test: eight flaky-test repairs and five failure diagnostics from the 2026-11-01 flaky pass (GSTA-240)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

bin/gstack-codex-probe

@@ -662,8 +662,8 @@ _gstack_codex_lock_acquire() {
       if [ "$_ohost" = "$_host" ] && ! kill -0 "$_pid" 2>/dev/null; then _dead=1; fi
       [ $((_now - _ts)) -ge "$_stale" ] && _dead=1
     else
-      _ts=$(stat -c %Y "$_dir" 2>/dev/null || stat -f %m "$_dir" 2>/dev/null || echo 0)
-      case "$_ts" in ''|*[!0-9]*) _ts=0 ;; esac
+      _ts=$(stat -c %Y "$_dir" 2>/dev/null || stat -f %m "$_dir" 2>/dev/null || echo "$_now")
+      case "$_ts" in ''|*[!0-9]*) _ts="$_now" ;; esac
       [ $((_now - _ts)) -ge 5 ] && _dead=1
     fi
     [ "$_dead" -eq 1 ] && _gstack_codex_lock_break "$_dir" "$_owner"

bin/gstack-evidence

@@ -400,7 +400,7 @@ async function cmdRun(argv: string[]): Promise<number> {
   try {
     if (shell && !shell.ok) throw new Error(shell.error);
     const spawnArgv = shell?.ok ? [shell.cmd, ...shell.argv] : cmdArgv;
-    proc = Bun.spawn(spawnArgv, { stdin: "inherit", stdout: "pipe", stderr: "pipe" });
+    proc = Bun.spawn(spawnArgv, { stdin: "inherit", stdout: "pipe", stderr: "pipe", env: log ? { ...process.env, GSTACK_EVIDENCE_LOG: log.path } : process.env });
   } catch (e: any) {
     // Spawn failure (ENOENT on argv-direct form): record exit 127, propagate 127.
     exitCode = 127;

changelog.d/capy-gsta240-flaky.md

@@ -0,0 +1,14 @@
+**Eight flaky tests from the 2026-11-01 flaky pass stop failing correct runs, and five more now name their cause when they fail.** One product lock broke a fresh lock it had misjudged as abandoned, the free-shard runner failed a shard over a browser child that had already exited, and the rest were fixtures that raced their own setup, leaned on wall-clock sleeps or read the caller's state root.
+
+### Fixed
+- **`bin/gstack-codex-probe`**: a waiter that cannot read an owner-less lock's age (the holder removed it in that instant, or `stat -f` printed filesystem text on Linux) now treats the lock as fresh instead of abandoned, so it no longer deletes the next owner's lock and the probe no longer ends `MODEL_PROBE_INCONCLUSIVE` (Free Tests 41216564482, 41235671867, 41263831361). A stat stub for both race windows fails without the fix; 64 stress runs went from 2 failures to 0.
+- **`scripts/test-free-shards.ts`**: a recorded browser child the runner never saw, belonging to a known daemon, settles when it has already exited; a live one still fails the shard and now names its pid and daemon (Free Tests 41264845860 shard 7). A live child from another shard still fails.
+- **`scripts/lib/free-home-guard.ts`, `bin/gstack-evidence`**: `gstack-evidence run` names its own lane log in `GSTACK_EVIDENCE_LOG`, and the real-home tripwire ignores exactly that file, so a /ship lane no longer trips over its own output. A foreign write under the home's `~/.gstack` still fails.
+- **`test/autoplan-publication-guard.test.ts`**: the render-root cases clear the state-root variables they don't name, so a `GSTACK_STATE_ROOT` exported by the gstack launch file no longer picks the root. Three cases failed every time under that variable, and the lookalike controls passed for the wrong reason.
+- **`test/gstack-design-detect.test.ts`**: the directory scan proves one batch by counting engine calls instead of sleeping near the 1,500 ms detect timeout (macOS job 124813933194). The product timeout is unchanged.
+- **`test/pregate-regate.test.ts`**: the two fixtures are built once and copied per test (`copyFixtureRepo` in `test/helpers/restamp-fixture.ts`), so 8 builds become 2.
+- **`test/ship-queue-train.test.ts`**: the planted seam has its own name, so the fixture's own background `git maintenance` lock no longer collides with it (EEXIST, Free Tests 41288253305, 41288417894), and the test now holds a real `maintenance.lock` beside it.
+- **`test/ship-budget.test.ts`**: the fake child writes its args to a temporary file and renames it, so the poll never reads an empty file (Free Tests 41242243205).
+
+### Changed
+- `test/bootstrap-retention-shard.test.ts`, `test/office-hours-attempt.test.ts`, `test/session-update-autostash.test.ts`, `test/shard-engine.test.ts` and `test/auq-parallel.test.ts` print the process state, exit status or cleanup events behind their assertion, so the next red names its cause.

