test(chat): pass mountTimeline options as an object

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/hub.md

@@ -61,6 +61,10 @@ The daemon journals the assigned agent ID before creation. Concurrent retries sh
 and a retry after a lost acknowledgement or restart returns the durable agent without creating a
 workspace or starting a turn. Deleting that agent does not make its old creation key reusable.
 Confirmed message delivery is also journaled, so retrying its message ID does not submit it again.
+A direct send (one without `sourceAgentId`) rejected before its prompt is handed to a run, for
+example because the agent could not be loaded or the requested mode could not be set, leaves no
+receipt, so retrying its message ID submits it. A failure during or after run startup is treated
+as an unfinished delivery.
 An unfinished delivery after restart reports `agent_request_outcome_unknown`: a provider can have
 accepted a prompt before the daemon recorded success, so automatic resubmission could duplicate
 work. Inspect the agent before choosing a new message ID. Receipts contain identity and request

packages/app/e2e/support/helpers/agent-timeline-gate.ts

@@ -21,7 +21,6 @@ export interface OlderTimelinePagesGate {
   getRepeatedEntryCount(): number;
   getOwnedEntryCountContaining(text: string): number;
   releasePage(pageNumber: number): void;
-  waitForRequestCount(count: number): Promise<void>;
 }
 
 export interface DaemonHydrationGate {
@@ -371,15 +370,6 @@ export async function holdAgentOlderTimelinePages(
   const ownedEntries = new Map<string, string>();
   const releasedPages = new Set<number>();
   const delayedForwards = new Map<number, Array<() => void>>();
-  const requestWaiters = new Map<number, Array<() => void>>();
-
-  const resolveRequestWaiters = () => {
-    for (const [count, resolvers] of requestWaiters) {
-      if (requestCount < count) continue;
-      requestWaiters.delete(count);
-      for (const resolve of resolvers) resolve();
-    }
-  };
 
   const routePattern =
     daemonPort === undefined ? daemonWsRoutePattern() : wsRoutePatternForPort(String(daemonPort));
@@ -393,7 +383,6 @@ export async function holdAgentOlderTimelinePages(
         sessionMessage.direction === "before"
       ) {
         requestCount += 1;
-        resolveRequestWaiters();
       }
       server.send(message);
     });
@@ -439,14 +428,6 @@ export async function holdAgentOlderTimelinePages(
       for (const forward of delayedForwards.get(pageNumber) ?? []) forward();
       delayedForwards.delete(pageNumber);
     },
-    waitForRequestCount(count) {
-      if (requestCount >= count) return Promise.resolve();
-      return new Promise<void>((resolve) => {
-        const resolvers = requestWaiters.get(count) ?? [];
-        resolvers.push(resolve);
-        requestWaiters.set(count, resolvers);
-      });
-    },
   };
 }
 

packages/app/e2e/support/helpers/timeline-pagination.ts

@@ -427,7 +427,11 @@ export async function holdOlderHistoryPages(
   const loader = page.getByTestId("load-older-history-spinner");
   return {
     async expectRequestedPages(count) {
-      await gate.waitForRequestCount(count);
+      await expect
+        .poll(() => gate.getRequestCount(), {
+          message: `older history requests ${count} page(s)`,
+        })
+        .toBeGreaterThanOrEqual(count);
       expect(gate.getRequestCount()).toBe(count);
     },
     async expectSettledWithRequestedPages(count) {

packages/app/src/agent-stream/strategy-web.browser.test.tsx

@@ -49,8 +49,21 @@ afterEach(() => {
   host.remove();
 });
 
