diff --git a/.changeset/quick-panthers-cross.md b/.changeset/quick-panthers-cross.md
new file mode 100644
index 000000000..a7f9d7dfa
--- /dev/null
+++ b/.changeset/quick-panthers-cross.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 4575
+---
+**The worktree-path guard no longer fails open under CI/process load** — it combined three sequential `git` subprocess spawns into one, cutting the worktree-escape check's worst-case latency so a busy runner can no longer push the guard past its own timeout into a silent allow. (#4515)
diff --git a/eslint-rules/no-adhoc-timeout-literal.allowlist.json b/eslint-rules/no-adhoc-timeout-literal.allowlist.json
index 58fd17217..00acade09 100644
--- a/eslint-rules/no-adhoc-timeout-literal.allowlist.json
+++ b/eslint-rules/no-adhoc-timeout-literal.allowlist.json
@@ -34,10 +34,8 @@
   "tests/emitted-ack-trailer.test.cjs",
   "tests/emitted-attribution.test.cjs",
   "tests/execute-wave-post-gate-pipeline-e2e.test.cjs",
-  "tests/faulty-deps.test.cjs",
   "tests/feat-2483-review-claude-mds-guard.test.cjs",
   "tests/federated-config.test.cjs",
-  "tests/fragment-single-edit-propagation.install.test.cjs",
   "tests/gate-predicate-evaluator.test.cjs",
   "tests/gemini-runtime-removed.test.cjs",
   "tests/gen-context-index.test.cjs",
@@ -54,11 +52,6 @@
   "tests/hooks-commonjs-marker.test.cjs",
   "tests/hooks-crash-policy.test.cjs",
   "tests/init.test.cjs",
-  "tests/install-minimal-hooks.test.cjs",
-  "tests/install-regressions.test.cjs",
-  "tests/install-runtime-artifacts.test.cjs",
-  "tests/install-write-confinement.test.cjs",
-  "tests/install.test.cjs",
   "tests/kilo-upgrades.test.cjs",
   "tests/kimi-upgrades.test.cjs",
   "tests/kimi-variant-disambiguation.test.cjs",
@@ -71,9 +64,7 @@
   "tests/loop-walk.qa.test.cjs",
   "tests/milestone-lock.test.cjs",
   "tests/no-pending-3212-markers.test.cjs",
-  "tests/npm-integrity-gate.test.cjs",
   "tests/opencode-plugin-adapter.test.cjs",
-  "tests/packaging-shipped-scripts-require-only-shipped.test.cjs",
   "tests/pattern.test.cjs",
   "tests/perf-316-state-lock-buffer-alloc.test.cjs",
   "tests/perf-317-context-monitor-fs.test.cjs",
@@ -83,7 +74,6 @@
   "tests/plan-phase-stall-detection.test.cjs",
   "tests/plan-pre-hook-e2e.test.cjs",
   "tests/plan-review-convergence.test.cjs",
-  "tests/plugin-manifest.test.cjs",
   "tests/policy-160-route0-resume.test.cjs",
   "tests/prohibition-enforcement.test.cjs",
   "tests/prompt-injection-scan.security.test.cjs",
@@ -92,7 +82,6 @@
   "tests/read-guard.test.cjs",
   "tests/read-injection-scanner.property.test.cjs",
   "tests/read-injection-scanner.security.test.cjs",
-  "tests/release-tarball-smoke.install.test.cjs",
   "tests/representative-corpus.test.cjs",
   "tests/review-lane-invocation.test.cjs",
   "tests/reviewer-manifest-body.test.cjs",
diff --git a/hooks/gsd-worktree-path-guard.js b/hooks/gsd-worktree-path-guard.js
index 691577900..186c02f5e 100644
--- a/hooks/gsd-worktree-path-guard.js
+++ b/hooks/gsd-worktree-path-guard.js
@@ -163,17 +163,37 @@ process.stdin.on('end', () => {
     // returns a path containing .git/worktrees/ as a component.
     // In the main repo or a submodule it returns .git (or a path without /worktrees/).
     // This approach works even when cwd is a subdirectory of the worktree.
-    const gitDirResult = git(['rev-parse', '--git-dir'], cwd);
+    // Combined into one spawn — git rev-parse accepts multiple query flags in
+    // one invocation and prints one line of output per flag, in the exact
+    // order given, reducing this guard's worst-case subprocess count under
+    // CI/load contention (three spawns collapse into one). `--abbrev-ref HEAD`
+    // is used instead of `symbolic-ref --short HEAD` because it is combinable
+    // (a single `rev-parse` call) and behaviorally equivalent for this guard's
+    // branch-acceptance check, including on detached HEAD: `--abbrev-ref`
+    // returns the literal string `HEAD` there (exit 0), which the acceptance
+    // regex below also rejects — the same guard outcome as symbolic-ref's
+    // exit-128/empty-stdout failure. Do not change any timeout value as part
+    // of this change, only the spawn count.
+    const combinedResult = git(['rev-parse', '--git-dir', '--abbrev-ref', 'HEAD', '--show-toplevel'], cwd);
     // #3911: a timeout/spawn-failure result is indistinguishable from a clean
     // "not a git repo" answer by status/stdout alone — reportIfUndetermined
     // is a no-op on a genuine negative and only fires the diagnostic when the
     // probe itself could not run. The allow() below is UNCHANGED either way.
-    reportIfUndetermined('gsd-worktree-path-guard', 'git rev-parse --git-dir', gitDirResult);
-    if (gitDirResult.status !== 0 || !gitDirResult.stdout) {
+    reportIfUndetermined(
+      'gsd-worktree-path-guard',
+      'git rev-parse --git-dir --abbrev-ref HEAD --show-toplevel',
+      combinedResult
+    );
+    if (combinedResult.status !== 0 || !combinedResult.stdout) {
       allow(undefined); // not a git repo — pass through
     }
 
