Fix queued prompt cancellation state synchronization

packages/control-plane/src/session/message-queue.test.ts

@@ -427,12 +427,15 @@ describe("SessionMessageQueue", () => {
     });
 
     expect(h.repository.cancelPendingMessage).toHaveBeenCalledWith("msg-1");
+    expect(h.broadcast).toHaveBeenCalledWith({ type: "prompt_queue_updated", promptQueue: [] });
     expect(h.wsManager.send).toHaveBeenCalledWith(ws, {
       type: "prompt_cancelled",
       clientRequestId: "request-1",
       messageId: "msg-1",
     });
-    expect(h.broadcast).toHaveBeenCalledWith({ type: "prompt_queue_updated", promptQueue: [] });
+    expect(h.broadcast.mock.invocationCallOrder[0]).toBeLessThan(
+      h.wsManager.send.mock.invocationCallOrder[0]
+    );
     expect(h.sessionStatus.reconcileAfterQueueRemoval).toHaveBeenCalledOnce();
   });
 
@@ -451,7 +454,10 @@ describe("SessionMessageQueue", () => {
       message: "This prompt is no longer pending and cannot be removed",
       clientRequestId: "request-1",
     });
-    expect(h.broadcast).not.toHaveBeenCalled();
+    expect(h.broadcast).toHaveBeenCalledWith({ type: "prompt_queue_updated", promptQueue: [] });
+    expect(h.broadcast.mock.invocationCallOrder[0]).toBeLessThan(
+      h.wsManager.send.mock.invocationCallOrder[0]
+    );
   });
 
   it("reconciles session status after removing a prompt", async () => {

packages/control-plane/src/session/message-queue.ts

@@ -328,7 +328,9 @@ export class SessionMessageQueue {
     ws: WebSocket,
     data: { messageId: string; clientRequestId: string }
   ): Promise<void> {
-    if (!this.messageRepository.cancelPendingMessage(data.messageId)) {
+    const cancelled = this.messageRepository.cancelPendingMessage(data.messageId);
+    this.broadcastPromptQueue();
+    if (!cancelled) {
       this.wsManager.send(ws, {
         type: "error",
         code: "PROMPT_NOT_CANCELLABLE",
@@ -343,7 +345,6 @@ export class SessionMessageQueue {
       clientRequestId: data.clientRequestId,
       messageId: data.messageId,
     });
-    this.broadcastPromptQueue();
     this.log.info("prompt.cancelled", {
       event: "prompt.cancelled",
       message_id: data.messageId,

packages/control-plane/src/session/message-repository.test.ts

@@ -125,10 +125,29 @@ describe("MessageRepository", () => {
 
   it("projects unfinished messages into the prompt queue", () => {
     vi.spyOn(repository, "listUnfinishedMessages").mockReturnValue([
-      { id: "msg-1", content: "Continue", status: "pending" } as never,
+      {
+        id: "msg-1",
+        content: "Continue",
+        status: "pending",
+        source: "web",
+        callback_context: null,
+      } as never,
+      {
+        id: "msg-2",
+        content: "Reply in Linear",
+        status: "pending",
+        source: "linear",
+        callback_context: null,
+      } as never,
     ]);
     expect(repository.listPromptQueue()).toEqual([
-      { messageId: "msg-1", content: "Continue", status: "pending" },
+      { messageId: "msg-1", content: "Continue", status: "pending", cancellable: true },
+      {
+        messageId: "msg-2",
+        content: "Reply in Linear",
+        status: "pending",
+        cancellable: false,
+      },
     ]);
   });
 

packages/control-plane/src/session/message-repository.ts

@@ -227,6 +227,10 @@ export class MessageRepository {
       messageId: message.id,
       content: message.content,
       status: message.status as "pending" | "processing",
+      cancellable:
+        message.status === "pending" &&
+        message.source === "web" &&
+        message.callback_context === null,
     }));
   }
 

packages/control-plane/test/integration/websocket-client.test.ts

@@ -634,7 +634,7 @@ describe("Client WebSocket (via SELF.fetch)", () => {
       promptQueue: Array<Record<string, unknown>>;
     };
     expect(subscribed.promptQueue).toEqual([
-      expect.objectContaining({ content: "Only once", status: "pending" }),
+      expect.objectContaining({ content: "Only once", status: "pending", cancellable: true }),
     ]);
     expect(subscribed.promptQueue[0]).not.toHaveProperty("model");
     expect(subscribed.promptQueue[0]).not.toHaveProperty("reasoningEffort");
@@ -931,7 +931,7 @@ describe("Client WebSocket (via SELF.fetch)", () => {
       promptQueue: Array<{ messageId: string }>;
     };
     expect(subscribed.promptQueue).toContainEqual(
-      expect.objectContaining({ messageId: "message-linear" })
+      expect.objectContaining({ messageId: "message-linear", cancellable: false })
     );
     const clientRequestId = crypto.randomUUID();
     const rejected = collectMessages(ws, {

