diff --git a/apps/electron-backend-e2e/src/data-dir-reaper.e2e.ts b/apps/electron-backend-e2e/src/data-dir-reaper.e2e.ts
new file mode 100644
index 000000000..767b8c72b
--- /dev/null
+++ b/apps/electron-backend-e2e/src/data-dir-reaper.e2e.ts
@@ -0,0 +1,204 @@
+import { test, expect } from '@playwright/test';
+import { spawn, ChildProcess } from 'child_process';
+import {
+    existsSync,
+    mkdirSync,
+    mkdtempSync,
+    rmSync,
+    utimesSync,
+    writeFileSync,
+} from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
+import {
+    dataDirHardMaxAgeMs,
+    dataDirOwnerMarker,
+    dataDirPrefix,
+    orphanDataDirMaxAgeMs,
+    readDataDirOwner,
+    reapOrphanedDataDirs,
+    writeDataDirOwnerMarker,
+} from './data-dir-reaper';
+
+/**
+ * Coverage for the orphaned-data-directory sweep.
+ *
+ * These are filesystem-level rather than app-level, but they belong in the
+ * Electron suite: it runs on Linux, macOS and Windows, and the sweep turns on
+ * `process.kill(pid, 0)` semantics that differ per platform.
+ */
+const roots: string[] = [];
+const children: ChildProcess[] = [];
+
+function makeRoot(): string {
+    const root = mkdtempSync(join(tmpdir(), 'reaper-spec-'));
+    roots.push(root);
+    return root;
+}
+
+/** A data directory shaped like a real one, optionally aged and/or owned. */
+function makeDataDir(
+    root: string,
+    name: string,
+    options: { ageHours?: number; pid?: number | string } = {}
+): string {
+    const dir = join(root, `${dataDirPrefix}${name}`);
+    mkdirSync(join(dir, 'databases'), { recursive: true });
+    writeFileSync(join(dir, 'databases', 'iptvnator.db'), 'db');
+    if (options.pid !== undefined) {
+        writeFileSync(join(dir, dataDirOwnerMarker), String(options.pid));
+    }
+    if (options.ageHours !== undefined) {
+        const when = new Date(Date.now() - options.ageHours * 3600_000);
+        utimesSync(dir, when, when);
+    }
+    return dir;
+}
+
+function spawnLiveProcess(): ChildProcess {
+    const child =
+        process.platform === 'win32'
+            ? spawn('cmd', ['/c', 'ping -n 30 127.0.0.1 > NUL'], {
+                  stdio: 'ignore',
+              })
+            : spawn('sleep', ['30'], { stdio: 'ignore' });
+    children.push(child);
+    return child;
+}
+
+test.afterAll(() => {
+    for (const child of children) {
+        child.kill();
+    }
+    for (const root of roots) {
+        rmSync(root, { force: true, recursive: true });
+    }
+});
+
+test.describe('orphaned data directory reaper', () => {
+    test('keeps a live owner well past the unmarked cutoff', () => {
+        const root = makeRoot();
+        const child = spawnLiveProcess();
+        // Age is deliberately past the cutoff: writes land under databases/ and
+        // never refresh the root's mtime, so a running suite can look this old.
+        const dir = makeDataDir(root, 'live', {
+            ageHours: 48,
+            pid: child.pid,
+        });
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(dir)).toBe(true);
+    });
+
+    test('reaps a live-looking owner once past the hard cap, since the pid must be recycled', () => {
+        const root = makeRoot();
+        // A pid that resolves to a live process, but on a directory far older
+        // than any suite could run — so the pid belongs to a stranger now.
+        const child = spawnLiveProcess();
+        const dir = makeDataDir(root, 'recycled', {
+            ageHours: 24 * 8,
+            pid: child.pid,
+        });
+
+        expect(readDataDirOwner(dir)).toBe('alive');
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(dir)).toBe(false);
+    });
+
+    test('reaps a dead owner immediately, without waiting out the cutoff', async () => {
+        const root = makeRoot();
+        const child = spawnLiveProcess();
+        const dir = makeDataDir(root, 'dead', {
+            ageHours: 0,
+            pid: child.pid,
+        });
+
+        child.kill('SIGKILL');
+        // The pid only leaves the table once the parent reaps the exit status,
+        // so wait for that rather than assuming kill() is synchronous.
