // outside the Task boundary
    pushMessage(m, imageUrlMessage("data:image/png;base64,xx"));
    pushMessage(m, tokenUsage(counts(700), counts(600)));
    notifyTaskIdle(m);
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    // Counts reset when the Task starts: the 100 outside the boundary isn't part of this Task's delta.
    expect(stats.stats!.tokensDelta).toBe(600);
  });

  it("manual compaction usage between Tasks is not misattributed to the next Task's delta", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("one"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(tokenUsage(counts(1000), counts(1000)), "2026-07-05T00:00:01.000Z"));
    notifyTaskIdle(m, Date.now());
    // Manual /compact (outside the Task boundary).
    pushMessage(
      m,
      compactionBegin({ reason: "manual", mode: "summarize", context: 1000, turns: 1 }),
    );
    pushMessage(m, tokenUsage(counts(1300), counts(300)));
    pushMessage(m, compactionEnd({ reason: "manual", mode: "summarize", status: "completed" }));
    // Next Task.
    pushMessage(m, at(userText("two"), "2026-07-05T00:02:00.000Z"));
    pushMessage(m, at(tokenUsage(counts(1800), counts(500)), "2026-07-05T00:02:01.000Z"));
    notifyTaskIdle(m, Date.now());
    const statsItems = items(m).filter((i) => i.kind === "task_stats") as TaskStatsItem[];
    const last = statsItems[statsItems.length - 1]!;
    expect(last.stats!.tokensDelta).toBe(500); // excludes the compaction's 300
    expect(last.stats!.context).toBe(500);
  });

  it("round end takes the last request_end: the next round's injection arriving after it does not inflate this round's elapsed time", () => {
    // During history rebuild, the compaction summary `[context_summary]` is written alongside the
    // next round, with its timestamp landing in that next round — it arrives while the previous
    // round is still open. If round-end took the latest message seen, this injection would
    // artificially inflate the previous round's elapsed time (the old bug where elapsed grows
    // after a refresh); taking the last request_end instead naturally excludes it from the round.
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("Q"), "2026-07-05T00:00:00.000Z"),
      at(requestBegin(), "2026-07-05T00:00:01.000Z"),
      at(tokenUsage(out(100), out(100)), "2026-07-05T00:00:02.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:03.000Z"), // this round's last request_end
      // Next round's summary injection, timestamped much later; it arrives while this round hasn't closed yet.
      at(userText("[context_summary]\nsummary\n[/context_summary]"), "2026-07-05T00:00:50.000Z"),
      at(userText("next question"), "2026-07-05T00:01:00.000Z"), // startTask: closes the previous round
    ]);
    finalizeHistory(m);
    const first = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(first.stats!.elapsedDeltaMs).toBe(3_000); // 00:00 -> 00:03, excludes the @00:50 injection
  });
});

describe("output TPS (request event pair timing)", () => {
  it("request_begin/request_end pairs accumulate this Task's LLM duration, producing output TPS (includes tool-argument generation, excludes tool execution)", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("q"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(requestBegin(), "2026-07-05T00:00:01.000Z"));
    // Main session outputs 900 tokens; request wall clock 01->04 = 3s (tool execution
    // happening between the two requests isn't counted).
    pushMessage(m, at(tokenUsage(out(900), out(900)), "2026-07-05T00:00:03.500Z"));
    pushMessage(m, at(requestEnd("completed"), "2026-07-05T00:00:04.000Z"));
    notifyTaskIdle(m, Date.now());
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(stats.stats!.outputTps).toBe(300); // 900 / 3s
    expect(stats.stats!.tokensByBucket).toEqual({ cacheRead: 0, cacheWrite: 0, output: 900 });
  });

  it("multiple request rounds in one Task accumulate duration; TPS is null without request pairs", () => {
    const m = createStreamModel();
    // No request events -> no LLM timing -> TPS is null.
    pushMessage(m, at(userText("q1"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(tokenUsage(out(100), out(100)), "2026-07-05T00:00:01.000Z"));
    notifyTaskIdle(m, Date.now());
    const s1 = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(s1.stats!.outputTps).toBeNull();
    // Next Task: two request rounds of 2s each, 400 output tokens each -> 800 / 4s = 200 tok/s.
    pushMessage(m, at(userText("q2"), "2026-07-05T00:01:00.000Z"));
    pushMessage(m, at(requestBegin(), "2026-07-05T00:01:01.000Z"));
    pushMessage(m, at(tokenUsage(out(400), out(400)), "2026-07-05T00:01:02.500Z"));
    pushMessage(m, at(requestEnd("completed"), "2026-07-05T00:01:03.000Z")); // 2s
    pushMessage(m, at(requestBegin(), "2026-07-05T00:01:05.000Z"));
    pushMessage(m, at(tokenUsage(out(400), out(400)), "2026-07-05T00:01:06.500Z"));
    pushMessage(m, at(requestEnd("completed"), "2026-07-05T00:01:07.000Z")); // 2s
    notifyTaskIdle(m, Date.now());
    const stats = items(m).filter((i) => i.kind === "task_stats") as TaskStatsItem[];
    expect(stats[stats.length - 1]!.stats!.outputTps).toBe(200);
  });