-    const gitDir = gitDirResult.stdout.trim();
+    const combinedLines = combinedResult.stdout.split('\n').map((l) => l.trim()).filter((l) => l.length > 0);
+    if (combinedLines.length < 3) {
+      allow(undefined); // malformed/short output — can't determine root, fail open
+    }
+    const [gitDir, branch, wtTopRaw] = combinedLines;
+
     // A linked worktree's --git-dir contains .git/worktrees/ as a path component
     const isLinkedWorktree = /[/\\]\.git[/\\]worktrees[/\\]/.test(gitDir);
     if (!isLinkedWorktree) {
@@ -186,23 +206,14 @@ process.stdin.on('end', () => {
     // created linked worktree (plain non-GSD work, e.g. Claude Code plan-mode) is
     // on the user's own branch, so the guard must be a no-op there. Detached HEAD
     // / error → not GSD-managed → no-op.
-    const branchResult = git(['symbolic-ref', '--short', 'HEAD'], cwd);
-    reportIfUndetermined('gsd-worktree-path-guard', 'git symbolic-ref --short HEAD', branchResult);
-    const branch = branchResult.status === 0 && branchResult.stdout ? branchResult.stdout.trim() : '';
     // #3021: accept worktree-wf_<runid>-<n> branches (Workflow backend's naming).
     if (!/^((worktree-)?agent-|worktree-wf_)[A-Za-z0-9._/-]+$/.test(branch)) {
       allow(undefined); // not a GSD-managed executor worktree — no-op
     }
 
-    // Get the raw --show-toplevel output for the worktree (cwd).
+    // wtTopRaw: the raw --show-toplevel output for the worktree (cwd).
     // We keep it raw (not path.resolve'd) to compare directly with the
     // file's toplevel — same git binary, same format, no normalization needed.
-    const wtTopResult = git(['rev-parse', '--show-toplevel'], cwd);
-    reportIfUndetermined('gsd-worktree-path-guard', 'git rev-parse --show-toplevel (worktree cwd)', wtTopResult);
-    if (wtTopResult.status !== 0 || !wtTopResult.stdout) {
-      allow(undefined); // can't determine root — fail open
-    }
-    const wtTopRaw = wtTopResult.stdout.trim();
 
     // #2595 (review Major 3): read the field TYPED. `?.file_path || ''` let a
     // non-string through — `[]` and `{}` are truthy, so they survived the
diff --git a/tests/faulty-deps.test.cjs b/tests/faulty-deps.test.cjs
index f6728404f..04b5ec75c 100644
--- a/tests/faulty-deps.test.cjs
+++ b/tests/faulty-deps.test.cjs
@@ -33,6 +33,17 @@ const { defaultPhaseCleanCommitTimesMs } = require(path.join(__dirname, '..', 'g
 const { createTempGitProject, createTempDir, cleanup } = require('./helpers.cjs');
 const { makeFaultyGit, withFaultyFs } = require('./helpers/faulty-deps.cjs');
 
+// A bound so small process creation cannot complete inside it, making the
+// ETIMEDOUT kill path deterministic on a real (unmocked) git call; used at
+// both sentinel sites in this file.
+const DETERMINISTIC_TIMEOUT_SENTINEL_MS = 1;
+
+// Bounds a real (unmocked) `git var GIT_EDITOR` call proving env passthrough;
+// deliberately not GIT_TIMEOUT_MS (15000ms) since this site's pre-existing
+// value differs and this migration never raises a bound without a fresh
+// bench citation.
+const GIT_VAR_PROBE_TIMEOUT_MS = 5000;
+
 // ─── A. execGit normalization (#3071) ──────────────────────────────────────
 
 describe('A. execGit normalization (#3071)', () => {
@@ -71,7 +82,7 @@ describe('A. execGit normalization (#3071)', () => {
     // complete inside 1ms, so the kill path is deterministic, matching the
     // existing "wall-clock timeout" pattern used for dispatchGsdCommand in
     // shell-command-projection-dispatch.test.cjs.
-    const result = execGit(['status', '--porcelain'], { cwd: tmpDir, timeout: 1 });
+    const result = execGit(['status', '--porcelain'], { cwd: tmpDir, timeout: DETERMINISTIC_TIMEOUT_SENTINEL_MS });
     assert.strictEqual(result.timedOut, true);
     assert.strictEqual(result.error && result.error.code, 'ETIMEDOUT');
   });
@@ -117,7 +128,7 @@ describe('A. execGit normalization (#3071)', () => {
     const result = execGit(['var', 'GIT_EDITOR'], {
       cwd: tmpDir,
       env: { GIT_EDITOR: 'fault-3056-sentinel-editor' },
-      timeout: 5000,
+      timeout: GIT_VAR_PROBE_TIMEOUT_MS,
     });
     assert.strictEqual(result.exitCode, 0);
     assert.strictEqual(result.stdout, 'fault-3056-sentinel-editor');
@@ -128,7 +139,7 @@ describe('A. execGit normalization (#3071)', () => {
     t.after(() => cleanup(tmpDir));
     const success = execGit(['status', '--porcelain'], { cwd: tmpDir });
     const enoent = execTool('definitely-not-a-real-program-fault-3056', []);
-    const timeout = execGit(['status', '--porcelain'], { cwd: tmpDir, timeout: 1 });
+    const timeout = execGit(['status', '--porcelain'], { cwd: tmpDir, timeout: DETERMINISTIC_TIMEOUT_SENTINEL_MS });
     assert.strictEqual(typeof success.exitCode, 'number');
     assert.strictEqual(typeof enoent.exitCode, 'number');
     assert.strictEqual(typeof timeout.exitCode, 'number');
diff --git a/tests/fragment-single-edit-propagation.install.test.cjs b/tests/fragment-single-edit-propagation.install.test.cjs
index 44e73274f..5442e0903 100644
--- a/tests/fragment-single-edit-propagation.install.test.cjs
+++ b/tests/fragment-single-edit-propagation.install.test.cjs
@@ -60,6 +60,7 @@ const { gitOrThrow } = require('./helpers/git-fixture.cjs');
 
 const { cleanup, createTempDir, readFileNormalized } = require('./helpers.cjs');
 const { RUNTIME_META, installerEnv } = require('./helpers/install-shared.cjs');
+const { INSTALL_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
 const {
   buildOverlayRepo,
   REPO_ROOT,
@@ -199,6 +200,37 @@ const ORIGINAL_WORKFLOW_CONTENT = readFileNormalized(PILOT_WORKFLOW_PATH);
 
 const FRAGMENT_SENTINEL = 'GSD-2933-FRAGMENT-EDIT-SENTINEL-4c1a9f';
 
