diff --git a/.configs/vitest.config.mjs b/.configs/vitest.config.mjs
index ce71ffb..426b385 100644
--- a/.configs/vitest.config.mjs
+++ b/.configs/vitest.config.mjs
@@ -11,6 +11,7 @@
  *	@Copyright: Copyright (c) 2026-2026 Catalyzed Motivation Inc. All rights reserved.
  */
 
+import { fileURLToPath } from "node:url";
 import { defineConfig } from "vitest/config";
 
 /**
@@ -22,6 +23,11 @@ export default defineConfig({
 	test: {
 		environment: "node",
 		include: ["tests/**/*.test.vitest.mjs"],
+		// Reap only STALE fixture directories (age-guarded) before/after the run so
+		// orphaned fixtures from a crashed/interrupted run self-heal, without touching
+		// a concurrent run's fresh fixtures (see tests/helpers/workspace.mjs).
+		// Absolute path so it resolves regardless of vitest's root.
+		globalSetup: [fileURLToPath(new URL("./vitest.globalSetup.mjs", import.meta.url))],
 		// "dot" keeps CI logs to one character per test file instead of a full
 		// "RUN vX.Y.Z" + per-file pass/fail block for every file — vitest's
 		// non-interactive fallback (no TTY to redraw) otherwise reprints that
diff --git a/.configs/vitest.globalSetup.mjs b/.configs/vitest.globalSetup.mjs
new file mode 100644
index 0000000..d3f8b4c
--- /dev/null
+++ b/.configs/vitest.globalSetup.mjs
@@ -0,0 +1,23 @@
+/**
+ * @fileoverview Vitest global setup for the fix-headers test suite.
+ *
+ * Reaps ONLY stale fixture directories (see reapStaleWorkspaces in
+ * tests/helpers/workspace.mjs) before and after the run, so orphans from a
+ * previously crashed/interrupted run self-heal WITHOUT touching fixtures a
+ * concurrent, still-running suite (another shard, or CI + local at once) is
+ * actively using — those have a fresh mtime and are left alone. Per-test cleanup
+ * (cleanupWorkspace) still handles the happy path; this is the crash-path backstop.
+ * @module fix-headers/vitest-global-setup
+ */
+
+import { reapStaleWorkspaces } from "../tests/helpers/workspace.mjs";
+
+/** Reap orphans left by a prior aborted run (age-guarded). @returns {Promise<void>} */
+export async function setup() {
+	await reapStaleWorkspaces();
+}
+
+/** Reap any now-stale orphans on the way out (never this run's or a peer's live fixtures). @returns {Promise<void>} */
+export async function teardown() {
+	await reapStaleWorkspaces();
+}
diff --git a/package-lock.json b/package-lock.json
index 85669b1..a4f6f08 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
 	"name": "@cldmv/fix-headers",
-	"version": "1.3.9",
+	"version": "1.3.10",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "@cldmv/fix-headers",
-			"version": "1.3.9",
+			"version": "1.3.10",
 			"license": "Apache-2.0",
 			"dependencies": {
 				"ignore": "^7.0.5"
@@ -548,9 +548,9 @@
 			"license": "MIT"
 		},
 		"node_modules/@types/node": {
-			"version": "26.1.2",
-			"resolved": "https://registry.npmjs.org/@types/node/-/node-26.1.2.tgz",
-			"integrity": "sha512-Vu4a5UFA9rIIFJ7rB/Vaafh9lrCQszopTCx6KjFboXTGQbPNasehVR5TEiithSDGyd1DEiUByggTZsg8jukeIg==",
+			"version": "26.2.0",
+			"resolved": "https://registry.npmjs.org/@types/node/-/node-26.2.0.tgz",
+			"integrity": "sha512-5IviulTZeRNp2vAJ514cc/HUlY5nZ9fCbq9DMyC52BrhFZACo3nI0R7qBxhQmo/d27NFe96ur/b7Wwxklda+kg==",
 			"dev": true,
 			"license": "MIT",
 			"dependencies": {
diff --git a/package.json b/package.json
index f1290f4..476a514 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@cldmv/fix-headers",
-	"version": "1.3.9",
+	"version": "1.3.10",
 	"description": "Multi-language project header normalizer with auto-detection and override support.",
 	"type": "module",
 	"main": "./index.cjs",
diff --git a/tests/helpers/workspace.mjs b/tests/helpers/workspace.mjs
index 4de9a09..a98b840 100644
--- a/tests/helpers/workspace.mjs
+++ b/tests/helpers/workspace.mjs
@@ -11,7 +11,8 @@
  *	@Copyright: Copyright (c) 2026-2026 Catalyzed Motivation Inc. All rights reserved.
  */
 
