feat(cli): historique de messages navigable haut/bas dans la CLI custom + contrôles de cellule visibles pendant busy — persistance localStorage du transcript custom (CustomAgentChatView), layering des contrôles sous l'overlay busy (LayoutGrid), bump pointeur IdeaSDK (docs plugin minimal + hot reload) (QA verte: 65 tests CustomAgentChatView, 25 tests LayoutGrid chat/layering, npm build frontend OK)

frontend/src/features/agents/CustomAgentChatView.test.tsx

@@ -140,6 +140,7 @@ function setMeasuredTextOverflow(
 describe("CustomAgentChatView", () => {
   beforeEach(() => {
     vi.clearAllMocks();
+    window.localStorage.clear();
     __clearCustomAgentChatViewCacheForTests();
     __resetProjectCliInteractionActivityForTests();
   });
@@ -236,6 +237,144 @@ describe("CustomAgentChatView", () => {
     expect(screen.queryByRole("button", { name: "Ouvrir en TUI native" })).toBeNull();
   });
 
+  it("recalls previously sent prompts with arrow up and down", async () => {
+    const agent = {
+      launchAgentChat: vi.fn(),
+      reattachAgentChat: vi.fn(async (sessionId: string) => ({
+        sessionId,
+        scrollback: [],
+      })),
+      sendAgentChat: vi.fn(
+        async (_sessionId: string, prompt: string, onChunk: (chunk: ReplyChunk) => void) => {
+          onChunk({ kind: "final", content: `answer ${prompt}` });
+        },
+      ),
+      cancelAgentChat: vi.fn(async () => {}),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+
+    render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <CustomAgentChatView
+          projectId="project-1"
+          agentId="agent-1"
+          agentName="Worker"
+          profile={profile}
+          cwd="/repo"
+          layoutId="layout-1"
+          nodeId="node-1"
+          sessionId="chat-session-1"
+          conversationId="conversation-1"
+          onSessionId={vi.fn()}
+          onConversationId={vi.fn()}
+        />
+      </DIProvider>,
+    );
+
+    const composer = await screen.findByLabelText(/message CLI custom/) as HTMLTextAreaElement;
+    await waitFor(() => expect(agent.reattachAgentChat).toHaveBeenCalled());
+
+    fireEvent.change(composer, { target: { value: "first prompt" } });
+    fireEvent.click(screen.getByRole("button", { name: "Envoyer" }));
+    await waitFor(() => expect(agent.sendAgentChat).toHaveBeenCalledWith(
+      "chat-session-1",
+      "first prompt",
+      expect.any(Function),
+    ));
+
+    fireEvent.change(composer, { target: { value: "second prompt" } });
+    fireEvent.click(screen.getByRole("button", { name: "Envoyer" }));
+    await waitFor(() => expect(agent.sendAgentChat).toHaveBeenCalledWith(
+      "chat-session-1",
+      "second prompt",
+      expect.any(Function),
+    ));
+
+    fireEvent.keyDown(composer, { key: "ArrowUp" });
+    await waitFor(() => expect(composer.value).toBe("second prompt"));
+    fireEvent.keyDown(composer, { key: "ArrowUp" });
+    await waitFor(() => expect(composer.value).toBe("first prompt"));
+    fireEvent.keyDown(composer, { key: "ArrowDown" });
+    await waitFor(() => expect(composer.value).toBe("second prompt"));
+
+    fireEvent.change(composer, { target: { value: "draft in progress" } });
+    fireEvent.keyDown(composer, { key: "ArrowUp" });
+    await waitFor(() => expect(composer.value).toBe("second prompt"));
+    fireEvent.keyDown(composer, { key: "ArrowDown" });
+    await waitFor(() => expect(composer.value).toBe("draft in progress"));
+  });
+
+  it("persists prompt history across a custom chat remount", async () => {
+    const agent = {
+      launchAgentChat: vi.fn(),
+      reattachAgentChat: vi.fn(async (sessionId: string) => ({
+        sessionId,
+        scrollback: [],
+      })),
+      sendAgentChat: vi.fn(
+        async (_sessionId: string, prompt: string, onChunk: (chunk: ReplyChunk) => void) => {
+          onChunk({ kind: "final", content: `answer ${prompt}` });
+        },
+      ),
+      cancelAgentChat: vi.fn(async () => {}),
+      closeAgentChat: vi.fn(async () => {}),
+    };
+    const props = {
+      projectId: "project-1",
+      agentId: "agent-1",
+      agentName: "Worker",
+      profile,
+      cwd: "/repo",
+      layoutId: "layout-1",
+      nodeId: "node-1",
+      sessionId: "chat-session-1",
+      conversationId: "conversation-1",
+      onSessionId: vi.fn(),
+      onConversationId: vi.fn(),
+    };
+
+    const view = render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <CustomAgentChatView {...props} />
+      </DIProvider>,
+    );
+
+    let composer = await screen.findByLabelText(/message CLI custom/) as HTMLTextAreaElement;
+    fireEvent.change(composer, { target: { value: "remember me" } });
+    fireEvent.click(screen.getByRole("button", { name: "Envoyer" }));
+    await waitFor(() => expect(agent.sendAgentChat).toHaveBeenCalledWith(
+      "chat-session-1",
+      "remember me",
+      expect.any(Function),
+    ));
+
+    view.unmount();
+    render(
+      <DIProvider
+        gateways={{
+          agent,
+          system: { pickFile: vi.fn(async () => null) },
+        } as unknown as Gateways}
+      >
+        <CustomAgentChatView {...props} />
+      </DIProvider>,
+    );
+
+    composer = await screen.findByLabelText(/message CLI custom/) as HTMLTextAreaElement;
+    fireEvent.keyDown(composer, { key: "ArrowUp" });
+    await waitFor(() => expect(composer.value).toBe("remember me"));
+  });
+
   it("repaints attachment labels from user prompt scrollback", async () => {
     const agent = {
       launchAgentChat: vi.fn(),

