feat(companion): add event surface snapshot helper

README.md

@@ -1190,7 +1190,7 @@ Methods:
 - `system.capabilities` returns gateway protocol and node policy snapshot.
 
 Companion runtime helper:
-- `src/companion/runtimeClient.ts` provides a typed Node/WebSocket client for companion runtimes (macOS/iOS/Android workers) with wrappers for `node.register`, `node.capabilities.get`, `node.location.set/get`, `node.status.set`, `node.push_token.set`, `system.capabilities`, `system.nodes`, and canvas artifact RPCs (`canvas.put/get/list/delete/clear`), plus convenience helpers (`bootstrapNode`, optional `autoConnect`, `dispose()`, `waitForIdle()` for pending-work drain synchronization) and event helpers (`subscribeEvents()`, `subscribeEvent()`, `subscribeAgentStream()`, `subscribeAgentTyping()`, `subscribeContextWarning()`, `waitForEvent()` with timeout/predicate/abort support plus event-name/timeout validation and deterministic teardown cancellation including socket-close rejection, `waitForAnyEvent()` with event-list/timeout validation, `waitForAgentStream()`, `waitForAgentTyping()`, `waitForContextWarning()`, `clearEventSubscriptions()`, `cancelPendingEventWaits()` returning cancelled waiter count, `listKnownEventNames()`, `eventSubscriptionCount`) plus in-flight observability via `pendingRequestCount`, `pendingEventWaitCount`, `hasPendingWork`, `idle`, and `getPendingWorkSnapshot()`.
+- `src/companion/runtimeClient.ts` provides a typed Node/WebSocket client for companion runtimes (macOS/iOS/Android workers) with wrappers for `node.register`, `node.capabilities.get`, `node.location.set/get`, `node.status.set`, `node.push_token.set`, `system.capabilities`, `system.nodes`, and canvas artifact RPCs (`canvas.put/get/list/delete/clear`), plus convenience helpers (`bootstrapNode`, optional `autoConnect`, `dispose()`, `waitForIdle()` for pending-work drain synchronization) and event helpers (`subscribeEvents()`, `subscribeEvent()`, `subscribeAgentStream()`, `subscribeAgentTyping()`, `subscribeContextWarning()`, `waitForEvent()` with timeout/predicate/abort support plus event-name/timeout validation and deterministic teardown cancellation including socket-close rejection, `waitForAnyEvent()` with event-list/timeout validation, `waitForAgentStream()`, `waitForAgentTyping()`, `waitForContextWarning()`, `clearEventSubscriptions()`, `cancelPendingEventWaits()` returning cancelled waiter count, `listKnownEventNames()`, `eventSubscriptionCount`) plus in-flight observability via `pendingRequestCount`, `pendingEventWaitCount`, `hasPendingWork`, `idle`, `getPendingWorkSnapshot()`, and `getEventSurfaceSnapshot()`.
 - `src/companion/platformClients.ts` provides platform-focused wrappers:
   - `MacOSCompanionClient` (`platform: "macos"`, APNs push registration)
   - `IOSCompanionClient` (`platform: "ios"`, APNs push registration)
@@ -1201,7 +1201,7 @@ Companion runtime helper:
   - optional `defaultSessionId` for canvas helper calls so `sessionId` can be omitted per call
   - lifecycle passthroughs for connection state/teardown (`connected`, `dispose(code?, reason?)`)
   - stream passthrough helpers (`subscribeEvents`, `subscribeEvent`, `clearEventSubscriptions`, `cancelPendingEventWaits`, `listKnownEventNames`, `eventSubscriptionCount`, `subscribeAgentStream/Typing/ContextWarning`, `waitForEvent`, `waitForAnyEvent`, `waitForAgentStream/Typing/ContextWarning`)
-  - runtime observability/control passthroughs (`pendingRequestCount`, `pendingEventWaitCount`, `hasPendingWork`, `idle`, `getPendingWorkSnapshot()`, `connected`, `waitForIdle()`)
+  - runtime observability/control passthroughs (`pendingRequestCount`, `pendingEventWaitCount`, `hasPendingWork`, `idle`, `getPendingWorkSnapshot()`, `getEventSurfaceSnapshot()`, `connected`, `waitForIdle()`)
 - `src/companion/heartbeatLoop.ts` provides `CompanionHeartbeatLoop` for periodic heartbeat scheduling (`publishHeartbeat`) with start/stop safety, optional interval jitter (`jitterRatio`) to spread load (with safe normalization for invalid random samples), `tickNow()` for manual sends, success/error hooks, loop observability (`successCount`, `lastSuccessAt`, `failureCount`, `lastFailure`, `getState()`), and optional auto-stop after repeated failures.
 