packages/shared/src/types/server-messages.test.ts

@@ -167,11 +167,13 @@ describe("session view contracts", () => {
         messageId: "message-running",
         content: "Run this",
         status: "processing",
+        cancellable: false,
       },
       {
         messageId: "message-pending",
         content: "Then this",
         status: "pending",
+        cancellable: true,
       },
     ];
 
@@ -188,6 +190,18 @@ describe("session view contracts", () => {
     ).toEqual(promptQueue);
   });
 
+  it("treats queue items from older servers as non-cancellable", () => {
+    const message = serverMessageSchema.parse({
+      type: "prompt_queue_updated",
+      promptQueue: [{ messageId: "message-1", content: "Wait", status: "pending" }],
+    });
+
+    expect(message).toMatchObject({
+      type: "prompt_queue_updated",
+      promptQueue: [{ cancellable: false }],
+    });
+  });
+
   it("echoes prompt request correlation", () => {
     expect(
       serverMessageSchema.parse({

packages/shared/src/types/server-messages.ts

@@ -11,6 +11,7 @@ export const promptQueueItemSchema = z.object({
   messageId: z.string(),
   content: z.string(),
   status: z.enum(["pending", "processing"]),
+  cancellable: z.boolean().default(false),
 });
 export type PromptQueueItem = z.infer<typeof promptQueueItemSchema>;
 

packages/web/src/app/(app)/(sidebar)/session/[id]/page.tsx

@@ -157,7 +157,7 @@ export default function SessionPage() {
       if (!capabilities.lifecycle) return;
       if (cancellingPromptIdsRef.current.has(messageId)) return;
       const queuedPrompt = promptQueue.find((item) => item.messageId === messageId);
-      if (!queuedPrompt || queuedPrompt.status !== "pending") return;
+      if (!queuedPrompt?.cancellable) return;
 
       cancellingPromptIdsRef.current.add(messageId);
       setCancellingPromptIds(new Set(cancellingPromptIdsRef.current));

packages/web/src/components/queued-prompt-stack.test.tsx

@@ -22,7 +22,9 @@ describe("QueuedPromptStack", () => {
   it("shows queued prompts without removal controls in read-only mode", () => {
     render(
       <QueuedPromptStack
-        promptQueue={[{ messageId: "queued-1", content: "Review this", status: "pending" }]}
+        promptQueue={[
+          { messageId: "queued-1", content: "Review this", status: "pending", cancellable: true },
+        ]}
         cancellingPromptIds={new Set()}
         onRemove={vi.fn()}
         capabilities={{ ...FULL_CAPABILITIES, lifecycle: false }}
@@ -39,9 +41,14 @@ describe("QueuedPromptStack", () => {
         onRemove={vi.fn()}
         capabilities={FULL_CAPABILITIES}
         promptQueue={[
-          { messageId: "running", content: "Already running", status: "processing" },
-          { messageId: "next", content: "Run next", status: "pending" },
-          { messageId: "later", content: "Run after that", status: "pending" },
+          {
+            messageId: "running",
+            content: "Already running",
+            status: "processing",
+            cancellable: false,
+          },
+          { messageId: "next", content: "Run next", status: "pending", cancellable: true },
+          { messageId: "later", content: "Run after that", status: "pending", cancellable: true },
         ]}
       />
     );
@@ -60,7 +67,14 @@ describe("QueuedPromptStack", () => {
         cancellingPromptIds={new Set()}
         onRemove={vi.fn()}
         capabilities={FULL_CAPABILITIES}
-        promptQueue={[{ messageId: "running", content: "Already running", status: "processing" }]}
+        promptQueue={[
+          {
+            messageId: "running",
+            content: "Already running",
+            status: "processing",
+            cancellable: false,
+          },
+        ]}
       />
     );
 