  it("human approval wait is excluded from the TPS denominator (same convention as the Trace page's activeMs)", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("q"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(requestBegin(), "2026-07-05T00:00:01.000Z"));
    // core does `await approve(tc)` in the streaming loop: until approval returns, it won't
    // consume the next chunk and request_end won't fire either, so this 30s of human approval
    // wait sits entirely between the pair of request events.
    pushMessage(
      m,
      at(
        toolCall({ name: "exec_command", arguments: "{}", toolCallId: "t1" }),
        "2026-07-05T00:00:02.000Z",
      ),
    );
    pushMessage(m, at(approvalDecision("allow", "t1"), "2026-07-05T00:00:32.000Z"));
    pushMessage(m, at(tokenUsage(out(1000), out(1000)), "2026-07-05T00:00:32.500Z"));
    pushMessage(m, at(requestEnd("completed"), "2026-07-05T00:00:33.000Z"));
    notifyTaskIdle(m, Date.now());
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    // Wall clock 32s, minus 30s approval -> 2s of generation: 1000 / 2s = 500 tok/s
    // (without subtracting it, it would be only 31 tok/s).
    expect(stats.stats!.outputTps).toBe(500);
  });

  it("compaction requests contribute neither timing nor output to TPS (only normal requests count, matching the Trace page where compaction is its own round)", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("q"), "2026-07-05T00:00:00.000Z"));
    pushMessage(m, at(requestBegin(), "2026-07-05T00:00:01.000Z"));
    pushMessage(m, at(tokenUsage(out(600), out(600)), "2026-07-05T00:00:02.000Z"));
    pushMessage(m, at(requestEnd("completed"), "2026-07-05T00:00:03.000Z")); // 2s
    // Compaction span: both its request timing and its output should be skipped.
    pushMessage(
      m,
      at(
        compactionBegin({ reason: "manual", mode: "summarize", context: 600, turns: 1 }),
        "2026-07-05T00:00:04.000Z",
      ),
    );
    pushMessage(m, at(requestBegin(), "2026-07-05T00:00:04.500Z"));
    pushMessage(m, at(tokenUsage(out(999), out(1599)), "2026-07-05T00:00:19.000Z")); // compaction summary output
    pushMessage(m, at(requestEnd("completed"), "2026-07-05T00:00:20.000Z")); // compaction request, 15.5s, excluded
    pushMessage(
      m,
      at(
        compactionEnd({ reason: "manual", mode: "summarize", status: "completed" }),
        "2026-07-05T00:00:21.000Z",
      ),
    );
    notifyTaskIdle(m, Date.now());
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(stats.stats!.outputTps).toBe(300); // 600 / 2s (the compaction request's 999 output and 15.5s are excluded)
  });
});

describe("compaction attribution by position: in-round counts toward the round, post-round does not", () => {
  it("round elapsed stops at the last request_end; tail compaction sits outside the round and naturally does not count; the stats row precedes the compaction banner", () => {
    // Auto-compaction triggered at the **end** of a round: compaction is itself a full LLM
    // request (here 20s). It sits entirely **after** the round's last request_end. Using "the
    // last request_end" as the round boundary naturally excludes it — no need to walk each
    // message or specially subtract time for tail compaction (consistent with its Token / TPS
    // already being excluded).
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("Q"), "2026-07-05T00:00:00.000Z"),
      at(requestBegin(), "2026-07-05T00:00:01.000Z"),
      at(assistantText("A"), "2026-07-05T00:00:02.500Z"),
      at(tokenUsage(out(600), out(600)), "2026-07-05T00:00:02.900Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:03.000Z"), // this round's last request_end
      // Tail compaction: 00:04 -> 00:24, a full 20s, entirely after the round end
      at(
        compactionBegin({ reason: "context", mode: "summarize", context: 600, turns: 1 }),
        "2026-07-05T00:00:04.000Z",
      ),
      at(tokenUsage(out(300), out(300)), "2026-07-05T00:00:20.000Z"), // the compaction request's own usage
      at(
        compactionEnd({ reason: "context", mode: "summarize", status: "completed" }),
        "2026-07-05T00:00:24.000Z",
      ),
    ]);
    finalizeHistory(m);

    // The stats row comes **before** the compaction banner: it's about this round of
    // conversation, not the compaction result.
    expect(items(m).map((i) => i.kind)).toEqual([
      "user_text",
      "assistant_text",
      "task_stats",
      "compaction",
    ]);

    const stats = items(m)[2] as TaskStatsItem;
    // This round: 00:00 -> last request_end 00:03 = 3s. Compaction sits entirely after the round end, none of it counts.
    expect(stats.stats!.elapsedDeltaMs).toBe(3_000);
  });