+/**
+ * Bounds `runOverlayCheck`/`runOverlayGenerate` — a single overlay
+ * `scripts/gen-*.cjs` generator invocation (never the installer proper).
+ * The digits coincide with `INSTALL_TIMEOUT_MS` (also 120000ms), but this
+ * is a different operation class kept as its own local constant —
+ * coincidence, not collision.
+ */
+const GENERATOR_SCRIPT_TIMEOUT_MS = 120000;
+
+/**
+ * Bounds `trackedFileSet`'s `git ls-files` over the FULL overlay tree.
+ * Deliberately NOT the shared `GIT_TIMEOUT_MS` (15000ms, `helpers/timeouts.cjs`),
+ * which describes small-fixture-repo git plumbing — a much lighter shape
+ * than scanning this file's overlay tree.
+ */
+const TRACKED_FILE_SET_TIMEOUT_MS = 120000;
+
+/**
+ * Bounds the real `npm run regen:derived` spawn (row 21) — a full build
+ * plus eight generators, the single heaviest subprocess in this suite.
+ * 300000 (5min) was observed to be killed (status: null) near the very end
+ * of a genuinely completed run on a loaded bench (linux-node22), not from a
+ * real hang. 900000 (15min) is deliberately generous so this can never
+ * again flake on load while still catching a true hang.
+ * allow-spawn-timeout-ceiling: regen:derived is a full build plus eight
+ * generators; 300000 was observed killing a genuinely-completed run near
+ * the end on a loaded bench, not a real hang, so 900000 is deliberately
+ * above the 600000 ceiling to never repeat that flake.
+ */
+const REGEN_DERIVED_TIMEOUT_MS = 900000;
+
 // ─── Helpers ────────────────────────────────────────────────────────────────
 
 /**
@@ -226,7 +258,7 @@ function installOverlay(overlayRoot, runtime, extraArgs = []) {
   const result = runNode(args, {
     cwd: root,
     env: installerEnv({ HOME: root, USERPROFILE: root }),
-    timeoutMs: 120000,
+    timeoutMs: INSTALL_TIMEOUT_MS,
   });
   result.status = result.exitCode;
   assert.equal(
@@ -262,7 +294,7 @@ function installOverlayExpectingFailure(overlayRoot, runtime, extraArgs = []) {
   const result = runNode(args, {
     cwd: root,
     env: installerEnv({ HOME: root, USERPROFILE: root }),
-    timeoutMs: 120000,
+    timeoutMs: INSTALL_TIMEOUT_MS,
   });
   result.status = result.exitCode;
   return { configDir: root, root, result };
@@ -281,7 +313,7 @@ function runOverlayCheck(overlayRoot, scriptRelPath, extraArgs = []) {
   const result = runNode([scriptPath, '--check', ...extraArgs], {
     cwd: overlayRoot,
     env: installerEnv(),
-    timeoutMs: 120000,
+    timeoutMs: GENERATOR_SCRIPT_TIMEOUT_MS,
   });
   result.status = result.exitCode;
   return result;
@@ -299,7 +331,7 @@ function runOverlayGenerate(overlayRoot, scriptRelPath) {
   const result = runNode([scriptPath], {
     cwd: overlayRoot,
     env: installerEnv(),
-    timeoutMs: 120000,
+    timeoutMs: GENERATOR_SCRIPT_TIMEOUT_MS,
   });
   result.status = result.exitCode;
   return result;
@@ -327,7 +359,7 @@ function runOverlayGenerate(overlayRoot, scriptRelPath) {
 function trackedFileSet(repoRoot) {
   const stdout = gitOrThrow(['-c', 'safe.directory=*', 'ls-files'], {
     cwd: repoRoot,
-    timeoutMs: 120000,
+    timeoutMs: TRACKED_FILE_SET_TIMEOUT_MS,
   });
   return stdout.split('\n').map((line) => line.trim()).filter(Boolean);
 }
@@ -1198,17 +1230,9 @@ test('regenDerivedPropagatesSingleFragmentEditWithNoSecondSourceSurface', {
     cwd: overlay,
     encoding: 'utf8',
     env: installerEnv(),
-    // `regen:derived` chains a full `npm run build` plus eight generators —
-    // the single heaviest subprocess in this suite. 300_000 (5min) was
-    // observed to be killed (status: null) near the very end of a genuinely
-    // completed run on a loaded bench (linux-node22), not from a real hang.
-    // 900_000 (15min) is deliberately generous so this can never again flake
-    // on load while still catching a true hang.
-    // allow-spawn-timeout-ceiling: regen:derived is a full build plus eight
-    // generators; 300_000 was observed killing a genuinely-completed run
-    // near the end on a loaded bench, not a real hang, so 900_000 is
-    // deliberately above the 600000 ceiling to never repeat that flake.
-    timeout: 900000,
+    // See REGEN_DERIVED_TIMEOUT_MS's own doc comment (top of file) for the
+    // full rationale, including the allow-spawn-timeout-ceiling annotation.
+    timeout: REGEN_DERIVED_TIMEOUT_MS,
     maxBuffer: 64 * 1024 * 1024,
   });
   assert.equal(
diff --git a/tests/helpers/timeouts.cjs b/tests/helpers/timeouts.cjs
index fb39959b7..f5b1b40fa 100644
--- a/tests/helpers/timeouts.cjs
+++ b/tests/helpers/timeouts.cjs
@@ -127,6 +127,20 @@ const SEAM_DEFAULT_TIMEOUT_MS = 60000;
  */
 const QUICK_SPAWN_TIMEOUT_MS = 10000;
 
+/**
+ * NOT a subprocess spawn timeout. This is fixture DATA -- the numeric value
+ * placed inside a fixture JSON object that mimics a Claude Code
+ * `settings.json` hook-entry's own `timeout` field, whose schema expresses
+ * that field in SECONDS. Do not pass this into a `spawnSync`/`execFileSync`
+ * options object -- every other constant in this file is milliseconds, this
+ * one is not.
+ *
+ * Shared across >=2 files in batch #4515 of the ad hoc timeout literal
+ * migration, epic #4445 -- that is why it lives here rather than as a
+ * file-local constant.
+ */
+const FIXTURE_HOOK_TIMEOUT_SECONDS = 5;
+
 module.exports = {
   PROBE_TIMEOUT_MS,
   HOOK_FANOUT_TIMEOUT_MS,
@@ -136,4 +150,5 @@ module.exports = {
   INSTALL_TIMEOUT_MS,
   SEAM_DEFAULT_TIMEOUT_MS,
   QUICK_SPAWN_TIMEOUT_MS,
+  FIXTURE_HOOK_TIMEOUT_SECONDS,
 };
diff --git a/tests/install-minimal-hooks.test.cjs b/tests/install-minimal-hooks.test.cjs
index 080c6a323..1fd8cbf83 100644
--- a/tests/install-minimal-hooks.test.cjs
+++ b/tests/install-minimal-hooks.test.cjs
@@ -29,6 +29,21 @@ const os = require('node:os');
 const { runNode } = require('./helpers/process-seam.cjs');
 const { throwIfFailed } = require('./helpers/git-fixture.cjs');
 
