feat(coding-runtime): add managed Pi extension host

tests/unit/pi-write-lease.test.ts

@@ -0,0 +1,42 @@
+// @vitest-environment node
+
+import { describe, expect, it } from 'vitest';
+import { PiProjectWriteLeaseCoordinator } from '../../electron/coding-runtime/pi/write-lease';
+
+describe('Pi project write lease', () => {
+  it('serializes mutations in one project while allowing other projects to proceed', async () => {
+    const coordinator = new PiProjectWriteLeaseCoordinator();
+    const first = await coordinator.acquire('project-a', 'write-a1');
+    let secondSettled = false;
+    const secondFlight = coordinator.acquire('project-a', 'write-a2').then((lease) => {
+      secondSettled = true;
+      return lease;
+    });
+    const otherProject = await coordinator.acquire('project-b', 'write-b1');
+
+    await Promise.resolve();
+    expect(secondSettled).toBe(false);
+    expect(coordinator.activeCount).toBe(2);
+    expect(coordinator.waitingCount('project-a')).toBe(1);
+
+    first.release();
+    const second = await secondFlight;
+    expect(second.holderId).toBe('write-a2');
+    second.release();
+    otherProject.release();
+    expect(coordinator.activeCount).toBe(0);
+  });
+
+  it('removes a cancelled waiter without disturbing the active lease', async () => {
+    const coordinator = new PiProjectWriteLeaseCoordinator();
+    const active = await coordinator.acquire('project-a', 'active');
+    const controller = new AbortController();
+    const waiting = coordinator.acquire('project-a', 'waiting', controller.signal);
+    controller.abort();
+
+    await expect(waiting).rejects.toThrow('cancelled');
+    expect(coordinator.activeCount).toBe(1);
+    expect(coordinator.waitingCount()).toBe(0);
+    active.release();
+  });
+});