  it("**mid-round** compaction: inside the round's span, both elapsed time and Tokens count toward the round", () => {
    // After compaction, the engine keeps running with the carry-over, and this round still has a
    // normal Request after compaction — so compaction sits between two of this round's
    // request_ends. It genuinely is time and cost spent to finish this round's work, so both
    // elapsed time (naturally spanned) and Token count it toward this round. The test is
    // "is there still a normal Request after compaction within this round?": yes -> counted
    // (within the round); no -> after the round (excluded, see the previous test case).
    // Compaction's output still doesn't count toward TPS (it isn't generation for a user request).
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("Q"), "2026-07-05T00:00:00.000Z"),
      at(requestBegin(), "2026-07-05T00:00:01.000Z"),
      at(tokenUsage(out(100), out(100)), "2026-07-05T00:00:02.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:03.000Z"), // own1: 2s, 100 output tokens
      // Mid-round compaction: 00:03 -> 00:23, a full 20s, 50 output tokens
      at(
        compactionBegin({ reason: "context", mode: "summarize", context: 100, turns: 1 }),
        "2026-07-05T00:00:03.000Z",
      ),
      at(requestBegin(), "2026-07-05T00:00:04.000Z"),
      at(tokenUsage(out(50), out(50)), "2026-07-05T00:00:20.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:22.000Z"), // compaction request, excluded from TPS
      at(
        compactionEnd({ reason: "context", mode: "summarize", status: "completed" }),
        "2026-07-05T00:00:23.000Z",
      ),
      // This round keeps running after compaction
      at(requestBegin(), "2026-07-05T00:00:24.000Z"),
      at(assistantText("A"), "2026-07-05T00:00:25.000Z"),
      at(tokenUsage(out(200), out(200)), "2026-07-05T00:00:25.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:26.000Z"), // own2: 2s, 200 output tokens
    ]);
    finalizeHistory(m);
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    // Elapsed = first message 00:00 -> last request_end 00:26 = 26s (includes the 20s of
    // compaction in between, which took up this round's wall clock).
    expect(stats.stats!.elapsedDeltaMs).toBe(26_000);
    // Token / cost includes compaction's 50: own1 100 + own2 200 + compaction 50 = 350.
    expect(stats.stats!.tokensByBucket.output).toBe(350);
    // But TPS only counts the two normal requests: 300 output / 4s LLM time (own1 2s + own2 2s,
    // compaction's 18s excluded) = 75 tok/s.
    expect(stats.stats!.outputTps).toBe(75);
  });

  it("next message sent long after the round was aborted: the previous round's elapsed excludes the gap", () => {
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("Q"), "2026-07-05T00:00:00.000Z"),
      at(requestBegin(), "2026-07-05T00:00:01.000Z"),
      at(tokenUsage(out(100), out(100)), "2026-07-05T00:00:02.000Z"),
      at(requestEnd("aborted"), "2026-07-05T00:00:03.000Z"),
      at(abortEvent("user"), "2026-07-05T00:00:03.000Z"),
      // The user doesn't send the next message until 60 seconds later
      at(userText("ask again"), "2026-07-05T00:01:03.000Z"),
      at(requestBegin(), "2026-07-05T00:01:04.000Z"),
      at(tokenUsage(out(50), out(50)), "2026-07-05T00:01:05.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:01:06.000Z"),
    ]);
    finalizeHistory(m);
    const all = items(m).filter((i) => i.kind === "task_stats") as TaskStatsItem[];
    expect(all[0]!.stats!.elapsedDeltaMs).toBe(3_000); // excludes the 60s the user was away
    expect(all[1]!.stats!.elapsedDeltaMs).toBe(3_000);
  });

  it("manual /compact between two rounds: the previous round's tally does not absorb compaction (history rebuild must match the live stream)", () => {
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("Q"), "2026-07-05T00:00:00.000Z"),
      at(requestBegin(), "2026-07-05T00:00:01.000Z"),
      at(tokenUsage(out(100), out(100)), "2026-07-05T00:00:02.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:03.000Z"),
      // This round ends here. The user reads the reply, thinks for 10 seconds, then types
      // /compact — in the live stream this round already closed at idle, so compaction's
      // usage and duration don't count toward it.
      at(
        compactionBegin({ reason: "manual", mode: "summarize", context: 100, turns: 1 }),
        "2026-07-05T00:00:13.000Z",
      ),
      at(requestBegin(), "2026-07-05T00:00:13.000Z"),
      at(tokenUsage(out(900), out(900)), "2026-07-05T00:00:32.000Z"),
      at(requestEnd("completed"), "2026-07-05T00:00:33.000Z"),
      at(
        compactionEnd({ reason: "manual", mode: "summarize", status: "completed" }),
        "2026-07-05T00:00:33.000Z",
      ),
      at(userText("[context_summary]\nsummary\n[/context_summary]"), "2026-07-05T00:00:33.000Z"),
    ]);
    finalizeHistory(m);
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    // Elapsed only runs to this round's last message (00:03) — it excludes both the 10-second
    // thinking gap and the 20-second compaction.
    expect(stats.stats!.elapsedDeltaMs).toBe(3_000);
    // Compaction's 900 output tokens also aren't charged to this round (otherwise cost would
    // double out of nowhere after a refresh).
    expect(stats.stats!.tokensByBucket.output).toBe(100);
  });
});