scripts/lib/free-home-guard.ts

@@ -5,8 +5,10 @@
  * the real home before and after each free shard, and names the shard's files
  * when one of those entries changed. It watches only these surfaces; it is not
  * a universal write-containment check. Live agent-session logs that a
- * concurrently running host keeps writing are excluded, and directory mtimes
- * are ignored, so only file, link and directory-set changes count.
+ * concurrently running host keeps writing are excluded, as is the one lane log
+ * `gstack-evidence run` tees this run's own output into (its exact path, from
+ * GSTACK_EVIDENCE_LOG). Directory mtimes are ignored, so only file, link and
+ * directory-set changes count.
  *
  * A shard that runs alone owns its window, so its guard names its files.
  * Concurrent shards share one HOME and cannot tell whose write a change was, so
@@ -104,6 +106,7 @@ export type FreeHomeGuardFactory = (files: string[], env: NodeJS.ProcessEnv, sta
 /** Take the baseline now; verify() returns null or the failure to report. */
 export function guardFreeHome(files: string[], env: NodeJS.ProcessEnv = process.env, scope: FreeHomeScope = { kind: 'shard' }): FreeHomeGuard {
   const home = freeHomeDir(env);
+  const ownLog = env.GSTACK_EVIDENCE_LOG && path.isAbsolute(env.GSTACK_EVIDENCE_LOG) ? path.relative(home, env.GSTACK_EVIDENCE_LOG) : null;
   const unreadable = (error: unknown) => `real home surfaces could not be snapshotted (${(error as NodeJS.ErrnoException).code ?? 'error'}); shard files: ${files.join(', ')}`;
   let before: FreeHomeSnapshot | undefined;
   let baselineError: string | undefined;
@@ -112,7 +115,7 @@ export function guardFreeHome(files: string[], env: NodeJS.ProcessEnv = process.
     verify() {
       if (!before) return baselineError!;
       try {
-        const changed = diffFreeHome(before, snapshotFreeHome(home));
+        const changed = diffFreeHome(before, snapshotFreeHome(home)).filter(entry => entry !== ownLog);
         return changed.length ? formatFreeHomeChange(changed, files, scope) : null;
       } catch (error) { return unreadable(error); }
     },

scripts/test-free-shards.ts

@@ -1325,6 +1325,10 @@ function trackShardBrowser(stateDir: string, env: NodeJS.ProcessEnv) {
         check(operation);
         if (!Number.isSafeInteger(pid) || (pid as number) <= 1) throw new BrowserCleanupError('invalid browser child identity');
         const identity = identities.get(pid as number);
+        if (!identity && identities.get(daemon as number)?.root) {
+          if (!await inspect(operation, pid as number)) return;
+          throw new BrowserCleanupError(`browser child ownership is unconfirmed: recorded pid ${pid} is alive outside daemon ${daemon}'s process tree`);
+        }
         if (!identity || identity.daemon !== daemon || identity.root) throw new BrowserCleanupError('browser child ownership is unconfirmed');
         if (await live(operation, identity) && (typeof start !== 'string' || !start
           || await nativeStart(operation, identity) !== start.replace(/\s+/g, ' '))) throw new BrowserCleanupError('browser child identity was replaced');