-function mountTimeline(historyMounted: StreamItem[]) {
-  const strategy = createWebStreamStrategy({ isMobileBreakpoint: true });
+type OlderHistoryInput = Pick<
+  StreamRenderInput,
+  "onNearHistoryStart" | "hasOlderHistory" | "olderHistoryProgressKey"
+>;
+
+interface MountTimelineOptions {
+  olderHistory?: OlderHistoryInput;
+  isMobileBreakpoint?: boolean;
+}
+
+function mountTimeline(
+  historyMounted: StreamItem[],
+  { olderHistory, isMobileBreakpoint = true }: MountTimelineOptions = {},
+) {
+  const strategy = createWebStreamStrategy({ isMobileBreakpoint });
   const viewportRef = React.createRef<StreamViewportHandle>();
   const input: StreamRenderInput = {
     agentId: "agent",
@@ -76,6 +89,7 @@ function mountTimeline(historyMounted: StreamItem[]) {
     baseListContentContainerStyle: null,
     forwardListContentContainerStyle: null,
     contentMaxWidth: DEFAULT_CONTENT_MAX_WIDTH,
+    ...olderHistory,
   };
   const render = (segments: Partial<StreamRenderInput["segments"]>) =>
     root.render(strategy.render({ ...input, segments: { ...input.segments, ...segments } }));
@@ -100,8 +114,20 @@ function mountTimeline(historyMounted: StreamItem[]) {
     scrollTo: (top: number) => {
       scrollContainer.scrollTop = top;
     },
+    // A wheel listener runs before the browser applies the scroll the wheel causes.
+    wheelUpTo: (top: number) => {
+      scrollContainer.dispatchEvent(new WheelEvent("wheel", { bubbles: true, deltaY: -1000 }));
+      scrollContainer.scrollTop = top;
+    },
     distanceFromEnd: () =>
       scrollContainer.scrollHeight - scrollContainer.clientHeight - scrollContainer.scrollTop,
+    scrollTop: () => scrollContainer.scrollTop,
+    scrollUp: (distance: number) =>
+      act(() => {
+        scrollContainer.dispatchEvent(new WheelEvent("wheel", { deltaY: -distance }));
+        scrollContainer.scrollTop -= distance;
+        scrollContainer.dispatchEvent(new Event("scroll"));
+      }),
     // Resize observers and the hold's settle run on animation frames.
     settle: () =>
       act(async () => {
@@ -113,6 +139,53 @@ function mountTimeline(historyMounted: StreamItem[]) {
 }
 
 describe("web disclosure hold", () => {
+  it.each([{ isMobileBreakpoint: true }, { isMobileBreakpoint: false }])(
+    "keeps the reading position when mounted history becomes virtualized (compact: $isMobileBreakpoint)",
+    async (options) => {
+      const history = Array.from({ length: 80 }, (_, index) => row(index));
+      const timeline = mountTimeline(history, options);
+      await timeline.settle();
+      timeline.scrollUp(600);
+      await timeline.settle();
+      const offset = timeline.scrollTop();
+      const readingTop = timeline.rowTop("message-64");
+      expect(offset).toBeGreaterThan(0);
+
+      timeline.render({
+        historyVirtualized: history.slice(0, 60),
+        historyMounted: history.slice(60),
+      });
+      await timeline.settle();
+
+      expect(timeline.scrollTop()).toBe(offset);
+      expect(timeline.rowTop("message-64")).toBe(readingTop);
+    },
+  );
+
+  it.each([{ isMobileBreakpoint: true }, { isMobileBreakpoint: false }])(
+    "keeps following output when mounted history becomes virtualized at the end (compact: $isMobileBreakpoint)",
+    async (options) => {
+      const history = Array.from({ length: 80 }, (_, index) => row(index));
+      const timeline = mountTimeline(history, options);
+      await timeline.settle();
+
+      timeline.render({
+        historyVirtualized: history.slice(0, 60),
+        historyMounted: history.slice(60),
+      });
+      await timeline.settle();
+      expect(timeline.distanceFromEnd()).toBeLessThanOrEqual(1);
+
+      timeline.render({
+        historyVirtualized: history.slice(0, 60),
+        historyMounted: history.slice(60),
+        liveHead: [row(80)],
+      });
+      await timeline.settle();
+      expect(timeline.distanceFromEnd()).toBeLessThanOrEqual(1);
+    },
+  );
+
   it("keeps the trigger's top when an anchored toggle at the bottom opens rows below it, and stops following", async () => {
     const history = [1, 2, 3, 4, 5, 6].map((index) => row(index));
     const timeline = mountTimeline(history);
@@ -208,3 +281,32 @@ describe("web disclosure hold", () => {
     expect(timeline.distanceFromEnd()).toBeLessThanOrEqual(1);
   });
 });
+
+describe("web history start", () => {
+  it("loads older history when an upward wheel lands at the start after the reader stopped following", async () => {
+    let olderHistoryLoads = 0;
+    const history = [1, 2, 3, 4, 5, 6].map((index) => row(index));
+    const timeline = mountTimeline(history, {
+      olderHistory: {
+        hasOlderHistory: true,
+        olderHistoryProgressKey: "epoch:1",
+        onNearHistoryStart: async () => {
+          olderHistoryLoads += 1;
+          return true;
+        },
+      },
+    });
+    await timeline.settle();
+    // Opening a row at the bottom stops following output without any scroll.
+    timeline.hold("message-5", () =>
+      timeline.render({ historyMounted: [...history.slice(0, 5), row(7, 200), history[5]!] }),
+    );
+    await timeline.settle();
+    expect(olderHistoryLoads).toBe(0);
+
+    timeline.wheelUpTo(0);
+    await timeline.settle();
+
+    expect(olderHistoryLoads).toBe(1);
+  });
+});