+const {
+  PROBE_TIMEOUT_MS,
+  INSTALL_TIMEOUT_MS,
+  FIXTURE_HOOK_TIMEOUT_SECONDS,
+} = require('./helpers/timeouts.cjs');
+
+/**
+ * Bounds executing a single already-staged hook script directly (not the
+ * installer itself, just the emitted script under a real node process).
+ * 30000ms digits coincide with the shared BUILD_TIMEOUT_MS, but this is a
+ * different operation class (running staged output vs. bundling it), so it
+ * is kept as its own local constant rather than aliased onto that norm.
+ */
+const INSTALLED_HOOK_EXEC_TIMEOUT_MS = 30000;
+
 const { createTempDir, cleanup } = require('./helpers.cjs');
 
 const {
@@ -115,7 +130,7 @@ describe('install-profiles: MINIMAL_SKILL_ALLOWLIST', () => {
 
 describe('install: --help profile counts match PROFILES (#834)', () => {
   function helpText() {
-    const r = runNode([INSTALL_SCRIPT, '--help'], { env: installerEnv(), timeoutMs: 15000 });
+    const r = runNode([INSTALL_SCRIPT, '--help'], { env: installerEnv(), timeoutMs: PROBE_TIMEOUT_MS });
     throwIfFailed(r, `node ${INSTALL_SCRIPT} --help`);
     return r.stdout;
   }
@@ -410,7 +425,7 @@ function sharedMinimalManifestInstall() {
   const targetDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gsd-minimal-shared-'));
   runNode(
     [INSTALL_SCRIPT, '--claude', '--global', '--config-dir', targetDir, '--minimal'],
-    { env: installerEnv(), timeoutMs: 120000 },
+    { env: installerEnv(), timeoutMs: INSTALL_TIMEOUT_MS },
   );
   const manifestPath = path.join(targetDir, MANIFEST_NAME);
   const m = fs.existsSync(manifestPath) ? JSON.parse(fs.readFileSync(manifestPath, 'utf8')) : {};
@@ -433,7 +448,7 @@ describe('install: manifest records mode for both profiles', () => {
     try {
       runNode(
         [INSTALL_SCRIPT, '--claude', '--global', '--config-dir', targetDir, ...extraArgs],
-        { env: installerEnv(), timeoutMs: 120000 },
+        { env: installerEnv(), timeoutMs: INSTALL_TIMEOUT_MS },
       );
       const manifestPath = path.join(targetDir, MANIFEST_NAME);
       if (!fs.existsSync(manifestPath)) return { mode: '<no manifest>', skillCount: 0, agentCount: 0 };
@@ -486,7 +501,7 @@ describe('install-minimal-backcompat: --minimal and --profile=core produce same
     try {
       runNode(
         [INSTALL_SCRIPT, '--claude', '--global', '--config-dir', targetDir, ...extraArgs],
-        { env: installerEnv(), timeoutMs: 120000 },
+        { env: installerEnv(), timeoutMs: INSTALL_TIMEOUT_MS },
       );
       const manifestPath = path.join(targetDir, MANIFEST_NAME);
       if (!fs.existsSync(manifestPath)) return { mode: null, skillCount: 0, profileMarker: null };
@@ -562,7 +577,7 @@ describe('install: Codex full → minimal downgrade cleans stale agent state', (
       // config.toml (both under targetDir), so the sandbox has no effect on intent.
       const result = runNode(
         [INSTALL_SCRIPT, '--codex', '--global', '--config-dir', targetDir, '--minimal'],
-        { env: installerEnv({ HOME: targetDir, USERPROFILE: targetDir }), timeoutMs: 120000 },
+        { env: installerEnv({ HOME: targetDir, USERPROFILE: targetDir }), timeoutMs: INSTALL_TIMEOUT_MS },
       );
       assert.ok(result.stdout || result.stderr);
 
@@ -599,7 +614,7 @@ describe('install: Claude full → minimal downgrade removes stale agents', () =
 
       runNode(
         [INSTALL_SCRIPT, '--claude', '--global', '--config-dir', targetDir, '--minimal'],
-        { env: installerEnv(), timeoutMs: 120000 },
+        { env: installerEnv(), timeoutMs: INSTALL_TIMEOUT_MS },
       );
 