test/auq-parallel.test.ts

@@ -111,7 +111,8 @@ test.each([
   expect(facts.receipts.filter((receipt: any) => receipt.outcome === 'timeout')).toHaveLength(3 - scenario.passed);
   expect(facts.receipts.every((receipt: any) => receipt.timeoutMs === 240_000 && !receipt.answered)).toBe(true);
   expect(facts.active).toBe(0); expect(facts.answers).toBe(0); expect(facts.pendingTimers).toBe(0);
-  expect(facts.leftovers).toEqual([]); expect(facts.ownedStateLeftovers).toEqual([]);
+  expect(facts.leftovers).toEqual([]);
+  expect(facts.ownedStateLeftovers, JSON.stringify({ fixtures: facts.fixtures, inputs: facts.inputs.map((input: any) => [input.id, input.config, input.state]), events: facts.events.filter((event: any) => ['query-close', 'capture-settle', 'cleanup'].includes(event.kind)) })).toEqual([]);
   expect(facts.events.filter((event: any) => event.kind === 'query-close')).toHaveLength(scenario.queries);
   expect(facts.events.filter((event: any) => event.kind === 'cleanup')).toHaveLength(3);
 }, 20_000);

test/autoplan-publication-guard.test.ts

@@ -1316,7 +1316,9 @@ describe('Autoplan phase entry through the gbrain :user render (#2569)', () => {
       edit(rewriteSectionBase(fs.readFileSync(path.join(ROOT, 'autoplan/sections', name), 'utf8'), linkRoot)));
     return root;
   }
-  function withEnv<T>(env: Record<string, string | undefined>, work: () => T): T {
+  /** The state-root chain the case does not name is cleared, so an ambient GSTACK_STATE_ROOT (every gstack launch file exports one) cannot pick the root. */
+  function withEnv<T>(given: Record<string, string | undefined>, work: () => T): T {
+    const env = { GSTACK_STATE_ROOT: undefined, GSTACK_STATE_DIR: undefined, CLAUDE_PLUGIN_DATA: undefined, ...given };
     const previous = Object.fromEntries(Object.keys(env).map(k => [k, process.env[k]]));
     for (const [k, v] of Object.entries(env)) if (v === undefined) delete process.env[k]; else process.env[k] = v;
     try { return work(); }

test/bootstrap-retention-shard.test.ts

@@ -62,7 +62,7 @@ describe.skipIf(process.platform !== 'linux')('bootstrap paid-shard cleanup inte
       fs.writeFileSync(path.join(root, 'controller.stdout.log'), controller.stdout ?? '', { mode: 0o600 });
       fs.writeFileSync(path.join(root, 'controller.stderr.log'), controller.stderr ?? '', { mode: 0o600 });
       expect(controller.error).toBeUndefined();
-      expect(controller.status).toBe(0);
+      expect(controller.status, `controller exited ${controller.status} (signal ${controller.signal}); stderr tail: ${(controller.stderr ?? '').slice(-600).replace(/\s*\n\s*/g, ' | ')}`).toBe(0);
       const outcome = JSON.parse(fs.readFileSync(outcomePath, 'utf8'));
       if (scenario === 'ack-failure') {
         expect(controller.stdout).toContain('(fail) qa-bootstrap');

test/codex-probe-cache.test.ts

@@ -247,6 +247,31 @@ describe('probe lock recovery and failure', () => {
     expect(calls(f)).toBe(1);
   }));
 
+  test('a lock released while a waiter reads its age is not abandoned; the next owner\'s fresh lock survives', withFixture((f) => {
+    const sig = sigOf(f);
+    const lock = path.join(f.locks, sig);
+    const once = path.join(f.home, 'vanish-once');
+    const real = JSON.stringify(Bun.which('stat'));
+    fs.mkdirSync(lock, { recursive: true });
+    fs.writeFileSync(path.join(f.home, 'bin/stat'), `#!/usr/bin/env bash
+if [ "$3" = "$RACE_LOCK" ] && [ -f "$RACE_ONCE" ]; then
+  case "$1" in
+    -c) rmdir "$RACE_LOCK"; [ "$RACE_PHASE" = early ] && mkdir "$RACE_LOCK"; exit 1 ;;
+    -f) ${real} "$@"; rc=$?; rm -f "$RACE_ONCE"; [ -d "$RACE_LOCK" ] || mkdir "$RACE_LOCK"; exit "$rc" ;;
+  esac
+fi
+exec ${real} "$@"
+`, { mode: 0o755 });
+    for (const phase of ['early', 'late']) {
+      fs.writeFileSync(once, 'armed');
+      const r = probe(f, { _GSTACK_CODEX_LOCK_WAIT: '1', RACE_LOCK: lock, RACE_ONCE: once, RACE_PHASE: phase });
+      expect(fs.existsSync(once)).toBe(false);
+      expect(r.stdout).toContain('MODEL_PROBE_INCONCLUSIVE (another probe of this model still holds its lock)');
+      expect(fs.existsSync(lock)).toBe(true);
+      expect(calls(f)).toBe(0);
+    }
+  }));
+
   test('an unreadable cache or uncreatable lock is unverified and launches no paid probe', withFixture((f) => {
     fs.mkdirSync(f.cache);
     const dir = probe(f);