describe("compaction-internal messages (#17: history rebuild aligned with the live stream)", () => {
  it("compaction prompt and summary output inside the span neither render nor affect Task segmentation; the context figure is not polluted", () => {
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("task"), "2026-07-05T00:00:00.000Z"),
      at(tokenUsage(counts(10000), counts(10000)), "2026-07-05T00:00:05.000Z"),
      at(
        compactionBegin({ reason: "context", mode: "summarize", context: 10000, turns: 5 }),
        "2026-07-05T00:00:06.000Z",
      ),
      // Compaction prompt (user text) and the compaction request's summary output (assistant text): internal messages.
      at(userText("Summarize the above (compaction prompt)"), "2026-07-05T00:00:06.100Z"),
      at(assistantText("[summary]summary content[/summary]"), "2026-07-05T00:00:09.000Z"),
      at(tokenUsage(counts(11000), counts(1000)), "2026-07-05T00:00:09.500Z"),
      at(
        compactionEnd({ reason: "context", mode: "summarize", status: "completed" }),
        "2026-07-05T00:00:10.000Z",
      ),
      // Summary injected at the start of the new context file: internal input.
      at(
        userText("[context_summary]\nsummary content\n[/context_summary]"),
        "2026-07-05T00:00:10.500Z",
      ),
      at(userText("next question"), "2026-07-05T00:01:00.000Z"),
      at(tokenUsage(counts(3000), counts(3000)), "2026-07-05T00:01:05.000Z"),
    ]);
    finalizeHistory(m);
    // Order: user(task), **stats(task1)**, compaction banner, user(next question), stats(task2)
    // — internal messages don't appear. The stats row comes **before** the compaction banner:
    // it's about this round of conversation, while compaction is housekeeping outside this
    // round, listed after the tally.
    expect(items(m).map((i) => i.kind)).toEqual([
      "user_text",
      "task_stats",
      "compaction",
      "user_text",
      "task_stats",
    ]);
    // The compaction-complete row only states "compaction happened, succeeded or not" — it doesn't show Token counts.
    const banner = items(m)[2] as CompactionItem;
    expect(banner.running).toBe(false);
    expect(banner).not.toHaveProperty("tokens");
    // task1: context takes the total from the normal pre-compaction request (the compaction
    // request doesn't update the context figure).
    const stats1 = items(m)[1] as TaskStatsItem;
    expect(stats1.stats!.context).toBe(10000);
    expect(stats1.stats!.tokensDelta).toBe(10000); // excludes compaction request usage: compaction is its own round, not attributed to a user round
    // task2: context is the actual usage after compaction, so the delta can be negative.
    const stats2 = items(m)[4] as TaskStatsItem;
    expect(stats2.stats!.context).toBe(3000);
    expect(stats2.stats!.contextDelta).toBe(-7000);
    expect(stats2.stats!.tokensDelta).toBe(3000); // excludes compaction usage
  });

  it("mid-Task compaction: messages after the span still belong to the same Task; context_summary does not start a new Task", () => {
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("fix a bug"), "2026-07-05T00:00:00.000Z"),
      at(tokenUsage(counts(9000), counts(9000)), "2026-07-05T00:00:05.000Z"),
      at(
        compactionBegin({ reason: "context", mode: "summarize", context: 9000, turns: 3 }),
        "2026-07-05T00:00:06.000Z",
      ),
      at(userText("compaction prompt"), "2026-07-05T00:00:06.100Z"),
      at(assistantText("[summary]progress summary[/summary]"), "2026-07-05T00:00:08.000Z"),
      at(
        compactionEnd({ reason: "context", mode: "summarize", status: "completed" }),
        "2026-07-05T00:00:09.000Z",
      ),
      // Mid-round compaction: the summary is written as the new context's first input, after end.
      at(
        userText("[context_summary]\nprogress summary\n[/context_summary]"),
        "2026-07-05T00:00:09.500Z",
      ),
      at(assistantText("continue fixing and finish"), "2026-07-05T00:00:12.000Z"),
    ]);
    finalizeHistory(m);
    const kinds = items(m).map((i) => i.kind);
    // Only one Task: user, banner, assistant (output after compaction continues), stats.
    expect(kinds).toEqual(["user_text", "compaction", "assistant_text", "task_stats"]);
    expect((items(m)[2] as AssistantTextItem).text).toBe("continue fixing and finish");
    expect(items(m).filter((i) => i.kind === "user_text")).toHaveLength(1);
  });

  it("legacy <context_summary> prefix (old Traces) is still treated as internal input, not a user bubble", () => {
    // Old Traces contain the angle-bracket form; re-rendering them must keep hiding the
    // summary injection exactly like the current [context_summary] form.
    const m = createStreamModel();
    pushMessages(m, [
      at(
        userText("<context_summary>\nold summary\n</context_summary>"),
        "2026-07-05T00:00:00.000Z",
      ),
      at(userText("continue the task"), "2026-07-05T00:00:01.000Z"),
      at(assistantText("resuming"), "2026-07-05T00:00:02.000Z"),
    ]);
    finalizeHistory(m);
    const users = items(m).filter((i) => i.kind === "user_text") as UserTextItem[];
    expect(users.map((u) => u.text)).toEqual(["continue the task"]);
  });

  it("[user_steering] user text renders as a steering chip inside the running Task — it never starts a new Task", () => {
    // Mid-run steering is delivered as a standalone [user_steering] user message: it must
    // stay inside the current Task (one stats row, one task) but render in-flow, marker
    // stripped, as a user_steering item.
    const m = createStreamModel();
    pushMessages(m, [
      at(userText("fix the bug"), "2026-07-05T00:00:00.000Z"),
      at(assistantText("looking"), "2026-07-05T00:00:02.000Z"),
      at(tokenUsage(counts(100), counts(100)), "2026-07-05T00:00:03.000Z"),
      at(
        userText("[user_steering]\nalso check the tests\n[/user_steering]"),
        "2026-07-05T00:00:04.000Z",
      ),
      at(assistantText("checking the tests too"), "2026-07-05T00:00:06.000Z"),
      at(tokenUsage(counts(200), counts(100)), "2026-07-05T00:00:07.000Z"),
    ]);
    finalizeHistory(m);
    const kinds = items(m).map((i) => i.kind);
    // One Task: user, assistant, steering chip, assistant, one stats row at the end.
    expect(kinds).toEqual([
      "user_text",
      "assistant_text",
      "user_steering",
      "assistant_text",
      "task_stats",
    ]);
    const steering = items(m).find((i) => i.kind === "user_steering") as UserSteeringItem;
    expect(steering.text).toBe("also check the tests");
    // Only the real prompt is a user bubble.
    expect(items(m).filter((i) => i.kind === "user_text")).toHaveLength(1);
  });
});

