diff --git a/packages/server/test/helpers/twoInstanceHarness.ts b/packages/server/test/helpers/twoInstanceHarness.ts
new file mode 100644
index 00000000..e8f2702b
--- /dev/null
+++ b/packages/server/test/helpers/twoInstanceHarness.ts
@@ -0,0 +1,215 @@
+import { spawn, type ChildProcess } from 'node:child_process';
+import { mkdir, rm, readFile } from 'node:fs/promises';
+import { createWriteStream } from 'node:fs';
+import path from 'node:path';
+import { createServer } from 'node:net';
+import { fileURLToPath } from 'node:url';
+import crypto from 'node:crypto';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export interface SpawnedInstance {
+  proc: ChildProcess;
+  port: number;
+  origin: string;        // 'http://127.0.0.1:<port>'
+  domain: string;        // 'home.test.local' / 'remote0.test.local' / ...
+  dbPath: string;
+  storagePath: string;
+  jwtSecret: string;
+  logPath: string;
+}
+
+export interface MultiRemoteHarness {
+  home: SpawnedInstance;
+  remotes: SpawnedInstance[];
+  runDir: string;
+  cleanup: () => Promise<void>;
+}
+
+// Convenience type alias for the common one-remote case.
+export interface TwoInstanceHarness {
+  home: SpawnedInstance;
+  remote: SpawnedInstance;
+  remotes: SpawnedInstance[]; // for code that wants the array form
+  runDir: string;
+  cleanup: () => Promise<void>;
+}
+
+async function allocateEphemeralPort(): Promise<number> {
+  return new Promise((resolve, reject) => {
+    const srv = createServer();
+    srv.listen(0, '127.0.0.1', () => {
+      const addr = srv.address();
+      if (addr && typeof addr === 'object') {
+        const port = addr.port;
+        srv.close(() => resolve(port));
+      } else {
+        srv.close(() => reject(new Error('Could not allocate ephemeral port')));
+      }
+    });
+    srv.on('error', reject);
+  });
+}
+
+async function waitForReady(origin: string, proc: ChildProcess, logPath: string, timeoutMs = 20_000): Promise<void> {
+  const deadline = Date.now() + timeoutMs;
+  let exited = false;
+  let exitInfo: { code: number | null; signal: NodeJS.Signals | null } | null = null;
+  const onExit = (code: number | null, signal: NodeJS.Signals | null) => {
+    exited = true;
+    exitInfo = { code, signal };
+  };
+  proc.once('exit', onExit);
+  try {
+    while (Date.now() < deadline) {
+      if (exited) {
+        throw new Error(
+          `Instance ${origin} exited during boot (code=${exitInfo?.code}, signal=${exitInfo?.signal}). ` +
+          `See log at ${logPath}`,
+        );
+      }
+      try {
+        const res = await fetch(`${origin}/api/instance/info`);
+        if (res.ok) return;
+      } catch {
+        // not ready yet
+      }
+      await new Promise(r => setTimeout(r, 200));
+    }
+    throw new Error(`Instance ${origin} did not become ready within ${timeoutMs}ms. See log at ${logPath}`);
+  } finally {
+    proc.off('exit', onExit);
+  }
+}
+
+async function spawnInstance(opts: {
+  domain: string;
+  port: number;
+  dbPath: string;
+  storagePath: string;
+  jwtSecret: string;
+  logPath: string;
+}): Promise<SpawnedInstance> {
+  const env = {
+    ...process.env,
+    NODE_ENV: 'test',
+    ENABLE_TEST_ROUTES: '1',
+    DISABLE_FEDERATION_WORKERS: '1',
+    PORT: String(opts.port),
+    HOST: '127.0.0.1',
+    DOMAIN: opts.domain,
+    DB_PATH: opts.dbPath,
+    STORAGE_PATH: opts.storagePath,
+    JWT_SECRET: opts.jwtSecret,
+    LIVEKIT_URL: '',
+    LIVEKIT_API_KEY: '',
+    LIVEKIT_API_SECRET: '',
+  };
+  // From packages/server/test/helpers → packages/server is up two levels.
