Fix composer workspace attachment update loop

packages/app/src/attachments/composer-workspace-attachments.tsx

@@ -112,9 +112,12 @@ function useWorkspaceAttachmentBinding({
   );
 
   useEffect(() => {
-    setSuppressedKeys((current) =>
-      current.filter((suppressedKey) => workspaceAttachmentKeys.includes(suppressedKey)),
-    );
+    setSuppressedKeys((current) => {
+      const next = current.filter((suppressedKey) =>
+        workspaceAttachmentKeys.includes(suppressedKey),
+      );
+      return next.length === current.length ? current : next;
+    });
   }, [workspaceAttachmentKeys]);
 
   const buildOutgoingAttachments = useCallback(

packages/app/src/components/composer.test.tsx

@@ -9,6 +9,7 @@ import type {
   ComposerAttachment,
   UserComposerAttachment,
 } from "@/attachments/types";
+import { composerWorkspaceAttachment } from "@/attachments/composer-workspace-attachments";
 import type { AgentAttachment, GitHubSearchItem } from "@server/shared/messages";
 import { Composer } from "./composer";
 import { splitComposerAttachmentsForSubmit } from "./composer-attachments";
@@ -569,6 +570,7 @@ let root: Root | null = null;
 let container: HTMLElement | null = null;
 let queryClient: QueryClient | null = null;
 let latestAttachments: ComposerAttachment[] = [];
+let workspaceBindingRenderCount = 0;
 
 type ReviewComposerAttachment = Extract<ComposerAttachment, { kind: "review" }>;
 type ReviewAttachment = Extract<AgentAttachment, { type: "review" }>;
@@ -617,6 +619,25 @@ function reviewComposerAttachment(body: string): ReviewComposerAttachment {
   };
 }
 
+function cloneReviewComposerAttachment(
+  attachment: ReviewComposerAttachment,
+): ReviewComposerAttachment {
+  return {
+    ...attachment,
+    attachment: {
+      ...attachment.attachment,
+      comments: attachment.attachment.comments.map((comment) => ({
+        ...comment,
+        context: {
+          ...comment.context,
+          targetLine: { ...comment.context.targetLine },
+          lines: comment.context.lines.map((line) => ({ ...line })),
+        },
+      })),
+    },
+  };
+}
+
 function seedReviewDraft(key: string) {
   addReviewDraftComment({
     key,
@@ -670,6 +691,7 @@ beforeEach(() => {
   agentDirectoryStatusMock.mockReset();
   agentDirectoryStatusMock.mockReturnValue("ready");
   appSendBehavior.current = "interrupt";
+  workspaceBindingRenderCount = 0;
   mockSessionState.sessions.server.serverInfo = {
     serverId: "server",
     hostname: "test",
@@ -785,6 +807,20 @@ function renderComposer(
   });
 }
 
+function WorkspaceAttachmentBindingHarness({
+  workspaceAttachment,
+}: {
+  workspaceAttachment: ReviewComposerAttachment;
+}) {
+  workspaceBindingRenderCount += 1;
+  const { selectedAttachments } = composerWorkspaceAttachment.useBinding({
+    normalAttachments: [],
+    workspaceAttachments: [workspaceAttachment],
+  });
+
+  return <div data-testid="workspace-binding-count">{selectedAttachments.length}</div>;
+}
+
 function click(element: Element) {
   act(() => {
     element.dispatchEvent(new window.MouseEvent("click", { bubbles: true }));
@@ -1007,6 +1043,30 @@ describe("Composer attachments", () => {
     });
   });
 
+  it("does not enqueue redundant binding renders for equivalent workspace attachments", async () => {
+    const review = reviewComposerAttachment("Stable workspace review.");
+
+    act(() => {
+      root?.render(<WorkspaceAttachmentBindingHarness workspaceAttachment={review} />);
+    });
+    await flushAsyncWork();
+
+    expect(workspaceBindingRenderCount).toBe(1);
+    expect(queryByTestId("workspace-binding-count")?.textContent).toBe("1");
+
+    act(() => {
+      root?.render(
+        <WorkspaceAttachmentBindingHarness
+          workspaceAttachment={cloneReviewComposerAttachment(review)}
+        />,
+      );
+    });
+    await flushAsyncWork();
+
+    expect(workspaceBindingRenderCount).toBe(2);
+    expect(queryByTestId("workspace-binding-count")?.textContent).toBe("1");
+  });
+
   it("renders and submits a workspace review attachment pill", async () => {
     const review = reviewComposerAttachment("Please simplify this.");
     renderComposer({