-import { mkdir, rm, writeFile } from "node:fs/promises";
+import { mkdir, mkdtemp, readdir, rm, stat, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
 import { join, resolve } from "node:path";
 
 /**
@@ -19,6 +20,20 @@ import { join, resolve } from "node:path";
  * @module fix-headers/tests/helpers/workspace
  */
 
+/**
+ * Root for every test fixture: the repo's OWN gitignored `tmp/` directory.
+ * Anchored to this file's location (not `process.cwd()`) so it's cwd-independent.
+ *
+ * Previously this was `join(resolve(process.cwd(), ".."), "tmp-fix-headers-tests")`,
+ * which resolved to the repo's PARENT (the shared repos root). Combined with
+ * unique-per-run names and cleanup that only runs on the happy path, every
+ * failed/interrupted run leaked its fixtures there, sprawling hundreds of orphaned
+ * git repos into the repos root. Keeping fixtures inside the gitignored `tmp/`
+ * contains any leak to a spot that's invisible to git and wiped by cleanup below.
+ * @type {string}
+ */
+export const FIXTURE_ROOT = resolve(import.meta.dirname, "..", "..", "tmp", "fix-headers-tests");
+
 /**
  * Creates an isolated test workspace under the project-local tmp directory.
  * @param {string} name - Workspace name suffix.
@@ -26,11 +41,31 @@ import { join, resolve } from "node:path";
  */
 export async function createWorkspace(name) {
 	const directoryName = `${name}-${Date.now()}-${Math.random().toString(16).slice(2)}`;
-	const workspacePath = join(resolve(process.cwd(), ".."), "tmp-fix-headers-tests", directoryName);
+	const workspacePath = join(FIXTURE_ROOT, directoryName);
 	await mkdir(workspacePath, { recursive: true });
 	return workspacePath;
 }
 
+/**
+ * Creates a workspace with NO ancestor `package.json` and NO ancestor `.git` —
+ * for tests that assert the "nothing detected" fallback path (unknown project
+ * language, unknown git author). {@link createWorkspace}'s fixture root now lives
+ * under this repo's own `tmp/` specifically so leaked fixtures don't sprawl into
+ * the shared repos root — but that means every fixture it creates sits under this
+ * repo's own `package.json` and `.git`, which upward marker/config search will
+ * always find. A fallback-path test needs a workspace with genuinely zero project
+ * ancestry, which no location under this repo can provide by definition. The OS
+ * temp directory is the right tool for that: it's outside any project tree, so it
+ * doesn't reintroduce the original clutter problem (a human-browsed shared repos
+ * root), and each call still cleans up via {@link cleanupWorkspace} same as any
+ * other workspace.
+ * @param {string} name - Workspace name prefix.
+ * @returns {Promise<string>} Absolute workspace path.
+ */
+export async function createIsolatedWorkspace(name) {
+	return mkdtemp(join(tmpdir(), `${name}-`));
+}
+
 /**
  * Writes a UTF-8 file ensuring parent folders are created.
  * @param {string} filePath - Absolute file path.
@@ -53,3 +88,41 @@ export async function writeWorkspaceFile(filePath, content) {
 export async function cleanupWorkspace(workspacePath) {
 	await rm(workspacePath, { recursive: true, force: true });
 }
+
+/**
+ * Reaps only STALE fixture directories under {@link FIXTURE_ROOT} — those whose
+ * mtime is older than `maxAgeMs`. This self-heals orphans from a crashed/interrupted
+ * run WITHOUT deleting fixtures a concurrent, still-running suite is actively using
+ * (an in-flight run's fixtures have a fresh mtime, so they're never reaped). A
+ * whole-root wipe would corrupt overlapping runs — CI + local, or two shards — so
+ * age is the guard. Per-test {@link cleanupWorkspace} still removes each fixture on
+ * the happy path; this is only the backstop for the crash/timeout path.
+ *
+ * The default 1h threshold is far longer than any real run of this suite (seconds)
+ * yet short enough to keep orphans from piling up; override for slower environments.
+ * Missing root and races (a dir removed mid-sweep by another run) are ignored.
+ * @param {number} [maxAgeMs=3600000] - Age past which a fixture counts as orphaned (default 1h).
+ * @returns {Promise<void>} Completion promise.
+ */
+export async function reapStaleWorkspaces(maxAgeMs = 60 * 60 * 1000) {
+	let entries;
+	try {
+		entries = await readdir(FIXTURE_ROOT, { withFileTypes: true });
+	} catch {
+		return; // fixture root doesn't exist yet — nothing to reap
+	}
+	const cutoff = Date.now() - maxAgeMs;
+	await Promise.all(
+		entries
+			.filter((entry) => entry.isDirectory())
+			.map(async (entry) => {
+				const full = join(FIXTURE_ROOT, entry.name);
+				try {
+					const info = await stat(full);
+					if (info.mtimeMs < cutoff) await rm(full, { recursive: true, force: true });
+				} catch {
+					/* vanished mid-sweep (a concurrent run cleaned it) — fine */
+				}
+			})
+	);
+}
diff --git a/tests/integration.module.test.vitest.mjs b/tests/integration.module.test.vitest.mjs
index 2939564..74a618b 100644
--- a/tests/integration.module.test.vitest.mjs
+++ b/tests/integration.module.test.vitest.mjs
@@ -24,7 +24,7 @@ import { detectProjectFromMarkers, resolveProjectMetadata } from "../src/detect/
 import { readFileDates, findProjectRoot, pathExists, readTextIfExists, walkFiles } from "../src/utils/fs.mjs";
 import { detectGitAuthor, getGitCreationDate, getGitLastModifiedDate, runGit } from "../src/utils/git.mjs";
 
