fix: address PR review comments for chroma server lifecycle

tests/services/sync/chroma-server-manager.test.ts

@@ -0,0 +1,139 @@
+import { describe, it, expect, beforeEach, afterEach, mock, spyOn } from 'bun:test';
+import { EventEmitter } from 'events';
+import * as childProcess from 'child_process';
+import { ChromaServerManager } from '../../../src/services/sync/ChromaServerManager.js';
+
+function createFakeProcess(pid: number = 4242): childProcess.ChildProcess {
+  const proc = new EventEmitter() as childProcess.ChildProcess & EventEmitter;
+  let exited = false;
+
+  (proc as any).stdout = new EventEmitter();
+  (proc as any).stderr = new EventEmitter();
+  (proc as any).pid = pid;
+  (proc as any).kill = mock(() => {
+    if (!exited) {
+      exited = true;
+      setTimeout(() => proc.emit('exit', 0, 'SIGTERM'), 0);
+    }
+    return true;
+  });
+
+  return proc as childProcess.ChildProcess;
+}
+
+describe('ChromaServerManager', () => {
+  const originalFetch = global.fetch;
+  const originalPlatform = process.platform;
+
+  beforeEach(() => {
+    mock.restore();
+    ChromaServerManager.reset();
+
+    // Avoid macOS cert bundle shelling in tests; these tests only exercise startup races.
+    Object.defineProperty(process, 'platform', {
+      value: 'linux',
+      writable: true,
+      configurable: true
+    });
+  });
+
+  afterEach(() => {
+    global.fetch = originalFetch;
+    mock.restore();
+    ChromaServerManager.reset();
+
+    Object.defineProperty(process, 'platform', {
+      value: originalPlatform,
+      writable: true,
+      configurable: true
+    });
+  });
+
+  it('reuses in-flight startup and only spawns one server process', async () => {
+    const fetchMock = mock(async () => {
+      // First call: existing server check fails, second call: waitForReady succeeds.
+      if (fetchMock.mock.calls.length === 1) {
+        throw new Error('no server yet');
+      }
+      return new Response(null, { status: 200 });
+    });
+    global.fetch = fetchMock as typeof fetch;
+
+    const spawnSpy = spyOn(childProcess, 'spawn').mockImplementation(
+      () => createFakeProcess() as unknown as ReturnType<typeof childProcess.spawn>
+    );
+
+    const manager = ChromaServerManager.getInstance({
+      dataDir: '/tmp/chroma-test',
+      host: '127.0.0.1',
+      port: 8000
+    });
+
+    const [first, second] = await Promise.all([
+      manager.start(2000),
+      manager.start(2000)
+    ]);
+
+    expect(first).toBe(true);
+    expect(second).toBe(true);
+    expect(spawnSpy).toHaveBeenCalledTimes(1);
+  });
+
+  it('reuses existing reachable server without spawning', async () => {
+    global.fetch = mock(async () => new Response(null, { status: 200 })) as typeof fetch;
+    const spawnSpy = spyOn(childProcess, 'spawn').mockImplementation(
+      () => createFakeProcess() as unknown as ReturnType<typeof childProcess.spawn>
+    );
+
+    const manager = ChromaServerManager.getInstance({
+      dataDir: '/tmp/chroma-test',
+      host: '127.0.0.1',
+      port: 8000
+    });
+
+    const ready = await manager.start(2000);
+    expect(ready).toBe(true);
+    expect(spawnSpy).not.toHaveBeenCalled();
+  });
+
+  it('waits for ongoing startup instead of returning early', async () => {
+    let resolveReady: ((value: Response) => void) | null = null;
+    const delayedReady = new Promise<Response>((resolve) => {
+      resolveReady = resolve;
+    });
+
+    const fetchMock = mock(async () => {
+      // 1st: existing server check -> fail, 2nd: waitForReady -> block until we resolve.
+      if (fetchMock.mock.calls.length === 1) {
+        throw new Error('no server yet');
+      }
+      return delayedReady;
+    });
+    global.fetch = fetchMock as typeof fetch;
+
+    spyOn(childProcess, 'spawn').mockImplementation(
+      () => createFakeProcess() as unknown as ReturnType<typeof childProcess.spawn>
+    );
+
+    const manager = ChromaServerManager.getInstance({
+      dataDir: '/tmp/chroma-test',
+      host: '127.0.0.1',
+      port: 8000
+    });
+
+    const firstStart = manager.start(5000);
+    let secondResolved = false;
+    const secondStart = manager.start(5000).then((value) => {
+      secondResolved = true;
+      return value;
+    });
+
+    await new Promise((resolve) => setTimeout(resolve, 50));
+    expect(secondResolved).toBe(false);
+
+    resolveReady!(new Response(null, { status: 200 }));
+
+    expect(await firstStart).toBe(true);
+    expect(await secondStart).toBe(true);
+  });
+});