feat(web): input history recall, sticky work-group header, chat outline (#164)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/web/test/input-history.test.ts

@@ -0,0 +1,114 @@
+/**
+ * input-history.ts unit tests: which stream items become recallable entries, and the
+ * ↑/↓ navigation state machine the composer drives (start-from-empty, edit-ends-navigation,
+ * pin-at-oldest, stash restore past the newest).
+ */
+import { describe, expect, it } from "vitest";
+import type { ChatItem } from "../src/lib/omni/stream-model";
+import { buildSkillsMessage } from "../src/features/chat/skill-use";
+import { handoffMessage } from "../src/features/chat/agent-handoff";
+import { buildScheduledMessage } from "@prismshadow/penguin-core/markers";
+import {
+  buildInputHistory,
+  caretOnFirstLine,
+  caretOnLastLine,
+  historyStepBack,
+  historyStepForward,
+} from "../src/features/chat/input-history";
+import type { HistoryNav } from "../src/features/chat/input-history";
+
+let nextId = 0;
+const user = (text: string): ChatItem => ({ kind: "user_text", id: nextId++, text });
+const steering = (text: string): ChatItem => ({ kind: "user_steering", id: nextId++, text });
+const assistant = (text: string): ChatItem => ({
+  kind: "assistant_text",
+  id: nextId++,
+  text,
+  streaming: false,
+});
+
+describe("buildInputHistory", () => {
+  it("collects typed prompts and steering in order, skipping machine-injected texts", () => {
+    const goalRound1 = `[goal]\nround: 1\nobjective: fix it\n[/goal]\nfix the bug`;
+    const goalRound2 = `[goal]\nround: 2\nobjective: fix it\n[/goal]\nfix the bug`;
+    const items: ChatItem[] = [
+      user("first question"),
+      assistant("answer"),
+      user(handoffMessage({ agentId: "agent-a", sessionId: "session-1", workspace: "/tmp/w" })),
+      user(buildScheduledMessage("nightly", "2026-08-01T00:00:00Z", "scheduled prompt")),
+      user(goalRound1),
+      user(goalRound2),
+      steering("please also check the tests"),
+      user(buildSkillsMessage(["my-skill"], "with a skill")),
+      user("first question"),
+    ];
+    expect(buildInputHistory(items)).toEqual([
+      "first question",
+      "fix the bug",
+      "please also check the tests",
+      "with a skill",
+      "first question",
+    ]);
+  });
+
+  it("collapses consecutive duplicates and drops empty bodies (image-only prompts)", () => {
+    const items: ChatItem[] = [user("same"), user("same"), user("  "), user("next")];
+    expect(buildInputHistory(items)).toEqual(["same", "next"]);
+  });
+});
+
+describe("history navigation", () => {
+  const history = ["one", "two", "three"];
+
+  it("starts from an empty draft at the newest entry and walks back, pinning at the oldest", () => {
+    const s1 = historyStepBack(history, null, "");
+    expect(s1?.text).toBe("three");
+    const s2 = historyStepBack(history, s1!.nav, "three");
+    expect(s2?.text).toBe("two");
+    const s3 = historyStepBack(history, s2!.nav, "two");
+    expect(s3?.text).toBe("one");
+    const s4 = historyStepBack(history, s3!.nav, "one");
+    expect(s4?.text).toBe("one"); // pinned: repeated ↑ at the oldest stays put
+    expect(s4?.nav?.index).toBe(0);
+  });
+
+  it("does not start from a non-empty draft, and stashes/restores the draft across a round trip", () => {
+    expect(historyStepBack(history, null, "half-written")).toBeNull();
+    const back = historyStepBack(history, null, "  ");
+    expect(back?.nav?.stash).toBe("  ");
+    const fwd = historyStepForward(history, back!.nav, "three");
+    expect(fwd).toEqual({ nav: null, text: "  " }); // past the newest: draft restored, navigation over
+  });
+
+  it("hands the keys back once the recalled text was edited", () => {
+    const nav: HistoryNav = { index: 2, stash: "", recalled: "three" };
+    expect(historyStepBack(history, nav, "three edited")).toBeNull();
+    expect(historyStepForward(history, nav, "three edited")).toBeNull();
+  });
+
+  it("steps forward through newer entries before restoring the stash", () => {
+    const nav: HistoryNav = { index: 0, stash: "draft", recalled: "one" };
+    const s1 = historyStepForward(history, nav, "one");
+    expect(s1?.text).toBe("two");
+    const s2 = historyStepForward(history, s1!.nav, "two");
+    expect(s2?.text).toBe("three");
+    const s3 = historyStepForward(history, s2!.nav, "three");
+    expect(s3).toEqual({ nav: null, text: "draft" });
+  });
+
+  it("never steps with an empty history", () => {
+    expect(historyStepBack([], null, "")).toBeNull();
+  });
+});
+
+describe("caret line guards", () => {
+  it("first/last line checks follow the newlines around the caret", () => {
+    const text = "line1\nline2";
+    expect(caretOnFirstLine(text, 3)).toBe(true);
+    expect(caretOnFirstLine(text, 8)).toBe(false);
+    expect(caretOnLastLine(text, 8)).toBe(true);
+    expect(caretOnLastLine(text, 3)).toBe(false);
+    expect(caretOnFirstLine("", 0)).toBe(true);
+    expect(caretOnLastLine("", 0)).toBe(true);
+  });
+});