 ## Canvas / A2UI Foundation

docs/plans/state.json

@@ -1040,6 +1040,22 @@
       ],
       "test_status": "pnpm test:run src/companion/runtimeClient.test.ts src/companion/platformClients.test.ts src/companion/heartbeatLoop.test.ts src/companion/platformClients.integration.test.ts + pnpm typecheck passing"
     },
+    "companion-runtime-event-surface-snapshot-helper": {
+      "status": "completed",
+      "date": "2026-02-17",
+      "updated": "2026-02-17",
+      "summary": "Added `getEventSurfaceSnapshot()` on runtime and platform wrappers for one-call event-surface inspection (`knownEventNames`, `eventSubscriptionCount`, `pendingEventWaitCount`).",
+      "files_modified": [
+        "src/companion/runtimeClient.ts",
+        "src/companion/runtimeClient.test.ts",
+        "src/companion/platformClients.ts",
+        "src/companion/platformClients.test.ts",
+        "src/companion/index.ts",
+        "README.md",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/companion/runtimeClient.test.ts src/companion/platformClients.test.ts src/companion/heartbeatLoop.test.ts src/companion/platformClients.integration.test.ts + pnpm typecheck passing"
+    },
     "companion-runtime-cancel-pending-event-waits": {
       "status": "completed",
       "date": "2026-02-17",

src/companion/index.ts

@@ -14,6 +14,7 @@ export type {
   CompanionRuntimeClientOptions,
   WaitForIdleOptions,
   PendingWorkSnapshot,
+  EventSurfaceSnapshot,
   CompanionEventHandler,
   CompanionTypedEventHandler,
   CompanionEventName,

src/companion/platformClients.test.ts

@@ -36,6 +36,7 @@ function createRuntimeMock(): {
   waitForEvent: ReturnType<typeof vi.fn>;
   waitForIdle: ReturnType<typeof vi.fn>;
   getPendingWorkSnapshot: ReturnType<typeof vi.fn>;
+  getEventSurfaceSnapshot: ReturnType<typeof vi.fn>;
   waitForAgentStream: ReturnType<typeof vi.fn>;
   waitForAgentTyping: ReturnType<typeof vi.fn>;
   waitForContextWarning: ReturnType<typeof vi.fn>;
@@ -86,6 +87,11 @@ function createRuntimeMock(): {
     pendingEventWaitCount: 1,
     hasPendingWork: true,
   }));
+  const getEventSurfaceSnapshot = vi.fn(() => ({
+    knownEventNames: ['agent.stream', 'agent.typing', 'context_warning'],
+    eventSubscriptionCount: 3,
+    pendingEventWaitCount: 1,
+  }));
   const waitForAgentStream = vi.fn(async () => ({ token: 'streamed' }));
   const waitForAgentTyping = vi.fn(async () => ({ active: true }));
   const waitForContextWarning = vi.fn(async () => ({ thresholdPct: 75, estimatedPct: 90 }));
@@ -126,6 +132,7 @@ function createRuntimeMock(): {
     waitForEvent,
     waitForIdle,
     getPendingWorkSnapshot,
+    getEventSurfaceSnapshot,
     waitForAgentStream,
     waitForAgentTyping,
     waitForContextWarning,
@@ -180,6 +187,7 @@ function createRuntimeMock(): {
     waitForEvent,
     waitForIdle,
     getPendingWorkSnapshot,
+    getEventSurfaceSnapshot,
     waitForAgentStream,
     waitForAgentTyping,
     waitForContextWarning,
@@ -395,6 +403,20 @@ describe('platform companion clients', () => {
     });
   });
 