-import { cleanupWorkspace, createWorkspace, writeWorkspaceFile } from "./helpers/workspace.mjs";
+import { cleanupWorkspace, createIsolatedWorkspace, createWorkspace, writeWorkspaceFile } from "./helpers/workspace.mjs";
 
 const execFileAsync = promisify(execFile);
 
@@ -155,7 +155,7 @@ describe("module integration and coverage", () => {
 		expect(markerDetection.marker).toBe("package.json");
 		expect(markerDetection.projectName).toBe("fixture-node-project");
 
-		const unknownWorkspace = await createWorkspace("detection-unknown");
+		const unknownWorkspace = await createIsolatedWorkspace("detection-unknown");
 		workspaces.push(unknownWorkspace);
 		await writeWorkspaceFile(join(unknownWorkspace, "file.txt"), "hello\n");
 		const unknownDetection = await detectProjectFromMarkers(unknownWorkspace);
diff --git a/tests/project-metadata-edge.test.vitest.mjs b/tests/project-metadata-edge.test.vitest.mjs
index 7f37f48..bcfb33a 100644
--- a/tests/project-metadata-edge.test.vitest.mjs
+++ b/tests/project-metadata-edge.test.vitest.mjs
@@ -17,7 +17,7 @@ import { join } from "node:path";
 import { describe, expect, it } from "vitest";
 import { detector as nodeDetector } from "../src/detectors/node.mjs";
 import { detectProjectFromMarkers, resolveProjectMetadata } from "../src/detect/project.mjs";
-import { cleanupWorkspace, createWorkspace, writeWorkspaceFile } from "./helpers/workspace.mjs";
+import { cleanupWorkspace, createIsolatedWorkspace, createWorkspace, writeWorkspaceFile } from "./helpers/workspace.mjs";
 
 const execFileAsync = promisify(execFile);
 
@@ -150,7 +150,7 @@ describe("project metadata edge branches", () => {
 	});
 
 	it("uses unknown author/email fallback when git identity is unavailable", async () => {
-		const workspace = await createWorkspace("project-unknown-author");
+		const workspace = await createIsolatedWorkspace("project-unknown-author");
 		const previousGlobalConfig = process.env.GIT_CONFIG_GLOBAL;
 		const previousHome = process.env.HOME;
 		try {