frontend/src/features/agents/CustomAgentChatView.tsx

@@ -83,6 +83,7 @@ const chatConversationViewCache = new Map<string, CachedChatView>();
 const EMPTY_MODEL_RESPONSE_MESSAGE = "Le modèle n'a renvoyé aucune réponse.";
 const COMPOSER_RESIZE_STEP = 12;
 const FALLBACK_COMPOSER_HEIGHT = 64;
+const COMPOSER_HISTORY_LIMIT = 100;
 const MIN_REASONABLE_CHAT_TIMESTAMP_MS = Date.UTC(2020, 0, 1);
 const MAX_REASONABLE_CHAT_TIMESTAMP_MS = Date.UTC(2100, 0, 1);
 const MIN_REASONABLE_CHAT_TIMESTAMP_SECONDS = Math.floor(
@@ -416,6 +417,55 @@ function conversationCacheKey(
   return conversationId ? `${projectId}::${agentId}::${conversationId}` : null;
 }
 
+function composerHistoryStorageKey(
+  projectId: string,
+  agentId: string,
+  layoutId: string | undefined,
+  nodeId: string | undefined,
+): string {
+  return [
+    "idea.custom-chat-history",
+    projectId,
+    layoutId ?? "default",
+    nodeId ?? "agent",
+    agentId,
+  ].join(".");
+}
+
+function readComposerHistory(storageKey: string): string[] {
+  if (typeof window === "undefined") return [];
+  try {
+    const parsed: unknown = JSON.parse(window.localStorage.getItem(storageKey) ?? "[]");
+    if (!Array.isArray(parsed)) return [];
+    return parsed
+      .filter((entry): entry is string => typeof entry === "string")
+      .map((entry) => entry.trim())
+      .filter(Boolean)
+      .slice(-COMPOSER_HISTORY_LIMIT);
+  } catch {
+    return [];
+  }
+}
+
+function writeComposerHistory(storageKey: string, history: string[]): void {
+  if (typeof window === "undefined") return;
+  try {
+    window.localStorage.setItem(
+      storageKey,
+      JSON.stringify(history.slice(-COMPOSER_HISTORY_LIMIT)),
+    );
+  } catch {
+    /* local history only */
+  }
+}
+
+function appendComposerHistoryEntry(history: string[], text: string): string[] {
+  const entry = text.trim();
+  if (!entry) return history;
+  const withoutDuplicateTail = history.at(-1) === entry ? history.slice(0, -1) : history;
+  return [...withoutDuplicateTail, entry].slice(-COMPOSER_HISTORY_LIMIT);
+}
+
 function appendProgress(state: ChatViewState, progress: ReplyProgress): ChatViewState {
   let key = progressUpsertKey(progress, state.progressScope);
   let existingIndex = state.turns.findIndex(
@@ -953,6 +1003,7 @@ export function CustomAgentChatView({
   const lastPersistedDraftRef = useRef("");
   const draftRef = useRef("");
   draftRef.current = draft;
+  const draftBeforeHistoryNavigationRef = useRef("");
   const attachmentsRef = useRef<AttachmentDraft[]>([]);
   attachmentsRef.current = attachments;
   const imageTokenSeqRef = useRef(0);
@@ -1061,6 +1112,14 @@ export function CustomAgentChatView({
     () => conversationCacheKey(projectId, agentId, conversationId),
     [agentId, conversationId, projectId],
   );
+  const composerHistoryKey = useMemo(
+    () => composerHistoryStorageKey(projectId, agentId, layoutId, nodeId),
+    [agentId, layoutId, nodeId, projectId],
+  );
+  const [composerHistory, setComposerHistory] = useState<string[]>(() =>
+    readComposerHistory(composerHistoryKey),
+  );
+  const [, setComposerHistoryIndex] = useState<number | null>(null);
   const displayTurns = turns;
   const sessionLabel = structuredSessionLabel(profile.structuredAdapter);
   const [requesterDelegation, setRequesterDelegation] =
@@ -1127,9 +1186,82 @@ export function CustomAgentChatView({
 