packages/app/src/agent-stream/strategy-web.tsx

@@ -457,6 +457,8 @@ function WebStreamViewport(props: StreamRenderInput & { isMobileBreakpoint: bool
   const rowVirtualizer = useVirtualizer({
     count: segments.historyVirtualized.length,
     enabled: shouldUseVirtualizer,
+    // History can become virtualized after the reader has already scrolled the mounted rows.
+    initialOffset: () => scrollContainerRef.current?.scrollTop ?? 0,
     initialRect: {
       width: scrollContainerRef.current?.clientWidth ?? 0,
       height: scrollContainerRef.current?.clientHeight ?? 0,
@@ -605,6 +607,15 @@ function WebStreamViewport(props: StreamRenderInput & { isMobileBreakpoint: bool
       window.performance.now() + UPWARD_INPUT_EVIDENCE_TIMEOUT_MS;
   }, []);
 
+  const hasUpwardInputEvidence = useCallback(() => {
+    const mouseGesture = mouseScrollGestureRef.current;
+    return (
+      mouseGesture?.kind === "scrollbar" ||
+      (mouseGesture?.kind === "autoscroll" && mouseGesture.hasUpwardEvidence) ||
+      window.performance.now() < upwardInputEvidenceUntilRef.current
+    );
+  }, []);
+
   useLayoutEffect(() => {
     if (isActive) {
       return;
@@ -791,16 +802,16 @@ function WebStreamViewport(props: StreamRenderInput & { isMobileBreakpoint: bool
     const scrolledUp = currentScrollTop < lastKnownScrollTopRef.current - USER_SCROLL_DELTA_EPSILON;
     const scrolledDown =
       currentScrollTop > lastKnownScrollTopRef.current + USER_SCROLL_DELTA_EPSILON;
-    const mouseGesture = mouseScrollGestureRef.current;
-    const hasUpwardInputEvidence =
-      mouseGesture?.kind === "scrollbar" ||
-      (mouseGesture?.kind === "autoscroll" && mouseGesture.hasUpwardEvidence) ||
-      window.performance.now() < upwardInputEvidenceUntilRef.current;
+    const userScrolledUp = scrolledUp && hasUpwardInputEvidence();
 