       const remaining = fs.existsSync(agentsDir) ? fs.readdirSync(agentsDir) : [];
@@ -691,7 +706,7 @@ describe('#1821/#2305: ZCode receives no dead hook files; Kilo/OpenCode/Claude k
     try {
       const result = runNode(
         [INSTALL_SCRIPT, `--${runtime}`, '--global', '--config-dir', targetDir],
-        { env: installerEnv(), timeoutMs: 120000 },
+        { env: installerEnv(), timeoutMs: INSTALL_TIMEOUT_MS },
       );
       assert.strictEqual(result.exitCode, 0,
         `installer exited with status ${result.exitCode} for --${runtime} --global\nstdout: ${result.stdout}\nstderr: ${result.stderr}`);
@@ -2851,7 +2866,7 @@ function runInstaller(configDir) {
   // in install-smoke.yml).
   throwIfFailed(
     runNode([INSTALL_SCRIPT, '--claude', '--global', '--yes', '--no-sdk'], {
-      timeoutMs: 120000,
+      timeoutMs: INSTALL_TIMEOUT_MS,
       env: {
         ...process.env,
         CLAUDE_CONFIG_DIR: configDir,
@@ -2970,7 +2985,7 @@ describe('#4087 regression: Codex install stages the hook helpers its hooks requ
     // child's env.
     throwIfFailed(
       runNode([INSTALL_SCRIPT, '--codex', '--global', '--yes', '--no-sdk', '--config-dir', configDir], {
-        timeoutMs: 120000,
+        timeoutMs: INSTALL_TIMEOUT_MS,
         env: { ...process.env, HOME: configDir, USERPROFILE: configDir },
       }),
       `node ${INSTALL_SCRIPT} --codex --global --config-dir ${configDir}`,
@@ -3224,7 +3239,7 @@ describe('#4087 review: Windsurf install stages the hook helpers its hooks requi
     // HOME/USERPROFILE sandboxed for the CHILD, for the same reason as installCodex.
     throwIfFailed(
       runNode([INSTALL_SCRIPT, '--windsurf', '--global', '--yes', '--config-dir', configDir], {
-        timeoutMs: 120000,
+        timeoutMs: INSTALL_TIMEOUT_MS,
         env: { ...process.env, HOME: configDir, USERPROFILE: configDir },
       }),
       `node ${INSTALL_SCRIPT} --windsurf --global --config-dir ${configDir}`,
@@ -3238,7 +3253,7 @@ describe('#4087 review: Windsurf install stages the hook helpers its hooks requi
     for (const script of ['gsd-windsurf-pre-write.js', 'gsd-windsurf-pre-command.js']) {
       const hook = path.join(hooksDir, script);
       assert.ok(fs.existsSync(hook), `precondition: ${script} must be staged`);
-      const result = runNode([hook], { timeoutMs: 30000, input: '{}', env: { ...process.env } });
+      const result = runNode([hook], { timeoutMs: INSTALLED_HOOK_EXEC_TIMEOUT_MS, input: '{}', env: { ...process.env } });
       assert.strictEqual(result.outcome, 'exited',
         `${script} must run to completion, not time out or be killed. outcome=${result.outcome}`);
       assert.strictEqual(result.exitCode, 0,
@@ -3391,7 +3406,7 @@ describe('bug #3981: blocking-guard timeout budget + migration', () => {
         hooks: {
           PreToolUse: [{
             matcher: 'Write|Edit',
-            hooks: [{ type: 'command', command: `node ${path.join(targetDir, 'hooks', guard)}`, timeout: 5 }],
+            hooks: [{ type: 'command', command: `node ${path.join(targetDir, 'hooks', guard)}`, timeout: FIXTURE_HOOK_TIMEOUT_SECONDS }],
           }],
         },
       };
@@ -3423,7 +3438,7 @@ describe('bug #3981: blocking-guard timeout budget + migration', () => {
   });
 
   test('non-managed timeout:5 entries are left alone (#3981)', () => {
-    const mine = { type: 'command', command: 'node /usr/local/bin/my-own-hook.js', timeout: 5 };
+    const mine = { type: 'command', command: 'node /usr/local/bin/my-own-hook.js', timeout: FIXTURE_HOOK_TIMEOUT_SECONDS };
     const settings = { hooks: { PreToolUse: [{ matcher: 'Write', hooks: [mine] }] } };
     const localCmd = (hookFile) => `node ${path.join(targetDir, 'hooks', hookFile)}`;
     captureConsole(() => {
diff --git a/tests/install-regressions.test.cjs b/tests/install-regressions.test.cjs
index 54db5a12a..6fb7d39dc 100644
--- a/tests/install-regressions.test.cjs
+++ b/tests/install-regressions.test.cjs
@@ -21,7 +21,12 @@ const fs = require('node:fs');
 const path = require('node:path');
 const { runNode } = require('./helpers/process-seam.cjs');
 const { throwIfFailed } = require('./helpers/git-fixture.cjs');
-const { INSTALL_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
+const { INSTALL_TIMEOUT_MS, FIXTURE_HOOK_TIMEOUT_SECONDS } = require('./helpers/timeouts.cjs');
+
+// Bounds a scoped/targeted runNode([INSTALL_SCRIPT, ...]) invocation — a
+// lighter shape than the shared full-install INSTALL_TIMEOUT_MS class
+// (120000ms), so kept as its own constant rather than raised to that bound.
+const SCOPED_INSTALL_TIMEOUT_MS = 60_000;
 
 const { createTempDir, cleanup, mockPartialWriteThenThrow } = require('./helpers.cjs');
 const {
@@ -95,7 +100,7 @@ describe('#2429 regression: Codex local skills stay project-scoped', () => {
 
     const result = runNode(
       [INSTALL_SCRIPT, '--codex', '--local', '--profile=core'],
-      { cwd: projectDir, env, timeoutMs: 60_000 },
+      { cwd: projectDir, env, timeoutMs: SCOPED_INSTALL_TIMEOUT_MS },
     );
 
     assert.strictEqual(
@@ -1118,7 +1123,7 @@ describe('#1004 regression: installer does not duplicate managed hooks when regi
               {
                 type: 'http',
                 url: hookUrl,
-                timeout: 5,
+                timeout: FIXTURE_HOOK_TIMEOUT_SECONDS,
               },
             ],
           },
@@ -1970,7 +1975,7 @@ describe('#1874 F6 (#338 migration): a malformed settings.local.json is preserve
     delete env.GSD_TEST_MODE;
     const result = runNode(
       [INSTALL_SCRIPT, '--claude', '--local'],
-      { cwd: root, env, timeoutMs: 60_000 },
+      { cwd: root, env, timeoutMs: SCOPED_INSTALL_TIMEOUT_MS },
     );
     assert.strictEqual(result.exitCode, 0,
       `installer exited ${result.exitCode}\n${result.stdout}\n${result.stderr}`);
@@ -2018,7 +2023,7 @@ describe('#1874 F6 adjacent: malformed settings.local.json does not crash the in
     delete env.GSD_TEST_MODE;
     const result = runNode(
       [INSTALL_SCRIPT, '--claude', '--local'],
-      { cwd: root, env, timeoutMs: 60_000 },
+      { cwd: root, env, timeoutMs: SCOPED_INSTALL_TIMEOUT_MS },
     );
 