test/evidence.test.ts

@@ -74,6 +74,14 @@ describe('gstack-evidence run', () => {
     expect(fs.readFileSync(rec.log_path, 'utf-8')).toContain('ok');
   });
 
+  test('the lane command sees its own log path as GSTACK_EVIDENCE_LOG (the free runner\'s home tripwire excludes exactly that file)', () => {
+    const r = run(['run', '--label', 'focused', '--', 'printf "%s" "$GSTACK_EVIDENCE_LOG"']);
+    expect(r.status).toBe(0);
+    const rec = records().pop();
+    expect(path.isAbsolute(rec.log_path)).toBe(true);
+    expect(r.stdout).toBe(rec.log_path);
+  });
+
   test('propagates a failing exit code and records it', () => {
     const r = run(['run', '--label', 'tests', '--', 'exit 3']);
     expect(r.status).toBe(3);

test/free-home-guard.test.ts

@@ -78,6 +78,34 @@ describe('free-suite home-write tripwire (#2895)', () => {
     expect(failure).toContain('only');
   });
 
+  test.skipIf(process.platform === 'win32')('the wrapping gstack-evidence lane log is excluded by its exact path; a foreign write beside it still trips', async () => {
+    const home = fakeHome();
+    const logs = path.join(home, '.gstack/projects/p/logs');
+    fs.mkdirSync(logs, { recursive: true });
+    const laneLog = path.join(logs, 'focused.log');
+    fs.writeFileSync(laneLog, 'lane start\n');
+    const unexcluded = guardFreeHome(['test/a.test.ts'], { HOME: home });
+    const options = (script: string, name: string) => ({ env: { ...process.env, HOME: home, GSTACK_EVIDENCE_LOG: laneLog }, quiet: true, log: () => {},
+      logFilePath: path.join(home, `${name}.log`),
+      commandFor: () => ({ command: process.execPath, args: ['-e', `${script}console.log('Ran 1 tests across 1 files. [1.00ms]')`] }) });
+    const grow = `require('fs').appendFileSync(${JSON.stringify(laneLog)}, 'lane output\\n');`;
+    const errors: string[] = [];
+    const spy = spyOn(console, 'error').mockImplementation((...args: unknown[]) => { errors.push(args.join(' ')); });
+    try {
+      expect((await runFreeShard(['test/a.test.ts'], 1, 1, options(grow, 'lane'))).status).toBe('passed');
+      expect(unexcluded.verify()).toContain('~/.gstack/projects/p/logs/focused.log');
+      const foreign = `${grow}require('fs').writeFileSync(${JSON.stringify(path.join(logs, 'other.log'))}, 'x');`;
+      expect((await runFreeShard(['test/a.test.ts'], 1, 1, options(foreign, 'foreign'))).status).toBe('failed');
+      expect(errors.join('\n')).toContain('~/.gstack/projects/p/logs/other.log');
+      expect(errors.join('\n')).not.toContain('focused.log');
+    } finally {
+      spy.mockRestore();
+      for (const retained of errors.flatMap(line => /retained (\S+)$/.exec(line)?.[1] ?? [])) {
+        if (/^gstack-free-shard-/.test(path.basename(retained))) fs.rmSync(retained, { recursive: true, force: true });
+      }
+    }
+  });
+
   test('a concurrent phase guard names no shard and points at attribution', () => {
     const home = fakeHome();
     const guard = guardFreeHome(['test/a.test.ts', 'test/b.test.ts'], { HOME: home }, { kind: 'concurrent', shards: 3 });