describe("live close-out elapsed (#5/#20: mid-join takes the message-timestamp lower bound)", () => {
  it("a Task ending right after a refresh: elapsed takes the message-timestamp span, not the local-clock delta", () => {
    const m = createStreamModel();
    const loadNow = 1_000_000;
    // History replay: the Task actually ran for 60s.
    pushMessages(
      m,
      [
        at(userText("long-running task"), "2026-07-05T00:00:00.000Z"),
        at(assistantText("output"), "2026-07-05T00:01:00.000Z"),
        at(tokenUsage(counts(500), counts(500)), "2026-07-05T00:01:00.000Z"),
      ],
      loadNow,
    );
    // task_state:idle arrives 2s after joining.
    notifyTaskIdle(m, loadNow + 2000);
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(stats.stats!.elapsedDeltaMs).toBe(60_000);
    expect(stats.stats!.elapsedMs).toBe(60_000); // sessionElapsedMs is corrected in sync
  });

  it("when the local-clock delta is larger (normal live stream), the local clock still wins", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("live question"), "2026-07-05T00:00:00.000Z"), 10_000);
    pushMessage(m, at(tokenUsage(counts(800), counts(800)), "2026-07-05T00:00:01.000Z"), 11_000);
    notifyTaskIdle(m, 15_100);
    const stats = items(m).find((i) => i.kind === "task_stats") as TaskStatsItem;
    expect(stats.stats!.elapsedDeltaMs).toBe(5100);
  });
});

describe("approval keys and tool-card lookup (#7/#19)", () => {
  it("approvalKey distinguishes identical toolCallIds by origin chain", () => {
    expect(approvalKey(undefined, "t1")).toBe(" t1");
    expect(approvalKey([], "t1")).toBe(" t1");
    expect(approvalKey(["c1"], "t1")).toBe("c1 t1");
    expect(approvalKey(["c1", "c2"], "t1")).toBe("c1/c2 t1");
    expect(approvalKey(["c1"], "t1")).not.toBe(approvalKey(undefined, "t1"));
  });

  it("findToolCard locates tool cards at any depth by origin chain", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "run_subagent", arguments: "{}", toolCallId: "t1" }));
    pushMessage(m, approvalDecision("allow", "t1"));
    // A child-session tool card with the same toolCallId.
    pushMessage(m, withOrigin(meta("c1"), "c1"));
    pushMessage(
      m,
      withOrigin(toolCall({ name: "exec_command", arguments: "{}", toolCallId: "t1" }), "c1"),
    );

    const main = findToolCard(m, undefined, "t1");
    const nested = findToolCard(m, ["c1"], "t1");
    expect(main?.name).toBe("run_subagent");
    expect(nested?.name).toBe("exec_command");
    expect(main).not.toBe(nested);
    expect(findToolCard(m, ["cX"], "t1")).toBeNull();
    expect(findToolCard(m, ["c1"], "tX")).toBeNull();
  });
});

describe("localDecisions shared set (#22: survives resync rebuild)", () => {
  it("a new model injected with the shared set still marks previously registered approvals as manual", () => {
    const shared = new Set<string>();
    const m1 = createStreamModel(shared);
    registerLocalDecision(m1, "t1");
    // resync rebuild: inject the same set into a fresh model, replaying history.
    const m2 = createStreamModel(shared);
    pushMessage(m2, toolCall({ name: "x", arguments: "{}", toolCallId: "t1" }));
    pushMessage(m2, approvalDecision("allow", "t1"));
    expect((items(m2)[0] as ToolCallItem).decisionSource).toBe("manual");
  });
});

describe("overlap dedup (contract §7.2)", () => {
  it("buildDedupIndex indexes only the last limit messages; isDuplicate matches on an identical envelope JSON", () => {
    const m1 = at(userText("one"), "2026-07-05T00:00:00.000Z");
    const m2 = at(assistantText("two"), "2026-07-05T00:00:01.000Z");
    const m3 = at(assistantText("three"), "2026-07-05T00:00:02.000Z");
    const index = buildDedupIndex([m1, m2, m3], 2);
    expect(isDuplicate(index, m1)).toBe(false); // already slid out of the window
    expect(isDuplicate(index, m2)).toBe(true);
    expect(isDuplicate(index, { ...m3 })).toBe(true); // matches on identical structure
  });