     if (!followOutputRef.current && isAtBottom && scrolledDown && !isJumpSettling()) {
       setFollowOutput(true);
-    } else if (followOutputRef.current && scrolledUp && hasUpwardInputEvidence) {
+    } else if (followOutputRef.current && userScrolledUp) {
       stopFollowingOutputFromUserIntent();
+    } else if (userScrolledUp) {
+      // Wheel listeners can run before or after the browser applies the scroll, so the
+      // upward scroll itself re-arms loading when it reaches the start.
+      rearmHistoryStartFromUserIntent();
     }
 
     lastKnownScrollTopRef.current = currentScrollTop;
@@ -811,8 +822,10 @@ function WebStreamViewport(props: StreamRenderInput & { isMobileBreakpoint: bool
     evaluateHistoryStart();
   }, [
     evaluateHistoryStart,
+    hasUpwardInputEvidence,
     isJumpSettling,
     readingAnchor,
+    rearmHistoryStartFromUserIntent,
     stopFollowingOutputFromUserIntent,
     updateScrollMetrics,
   ]);

packages/plugin/src/server/provider.test.ts

@@ -0,0 +1,66 @@
+import { describe, expect, it } from "vitest";
+import { ProviderInputSchema, type ProviderInput } from "./provider.js";
+
+type ReviewMode = "uncommitted" | "base" | "all";
+type Delivery = "auto" | "steer";
+
+const contextLine = {
+  oldLineNumber: null,
+  newLineNumber: 12,
+  type: "add",
+  content: "const value = 1;",
+} as const;
+
+function reviewPrompt(mode: ReviewMode, delivery: Delivery): ProviderInput {
+  return {
+    type: "session.prompt",
+    sessionId: "session-1",
+    prompt: {
+      clientMessageId: "message-1",
+      delivery,
+      input: {
+        type: "message",
+        content: [
+          {
+            type: "review",
+            mimeType: "application/paseo-review",
+            cwd: "/workspace",
+            mode,
+            baseRef: "main",
+            comments: [
+              {
+                filePath: "src/index.ts",
+                side: "new",
+                lineNumber: 12,
+                body: "Please review this change.",
+                context: {
+                  hunkHeader: "@@ -10,2 +10,3 @@",
+                  targetLine: contextLine,
+                  lines: [{ ...contextLine, type: "context", oldLineNumber: 11 }, contextLine],
+                },
+              },
+            ],
+          },
+        ],
+      },
+    },
+  };
+}
+
+describe("Provider review attachments", () => {
+  it.each(["uncommitted", "base", "all"] as const)(
+    "preserves mode %s on an ordinary prompt",
+    (mode) => {
+      const input = reviewPrompt(mode, "auto");
+      expect(ProviderInputSchema.parse(input)).toEqual(input);
+    },
+  );
+
+  it.each(["uncommitted", "base", "all"] as const)(
+    "preserves mode %s on a steering prompt",
+    (mode) => {
+      const input = reviewPrompt(mode, "steer");
+      expect(ProviderInputSchema.parse(input)).toEqual(input);
+    },
+  );
+});

packages/plugin/src/server/provider.ts

@@ -213,7 +213,7 @@ interface ProviderReviewAttachment {
   type: "review";
   mimeType: "application/paseo-review";
   cwd: string;
-  mode: "uncommitted" | "base";
+  mode: "uncommitted" | "base" | "all";
   baseRef?: string | null;
   comments: Array<{
     filePath: string;
@@ -881,7 +881,7 @@ const providerContentSchema: z.ZodType<ProviderContent> = z.union([
       type: z.literal("review"),
       mimeType: z.literal("application/paseo-review"),
       cwd: z.string(),
-      mode: z.enum(["uncommitted", "base"]),
+      mode: z.enum(["uncommitted", "base", "all"]),
       baseRef: z.string().nullable().optional(),
       comments: z.array(
         z

packages/server/src/server/agent/agent-prompt.ts

@@ -210,6 +210,8 @@ export async function unarchiveAgentState(
 }
 
 export interface SendPromptToAgentParams {
+  /** Awaited after the agent is loaded and its mode is set, before the prompt is handed to a run. */
+  beforeDispatch?: () => Promise<void>;
   onDispatch?: StartAgentRunOptions["onDispatch"];
   agentManager: AgentManager;
   agentStorage: AgentStorage;
@@ -357,6 +359,7 @@ export async function sendPreparedPromptToAgent(
     await params.agentManager.setAgentMode(params.agentId, params.sessionMode);
   }
 