test/gstack-design-detect.test.ts

@@ -1460,8 +1460,13 @@ describe('scan: option-like bases and page-controlled inline ignores', () => {
     fs.mkdirSync(many, { recursive: true });
     for (let i = 0; i < 1100; i++) fs.writeFileSync(path.join(many, `f${i}.css`), 'a{}');
     try {
-      const r = run(['scan', '--format', 'gstack', 'src/many'], { env: { IMPECCABLE_BIN: FAKE, IMPECCABLE_FAKE_SLEEP_MS: '1000', GSTACK_DESIGN_DETECT_TIMEOUT_MS: '1500' } });
+      const log = path.join(SANDBOX, 'argv-many.log');
+      fs.rmSync(log, { force: true });
+      const r = run(['scan', '--format', 'gstack', 'src/many'], { env: { IMPECCABLE_BIN: FAKE, IMPECCABLE_FAKE_LOG: log } });
       expect(r.code).toBe(2); // a directory target is one batch (the fake reports findings): the budget test needs files
+      const calls = fs.readFileSync(log, 'utf-8').trim().split('\n').map(l => JSON.parse(l).argv as string[]);
+      expect(calls).toHaveLength(1);
+      expect(calls[0].some(x => x.endsWith(path.join('src', 'many')))).toBe(true);
       const files = fs.readdirSync(many).map(f => path.join('src', 'many', f));
       const r2 = run(['scan', '--format', 'gstack', ...files], { env: { IMPECCABLE_BIN: FAKE, IMPECCABLE_FAKE_SLEEP_MS: '1000', GSTACK_DESIGN_DETECT_TIMEOUT_MS: '1500' } });
       expect(r2.err).toMatch(/DETECT_TIMEOUT: whole-scan budget 7500ms exceeded, \d+ of 11 batches not run/);

test/helpers/free-owned-browser-settlement.ts

@@ -17,7 +17,7 @@ const ROOT = path.resolve(import.meta.dir, '../..');
 export const SETTLEMENT_MODE_GROUPS = {
   lifecycle: ['success', 'failure', 'timeout', 'cancel', 'cancel-force', 'cancel-cold-probes', 'settle-cold-probes', 'settle-slow-exit', 'cancel-vanishing-record'],
   ownership: ['endpoint-mix', 'full-state-mix', 'terminal-mix', 'chromium-mix', 'replaced-pid', 'stale-child-start', 'replaced-start',
-    'exit-environment-race', 'unavailable-environment', 'directory-remove-failure'],
+    'exit-environment-race', 'unavailable-environment', 'directory-remove-failure', 'exited-child-race'],
 } as const;
 
 const OWNERSHIP_ACTOR = `
@@ -50,6 +50,7 @@ if (role === 'leaf') {
   }));
   await Bun.sleep(50);
   const owned = [identity(process.pid), ...children.map(child => identity(child.pid))];
+  if (mode === 'exited-child-race') await new Promise(resolve => { children[0].once('exit', resolve); children[0].kill('SIGKILL'); });
   const server = Bun.serve({hostname:'127.0.0.1', port:0, fetch() {
     fs.appendFileSync(file('.http'), 'request\\n'); return new Response('ok');
   }});

test/helpers/restamp-fixture.ts

@@ -32,6 +32,31 @@ export const BASE_POLICY = {
   stamp_sensitive_gates: ['digest'],
 };
 