+        await expect
+            .poll(() => readDataDirOwner(dir), { timeout: 10_000 })
+            .toBe('dead');
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(dir)).toBe(false);
+    });
+
+    test('reaps an unmarked directory once it is past the cutoff', () => {
+        const root = makeRoot();
+        const dir = makeDataDir(root, 'legacy', { ageHours: 48 });
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(dir)).toBe(false);
+    });
+
+    test('keeps a fresh unmarked directory', () => {
+        const root = makeRoot();
+        const dir = makeDataDir(root, 'fresh', { ageHours: 1 });
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(dir)).toBe(true);
+    });
+
+    test('treats an empty or malformed marker as undeterminable, not dead', () => {
+        const root = makeRoot();
+        // A half-written marker must not bypass the age guard and take out a
+        // suite that is still starting up.
+        const empty = makeDataDir(root, 'empty', { ageHours: 1, pid: '' });
+        const partial = makeDataDir(root, 'partial', {
+            ageHours: 1,
+            pid: 'not-a-pid',
+        });
+
+        expect(readDataDirOwner(empty)).toBe('unknown');
+        expect(readDataDirOwner(partial)).toBe('unknown');
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(empty)).toBe(true);
+        expect(existsSync(partial)).toBe(true);
+    });
+
+    test('publishes the owner marker atomically', () => {
+        const root = makeRoot();
+        const dir = makeDataDir(root, 'atomic', { ageHours: 0 });
+
+        writeDataDirOwnerMarker(dir);
+
+        // No `.pending` residue, and the marker resolves to this live process.
+        expect(existsSync(`${join(dir, dataDirOwnerMarker)}.pending`)).toBe(
+            false
+        );
+        expect(readDataDirOwner(dir)).toBe('alive');
+    });
+
+    test('ignores directories that do not carry the suite prefix', () => {
+        const root = makeRoot();
+        const foreign = join(root, 'some-other-tool-XYZ');
+        mkdirSync(foreign, { recursive: true });
+        const when = new Date(Date.now() - 99 * 3600_000);
+        utimesSync(foreign, when, when);
+
+        reapOrphanedDataDirs(root);
+
+        expect(existsSync(foreign)).toBe(true);
+    });
+
+    test('survives a missing root instead of throwing', () => {
+        expect(() =>
+            reapOrphanedDataDirs(join(tmpdir(), 'reaper-spec-does-not-exist'))
+        ).not.toThrow();
+    });
+
+    test('cutoffs are a day and a week, and the hard cap is the looser one', () => {
+        expect(orphanDataDirMaxAgeMs).toBe(24 * 60 * 60 * 1000);
+        expect(dataDirHardMaxAgeMs).toBe(7 * 24 * 60 * 60 * 1000);
+        expect(dataDirHardMaxAgeMs).toBeGreaterThan(orphanDataDirMaxAgeMs);
+    });
+});
diff --git a/apps/electron-backend-e2e/src/data-dir-reaper.ts b/apps/electron-backend-e2e/src/data-dir-reaper.ts
new file mode 100644
index 000000000..1ec460035
--- /dev/null
+++ b/apps/electron-backend-e2e/src/data-dir-reaper.ts
@@ -0,0 +1,123 @@
+import {
+    readdirSync,
+    readFileSync,
+    renameSync,
+    rmSync,
+    statSync,
+    writeFileSync,
+} from 'fs';
+import { tmpdir } from 'os';
+import { join } from 'path';
+
+export const dataDirPrefix = 'iptvnator-electron-e2e-';
+export const dataDirOwnerMarker = '.e2e-owner-pid';
+/** Fallback cutoff, used only for leftovers whose owner cannot be determined. */
+export const orphanDataDirMaxAgeMs = 24 * 60 * 60 * 1000;
+/**
+ * Backstop for pid reuse. A pid that looks alive is normally decisive, but the
+ * OS recycles pids — aggressively so on the long-lived Windows runners this
+ * sweep exists for — and an unrelated service inheriting an abandoned run's pid
+ * would otherwise pin that directory forever, defeating the whole point. No
+ * suite survives a week, so past this age a live-looking pid is a stranger.
+ */
+export const dataDirHardMaxAgeMs = 7 * 24 * 60 * 60 * 1000;
+
+export type DataDirOwner = 'alive' | 'dead' | 'unknown';
+
+/**
+ * Records the current process as the owner of `dataDir`.
+ *
+ * Written to a temporary name and renamed into place, because `writeFileSync`
+ * creates the file before its bytes land: a concurrent sweep could otherwise
+ * observe an empty marker and misjudge a starting run. `rename` is atomic
+ * within a filesystem, so the marker is either absent or complete.
+ */
+export function writeDataDirOwnerMarker(dataDir: string): void {
+    const markerPath = join(dataDir, dataDirOwnerMarker);
+    const pendingPath = `${markerPath}.pending`;
+    writeFileSync(pendingPath, String(process.pid));
+    renameSync(pendingPath, markerPath);
+}
+
+/**
+ * Resolves whether the run that created `dataDir` is still alive.