+  await params.beforeDispatch?.();
   return await startAgentRun(params.agentManager, params.agentId, params.prompt, params.logger, {
     replaceRunning: true,
     onDispatch: params.onDispatch,

packages/server/src/server/hub/execution-session.websocket.test.ts

@@ -182,6 +182,46 @@ test("ordinary Hub create and message retries do not duplicate agents or prompts
   ).toMatchObject({ payload: { accepted: false } });
 });
 
+test("Hub retries a message whose send failed before reaching the provider", async () => {
+  const hub = await launchRelationship();
+  const agentId = await hub.createUnrelatedLocalAgent();
+  const message = {
+    type: "send_agent_message_request",
+    agentId,
+    messageId: "mode-change-failed",
+    text: "retry me",
+    sessionMode: "full-access",
+  };
+  hub.failNextProviderModeChange();
+  expect(await hub.requestOrdinary({ ...message, requestId: "first-attempt" })).toMatchObject({
+    payload: { accepted: false, error: expect.stringContaining("mode change failure") },
+  });
+  expect(hub.providerPromptTexts().filter((text) => text === "retry me")).toHaveLength(0);
+
+  expect(await hub.requestOrdinary({ ...message, requestId: "retry" })).toMatchObject({
+    payload: { accepted: true, error: null },
+  });
+  expect(hub.providerPromptTexts().filter((text) => text === "retry me")).toHaveLength(1);
+});
+
+test("Hub never resubmits a message whose send failed after reaching the provider", async () => {
+  const hub = await launchRelationship();
+  const agentId = await hub.createUnrelatedLocalAgent();
+  const message = {
+    type: "send_agent_message_request",
+    agentId,
+    messageId: "turn-start-failed",
+    text: "do not repeat me",
+  };
+  hub.failProviderPromptStart("do not repeat me");
+  await hub.requestOrdinary({ ...message, requestId: "first-attempt" });
+
+  expect(await hub.requestOrdinary({ ...message, requestId: "retry" })).toMatchObject({
+    payload: { accepted: false, error: "agent_request_outcome_unknown" },
+  });
+  expect(hub.providerPromptTexts().filter((text) => text === "do not repeat me")).toHaveLength(0);
+});
+
 test("ordinary Hub requests survive daemon restart and restore an archived workspace", async () => {
   const hub = await launchRelationship();
   const create = {

packages/server/src/server/hub/test-utils/relationship-harness.ts

@@ -458,6 +458,7 @@ export class HubRelationshipHarness {
   private readonly claimedCliSockets = new Set<WebSocket>();
   private readonly promptsToFail = new Set<string>();
   private failNextSessionClose = false;
+  private failNextModeChange = false;
   private observedEnrollments = 0;
   private observedSockets = 0;
   private readonly codex: ControlledAgentClient;
@@ -474,6 +475,11 @@ export class HubRelationshipHarness {
           this.failNextSessionClose = false;
           throw new Error("Requested provider session close failure");
         },
+        beforeSetMode: async () => {
+          if (!this.failNextModeChange) return;
+          this.failNextModeChange = false;
+          throw new Error("Requested provider mode change failure");
+        },
         onStartTurn: (prompt) => {
           const promptText = typeof prompt === "string" ? prompt : JSON.stringify(prompt);
           if (this.promptsToFail.delete(promptText)) {
@@ -674,6 +680,10 @@ export class HubRelationshipHarness {
     this.promptsToFail.add(prompt);
   }
 
