feat(companion): complete platform stream helper parity

README.md

@@ -1200,7 +1200,7 @@ Companion runtime helper:
   - `createHeartbeatLoop()` convenience helper that returns a bound `CompanionHeartbeatLoop`
   - optional `defaultSessionId` for canvas helper calls so `sessionId` can be omitted per call
   - `dispose()` lifecycle helper for unified runtime teardown
-  - stream passthrough helpers (`subscribeAgentStream()`, `waitForAgentStream()`)
+  - stream passthrough helpers (`subscribeAgentStream/Typing/ContextWarning`, `waitForAgentStream/Typing/ContextWarning`)
 - `src/companion/heartbeatLoop.ts` provides `CompanionHeartbeatLoop` for periodic heartbeat scheduling (`publishHeartbeat`) with start/stop safety, optional interval jitter (`jitterRatio`) to spread load, `tickNow()` for manual sends, success/error hooks, failure observability (`failureCount`, `lastFailure`, `getState()`), and optional auto-stop after repeated failures.
 
 ## Canvas / A2UI Foundation

docs/plans/state.json

@@ -567,6 +567,19 @@
       ],
       "test_status": "pnpm test:run src/companion/platformClients.test.ts src/companion/runtimeClient.test.ts src/companion/heartbeatLoop.test.ts src/companion/platformClients.integration.test.ts + pnpm typecheck passing"
     },
+    "companion-platform-stream-helper-parity": {
+      "status": "completed",
+      "date": "2026-02-17",
+      "updated": "2026-02-17",
+      "summary": "Extended platform wrapper event parity by adding passthroughs for typing/context warning stream subscriptions and wait helpers alongside existing stream-token helpers.",
+      "files_modified": [
+        "src/companion/platformClients.ts",
+        "src/companion/platformClients.test.ts",
+        "README.md",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/companion/platformClients.test.ts src/companion/runtimeClient.test.ts src/companion/heartbeatLoop.test.ts src/companion/platformClients.integration.test.ts + pnpm typecheck passing"
+    },
     "browser-tools-activation-clarity": {
       "status": "completed",
       "date": "2026-02-17",

src/companion/platformClients.test.ts

@@ -26,7 +26,11 @@ function createRuntimeMock(): {
   deleteCanvasArtifact: ReturnType<typeof vi.fn>;
   clearCanvasArtifacts: ReturnType<typeof vi.fn>;
   subscribeAgentStream: ReturnType<typeof vi.fn>;
+  subscribeAgentTyping: ReturnType<typeof vi.fn>;
+  subscribeContextWarning: ReturnType<typeof vi.fn>;
   waitForAgentStream: ReturnType<typeof vi.fn>;
+  waitForAgentTyping: ReturnType<typeof vi.fn>;
+  waitForContextWarning: ReturnType<typeof vi.fn>;
 } {
   const connect = vi.fn(async () => undefined);
   const disconnect = vi.fn(() => undefined);
@@ -53,7 +57,11 @@ function createRuntimeMock(): {
   const deleteCanvasArtifact = vi.fn(async () => ({ deleted: true }));
   const clearCanvasArtifacts = vi.fn(async () => ({ cleared: 1 }));
   const subscribeAgentStream = vi.fn(() => () => undefined);
+  const subscribeAgentTyping = vi.fn(() => () => undefined);
+  const subscribeContextWarning = vi.fn(() => () => undefined);
   const waitForAgentStream = vi.fn(async () => ({ token: 'streamed' }));
+  const waitForAgentTyping = vi.fn(async () => ({ active: true }));
+  const waitForContextWarning = vi.fn(async () => ({ thresholdPct: 75, estimatedPct: 90 }));
 
   const runtime = {
     connect,
@@ -74,7 +82,11 @@ function createRuntimeMock(): {
     deleteCanvasArtifact,
     clearCanvasArtifacts,
     subscribeAgentStream,
+    subscribeAgentTyping,
+    subscribeContextWarning,
     waitForAgentStream,
+    waitForAgentTyping,
+    waitForContextWarning,
   } as unknown as CompanionRuntimeClient;
 
   return {
@@ -97,7 +109,11 @@ function createRuntimeMock(): {
     deleteCanvasArtifact,
     clearCanvasArtifacts,
     subscribeAgentStream,
+    subscribeAgentTyping,
+    subscribeContextWarning,
     waitForAgentStream,
+    waitForAgentTyping,
+    waitForContextWarning,
   };
 }
 
@@ -162,14 +178,28 @@ describe('platform companion clients', () => {
     const mock = createRuntimeMock();
     const client = new AndroidCompanionClient({ runtime: mock.runtime, nodeId: 'android-node' });
     const streamHandler = vi.fn();
+    const typingHandler = vi.fn();
+    const warningHandler = vi.fn();
 
