test(FN-4834): complete Step 2 — add reliability init stderr regression coverage

Fusion-Task-Id: FN-4834
Fusion-Task-Lineage: 714c9c73-ca66-4c3f-980c-d03e6b50316a

packages/engine/src/__tests__/reliability-interactions/worktree-init-stderr-surfacing.test.ts

@@ -0,0 +1,104 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { acquireTaskWorktree } from "../../worktree-acquisition.js";
+import { hasGit, makeReliabilityFixture } from "./_helpers.js";
+
+describe.skipIf(!hasGit)("reliability interactions: worktree init stderr surfacing", () => {
+  const fixtures: Array<Awaited<ReturnType<typeof makeReliabilityFixture>>> = [];
+
+  afterEach(async () => {
+    await Promise.all(fixtures.splice(0).map((fixture) => fixture.cleanup()));
+  });
+
+  async function setup() {
+    const fixture = await makeReliabilityFixture({
+      taskId: "FN-4834-T",
+      settings: {
+        worktreeInitCommand: "pnpm install --frozen-lockfile",
+      },
+      task: {
+        column: "todo",
+        branch: null,
+        worktree: null,
+      },
+    });
+    fixtures.push(fixture);
+    const store = {
+      updateTask: fixture.store.updateTask.bind(fixture.store),
+      logEntry: vi.fn(fixture.store.logEntry.bind(fixture.store)),
+    } as const;
+    return { fixture, store };
+  }
+
+  it("FN-4834: surfaces stderr output in init failure outcome", async () => {
+    const { fixture, store } = await setup();
+    const runConfiguredCommand = vi.fn().mockResolvedValue({
+      exitCode: 1,
+      stderr: `${"x".repeat(220)}\nERR_PNPM_FROZEN_LOCKFILE_WITH_OUTDATED_LOCKFILE\n${"y".repeat(220)}`,
+      stdout: "",
+    });
+
+    await expect(acquireTaskWorktree({
+      task: fixture.task,
+      rootDir: fixture.rootDir,
+      store: store as any,
+      settings: fixture.settings,
+      createWorktree: vi.fn().mockResolvedValue({ path: `${fixture.rootDir}/.worktrees/fn-4834-t`, branch: "fusion/fn-4834-t" }),
+      runConfiguredCommand,
+      runInitCommand: true,
+      logger: { log: vi.fn(), warn: vi.fn(), error: vi.fn() },
+    })).resolves.toBeTruthy();
+
+    const failureCall = store.logEntry.mock.calls.find((call: unknown[]) => String(call[1]).startsWith("Worktree init command failed"));
+    expect(failureCall).toBeDefined();
+    const outcome = String(failureCall?.[2] ?? "");
+    expect(outcome).toContain("ERR_PNPM_FROZEN_LOCKFILE_WITH_OUTDATED_LOCKFILE");
+    expect(outcome.length).toBeLessThanOrEqual(2_100);
+  });
+
+  it("FN-4834: falls back to stdout when stderr is empty", async () => {
+    const { fixture, store } = await setup();
+    const runConfiguredCommand = vi.fn().mockResolvedValue({
+      exitCode: 1,
+      stderr: "   ",
+      stdout: "pnpm diagnostic: lockfile is out of sync",
+    });
+
+    await expect(acquireTaskWorktree({
+      task: fixture.task,
+      rootDir: fixture.rootDir,
+      store: store as any,
+      settings: fixture.settings,
+      createWorktree: vi.fn().mockResolvedValue({ path: `${fixture.rootDir}/.worktrees/fn-4834-t`, branch: "fusion/fn-4834-t" }),
+      runConfiguredCommand,
+      runInitCommand: true,
+      logger: { log: vi.fn(), warn: vi.fn(), error: vi.fn() },
+    })).resolves.toBeTruthy();
+
+    const failureCall = store.logEntry.mock.calls.find((call: unknown[]) => String(call[1]).startsWith("Worktree init command failed"));
+    expect(String(failureCall?.[2] ?? "")).toContain("pnpm diagnostic: lockfile is out of sync");
+  });
+
+  it("FN-4834: falls back to spawnError when streams are absent", async () => {
+    const { fixture, store } = await setup();
+    const runConfiguredCommand = vi.fn().mockResolvedValue({
+      exitCode: 1,
+      spawnError: new Error("ENOENT: pnpm not found"),
+    });
+
+    await expect(acquireTaskWorktree({
+      task: fixture.task,
+      rootDir: fixture.rootDir,
+      store: store as any,
+      settings: fixture.settings,
+      createWorktree: vi.fn().mockResolvedValue({ path: `${fixture.rootDir}/.worktrees/fn-4834-t`, branch: "fusion/fn-4834-t" }),
+      runConfiguredCommand,
+      runInitCommand: true,
+      logger: { log: vi.fn(), warn: vi.fn(), error: vi.fn() },
+    })).resolves.toBeTruthy();
+
+    const failureCall = store.logEntry.mock.calls.find((call: unknown[]) => String(call[1]).startsWith("Worktree init command failed"));
+    const outcome = String(failureCall?.[2] ?? "");
+    expect(outcome).toContain("ENOENT");
+    expect(outcome.length).toBeGreaterThan(0);
+  });
+});