  it("a full message hitting dedup discards the matching in-flight fragment (discardFragmentFor)", () => {
    const m = createStreamModel();
    // History already contains the full message.
    const complete = at(assistantText("hello"), "2026-07-05T00:00:00.000Z");
    pushMessage(m, complete);
    expect(items(m)).toHaveLength(1);
    // The streaming copy from the replay buffer reaches the reducer first.
    pushMessage(m, partialText("start"));
    pushMessage(m, partialText("delta", "hello"));
    expect(items(m)).toHaveLength(2);
    // The subsequent full message matches on dedup -> the in-flight fragment is discarded.
    discardFragmentFor(m, complete);
    expect(items(m)).toHaveLength(1);
    expect((items(m)[0] as AssistantTextItem).text).toBe("hello");
  });

  it("nested (origin-tagged) in-flight fragments can be discarded too", () => {
    const m = createStreamModel();
    pushMessage(m, withOrigin(meta("c1"), "c1"));
    pushMessage(m, withOrigin(partialText("start"), "c1"));
    pushMessage(m, withOrigin(partialText("delta", "child text"), "c1"));
    const sub = (items(m).find((i) => i.kind === "subagent") as SubagentItem).model;
    expect(sub.items).toHaveLength(1);
    discardFragmentFor(m, withOrigin(assistantText("child text"), "c1"));
    expect(sub.items).toHaveLength(0);
  });
});

describe("thinking/tool durations (collapsed-row display data)", () => {
  const T0 = "2026-07-07T00:00:00.000Z";
  const T1 = "2026-07-07T00:00:03.200Z";
  const T2 = "2026-07-07T00:00:08.000Z";
  const TAPPROVE = "2026-07-07T00:00:05.000Z";

  it("streaming tool (with approval): duration = generation segment + execution segment, minus the approval wait", () => {
    const m = createStreamModel();
    pushMessage(
      m,
      at(partialToolCall({ eventType: "start", name: "exec_command", toolCallId: "ta" }), T0),
    );
    pushMessage(m, at(partialToolCall({ eventType: "stop", name: "", toolCallId: "ta" }), T1));
    // Approval waits between T1 and TAPPROVE (1.8s), which isn't counted toward duration.
    pushMessage(m, at(approvalDecision("allow", "ta"), TAPPROVE));
    pushMessage(m, at(partialToolCallOutput({ eventType: "start", toolCallId: "ta" }), TAPPROVE));
    pushMessage(m, at(partialToolCallOutput({ eventType: "stop", toolCallId: "ta" }), T2));
    const card = items(m)[0] as ToolCallItem;
    // Generation segment T0->T1 (3200ms) + execution segment TAPPROVE->T2 (3000ms) = 6200ms; the 1800ms approval wait is subtracted.
    expect(card.durationMs).toBe(6200);
  });

  it("streaming thinking: partial start records the start; the full message settles duration by timestamp", () => {
    const m = createStreamModel();
    pushMessage(m, at(partialThinking("start"), T0));
    pushMessage(m, at(partialThinking("delta", "reasoning"), T0));
    pushMessage(m, at(partialThinking("stop"), T1));
    pushMessage(m, at(thinkingMessage("reasoning", "completed"), T1));
    const th = items(m)[0] as ThinkingItem;
    expect(th.startedAtMs).toBe(Date.parse(T0));
    expect(th.durationMs).toBe(3200);
  });

  it("history thinking (no fragments): approximates the start with the previous message's time", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("question"), T0));
    pushMessage(m, at(thinkingMessage("reasoning", "completed"), T1));
    const th = items(m).find((i) => i.kind === "thinking") as ThinkingItem;
    expect(th.startedAtMs).toBe(Date.parse(T0));
    expect(th.durationMs).toBe(3200);
  });

  it("tool duration: tool_call close → full tool_call_output (same convention as Trace analysis)", () => {
    const m = createStreamModel();
    pushMessage(m, at(toolCall({ name: "exec_command", arguments: "{}", toolCallId: "t1" }), T1));
    const card = items(m)[0] as ToolCallItem;
    expect(card.callStartedAtMs).toBe(Date.parse(T1));
    expect(card.durationMs).toBeUndefined();
    pushMessage(m, at(toolCallOutput({ output: "ok", toolCallId: "t1" }), T2));
    expect(card.durationMs).toBe(4800);
  });

  it("tool duration subtracts the approval wait: measured from approval time (not call time) to output", () => {
    const m = createStreamModel();
    const Ta = "2026-07-07T00:00:05.000Z"; // approval granted: after call(T1), before output(T2)
    pushMessage(m, at(toolCall({ name: "exec_command", arguments: "{}", toolCallId: "t1" }), T1));
    pushMessage(m, at(approvalDecision("allow", "t1"), Ta));
    pushMessage(m, at(toolCallOutput({ output: "ok", toolCallId: "t1" }), T2));
    const card = items(m)[0] as ToolCallItem;
    expect(card.approvalAtMs).toBe(Date.parse(Ta));
    expect(card.durationMs).toBe(3000); // T2 - Ta (subtracting the T1->Ta approval wait), not 4800
  });

  it("abort close-out: running tool cards stop ticking (outputComplete set, duration left unset)", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("Q"), T0));
    pushMessage(m, at(toolCall({ name: "exec_command", arguments: "{}", toolCallId: "ta" }), T1));
    pushMessage(m, at(abortEvent("user"), T2));
    const card = items(m).find((i) => i.kind === "tool_call") as ToolCallItem;
    expect(card.outputComplete).toBe(true);
    expect(card.outputStreaming).toBe(false);
    expect(card.durationMs).toBeUndefined();
    // Never produced a result: it must be recorded as aborted, otherwise it renders as a "completed" checkmark.
    expect(card.outputStopReason).toBe("aborted");
  });