   const editDraft = useCallback((text: string) => {
     if (!draftHydratedRef.current) draftEditedBeforeHydrationRef.current = true;
+    setComposerHistoryIndex(null);
+    draftBeforeHistoryNavigationRef.current = "";
     setDraft(text);
   }, []);
 
+  const recallComposerHistory = useCallback(
+    (direction: "previous" | "next") => {
+      if (composerHistory.length === 0) return;
+      setComposerHistoryIndex((current) => {
+        if (current === null && direction === "previous") {
+          draftBeforeHistoryNavigationRef.current = draftRef.current;
+        }
+        const nextIndex =
+          direction === "previous"
+            ? current === null
+              ? composerHistory.length - 1
+              : Math.max(0, current - 1)
+            : current === null
+              ? null
+              : current >= composerHistory.length - 1
+                ? null
+                : current + 1;
+        if (nextIndex === null) {
+          setDraft(draftBeforeHistoryNavigationRef.current);
+          draftBeforeHistoryNavigationRef.current = "";
+        } else {
+          setDraft(composerHistory[nextIndex] ?? "");
+        }
+        return nextIndex;
+      });
+    },
+    [composerHistory],
+  );
+
+  const handleComposerHistoryKeyDown = useCallback(
+    (event: KeyboardEvent<HTMLTextAreaElement>): boolean => {
+      if (
+        event.altKey ||
+        event.ctrlKey ||
+        event.metaKey ||
+        event.shiftKey ||
+        (event.key !== "ArrowUp" && event.key !== "ArrowDown")
+      ) {
+        return false;
+      }
+      const target = event.currentTarget;
+      if (
+        event.key === "ArrowUp" &&
+        target.value.slice(0, target.selectionStart).includes("\n")
+      ) {
+        return false;
+      }
+      if (
+        event.key === "ArrowDown" &&
+        target.value.slice(target.selectionEnd).includes("\n")
+      ) {
+        return false;
+      }
+      event.preventDefault();
+      recallComposerHistory(event.key === "ArrowUp" ? "previous" : "next");
+      return true;
+    },
+    [recallComposerHistory],
+  );
+
+  useEffect(() => {
+    const restored = readComposerHistory(composerHistoryKey);
+    setComposerHistory(restored);
+    setComposerHistoryIndex(null);
+    draftBeforeHistoryNavigationRef.current = "";
+  }, [composerHistoryKey]);
+
+  useEffect(() => {
+    writeComposerHistory(composerHistoryKey, composerHistory);
+  }, [composerHistory, composerHistoryKey]);
+
   useEffect(() => {
     void refreshRequesterDelegation();
   }, [refreshRequesterDelegation]);
@@ -1913,6 +2045,11 @@ export function CustomAgentChatView({
       markProjectCliInteractionFinished(projectId, interactionId);
       activeInteractionIdRef.current = null;
     };
+    if (text) {
+      setComposerHistory((prev) => appendComposerHistoryEntry(prev, text));
+      setComposerHistoryIndex(null);
+      draftBeforeHistoryNavigationRef.current = "";
+    }
     setDraft("");
     setAttachments([]);
     imageTokenSeqRef.current = 0;
@@ -2373,6 +2510,7 @@ export function CustomAgentChatView({
                     return;
                   }
                 }
+                if (handleComposerHistoryKeyDown(e)) return;
                 if (e.key === "Enter" && !e.shiftKey) {
                   e.preventDefault();
                   void send();