+  failNextProviderModeChange(): void {
+    this.failNextModeChange = true;
+  }
+
   failNextProviderSessionClose(): void {
     this.failNextSessionClose = true;
   }

packages/server/src/server/message-receipts/index.test.ts

@@ -23,7 +23,8 @@ test("message retries survive reconstruction without submitting twice", async ()
     agentId: "agent",
     messageId: "arrival",
     request: { text: "hello" },
-    send: async () => {
+    send: async (beforeDispatch: () => Promise<void>) => {
+      await beforeDispatch();
       deliveries++;
     },
   };
@@ -41,7 +42,8 @@ test("ambiguous provider delivery is never blindly replayed after restart", asyn
     agentId: "agent",
     messageId: "arrival",
     request: {},
-    send: async () => {
+    send: async (beforeDispatch: () => Promise<void>) => {
+      await beforeDispatch();
       deliveries++;
       throw new Error("connection lost");
     },
@@ -53,7 +55,7 @@ test("ambiguous provider delivery is never blindly replayed after restart", asyn
   expect(deliveries).toBe(1);
 });
 
-test("failed local message preparation does not leave an ambiguous receipt", async () => {
+test("a send that fails before beforeDispatch can be retried with the same message", async () => {
   const { requests, directory } = await fixture();
   let available = false;
   let sends = 0;
@@ -61,14 +63,13 @@ test("failed local message preparation does not leave an ambiguous receipt", asy
     agentId: "agent",
     messageId: "message",
     request: {},
-    prepare: async () => {
-      if (!available) throw new Error("load failed");
-    },
-    send: async () => {
+    send: async (beforeDispatch: () => Promise<void>) => {
+      if (!available) throw new Error("mode change failed");
+      await beforeDispatch();
       sends++;
     },
   };
-  await expect(requests.send(input)).rejects.toThrow("load failed");
+  await expect(requests.send(input)).rejects.toThrow("mode change failed");
   available = true;
   await new MessageReceipts(directory).send(input);
   available = false;

packages/server/src/server/message-receipts/index.ts

@@ -13,8 +13,11 @@ interface SendMessageInput {
   agentId: string;
   messageId: string;
   request: unknown;
-  send: () => Promise<void>;
-  prepare?: () => Promise<void>;
+  /**
+   * Delivers the message. It awaits `beforeDispatch` immediately before the provider can receive
+   * the message; a failure before that call proves nothing was submitted and leaves no receipt.
+   */
+  send: (beforeDispatch: () => Promise<void>) => Promise<void>;
 }
 
 /** Owns message delivery receipts; creation is owned by CreationService. */
@@ -48,10 +51,12 @@ export class MessageReceipts {
       // A provider may have accepted the message before its receipt was committed.
       throw new Error("agent_request_outcome_unknown");
     }
-    await input.prepare?.();
     const receipt = { fingerprint, agentId: input.agentId };
-    await writeJsonFileAtomic(file, { ...receipt, state: "pending" });
-    await input.send();
+    let pending: Promise<void> | null = null;
+    await input.send(() => {
+      pending ??= writeJsonFileAtomic(file, { ...receipt, state: "pending" });
+      return pending;
+    });
     await writeJsonFileAtomic(file, { ...receipt, state: "completed" });
   }
 }

packages/server/src/server/session.ts

@@ -8918,8 +8918,9 @@ export class Session {
         queued = acceptAdmission;
       });
       let deliveryStatus: "queued" | undefined;
-      const send = async () => {
+      const send = async (beforeDispatch: () => Promise<void>) => {
         if (msg.sourceAgentId) {
+          await beforeDispatch();
           const receipt = this.agentMessages.enqueue({
             recipientId: agentId,
             messageId: msg.messageId,
@@ -8950,6 +8951,7 @@ export class Session {
           activeTurnBehavior: msg.activeTurnBehavior ?? "interrupt",
           sessionMode: msg.sessionMode,
           clearPendingPermissions: true,
+          beforeDispatch,
           logger: this.sessionLogger,
         });
         if (result.disposition === "turn_started") {
@@ -8972,12 +8974,12 @@ export class Session {
               activeTurnBehavior:
                 msg.activeTurnBehavior ?? (msg.sourceAgentId ? "steer" : "interrupt"),
             },
-            prepare: async () => {
+            send: async (beforeDispatch) => {
               if (!msg.sourceAgentId) await this.prepareAgentMessage(agentId, msg.text);
+              await send(beforeDispatch);
             },
-            send,
           })
-        : send();
+        : send(async () => {});
       void sent.catch((error) => {
         if (deliveryStatus === "queued") {
           this.handleAgentRunError(agentId, error, "Failed to dispatch queued agent message");