+function fixtureGit(root: string) {
+  const home = path.join(root, 'home');
+  const work = path.join(root, 'work');
+  const env = { GSTACK_HOME: home, GSTACK_STATE_DIR: home, HOME: home, GIT_CONFIG_GLOBAL: path.join(root, 'gitconfig'), GIT_CONFIG_NOSYSTEM: '1' };
+  const git = (...args: string[]): string => {
+    const r = gitArgvIn(work, args, 30_000, { ...process.env, ...env });
+    if (r.status !== 0) throw new Error(`git ${args.join(' ')} failed: ${r.stderr?.toString()}`);
+    return r.stdout?.toString().trim() ?? '';
+  };
+  return { env, git };
+}
+
+/**
+ * A private copy of a built fixture (origin, clone, home, and any files under its root), for a test file that
+ * would otherwise rebuild the same multi-second fixture in every test. Only the origin remote holds an absolute path.
+ */
+export function copyFixtureRepo(src: FixtureRepo, prefix = 'gstack-restamp-fx-'): FixtureRepo {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), prefix));
+  fs.cpSync(src.root, root, { recursive: true, preserveTimestamps: true });
+  const { env, git } = fixtureGit(root);
+  const origin = path.join(root, 'origin.git');
+  git('remote', 'set-url', 'origin', origin);
+  return { root, work: path.join(root, 'work'), origin, home: env.HOME, git, env };
+}
+
 export function makeFixtureRepo(opts: { policy?: Record<string, unknown> | null; version?: string; prefix?: string } = {}): FixtureRepo {
   const root = fs.mkdtempSync(path.join(os.tmpdir(), opts.prefix ?? 'gstack-restamp-fx-'));
   const origin = path.join(root, 'origin.git');
@@ -39,13 +64,8 @@ export function makeFixtureRepo(opts: { policy?: Record<string, unknown> | null;
   const home = path.join(root, 'home');
   fs.mkdirSync(home, { recursive: true });
   fs.mkdirSync(work, { recursive: true });
-  const env = { GSTACK_HOME: home, GSTACK_STATE_DIR: home, HOME: home, GIT_CONFIG_GLOBAL: path.join(root, 'gitconfig'), GIT_CONFIG_NOSYSTEM: '1' };
+  const { env, git } = fixtureGit(root);
   fs.writeFileSync(env.GIT_CONFIG_GLOBAL, '[user]\n\tname = t\n\temail = t@test\n[commit]\n\tgpgsign = false\n[init]\n\tdefaultBranch = main\n');
-  const git = (...args: string[]): string => {
-    const r = gitArgvIn(work, args, 30_000, { ...process.env, ...env });
-    if (r.status !== 0) throw new Error(`git ${args.join(' ')} failed: ${r.stderr?.toString()}`);
-    return r.stdout?.toString().trim() ?? '';
-  };
   spawnSync('git', ['init', '-q', '--bare', origin], { timeout: 30_000, env: { ...process.env, ...env } });
   git('init', '-q', '-b', 'main');
   const version = opts.version ?? '1.2.3.0';

test/office-hours-attempt.test.ts

@@ -312,7 +312,8 @@ describe('Office Hours real session runner with fake processes', () => {
         expect(captured.output).toBe('captured output');
         const diagnostic = JSON.parse(fs.readFileSync(path.join(dir, '.gstack/test-transcripts/drain-failure.json'), 'utf8'));
         expect(diagnostic.stderr).toContain('fixture auth failure');
-        expect(running(Number(fs.readFileSync(path.join(dir, 'child.pid'), 'utf8')))).toBe(false);
+        const child = fs.readFileSync(path.join(dir, 'child.pid'), 'utf8').trim();
+        expect(running(Number(child)), `held-pipe child after the runner returned (group ${fs.readFileSync(path.join(dir, 'parent.pid'), 'utf8').trim()}): ${spawnSync('ps', ['-o', 'pid=,ppid=,pgid=,stat=,etime=', '-p', child], { encoding: 'utf8', timeout: 5_000 }).stdout.trim() || 'gone now'}`).toBe(false);
       });
     }, 10_000);
   }

test/pregate-regate.test.ts

@@ -6,11 +6,11 @@
  * the base branch and every other open PR, and a lookup that cannot finish is
  * `unknown`, which withholds `REGATE: not-needed`.
  */
-import { afterEach, describe, expect, test } from 'bun:test';
+import { afterAll, afterEach, beforeAll, describe, expect, test } from 'bun:test';
 import * as fs from 'node:fs';
 import * as path from 'node:path';
 import { EXIT } from '../lib/headless-artifacts';
-import { BASE_POLICY, cleanup, makeFixtureRepo, makePr, recordAndBundle, restamp, runBin, type FixtureRepo } from './helpers/restamp-fixture';
+import { BASE_POLICY, cleanup, copyFixtureRepo, makeFixtureRepo, makePr, recordAndBundle, restamp, runBin, type FixtureRepo } from './helpers/restamp-fixture';
 
 const repos: FixtureRepo[] = [];
 afterEach(() => { while (repos.length) cleanup(repos.pop()!); });
@@ -39,10 +39,13 @@ console.error("gh shim: unsupported "+a.join(" ")); process.exit(1)' "${file}" "
 }
 const ghCalls = (repo: FixtureRepo) => fs.readFileSync(path.join(repo.root, 'gh-regate', 'calls.log'), 'utf8');
 