+  it('platform getEventSurfaceSnapshot forwards to runtime client', async () => {
+    const mock = createRuntimeMock();
+    const client = new IOSCompanionClient({ runtime: mock.runtime, nodeId: 'ios-node' });
+
+    const snapshot = client.getEventSurfaceSnapshot();
+
+    expect(mock.getEventSurfaceSnapshot).toHaveBeenCalledOnce();
+    expect(snapshot).toEqual({
+      knownEventNames: ['agent.stream', 'agent.typing', 'context_warning'],
+      eventSubscriptionCount: 3,
+      pendingEventWaitCount: 1,
+    });
+  });
+
   it('macOS client forwards canvas methods to runtime client', async () => {
     const mock = createRuntimeMock();
     const client = new MacOSCompanionClient({ runtime: mock.runtime, nodeId: 'mac-node' });

src/companion/platformClients.ts

@@ -1,6 +1,7 @@
 import type {
   CompanionEventName,
   CompanionEventEnvelope,
+  EventSurfaceSnapshot,
   CompanionEventHandler,
   CanvasClearResult,
   CanvasDeleteResult,
@@ -301,6 +302,10 @@ export class MacOSCompanionClient {
     return this.runtime.getPendingWorkSnapshot();
   }
 
+  getEventSurfaceSnapshot(): EventSurfaceSnapshot {
+    return this.runtime.getEventSurfaceSnapshot();
+  }
+
   waitForAnyEvent<TData = unknown>(
     eventNames: readonly (CompanionEventName | string)[],
     options?: {
@@ -571,6 +576,10 @@ export class IOSCompanionClient {
     return this.runtime.getPendingWorkSnapshot();
   }
 
+  getEventSurfaceSnapshot(): EventSurfaceSnapshot {
+    return this.runtime.getEventSurfaceSnapshot();
+  }
+
   waitForAnyEvent<TData = unknown>(
     eventNames: readonly (CompanionEventName | string)[],
     options?: {
@@ -839,6 +848,10 @@ export class AndroidCompanionClient {
     return this.runtime.getPendingWorkSnapshot();
   }
 
+  getEventSurfaceSnapshot(): EventSurfaceSnapshot {
+    return this.runtime.getEventSurfaceSnapshot();
+  }
+
   waitForAnyEvent<TData = unknown>(
     eventNames: readonly (CompanionEventName | string)[],
     options?: {

src/companion/runtimeClient.test.ts

@@ -703,6 +703,24 @@ describe('CompanionRuntimeClient', () => {
     });
   });
 
+  it('returns event surface snapshot', async () => {
+    const client = new CompanionRuntimeClient({
+      url: 'ws://127.0.0.1:1',
+    });
+    const pendingWait = client.waitForEvent('agent.stream', { timeoutMs: 10_000 }).catch(() => undefined);
+    const unsubscribe = client.subscribeEvents(() => undefined);
+
+    expect(client.getEventSurfaceSnapshot()).toEqual({
+      knownEventNames: ['agent.stream', 'agent.typing', 'context_warning'],
+      eventSubscriptionCount: 2,
+      pendingEventWaitCount: 1,
+    });
+
+    unsubscribe();
+    client.clearEventSubscriptions();
+    await pendingWait;
+  });
+
   it('waitForIdle resolves immediately when no work is pending', async () => {
     const client = new CompanionRuntimeClient({
       url: 'ws://127.0.0.1:1',

src/companion/runtimeClient.ts

@@ -53,6 +53,12 @@ export interface PendingWorkSnapshot {
   hasPendingWork: boolean;
 }
 
+export interface EventSurfaceSnapshot {
+  knownEventNames: CompanionEventName[];
+  eventSubscriptionCount: number;
+  pendingEventWaitCount: number;
+}
+
 export type CompanionEventHandler = (event: string, data: unknown) => void;
 export type CompanionTypedEventHandler<TData = unknown> = (data: TData) => void;
 export type CompanionEventPredicate<TData = unknown> = (data: TData) => boolean;
@@ -338,6 +344,14 @@ export class CompanionRuntimeClient {
     };
   }
 
+  getEventSurfaceSnapshot(): EventSurfaceSnapshot {
+    return {
+      knownEventNames: this.listKnownEventNames(),
+      eventSubscriptionCount: this.eventSubscriptionCount,
+      pendingEventWaitCount: this.pendingEventWaitCount,
+    };
+  }
+
   async connect(): Promise<void> {
     if (this.connected) {
       return;