packages/server/src/server/test-utils/fake-agent-client.ts

@@ -84,6 +84,7 @@ interface FakeAgentSessionOptions {
   beforeTurnComplete?: (prompt: AgentPromptInput) => Promise<void>;
   steerActiveTurn?: AgentSession["steerActiveTurn"];
   onInterrupt?: () => void;
+  beforeSetMode?: (modeId: string) => Promise<void>;
   historyEvents?: readonly AgentStreamEvent[];
 }
 
@@ -95,6 +96,7 @@ export interface TestAgentClientOptions {
   beforeTurnComplete?: (prompt: AgentPromptInput) => Promise<void>;
   steerActiveTurn?: AgentSession["steerActiveTurn"];
   onInterrupt?: () => void;
+  beforeSetMode?: (modeId: string) => Promise<void>;
   supportsMcpServers?: boolean;
   historyEvents?: readonly AgentStreamEvent[];
 }
@@ -369,6 +371,7 @@ class FakeAgentSession implements AgentSession {
 
   readonly steerActiveTurn: AgentSession["steerActiveTurn"];
   private readonly onInterrupt: (() => void) | undefined;
+  private readonly beforeSetMode: ((modeId: string) => Promise<void>) | undefined;
   private readonly closeSession: (() => Promise<void>) | undefined;
   private readonly onStartTurn: TestAgentClientOptions["onStartTurn"];
   private readonly beforeTurnComplete: ((prompt: AgentPromptInput) => Promise<void>) | undefined;
@@ -385,6 +388,7 @@ class FakeAgentSession implements AgentSession {
     this.memoryMarker = options.memoryMarker ?? null;
     this.steerActiveTurn = options.steerActiveTurn;
     this.onInterrupt = options.onInterrupt;
+    this.beforeSetMode = options.beforeSetMode;
     this.closeSession = options.closeSession;
     this.onStartTurn = options.onStartTurn;
     this.beforeTurnComplete = options.beforeTurnComplete;
@@ -891,6 +895,7 @@ class FakeAgentSession implements AgentSession {
   }
 
   async setMode(modeId: string): Promise<void> {
+    await this.beforeSetMode?.(modeId);
     this.config.modeId = modeId;
   }
 
@@ -1264,6 +1269,7 @@ class FakeAgentClient implements AgentClient {
       beforeTurnComplete: this.options.beforeTurnComplete,
       steerActiveTurn: this.options.steerActiveTurn,
       onInterrupt: this.options.onInterrupt,
+      beforeSetMode: this.options.beforeSetMode,
       historyEvents: this.options.historyEvents,
     });
   }
@@ -1294,6 +1300,7 @@ class FakeAgentClient implements AgentClient {
       beforeTurnComplete: this.options.beforeTurnComplete,
       steerActiveTurn: this.options.steerActiveTurn,
       onInterrupt: this.options.onInterrupt,
+      beforeSetMode: this.options.beforeSetMode,
       historyEvents: this.options.historyEvents,
     });
   }

packages/server/src/server/test-utils/session-stubs.ts

@@ -306,7 +306,7 @@ export function createProviderSnapshotManagerStub(): {
 
 export function createMessageReceiptsStub(): SessionOptions["messageReceipts"] {
   return {
-    send: (input) => input.send(),
+    send: (input) => input.send(async () => {}),
   };
 }