+type Lanes = Array<{ label: string; command: string }>;
+const TESTS_LANE: Lanes = [{ label: 'tests', command: 'true' }];
+const DIGEST_LANES: Lanes = [...TESTS_LANE, { label: 'digest', command: 'cat generated/digest.md' }];
+
 /** pr-a adds migration v240, is stamped 1.2.4.0 and gated (lanes recorded and bundled); then restamped to 1.2.5.0. */
-function gatedThenRestamped(lanes: Array<{ label: string; command: string }> = [{ label: 'tests', command: 'true' }]) {
+function buildGated(lanes: Lanes) {
   const repo = makeFixtureRepo({ prefix: 'pregate-regate-', policy: POLICY });
-  repos.push(repo);
   makePr(repo, 'pr-a', { expects: '1.2.4.0' });
   fs.mkdirSync(path.join(repo.work, 'migrations'), { recursive: true });
   fs.writeFileSync(path.join(repo.work, 'migrations', 'v240-add-index.sql'), 'create index a;\n');
@@ -54,7 +57,20 @@ function gatedThenRestamped(lanes: Array<{ label: string; command: string }> = [
   const head = repo.git('rev-parse', 'HEAD');
   expect(restamp(repo, ['--version', '1.2.5.0']).status).toBe(EXIT.ok);
   repo.git('commit', '-qam', 'stamp 1.2.5.0');
-  return { repo, head, bundle, current: repo.git('rev-parse', 'HEAD') };
+  return { repo, head, current: repo.git('rev-parse', 'HEAD') };
+}
+
+// Each fixture costs four gstack bin runs (two restamps, an evidence run and a bundle); build each lane set once
+// and give every test its own copy instead of rebuilding it per test.
+const templates = new Map<Lanes, ReturnType<typeof buildGated>>();
+beforeAll(() => { for (const lanes of [TESTS_LANE, DIGEST_LANES]) templates.set(lanes, buildGated(lanes)); }, 60_000);
+afterAll(() => { for (const t of templates.values()) cleanup(t.repo); });
+
+function gatedThenRestamped(lanes: Lanes = TESTS_LANE) {
+  const { repo: template, head, current } = templates.get(lanes)!;
+  const repo = copyFixtureRepo(template, 'pregate-regate-');
+  repos.push(repo);
+  return { repo, head, bundle: path.join(repo.root, 'bundle.json'), current };
 }
 const regate = (repo: FixtureRepo, args: string[], env: Record<string, string>) => runBin(repo, 'gstack-pregate', ['regate', '--base', 'main', ...args], env);
 
@@ -97,7 +113,7 @@ describe('gstack-pregate regate: evidence, stamps and lane verdicts', () => {
   });
 
   test('a stamp-sensitive lane reruns, so a regate is needed; a code edit is not stamp-only and names the file and line', () => {
-    const { repo, head, bundle } = gatedThenRestamped([{ label: 'tests', command: 'true' }, { label: 'digest', command: 'cat generated/digest.md' }]);
+    const { repo, head, bundle } = gatedThenRestamped(DIGEST_LANES);
     const env = ghShim(repo, { list: [] });
     const r = regate(repo, ['--against', head, '--bundle', bundle], env);
     expect(r.status).toBe(EXIT.fail);

test/session-update-autostash.test.ts

@@ -284,7 +284,8 @@ describe('gstack-session-update lock identity + TTL (#2613)', () => {
       const r = runScript(base, install, state);
       expect(r.status).toBe(0);
       const log = await waitForLog(state, /UP_TO_DATE|UPDATING/);
-      expect(log).toMatch(/UP_TO_DATE|UPDATING/);
+      const lockPid = fs.existsSync(path.join(lockDir, 'pid')) ? fs.readFileSync(path.join(lockDir, 'pid'), 'utf8').trim() : 'no lock';
+      expect(log, `planted dead pid ${dead.pid} (alive now: ${isAlive(dead.pid)}); lock pid after 15 s: ${lockPid} (alive: ${isAlive(Number(lockPid))}); script exit ${r.status}, stderr: ${r.stderr}`).toMatch(/UP_TO_DATE|UPDATING/);
     } finally {
       fs.rmSync(base, { recursive: true, force: true });
     }