+  const serverDir = path.resolve(__dirname, '../../');
+  const proc = spawn('pnpm', ['exec', 'tsx', 'src/index.ts'], {
+    cwd: serverDir,
+    env,
+    stdio: ['ignore', 'pipe', 'pipe'],
+  });
+  const logStream = createWriteStream(opts.logPath);
+  proc.stdout!.pipe(logStream);
+  proc.stderr!.pipe(logStream);
+  const origin = `http://127.0.0.1:${opts.port}`;
+  await waitForReady(origin, proc, opts.logPath);
+  return {
+    proc,
+    port: opts.port,
+    origin,
+    domain: opts.domain,
+    dbPath: opts.dbPath,
+    storagePath: opts.storagePath,
+    jwtSecret: opts.jwtSecret,
+    logPath: opts.logPath,
+  };
+}
+
+/** Boot home + N remotes. All instances ready before the function returns. */
+export async function bootHomePlusRemotes(remoteCount: number): Promise<MultiRemoteHarness> {
+  if (remoteCount < 1) throw new Error('remoteCount must be >= 1');
+  const runId = crypto.randomBytes(4).toString('hex');
+  // From packages/server/test/helpers → repo root is up four levels: helpers → test → server → packages → repo-root.
+  const runDir = path.resolve(__dirname, `../../../../tests/.tmp/${runId}`);
+  await mkdir(`${runDir}/home-uploads`, { recursive: true });
+
+  const homePort = await allocateEphemeralPort();
+  const home = await spawnInstance({
+    domain: 'home.test.local',
+    port: homePort,
+    dbPath: `${runDir}/home.db`,
+    storagePath: `${runDir}/home-uploads`,
+    jwtSecret: crypto.randomBytes(32).toString('hex'),
+    logPath: `${runDir}/home.log`,
+  });
+
+  const remotes: SpawnedInstance[] = [];
+  for (let i = 0; i < remoteCount; i++) {
+    await mkdir(`${runDir}/remote${i}-uploads`, { recursive: true });
+    const port = await allocateEphemeralPort();
+    const r = await spawnInstance({
+      domain: `remote${i}.test.local`,
+      port,
+      dbPath: `${runDir}/remote${i}.db`,
+      storagePath: `${runDir}/remote${i}-uploads`,
+      jwtSecret: crypto.randomBytes(32).toString('hex'),
+      logPath: `${runDir}/remote${i}.log`,
+    });
+    remotes.push(r);
+  }
+
+  let cleanedUp = false;
+  const cleanup = async () => {
+    if (cleanedUp) return;
+    cleanedUp = true;
+    for (const inst of [home, ...remotes]) {
+      if (!inst.proc.killed) {
+        inst.proc.kill('SIGTERM');
+        await new Promise(r => setTimeout(r, 500));
+        if (!inst.proc.killed) inst.proc.kill('SIGKILL');
+      }
+    }
+    await rm(runDir, { recursive: true, force: true });
+  };
+
+  return { home, remotes, runDir, cleanup };
+}
+
+/** Convenience: 1 home + 1 remote. Exposes both `remote` (singular) and `remotes` (array). */
+export async function bootTwoInstances(): Promise<TwoInstanceHarness> {
+  const m = await bootHomePlusRemotes(1);
+  return {
+    home: m.home,
+    remote: m.remotes[0],
+    remotes: m.remotes,
+    runDir: m.runDir,
+    cleanup: m.cleanup,
+  };
+}
+
+/**
+ * Read the contents of an instance's log file. Used by tests that need to assert
+ * a specific request did or did not reach an instance (Task 14 / Test #1).
+ */
+export async function readInstanceLog(inst: SpawnedInstance): Promise<string> {
+  try {
+    return await readFile(inst.logPath, 'utf8');
+  } catch {
+    return '';
+  }
+}
+
+/**
+ * Wait `delayMs` (to let any in-flight request settle into the log file), then
+ * return whether `pattern` appears in `inst`'s log. Used to prove a request did
+ * NOT happen — assert the result is false.
+ */
+export async function logMatched(inst: SpawnedInstance, pattern: RegExp, delayMs = 1_000): Promise<boolean> {
+  await new Promise(r => setTimeout(r, delayMs));
+  const log = await readInstanceLog(inst);
+  return pattern.test(log);
+}