     assert.strictEqual(result.exitCode, 0,
diff --git a/tests/install-runtime-artifacts.test.cjs b/tests/install-runtime-artifacts.test.cjs
index 4d6a1d4b5..5d189134b 100644
--- a/tests/install-runtime-artifacts.test.cjs
+++ b/tests/install-runtime-artifacts.test.cjs
@@ -32,6 +32,20 @@ const { splitLines, joinLines } = require('../gsd-core/bin/lib/text-lines.cjs');
 const { createTempDir, cleanup, writePackageSourceMarkerFixture } = require('./helpers.cjs');
 const { runNode } = require('./helpers/process-seam.cjs');
 const { INSTALL_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
+
+// Bound the writer subprocess so a regression that hangs the writer
+// (or the dispatcher) cannot deadlock CI (PR #3003 CR feedback).
+// 30s is generous for what should complete in <1s; if it trips,
+// surface that as a clear test failure rather than CI hanging.
+const WRITER_SUBPROCESS_TIMEOUT_MS = 30_000;
+
+// Bounds a real `gsd-tools.cjs capability install` subprocess run against a
+// fully-installed tree; digits coincide with the shared
+// HOOK_FANOUT_TIMEOUT_MS/SEAM_DEFAULT_TIMEOUT_MS constants but this is
+// neither a hook fan-out nor an omitted-default seam call, so kept as its
+// own constant.
+const CAPABILITY_INSTALL_TIMEOUT_MS = 60000;
+
 const {
   INSTALL_SCRIPT,
   MANIFEST_NAME,
@@ -5564,11 +5578,9 @@ describe('Bug #2973: dev-preferences default writer path is skills/gsd-dev-prefe
         // landed in the developer's live config dir instead of tmpHome.
         env: Object.assign({}, process.env, TEST_ENV_BASE, { HOME: tmpHome, USERPROFILE: tmpHome }),
         encoding: 'utf-8',
-        // Bound the subprocess so a regression that hangs the writer
-        // (or the dispatcher) cannot deadlock CI (PR #3003 CR feedback).
-        // 30s is generous for what should complete in <1s; if it trips,
-        // surface that as a clear test failure rather than CI hanging.
-        timeout: 30_000,
+        // See WRITER_SUBPROCESS_TIMEOUT_MS's own doc comment (top of file)
+        // for the full rationale.
+        timeout: WRITER_SUBPROCESS_TIMEOUT_MS,
       });
       assert.equal(result.signal, null,
         `writer subprocess was killed by signal ${result.signal} (likely timeout): ${result.stderr}`);
@@ -6948,7 +6960,7 @@ function realInstall() {
   const res = spawnSync(
     process.execPath,
     [INSTALL, '--claude', '--global', '--config-dir', dir],
-    { encoding: 'utf8', timeout: 120000, env: childEnv },
+    { encoding: 'utf8', timeout: INSTALL_TIMEOUT_MS, env: childEnv },
   );
   assert.strictEqual(res.status, 0, `install --claude failed: ${res.stderr || res.stdout}`);
   return dir;
@@ -6992,7 +7004,7 @@ describe('Gap 1 (end-to-end CLI): installed capability install uses the real hos
       const res = spawnSync(
         process.execPath,
         [installedTools, 'capability', 'install', src, '--scope', 'global', '--yes', '--json'],
-        { cwd, env, encoding: 'utf8', timeout: 60000 },
+        { cwd, env, encoding: 'utf8', timeout: CAPABILITY_INSTALL_TIMEOUT_MS },
       );
       const combined = `${res.stdout || ''}\n${res.stderr || ''}`;
       assert.doesNotMatch(
diff --git a/tests/install-write-confinement.test.cjs b/tests/install-write-confinement.test.cjs
index 138f7d97f..663c7236c 100644
--- a/tests/install-write-confinement.test.cjs
+++ b/tests/install-write-confinement.test.cjs
@@ -2048,6 +2048,7 @@ const os = require('node:os');
 const path = require('node:path');
 const { runNode } = require('./helpers/process-seam.cjs');
 const { cleanup } = require('./helpers.cjs');
+const { PROBE_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
 
 const ROOT = path.resolve(__dirname, '..');
 const DRIFT_LINT = path.join(ROOT, 'scripts', 'lint-shell-command-projection-drift.cjs');
@@ -2055,7 +2056,7 @@ const DRIFT_LINT = path.join(ROOT, 'scripts', 'lint-shell-command-projection-dri
 function runLint(targetFile) {
   const result = runNode([DRIFT_LINT, targetFile], {
     cwd: ROOT,
-    timeoutMs: 15000,
+    timeoutMs: PROBE_TIMEOUT_MS,
   });
   result.status = result.exitCode;
   return result;
@@ -3836,6 +3837,7 @@ const crypto = require('node:crypto');
 const ROOT = path.join(__dirname, '..');
 const INSTALL = require(path.join(ROOT, 'bin', 'install.js'));
 const { cleanup, sandboxHome, scrubConfigLocationEnv } = require('./helpers.cjs');
+const { INSTALL_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
 
 const MANIFEST_NAME = 'gsd-file-manifest.json';
 const PATCHES_DIR_NAME = 'gsd-local-patches';
@@ -3977,7 +3979,7 @@ describe('Bug #4086: saveLocalPatches resolves skills/ manifest keys at the runt
     assert.deepEqual(modifiedList, [], 'without a runtime the old skip behavior applies');
   });
 
-  test('end-to-end codex reinstall backs up the modified skill (#4086)', { timeout: 120_000 }, () => {
+  test('end-to-end codex reinstall backs up the modified skill (#4086)', { timeout: INSTALL_TIMEOUT_MS }, () => {
     const origLog = console.log;
     const origWarn = console.warn;
     console.log = () => {};
diff --git a/tests/install.test.cjs b/tests/install.test.cjs
index 4dfa07d04..17dd24085 100644
--- a/tests/install.test.cjs
+++ b/tests/install.test.cjs
@@ -34,7 +34,20 @@ const { runNode } = require('./helpers/process-seam.cjs');
 const pkg = require('../package.json');
 
 // #3145: class-norm timeout, not a per-suite value — see helpers/timeouts.cjs.
-const { PROBE_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
+const { PROBE_TIMEOUT_MS, QUICK_SPAWN_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
+
+// Fixture-JSON value (seconds, not ms) simulating the PRE-migration legacy
+// settings.json hook-entry timeout under test (#3981-style migration test).
+// Deliberately a different value than the shared FIXTURE_HOOK_TIMEOUT_SECONDS
+// constant (5) since this site tests the old value specifically (batch #4515,
+// epic #4445).
+const FIXTURE_LEGACY_HOOK_TIMEOUT_SECONDS = 10;
+
+// Bounds an `install.js --dry-run` run (no file writes) — a lighter shape than
+// the shared full-write INSTALL_TIMEOUT_MS class (120000ms), kept separate
+// rather than raised. Shared by both dry-run sites in this file (batch #4515,
+// epic #4445).
+const DRY_RUN_INSTALL_TIMEOUT_MS = 30_000;
 