  it("Task close-out (task_state:idle) also closes running tool cards", () => {
    const m = createStreamModel();
    pushMessage(m, at(userText("Q"), T0));
    pushMessage(m, at(toolCall({ name: "x", arguments: "{}", toolCallId: "tb" }), T1));
    notifyTaskIdle(m, Date.parse(T2));
    const card = items(m).find((i) => i.kind === "tool_call") as ToolCallItem;
    expect(card.outputComplete).toBe(true);
    expect(card.outputStopReason).toBe("aborted");
  });

  it("history tools (no fragments): approximate the argument-generation start with the previous message's time; duration includes the generation segment", () => {
    // Replaying Trace after a page refresh: there's no partial_tool_call start. Without
    // approximating the generation start, tool duration would silently lose the argument
    // generation segment (the model emits arguments token by token, often the bulk of the time).
    const m = createStreamModel();
    pushMessage(m, at(userText("question"), T0));
    pushMessage(m, at(toolCall({ name: "exec_command", arguments: "{}", toolCallId: "th" }), T1));
    const card = items(m).find((i) => i.kind === "tool_call") as ToolCallItem;
    expect(card.argStartedAtMs).toBe(Date.parse(T0));
    pushMessage(m, at(toolCallOutput({ output: "ok", toolCallId: "th" }), T2));
    // Generation segment T0->T1 (3200ms) + execution segment T1->T2 (4800ms).
    expect(card.durationMs).toBe(8000);
  });

  it("streaming tool: duration = argument-generation segment + execution segment (no approval); the full message does not shrink it", () => {
    const m = createStreamModel();
    pushMessage(
      m,
      at(partialToolCall({ eventType: "start", name: "read_file", toolCallId: "t2" }), T0),
    );
    pushMessage(m, at(partialToolCall({ eventType: "stop", name: "", toolCallId: "t2" }), T1));
    const card = items(m)[0] as ToolCallItem;
    expect(card.argStartedAtMs).toBe(Date.parse(T0));
    expect(card.callStartedAtMs).toBe(Date.parse(T1));
    pushMessage(m, at(partialToolCallOutput({ eventType: "start", toolCallId: "t2" }), T1));
    pushMessage(m, at(partialToolCallOutput({ eventType: "stop", toolCallId: "t2" }), T2));
    // Generation segment T0->T1 (3200ms) + execution segment T1->T2 (4800ms) = 8000ms (no approval wait).
    expect(card.durationMs).toBe(8000);
    // The later full tool_call_output only fills in the execution segment, without overwriting the generation segment already included.
    pushMessage(m, at(toolCallOutput({ output: "x", toolCallId: "t2" }), T2));
    expect(card.durationMs).toBe(8000);
  });
});

describe("multiple calls with a repeated tool_call_id (fallback for legacy Traces of name-as-id providers)", () => {
  it("a completed card receiving another full tool_call with the same id: a new card is built, the old one untouched", () => {
    const m = createStreamModel();
    // Round 1: get_time(Tokyo) call + output.
    pushMessage(
      m,
      toolCall({ name: "get_time", arguments: '{"city":"Tokyo"}', toolCallId: "get_time" }),
    );
    pushMessage(m, toolCallOutput({ output: "10:00 Tokyo", toolCallId: "get_time" }));
    // Round 2: same id called again (a legacy Trace where Gemini uses the function name as id).
    pushMessage(
      m,
      toolCall({ name: "get_time", arguments: '{"city":"Paris"}', toolCallId: "get_time" }),
    );
    pushMessage(m, toolCallOutput({ output: "03:00 Paris", toolCallId: "get_time" }));

    const cards = items(m).filter((it) => it.kind === "tool_call") as ToolCallItem[];
    expect(cards).toHaveLength(2);
    expect(cards[0]!.argumentsText).toBe('{"city":"Tokyo"}');
    expect(cards[0]!.output).toBe("10:00 Tokyo");
    expect(cards[0]!.outputComplete).toBe(true);
    expect(cards[1]!.argumentsText).toBe('{"city":"Paris"}');
    expect(cards[1]!.output).toBe("03:00 Paris");
    expect(cards[1]!.outputComplete).toBe(true);
  });

  it("second call with a repeated id: streaming output and approval decisions attach to the newest card", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "exec", arguments: '{"cmd":"a"}', toolCallId: "exec" }));
    pushMessage(m, toolCallOutput({ output: "out-a", toolCallId: "exec" }));
    pushMessage(m, toolCall({ name: "exec", arguments: '{"cmd":"b"}', toolCallId: "exec" }));
    pushMessage(m, approvalDecision("allow", "exec"));
    pushMessage(m, partialToolCallOutput({ eventType: "start", toolCallId: "exec" }));
    pushMessage(
      m,
      partialToolCallOutput({ eventType: "delta", output: "out-b", toolCallId: "exec" }),
    );
    pushMessage(m, partialToolCallOutput({ eventType: "stop", toolCallId: "exec" }));

    const cards = items(m).filter((it) => it.kind === "tool_call") as ToolCallItem[];
    expect(cards).toHaveLength(2);
    expect(cards[0]!.output).toBe("out-a"); // old card isn't touched by the second call
    expect(cards[0]!.decision).toBeUndefined();
    expect(cards[1]!.decision).toBe("allow");
    expect(cards[1]!.output).toBe("out-b");
  });