frontend/src/features/layout/LayoutGrid.cellControlsLayering.test.tsx

@@ -64,6 +64,7 @@ import { LayoutGrid } from "./LayoutGrid";
 
 interface GridSetup {
   agentId: string;
+  otherAgentId: string;
   bId: string;
   gateways: Gateways;
   layout: MockLayoutGateway;
@@ -84,6 +85,10 @@ async function makeSplitAgentGrid(): Promise<GridSetup> {
     name: "Worker",
     profileId: "mock-claude",
   });
+  const otherAgent = await agentGateway.createAgent("p1", {
+    name: "Reviewer",
+    profileId: "mock-claude",
+  });
 
   const initial = await layout.loadLayout("p1");
   const aId = leaves(initial)[0].id;
@@ -102,6 +107,7 @@ async function makeSplitAgentGrid(): Promise<GridSetup> {
 
   return {
     agentId: agent.id,
+    otherAgentId: otherAgent.id,
     bId: "b",
     gateways: {
       layout,
@@ -206,7 +212,7 @@ describe("LayoutGrid — ticket #48 cell control layering", () => {
     expect(controls.style.overflow).toBe("hidden");
   });
 
-  it("does not render persistent cell chrome over the custom CLI surface (#249)", async () => {
+  it("keeps cell controls available over a busy custom CLI surface (#249)", async () => {
     const setup = await makeSplitAgentGrid();
     window.localStorage.setItem(`idea.agent-cell-mode.p1.${setup.bId}`, "custom");
     setup.workState._setProjectWorkState("p1", {
@@ -227,19 +233,47 @@ describe("LayoutGrid — ticket #48 cell control layering", () => {
     const customToolbar = screen.getByRole("toolbar", {
       name: "custom agent chat actions",
     });
+    const mutate = vi.spyOn(setup.layout, "mutateLayout");
 
     expect(customToolbar.className).toContain("z-20");
-    expect(screen.queryByLabelText(`agent selector ${setup.bId}`)).toBeNull();
+    expect(screen.getByLabelText(`agent selector ${setup.bId}`)).toBeTruthy();
-    expect(screen.queryByRole("group", {
+    expect(screen.getByRole("group", {
       name: `mode CLI agent ${setup.bId}`,
-    })).toBeNull();
+    })).toBeTruthy();
-    expect(screen.queryByLabelText(`split ${setup.bId} columns`)).toBeNull();
+    expect(screen.getByLabelText(`split ${setup.bId} columns`)).toBeTruthy();
-    expect(screen.queryByLabelText(`split ${setup.bId} rows`)).toBeNull();
+    expect(screen.getByLabelText(`split ${setup.bId} rows`)).toBeTruthy();
-    expect(screen.queryByLabelText(`close ${setup.bId}`)).toBeNull();
+    expect(screen.getByLabelText(`close ${setup.bId}`)).toBeTruthy();
-    expect(screen.queryByRole("button", {
+    expect(screen.getByRole("button", {
       name: `cancel current turn ${setup.bId}`,
-    })).toBeNull();
+    })).toBeTruthy();
-    expect(screen.queryByText("Busy")).toBeNull();
+    expect(screen.getByText("Busy")).toBeTruthy();
+
+    fireEvent.click(screen.getByLabelText(`split ${setup.bId} columns`));
+    await waitFor(() =>
+      expect(mutate).toHaveBeenCalledWith(
+        "p1",
+        expect.objectContaining({
+          type: "split",
+          target: setup.bId,
+          direction: "row",
+        }),
+        undefined,
+      ),
+    );
+
+    const selector = screen.getByLabelText(`agent selector ${setup.bId}`);
+    fireEvent.change(selector, { target: { value: setup.otherAgentId } });
+    await waitFor(() =>
+      expect(mutate).toHaveBeenCalledWith(
+        "p1",
+        expect.objectContaining({
+          type: "setCellAgent",
+          target: setup.bId,
+          agent: setup.otherAgentId,
+        }),
+        undefined,
+      ),
+    );
   });
 
   it("keeps busy Cancel above persistent cell controls and removes History (#151, #160)", async () => {