 const {
   getConfigDirFromHome,
@@ -1127,7 +1140,7 @@ describe('install — fix-slash-commands.cjs lands at scripts/fix-slash-commands
     const result = spawnSync(
       process.execPath,
       [gsdToolsPath, 'query', 'init.new-project'],
-      { encoding: 'utf8', timeout: 15000 },
+      { encoding: 'utf8', timeout: PROBE_TIMEOUT_MS },
     );
     assert.ok(
       !result.stderr.includes('MODULE_NOT_FOUND'),
@@ -1215,7 +1228,7 @@ describe('readCmdNames() — tolerates missing commands/gsd directory (#1223)',
 
       const spawnResult = spawnSync(process.execPath, ['-e', script], {
         encoding: 'utf8',
-        timeout: 10000,
+        timeout: QUICK_SPAWN_TIMEOUT_MS,
         env: { ...process.env, GSD_TEST_MODE: '1' },
       });
       assert.ok(
@@ -5568,7 +5581,7 @@ describe('#338 case 3: migration of prior local install GSD entries from setting
               {
                 type: 'command',
                 command: `${process.execPath} ${path.join(claudeDir, 'hooks', 'gsd-context-monitor.js')}`,
-                timeout: 10,
+                timeout: FIXTURE_LEGACY_HOOK_TIMEOUT_SECONDS,
               }
             ]
           }
@@ -7368,7 +7381,7 @@ function installAndRead(runtime) {
   const res = spawnSync(
     process.execPath,
     [INSTALL, `--${runtime}`, '--global', '--config-dir', dir],
-    { encoding: 'utf8', timeout: 120000, env: { ...process.env, HOME: dir, USERPROFILE: dir } },
+    { encoding: 'utf8', timeout: INSTALL_TIMEOUT_MS, env: { ...process.env, HOME: dir, USERPROFILE: dir } },
   );
   assert.strictEqual(res.status, 0, `install --${runtime} failed: ${res.stderr || res.stdout}`);
   const wf = path.join(dir, 'gsd-core', 'workflows', 'execute-phase.md');
@@ -7809,7 +7822,7 @@ describe('#3026: installer --help documents every accepted runtime flag', () =>
 
   test('every accepted runtime flag appears in --help output', () => {
     // Derive accepted flags behaviorally from the installer's argument parser.
-    const r = spawnSync(process.execPath, [INSTALL_PATH, '--help'], { encoding: 'utf-8', timeout: 10000 });
+    const r = spawnSync(process.execPath, [INSTALL_PATH, '--help'], { encoding: 'utf-8', timeout: QUICK_SPAWN_TIMEOUT_MS });
     const helpText = r.stdout;
 
     // The installer's getRuntimeArgs defines which --<runtime> flags it accepts.
@@ -7976,7 +7989,7 @@ describe('#607 --dry-run flag: spawned installer exits 0 and mutates nothing', (
         },
         cwd: REPO_ROOT,
         encoding: 'utf8',
-        timeout: 30_000,
+        timeout: DRY_RUN_INSTALL_TIMEOUT_MS,
       }
     );
 
@@ -8051,7 +8064,7 @@ describe('#607 --dry-run flag: spawned installer exits 0 and mutates nothing', (
         },
         cwd: REPO_ROOT,
         encoding: 'utf8',
-        timeout: 30_000,
+        timeout: DRY_RUN_INSTALL_TIMEOUT_MS,
       }
     );
 
diff --git a/tests/npm-integrity-gate.test.cjs b/tests/npm-integrity-gate.test.cjs
index 7cde6ff77..28b480a90 100644
--- a/tests/npm-integrity-gate.test.cjs
+++ b/tests/npm-integrity-gate.test.cjs
@@ -23,11 +23,18 @@ const assert = require('node:assert/strict');
 const { spawnSync } = require('node:child_process');
 const path = require('node:path');
 const { runNode } = require('./helpers/process-seam.cjs');
+const { QUICK_SPAWN_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
 
 const ROOT = path.resolve(__dirname, '..');
 const SCRIPT = path.join(ROOT, 'scripts', 'check-npm-integrity.cjs');
 const FIXTURES = path.join(__dirname, 'fixtures', 'npm-integrity');
 
+// Bounds a real check-npm-integrity.cjs run via the process seam; digits
+// coincide with the shared BUILD_TIMEOUT_MS but this is a different
+// operation class (an integrity check, not a hooks build), so kept as its
+// own constant rather than aliased.
+const NPM_INTEGRITY_CHECK_TIMEOUT_MS = 30_000;
+
 /**
  * Run the integrity gate script against a fixture directory.
  *
@@ -37,7 +44,7 @@ const FIXTURES = path.join(__dirname, 'fixtures', 'npm-integrity');
  */
 function runGate(fixtureName, extraArgs = []) {
   const fixtureDir = path.join(FIXTURES, fixtureName);
-  const r = runNode([SCRIPT, ...extraArgs], { cwd: fixtureDir, timeoutMs: 30_000 });
+  const r = runNode([SCRIPT, ...extraArgs], { cwd: fixtureDir, timeoutMs: NPM_INTEGRITY_CHECK_TIMEOUT_MS });
   return {
     status: r.exitCode ?? 1,
     stdout: r.stdout,
@@ -145,7 +152,7 @@ describe('#114: npm integrity gate — --help output', () => {
     const result = spawnSync(process.execPath, [SCRIPT, '--help'], {
       cwd: ROOT,
       encoding: 'utf-8',
-      timeout: 10_000,
+      timeout: QUICK_SPAWN_TIMEOUT_MS,
     });
     assert.strictEqual(result.status, 0, '--help should exit 0');
   });
@@ -154,7 +161,7 @@ describe('#114: npm integrity gate — --help output', () => {
     const result = spawnSync(process.execPath, [SCRIPT, '--help'], {
       cwd: ROOT,
       encoding: 'utf-8',
-      timeout: 10_000,
+      timeout: QUICK_SPAWN_TIMEOUT_MS,
     });
     // The .cjs script writes --help to stdout.
     const helpText = (result.stdout ?? '') + (result.stderr ?? '');
diff --git a/tests/packaging-shipped-scripts-require-only-shipped.test.cjs b/tests/packaging-shipped-scripts-require-only-shipped.test.cjs
index b140ab8ec..7684fc952 100644
--- a/tests/packaging-shipped-scripts-require-only-shipped.test.cjs
+++ b/tests/packaging-shipped-scripts-require-only-shipped.test.cjs
@@ -23,6 +23,19 @@ const REPO_ROOT = path.join(__dirname, '..');
 
 const { extractRequires } = require('./helpers/copy-script-fixture.cjs');
 