+ *
+ * Directory age cannot answer this. The suite writes beneath `databases/` and
+ * `user-data/`, which never refreshes the root's mtime, so a run paused in a
+ * debugger or blocked on a native process looks arbitrarily old while still
+ * using its data — and Unix would let a sweep unlink files the live Electron
+ * still has open. So the owner is asked of the OS directly.
+ *
+ * `unknown` covers a missing, unreadable, empty or malformed marker. Callers
+ * must treat it as "cannot tell", never as "dead".
+ */
+export function readDataDirOwner(dataDir: string): DataDirOwner {
+    let raw: string;
+    try {
+        raw = readFileSync(join(dataDir, dataDirOwnerMarker), 'utf8').trim();
+    } catch {
+        return 'unknown';
+    }
+
+    const pid = Number.parseInt(raw, 10);
+    if (!raw || !Number.isInteger(pid) || pid <= 0 || String(pid) !== raw) {
+        return 'unknown';
+    }
+
+    try {
+        // Signal 0 runs the existence/permission check without delivering.
+        process.kill(pid, 0);
+        return 'alive';
+    } catch (error) {
+        // EPERM means the pid exists but belongs to another user — still alive.
+        return (error as NodeJS.ErrnoException).code === 'EPERM'
+            ? 'alive'
+            : 'dead';
+    }
+}
+
+/**
+ * Best-effort sweep of data directories abandoned by earlier runs.
+ *
+ * `removeDataDir` tolerates a locked directory rather than failing the run, but
+ * then abandons it, and nothing collects it on our behalf: Windows never clears
+ * %TEMP% on process exit, and the Unix equivalents only run on a schedule. So
+ * every teardown that loses that race leaks a database and user-data tree on a
+ * developer machine or a long-lived self-hosted runner, invisibly.
+ *
+ * A live owner is kept — this repo is routinely checked out into several
+ * worktrees at once — up to `dataDirHardMaxAgeMs`, past which the pid is
+ * assumed recycled rather than still ours. A dead owner is collected at once,
+ * since the pid settles what age only guesses at. An undeterminable owner
+ * falls back to `orphanDataDirMaxAgeMs`.
+ */
+export function reapOrphanedDataDirs(root: string = tmpdir()): void {
+    const now = Date.now();
+    let entries: string[];
+    try {
+        entries = readdirSync(root);
+    } catch {
+        return;
+    }
+
+    for (const entry of entries) {
+        if (!entry.startsWith(dataDirPrefix)) {
+            continue;
+        }
+
+        const candidate = join(root, entry);
+        try {
+            const owner = readDataDirOwner(candidate);
+            const age = now - statSync(candidate).mtimeMs;
+            if (owner === 'alive' && age < dataDirHardMaxAgeMs) {
+                continue;
+            }
+            if (owner === 'unknown' && age < orphanDataDirMaxAgeMs) {
+                continue;
+            }
+            rmSync(candidate, { force: true, recursive: true, maxRetries: 3 });
+        } catch {
+            // Still locked, or owned by another user — leave it for next time.
+        }
+    }
+}
diff --git a/apps/electron-backend-e2e/src/electron-test-fixtures.ts b/apps/electron-backend-e2e/src/electron-test-fixtures.ts
index 12424acd7..80f4f119a 100644
--- a/apps/electron-backend-e2e/src/electron-test-fixtures.ts
+++ b/apps/electron-backend-e2e/src/electron-test-fixtures.ts
@@ -22,6 +22,11 @@ import {
 } from 'fs';
 import { tmpdir } from 'os';
 import { dirname, join, resolve } from 'path';
+import {
+    dataDirPrefix,
+    reapOrphanedDataDirs,
+    writeDataDirOwnerMarker,
+} from './data-dir-reaper';
 
 export const workspaceRoot = resolve(__dirname, '../../..');
 export const electronMainPath = join(
@@ -154,10 +159,17 @@ function removeDataDir(dataDir: string): void {
     }
 }
 
+let reapedOrphanedDataDirs = false;
+
 export const test = base.extend<ElectronFixtures>({
     dataDir: async ({ browserName }, use) => {
         void browserName;
-        const dataDir = mkdtempSync(join(tmpdir(), 'iptvnator-electron-e2e-'));
+        if (!reapedOrphanedDataDirs) {
+            reapedOrphanedDataDirs = true;
+            reapOrphanedDataDirs();
+        }
+        const dataDir = mkdtempSync(join(tmpdir(), dataDirPrefix));
+        writeDataDirOwnerMarker(dataDir);
 
         await use(dataDir);