frontend/src/features/layout/LayoutGrid.chat.test.tsx

@@ -219,11 +219,11 @@ describe("LayoutGrid custom agent CLI (#147)", () => {
 
     expect(await screen.findByTestId("custom-agent-chat-view")).toBeTruthy();
     expect(screen.queryByTestId("target-announcements-overlay")).toBeNull();
-    expect(screen.queryByText("Busy · Main")).toBeNull();
+    expect(screen.getByText("Busy · Main")).toBeTruthy();
-    expect(screen.queryByLabelText(`agent selector ${leaf.id}`)).toBeNull();
+    expect(screen.getByLabelText(`agent selector ${leaf.id}`)).toBeTruthy();
-    expect(screen.queryByRole("button", {
+    expect(screen.getByRole("button", {
       name: `cancel current turn ${leaf.id}`,
-    })).toBeNull();
+    })).toBeTruthy();
     await waitFor(() =>
       expect(screen.getByLabelText(/message CLI custom/)).toHaveProperty(
         "disabled",

frontend/src/features/layout/LayoutGrid.tsx

@@ -655,13 +655,6 @@ function LeafView({
     customCliAvailable && pinnedAgent ? pinnedAgent : trustedCustomCli?.agent;
   const customCliProfile =
     customCliAvailable && pinnedProfile ? pinnedProfile : trustedCustomCli?.profile;
-  const customCliActive = Boolean(
-    agentId &&
-      cellMode === "custom" &&
-      effectiveCustomCliAvailable &&
-      customCliAgent &&
-      customCliProfile,
-  );
   useEffect(() => {
     if (cellMode !== "custom") {
       setTrustedCustomCli(null);
@@ -774,7 +767,6 @@ function LeafView({
       task.status === "completed" || task.status === "failed" || task.status === "cancelled",
     ) ?? [];
   const busyByWorkState = agentWork?.busy.state === "busy" || Boolean(activeTicket);
-  const suppressCellChrome = customCliActive && busyByWorkState;
   const delegatedTicket = activeTicket?.source.kind === "agent" ? activeTicket : undefined;
   const busyActive = announcementBusyActive || busyByWorkState;
   const targetAnnouncementsFallback = delegatedTicket?.requesterLabel
@@ -1138,27 +1130,27 @@ function LeafView({
         overflow: "hidden",
       }}
     >
-      {!suppressCellChrome && (
+      <div
-        <div
+        style={{
-          style={{
+          position: "absolute",
-            position: "absolute",
+          top: 2,
-            top: 2,
+          left: 4,
-            left: 4,
+          // Clear the xterm viewport scrollbar (rendered flush against the right
-            // Clear the xterm viewport scrollbar (rendered flush against the right
+          // edge, ~15px wide). Without this offset the right-most control — the
-            // edge, ~15px wide). Without this offset the right-most control — the
+          // close button — sits *behind* the scrollbar and is hard to click.
-            // close button — sits *behind* the scrollbar and is hard to click.
+          right: 16,
-            right: 16,
+          // Above every banner/veil so a cell in an error state stays manageable
-            // Above every banner/veil so a cell in an error state stays manageable
+          // (ticket #48). Custom CLI cells also keep these controls available
-            // (ticket #48). Hidden while a custom CLI turn is busy: that surface
+          // while busy so the cell remains a view that can be split or retargeted
-            // owns its own header, and cell chrome must not overlap the chat viewport.
+          // without stopping the running agent session.
-            zIndex: CELL_Z.controls,
+          zIndex: CELL_Z.controls,
-            display: "flex",
+          display: "flex",
-            gap: 2,
+          gap: 2,
-            alignItems: "center",
+          alignItems: "center",
-            justifyContent: "flex-end",
+          justifyContent: "flex-end",
-            overflow: "hidden",
+          overflow: "hidden",
-          }}
+        }}
-        >
+      >
         {/* Agent selector */}
         <select
           aria-label={`agent selector ${id}`}
@@ -1330,9 +1322,8 @@ function LeafView({
             ✕
           </button>
         )}
-        </div>
+      </div>
-      )}
+      {agentId && busyByWorkState && (
-      {agentId && busyByWorkState && !suppressCellChrome && (
         <button
           type="button"
           aria-label={`cancel current turn ${id}`}
@@ -1358,7 +1349,7 @@ function LeafView({
           Cancel
         </button>
       )}
-      {agentId && !suppressCellChrome && (busyByWorkState || inboxDepth > 0 || completedBackgroundTasks.length > 0) && (
+      {agentId && (busyByWorkState || inboxDepth > 0 || completedBackgroundTasks.length > 0) && (
         <div
           role="status"
           aria-live="polite"