+/**
+ * package.json's `prepack`/`prepare` runs a full `npm run build:lib` (tsc)
+ * before `npm pack` computes the file list — a bounded but non-trivial
+ * subprocess (~2s in isolation). Under the full parallel 28,000+-test CI
+ * matrix this has been observed to take 60.6s and trip a 60_000ms bound
+ * (#2931 gsd-test run d52d2ee4, linux-node24, duration_ms 60637.56),
+ * aborting this file's `before()` hook and cascading every sibling test to
+ * "cancelled". 120s keeps the bound finite (never unbounded, per the
+ * subprocess-timeout convention) while giving real headroom for a
+ * contended CI box.
+ */
+const NPM_PACK_TIMEOUT_MS = 120_000;
+
 /**
  * Resolve the tarball file list via `npm pack --dry-run --json`.
  * This is the ACTUAL set of files that ship — not a hardcoded list — so adding
@@ -34,16 +47,7 @@ function resolveTarballFiles() {
     encoding: 'utf-8',
     shell: true, // Windows: npm is npm.cmd and needs a shell
     stdio: ['pipe', 'pipe', 'pipe'],
-    // package.json's `prepack`/`prepare` runs a full `npm run build:lib`
-    // (tsc) before `npm pack` computes the file list — a bounded but
-    // non-trivial subprocess (~2s in isolation). Under the full parallel
-    // 28,000+-test CI matrix this has been observed to take 60.6s and trip
-    // a 60_000ms bound (#2931 gsd-test run d52d2ee4, linux-node24,
-    // duration_ms 60637.56), aborting this file's `before()` hook and
-    // cascading every sibling test to "cancelled". 120s keeps the bound
-    // finite (never unbounded, per the subprocess-timeout convention) while
-    // giving real headroom for a contended CI box.
-    timeout: 120_000,
+    timeout: NPM_PACK_TIMEOUT_MS,
   });
   const parsed = JSON.parse(raw);
   return packListToPathSet(parsed);
diff --git a/tests/plugin-manifest.test.cjs b/tests/plugin-manifest.test.cjs
index d06c9c6a1..99c156c50 100644
--- a/tests/plugin-manifest.test.cjs
+++ b/tests/plugin-manifest.test.cjs
@@ -25,10 +25,16 @@ const identity = require(path.join(ROOT, 'gsd-core', 'bin', 'lib', 'package-iden
 const pkg = require(path.join(ROOT, 'package.json'));
 const { MANAGED_HOOKS } = require(path.join(ROOT, 'hooks', 'managed-hooks-registry.cjs'));
 const { cleanup, TEST_ENV_BASE } = require('./helpers.cjs');
+const { PROBE_TIMEOUT_MS } = require('./helpers/timeouts.cjs');
 
 const PLUGIN_JSON_PATH = path.join(ROOT, '.claude-plugin', 'plugin.json');
 const HOOKS_JSON_PATH  = path.join(ROOT, 'hooks', 'hooks.json');
 
+// Bounds a `claude --version` PATH probe; kept separate from the shared
+// PROBE_TIMEOUT_MS (15000ms) since this site's pre-existing value differs
+// and this migration never raises a bound without a fresh bench citation.
+const CLAUDE_VERSION_PROBE_TIMEOUT_MS = 5000;
+
 // ─── Section A: plugin.json ───────────────────────────────────────────────────
 describe('A: .claude-plugin/plugin.json', () => {
 
@@ -401,7 +407,7 @@ describe('C: plugin.json schema validation', () => {
     try {
       const result = spawnSync('claude', ['--version'], {
         encoding: 'utf-8',
-        timeout: 5000,
+        timeout: CLAUDE_VERSION_PROBE_TIMEOUT_MS,
         env: claudeCliEnv(),
       });
       return result.status === 0;
@@ -524,7 +530,7 @@ describe('C: plugin.json schema validation', () => {
         const result = spawnSync('claude', ['plugin', 'validate', pluginRoot, '--strict'], {
           cwd: ROOT,
           encoding: 'utf-8',
-          timeout: 15000,
+          timeout: PROBE_TIMEOUT_MS,
           env: claudeCliEnv(),
         });
         assert.equal(
diff --git a/tests/release-tarball-smoke.install.test.cjs b/tests/release-tarball-smoke.install.test.cjs
index f54db4e2c..f33ead312 100644
--- a/tests/release-tarball-smoke.install.test.cjs
+++ b/tests/release-tarball-smoke.install.test.cjs
@@ -474,6 +474,11 @@ const { execFileSync } = require('node:child_process');
 // The helpers under test.
 const { isolatedNpmEnv, cleanup } = require('./helpers.cjs');
 
+// Bounds the `node -e` npm-harness spawn pattern shared by the three
+// execFileSync(process.execPath, ['-e', script], ...) sites in this file,
+// each of which requires helpers.cjs and calls runNpm(...).
+const NPM_HARNESS_SPAWN_TIMEOUT_MS = 30_000;
+
 // Resolve a filesystem path to its canonical (symlink-free) form even if the
 // leaf does not exist yet (e.g. ~/.npm before npm has written its cache).
 // Walks up to the nearest existing ancestor, resolves that, then re-appends
@@ -540,7 +545,7 @@ describe('bug-131: runNpm isolates HOME from the caller environment', () => {
       try {
         stdout = execFileSync(process.execPath, ['-e', script], {
           encoding: 'utf-8',
-          timeout: 30_000,
+          timeout: NPM_HARNESS_SPAWN_TIMEOUT_MS,
         });
       } catch (err) {
         stdout = err.stdout || '';
@@ -594,7 +599,7 @@ describe('bug-131: runNpm isolates HOME from the caller environment', () => {
     try {
       stdout = execFileSync(process.execPath, ['-e', script], {
         encoding: 'utf-8',
-        timeout: 30_000,
+        timeout: NPM_HARNESS_SPAWN_TIMEOUT_MS,
       });
     } catch (err) {
       stdout = err.stdout || '';
@@ -728,7 +733,7 @@ describe('bug-131: runNpm isolates HOME from the caller environment', () => {
     try {
       stdout = execFileSync(process.execPath, ['-e', script], {
         encoding: 'utf-8',
-        timeout: 30_000,
+        timeout: NPM_HARNESS_SPAWN_TIMEOUT_MS,
       });
     } catch (err) {
       stdout = err.stdout || '';