  it("old card still running (no output) when superseded: closed as aborted instead of waiting for output", () => {
    const m = createStreamModel();
    pushMessage(m, toolCall({ name: "exec", arguments: '{"cmd":"slow"}', toolCallId: "exec" }));
    // Old card's output isn't closed (callComplete with outputComplete=false) when a new same-id call arrives.
    pushMessage(m, toolCall({ name: "exec", arguments: '{"cmd":"next"}', toolCallId: "exec" }));

    const cards = items(m).filter((it) => it.kind === "tool_call") as ToolCallItem[];
    expect(cards).toHaveLength(2);
    expect(cards[0]!.outputComplete).toBe(true);
    expect(cards[0]!.outputStopReason).toBe("aborted");
    expect(cards[1]!.outputComplete).toBe(false); // new card waits for output as normal
  });
});

describe("fidelity-only messages render nothing (empty assistant bubble after thinking)", () => {
  // Core emits a complete text/thinking message with an empty body when a provider attaches an
  // opaque payload to an otherwise empty part (Gemini's thoughtSignature on a text part, GPT-5's
  // encrypted-reasoning phase markers) — see flushText / flushThinking. It must exist so the
  // fidelity round-trips into history; it must not become a visible item.
  it("an empty assistant text after thinking adds no item", () => {
    const m = createStreamModel();
    pushMessage(m, userText("hi"));
    pushMessage(m, thinkingMessage("pondering"));
    pushMessage(m, assistantText(""));
    expect(items(m).map((i) => i.kind)).toEqual(["user_text", "thinking"]);
  });

  it("a whitespace-only body counts as empty too", () => {
    const m = createStreamModel();
    pushMessage(m, assistantText("\n  \n"));
    pushMessage(m, thinkingMessage("   "));
    expect(items(m)).toEqual([]);
  });

  it("real content is unaffected, including a lone space inside real text", () => {
    const m = createStreamModel();
    pushMessage(m, thinkingMessage("thought"));
    pushMessage(m, assistantText("answer"));
    expect(items(m).map((i) => i.kind)).toEqual(["thinking", "assistant_text"]);
    expect((items(m)[1] as AssistantTextItem).text).toBe("answer");
  });

  it("a streamed segment is still settled by its complete message, not dropped", () => {
    // The guard must only skip the append path — a fragment that streamed real content is
    // replaced by its complete message as before.
    const m = createStreamModel();
    pushMessage(m, partialText("start", "Hel"));
    pushMessage(m, partialText("delta", "lo"));
    pushMessage(m, partialText("stop"));
    pushMessage(m, assistantText("Hello"));
    const texts = items(m).filter((i) => i.kind === "assistant_text");
    expect(texts).toHaveLength(1);
    expect((texts[0] as AssistantTextItem).text).toBe("Hello");
    expect((texts[0] as AssistantTextItem).streaming).toBe(false);
  });

  // A blank body can also arrive through a fragment: core starts a text segment on the first
  // truthy delta (`if (!item.text) break;`), and "\n\n" is truthy, so a whitespace-only segment
  // really does stream. Guarding only the append path would leave live and after-refresh
  // disagreeing — the fragment kept a blank bubble that a reload then dropped.
  it("a blank streamed text segment is discarded, so live matches the history rebuild", () => {
    const live = createStreamModel();
    pushMessage(live, thinkingMessage("pondering"));
    pushMessage(live, partialText("start", "\n\n"));
    pushMessage(live, partialText("stop"));
    pushMessage(live, assistantText("\n\n"));

    const history = createStreamModel();
    pushMessage(history, thinkingMessage("pondering"));
    pushMessage(history, assistantText("\n\n"));

    expect(items(live).map((i) => i.kind)).toEqual(["thinking"]);
    expect(items(live).map((i) => i.kind)).toEqual(items(history).map((i) => i.kind));
  });

  it("a blank streamed thinking segment is discarded too", () => {
    const live = createStreamModel();
    pushMessage(live, partialThinking("start", "  "));
    pushMessage(live, partialThinking("stop"));
    pushMessage(live, thinkingMessage("  "));

    const history = createStreamModel();
    pushMessage(history, thinkingMessage("  "));

    expect(items(live)).toEqual([]);
    expect(items(history)).toEqual([]);
  });

  it("discarding a blank fragment clears the open-fragment slots, leaving no stuck spinner", () => {
    // The fragment must be removed rather than blanked: a leftover openText would keep
    // `streaming: true` forever (a permanent blinking cursor), and a stale pendingText would
    // let the next complete message replace the wrong item.
    const m = createStreamModel();
    pushMessage(m, partialText("start", " "));
    pushMessage(m, partialText("stop"));
    pushMessage(m, assistantText(" "));
    expect(items(m)).toEqual([]);

    // The next real reply must append cleanly, not resurrect the discarded fragment.
    pushMessage(m, partialText("start", "Hi"));
    pushMessage(m, partialText("stop"));
    pushMessage(m, assistantText("Hi"));
    const texts = items(m).filter((i) => i.kind === "assistant_text");
    expect(texts).toHaveLength(1);
    expect((texts[0] as AssistantTextItem).text).toBe("Hi");
    expect((texts[0] as AssistantTextItem).streaming).toBe(false);
  });
});