@@ -71,7 +85,9 @@ describe("QueuedPromptStack", () => {
     const onRemove = vi.fn();
     render(
       <QueuedPromptStack
-        promptQueue={[{ messageId: "next", content: "Run next", status: "pending" }]}
+        promptQueue={[
+          { messageId: "next", content: "Run next", status: "pending", cancellable: true },
+        ]}
         cancellingPromptIds={new Set(["next"])}
         onRemove={onRemove}
         capabilities={FULL_CAPABILITIES}
@@ -88,7 +104,9 @@ describe("QueuedPromptStack", () => {
     const onRemove = vi.fn();
     render(
       <QueuedPromptStack
-        promptQueue={[{ messageId: "next", content: "Run next", status: "pending" }]}
+        promptQueue={[
+          { messageId: "next", content: "Run next", status: "pending", cancellable: true },
+        ]}
         cancellingPromptIds={new Set()}
         onRemove={onRemove}
         capabilities={FULL_CAPABILITIES}
@@ -99,7 +117,7 @@ describe("QueuedPromptStack", () => {
     expect(onRemove).toHaveBeenCalledWith("next");
   });
 
-  it("offers removal for pending prompts whose eligibility is server-owned", () => {
+  it("does not offer removal for a server-owned prompt", () => {
     const onRemove = vi.fn();
     render(
       <QueuedPromptStack
@@ -108,6 +126,7 @@ describe("QueuedPromptStack", () => {
             messageId: "linear-prompt",
             content: "Reply in Linear",
             status: "pending",
+            cancellable: false,
           },
         ]}
         cancellingPromptIds={new Set()}
@@ -116,7 +135,10 @@ describe("QueuedPromptStack", () => {
       />
     );
 
-    fireEvent.click(screen.getByRole("button", { name: "Remove queued prompt: Reply in Linear" }));
-    expect(onRemove).toHaveBeenCalledWith("linear-prompt");
+    expect(screen.getByText("Reply in Linear")).toBeInTheDocument();
+    expect(
+      screen.queryByRole("button", { name: "Remove queued prompt: Reply in Linear" })
+    ).not.toBeInTheDocument();
+    expect(onRemove).not.toHaveBeenCalled();
   });
 });

packages/web/src/components/queued-prompt-stack.tsx

@@ -31,7 +31,7 @@ export function QueuedPromptStack({
               <p className="min-w-0 flex-1 whitespace-pre-wrap break-words text-sm text-secondary-foreground">
                 {prompt.content}
               </p>
-              {capabilities.lifecycle && (
+              {capabilities.lifecycle && prompt.cancellable && (
                 <button
                   type="button"
                   onClick={() => onRemove(prompt.messageId)}

packages/web/src/components/session-timeline-scroll.test.tsx

@@ -359,7 +359,14 @@ describe("timeline auto-scrolling", () => {
       <SessionTimeline
         {...baseTimelineProps}
         events={events}
-        promptQueue={[{ messageId: "queued", content: "Next prompt", status: "pending" }]}
+        promptQueue={[
+          {
+            messageId: "queued",
+            content: "Next prompt",
+            status: "pending",
+            cancellable: true,
+          },
+        ]}
       />
     );
 

packages/web/src/components/session-timeline.test.tsx

@@ -246,9 +246,9 @@ describe("prompt queue status", () => {
         {...baseTimelineProps}
         events={events}
         promptQueue={[
-          { messageId: "running", content: "First", status: "processing" },
-          { messageId: "next", content: "Second", status: "pending" },
-          { messageId: "later", content: "Third", status: "pending" },
+          { messageId: "running", content: "First", status: "processing", cancellable: false },
+          { messageId: "next", content: "Second", status: "pending", cancellable: true },
+          { messageId: "later", content: "Third", status: "pending", cancellable: true },
         ]}
       />
     );
@@ -268,11 +268,13 @@ describe("prompt queue status", () => {
             messageId: "canonical",
             content: "Canonical prompt",
             status: "processing",
+            cancellable: false,
           },
           {
             messageId: "outside-replay",
             content: "Queued outside replay",
             status: "pending",
+            cancellable: true,
           },
         ]}
       />

packages/web/src/lib/session-socket/reducer.test.ts

@@ -93,6 +93,7 @@ describe("sessionSocketReducer", () => {
           messageId: "message-1",
           content: "Running",
           status: "processing" as const,
+          cancellable: false,
         },
       ];
       const state = createSessionSocketState({
@@ -166,6 +167,7 @@ describe("sessionSocketReducer", () => {
         messageId: "message-2",
         content: "Next",
         status: "pending" as const,
+        cancellable: true,
       },
     ];
     const state = reduce(
@@ -177,7 +179,9 @@ describe("sessionSocketReducer", () => {
 
   it("waits for the authoritative queue update after cancellation acknowledgement", () => {
     const initial = subscribedState({
-      promptQueue: [{ messageId: "message-2", content: "Next", status: "pending" }],
+      promptQueue: [
+        { messageId: "message-2", content: "Next", status: "pending", cancellable: true },
+      ],
     });
     const state = reduce(
       initial,