test/shard-engine.test.ts

@@ -171,7 +171,10 @@ describe('shard engine: process lifecycle', () => {
     });
     expect(paid.status).toBe('timed-out');
     expect(summaryExitCode(summarize([paid]))).toBe(1);
-    expect(await waitDead(Number(fs.readFileSync(pidFile, 'utf8')))).toBe(true);
+    const paidChild = Number(fs.readFileSync(pidFile, 'utf8'));
+    const paidChildDead = await waitDead(paidChild);
+    const procStat = (pid: number) => { try { return fs.readFileSync(`/proc/${pid}/stat`, 'utf8').trim(); } catch { return 'no /proc entry'; } };
+    expect(paidChildDead, `paid grandchild ${paidChild} of group ${paid.groupPid} 2 s after the timeout kill: ${procStat(paidChild)}`).toBe(true);
   }, 30_000);
 
   test('win32 semantics: no process group and never a negative-pid kill', async () => {

test/ship-budget.test.ts

@@ -308,7 +308,7 @@ describe('Claude Code child launch', () => {
     const file = ho.out.match(/^HANDOFF: (\S+)/m)![1]!;
     const argsFile = path.join(h.root, 'claude-args.txt');
     const fake = path.join(h.root, 'fake-claude');
-    fs.writeFileSync(fake, `#!/bin/sh\nprintf '%s\\n' "$@" > "${argsFile}"\n`, { mode: 0o755 });
+    fs.writeFileSync(fake, `#!/bin/sh\nprintf '%s\\n' "$@" > "${argsFile}.tmp" && mv "${argsFile}.tmp" "${argsFile}"\n`, { mode: 0o755 });
     const r = h.sb(['launch', '--in', file], { GSTACK_CLAUDE_BIN: fake });
     expect(r.code).toBe(0);
     const session = h.field(r.out, 'CHILD', 'session');

test/ship-queue-train.test.ts

@@ -35,13 +35,16 @@ const result = (out: string) => line(out, 'GSTACK_RESULT:');
 const next = (out: string) => line(out, 'NEXT:');
 const remoteRefs = (fx: TrainFixture) => fx.repo.git('ls-remote', 'origin');
 
-// fails_when=coordinatorClone copies origin.git/objects file by file again, so an entry that appears or vanishes there mid-copy (the detached maintenance.lock every push into the fixture origin leaves) fails the clone, as in two Free Tests reds on 2026-10-28 (GSTA-139 ledger); why_new=no other test clones while origin's objects directory changes; seam=a dangling symlink planted under objects/, which a local copy refuses on every run; no_claim=which process removed the loose object those runs named
+// fails_when=coordinatorClone copies origin.git/objects file by file again, so an entry that appears or vanishes there mid-copy (the detached maintenance.lock every push into the fixture origin leaves) fails the clone, as in two Free Tests reds on 2026-10-28 (GSTA-139 ledger); why_new=no other test clones while origin's objects directory changes; seam=a dangling symlink planted under objects/ beside a held maintenance.lock, which a local copy refuses on every run; the seam has its own name because the fixture push's own detached maintenance can hold objects/maintenance.lock at that moment (EEXIST in Free Tests 41288253305 and 41288417894, 2026-11-01); no_claim=which process removed the loose object those runs named
 test('the coordinator clone reads origin through git, never by copying its objects directory (GSTA-139)', () => {
   const fx = make();
-  fs.symlinkSync(path.join(fx.repo.root, 'gone'), path.join(fx.repo.origin, 'objects', 'maintenance.lock'));
+  const objects = path.join(fx.repo.origin, 'objects');
+  fs.writeFileSync(path.join(objects, 'maintenance.lock'), '');
+  fs.symlinkSync(path.join(fx.repo.root, 'gone'), path.join(objects, 'gstack-dangling-seam'));
   const coord = coordinatorClone(fx.repo);
   expect(spawnSync('git', ['-C', coord, 'rev-parse', 'origin/main'], { encoding: 'utf8', timeout: 30_000, env: { ...process.env, ...fx.repo.env } }).stdout.trim()).toBe(fx.repo.git('rev-parse', 'origin/main'));
   expect(fs.existsSync(path.join(coord, '.git', 'objects', 'maintenance.lock'))).toBe(false);
+  expect(fs.readdirSync(path.join(coord, '.git', 'objects'))).not.toContain('gstack-dangling-seam');
 });
 
 describe('the train command surface', () => {