feat(FN-3756): extract roadmap UI into bundled plugin and add autostash orp

Merges major roadmap plugin extraction (FN-3160/3161/3162), hardening the merger with autostash orphan cleanup and TOCTOU defenses (FN-3755/3756), adding shared state snapshots for mesh sync (FN-3451), shipping polling task notifications for the even realities plugin (FN-3743), defaulting non-epheme

Fusion-Task-Id: FN-3756

packages/engine/src/__tests__/merger-autostash-cleanup.test.ts

@@ -0,0 +1,125 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { execSync } from "node:child_process";
+import type { TaskStore } from "@fusion/core";
+import { __test__ } from "../merger.js";
+
+const { sweepAutostashOrphans, parseAutostashTaskId } = __test__;
+
+function git(cwd: string, cmd: string): string {
+  return execSync(cmd, { cwd, stdio: "pipe" }).toString("utf-8").trim();
+}
+
+function initRepo(dir: string): void {
+  git(dir, "git init -b main");
+  git(dir, 'git config user.email "test@example.com"');
+  git(dir, 'git config user.name "Test"');
+  writeFileSync(join(dir, "file.txt"), "base\n");
+  git(dir, "git add file.txt");
+  git(dir, 'git commit -m "init"');
+}
+
+function createAutostash(dir: string, taskId: string, content: string): string {
+  const label = `fusion-merger-autostash:${taskId}:${Date.now()}`;
+  writeFileSync(join(dir, "file.txt"), content);
+  git(dir, "git add file.txt");
+  const sha = git(dir, "git stash create");
+  git(dir, `git stash store -m ${JSON.stringify(label)} ${sha}`);
+  git(dir, "git reset --hard HEAD");
+
+  const list = stashList(dir);
+  if (!list.includes(label)) {
+    // Older git versions may ignore `stash store -m` for create/store objects.
+    git(dir, "git stash drop stash@{0}");
+    writeFileSync(join(dir, "file.txt"), content);
+    git(dir, `git stash push -m ${JSON.stringify(label)} file.txt`);
+    return git(dir, 'git stash list --format="%H" -n 1');
+  }
+  return sha;
+}
+
+function stashList(dir: string): string {
+  return git(dir, 'git stash list --format="%H %gd %s"');
+}
+
+function makeStore(tasks: Record<string, string>, opts?: { throwOnGetTask?: boolean }): TaskStore {
+  return {
+    getTask: async (taskId: string) => {
+      if (opts?.throwOnGetTask) throw new Error("boom");
+      const column = tasks[taskId];
+      if (!column) return null;
+      return { id: taskId, column } as any;
+    },
+    logEntry: async () => undefined,
+  } as unknown as TaskStore;
+}
+
+describe("parseAutostashTaskId", () => {
+  it("parses valid labels and rejects malformed/foreign labels", () => {
+    expect(parseAutostashTaskId("fusion-merger-autostash:FN-3485:123")).toBe("FN-3485");
+    expect(parseAutostashTaskId("fusion-merger-autostash:FN-3485")).toBeNull();
+    expect(parseAutostashTaskId("fusion-merger-autostash::123")).toBeNull();
+    expect(parseAutostashTaskId("WIP on main: abcdef")).toBeNull();
+  });
+});
+
+describe("sweepAutostashOrphans", () => {
+  let dir: string;
+
+  beforeEach(() => {
+    dir = mkdtempSync(join(tmpdir(), "fn-autostash-"));
+    initRepo(dir);
+  });
+
+  afterEach(() => {
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  it("drops closed-task done orphan when net diff is empty", async () => {
+    createAutostash(dir, "FN-1001", "done-content\n");
+    writeFileSync(join(dir, "file.txt"), "done-content\n");
+    git(dir, "git add file.txt");
+    git(dir, 'git commit -m "match stash"');
+
+    await sweepAutostashOrphans(dir, "FN-MERGE", makeStore({ "FN-1001": "done" }));
+
+    expect(stashList(dir)).toBe("");
+  });
+
+  it("preserves closed-task archived orphan when stash still differs", async () => {
+    const sha = createAutostash(dir, "FN-1002", "archived-content\n");
+
+    await sweepAutostashOrphans(dir, "FN-MERGE", makeStore({ "FN-1002": "archived" }));
+
+    expect(stashList(dir)).toContain(sha);
+  });
+
+  it("drops open-task orphan with empty path diff via existing subsumed path", async () => {
+    createAutostash(dir, "FN-1003", "open-matched\n");
+    writeFileSync(join(dir, "file.txt"), "open-matched\n");
+    git(dir, "git add file.txt");
+    git(dir, 'git commit -m "match open stash"');
+
+    await sweepAutostashOrphans(dir, "FN-MERGE", makeStore({ "FN-1003": "in-progress" }));
+
+    expect(stashList(dir)).toBe("");
+  });
+
+  it("preserves open-task orphan with real diff", async () => {
+    const sha = createAutostash(dir, "FN-1004", "open-live\n");
+
+    await sweepAutostashOrphans(dir, "FN-MERGE", makeStore({ "FN-1004": "in-progress" }));
+
+    expect(stashList(dir)).toContain(sha);
+  });
+
+  it("preserves orphan when store.getTask throws", async () => {
+    const sha = createAutostash(dir, "FN-1005", "throw-case\n");
+
+    await sweepAutostashOrphans(dir, "FN-MERGE", makeStore({}, { throwOnGetTask: true }));
+
+    expect(stashList(dir)).toContain(sha);
+  });
+});