-    const unsubscribe = client.subscribeAgentStream(streamHandler);
+    const unsubscribeStream = client.subscribeAgentStream(streamHandler);
+    const unsubscribeTyping = client.subscribeAgentTyping(typingHandler);
+    const unsubscribeWarning = client.subscribeContextWarning(warningHandler);
     const awaited = await client.waitForAgentStream<{ token: string }>({ timeoutMs: 500 });
+    const waitedTyping = await client.waitForAgentTyping<{ active: boolean }>({ timeoutMs: 500 });
+    const waitedWarning = await client.waitForContextWarning<{ thresholdPct: number; estimatedPct: number }>({ timeoutMs: 500 });
 
     expect(mock.subscribeAgentStream).toHaveBeenCalledWith(streamHandler);
+    expect(mock.subscribeAgentTyping).toHaveBeenCalledWith(typingHandler);
+    expect(mock.subscribeContextWarning).toHaveBeenCalledWith(warningHandler);
     expect(mock.waitForAgentStream).toHaveBeenCalledWith({ timeoutMs: 500 });
+    expect(mock.waitForAgentTyping).toHaveBeenCalledWith({ timeoutMs: 500 });
+    expect(mock.waitForContextWarning).toHaveBeenCalledWith({ timeoutMs: 500 });
     expect(awaited).toEqual({ token: 'streamed' });
-    unsubscribe();
+    expect(waitedTyping).toEqual({ active: true });
+    expect(waitedWarning).toEqual({ thresholdPct: 75, estimatedPct: 90 });
+    unsubscribeStream();
+    unsubscribeTyping();
+    unsubscribeWarning();
   });
 
   it('macOS client forwards canvas methods to runtime client', async () => {

src/companion/platformClients.ts

@@ -225,6 +225,18 @@ export class MacOSCompanionClient {
     return this.runtime.subscribeAgentStream(handler);
   }
 
+  subscribeAgentTyping<TData = unknown>(
+    handler: CompanionTypedEventHandler<TData>,
+  ): () => void {
+    return this.runtime.subscribeAgentTyping(handler);
+  }
+
+  subscribeContextWarning<TData = unknown>(
+    handler: CompanionTypedEventHandler<TData>,
+  ): () => void {
+    return this.runtime.subscribeContextWarning(handler);
+  }
+
   waitForAgentStream<TData = unknown>(options?: {
     timeoutMs?: number;
     predicate?: CompanionEventPredicate<TData>;
@@ -233,6 +245,22 @@ export class MacOSCompanionClient {
     return this.runtime.waitForAgentStream(options);
   }
 
+  waitForAgentTyping<TData = unknown>(options?: {
+    timeoutMs?: number;
+    predicate?: CompanionEventPredicate<TData>;
+    signal?: AbortSignal;
+  }): Promise<TData> {
+    return this.runtime.waitForAgentTyping(options);
+  }
+
+  waitForContextWarning<TData = unknown>(options?: {
+    timeoutMs?: number;
+    predicate?: CompanionEventPredicate<TData>;
+    signal?: AbortSignal;
+  }): Promise<TData> {
+    return this.runtime.waitForContextWarning(options);
+  }
+
   private resolveSessionId(sessionId?: string): string {
     const resolved = sessionId ?? this.defaultSessionId;
     if (!resolved) {
@@ -390,6 +418,18 @@ export class IOSCompanionClient {
     return this.runtime.subscribeAgentStream(handler);
   }
 
+  subscribeAgentTyping<TData = unknown>(
+    handler: CompanionTypedEventHandler<TData>,
+  ): () => void {
+    return this.runtime.subscribeAgentTyping(handler);
+  }
+
+  subscribeContextWarning<TData = unknown>(
+    handler: CompanionTypedEventHandler<TData>,
+  ): () => void {
+    return this.runtime.subscribeContextWarning(handler);
+  }
+
   waitForAgentStream<TData = unknown>(options?: {
     timeoutMs?: number;
     predicate?: CompanionEventPredicate<TData>;
@@ -398,6 +438,22 @@ export class IOSCompanionClient {
     return this.runtime.waitForAgentStream(options);
   }
 
+  waitForAgentTyping<TData = unknown>(options?: {
+    timeoutMs?: number;
+    predicate?: CompanionEventPredicate<TData>;
+    signal?: AbortSignal;
+  }): Promise<TData> {
+    return this.runtime.waitForAgentTyping(options);
+  }
+
+  waitForContextWarning<TData = unknown>(options?: {
+    timeoutMs?: number;
+    predicate?: CompanionEventPredicate<TData>;
+    signal?: AbortSignal;
+  }): Promise<TData> {
+    return this.runtime.waitForContextWarning(options);
+  }
+
   private resolveSessionId(sessionId?: string): string {
     const resolved = sessionId ?? this.defaultSessionId;
     if (!resolved) {
@@ -553,6 +609,18 @@ export class AndroidCompanionClient {
     return this.runtime.subscribeAgentStream(handler);
   }
 
+  subscribeAgentTyping<TData = unknown>(
+    handler: CompanionTypedEventHandler<TData>,
+  ): () => void {
+    return this.runtime.subscribeAgentTyping(handler);
+  }
+
+  subscribeContextWarning<TData = unknown>(
+    handler: CompanionTypedEventHandler<TData>,
+  ): () => void {
+    return this.runtime.subscribeContextWarning(handler);
+  }
+
   waitForAgentStream<TData = unknown>(options?: {
     timeoutMs?: number;
     predicate?: CompanionEventPredicate<TData>;
@@ -561,6 +629,22 @@ export class AndroidCompanionClient {
     return this.runtime.waitForAgentStream(options);
   }
 
+  waitForAgentTyping<TData = unknown>(options?: {
+    timeoutMs?: number;
+    predicate?: CompanionEventPredicate<TData>;
+    signal?: AbortSignal;
+  }): Promise<TData> {
+    return this.runtime.waitForAgentTyping(options);
+  }
+
+  waitForContextWarning<TData = unknown>(options?: {
+    timeoutMs?: number;
+    predicate?: CompanionEventPredicate<TData>;
+    signal?: AbortSignal;
+  }): Promise<TData> {
+    return this.runtime.waitForContextWarning(options);
+  }
+
   private resolveSessionId(sessionId?: string): string {
     const resolved = sessionId ?? this.defaultSessionId;
     if (!resolved) {