diff --git a/src/tui/tui-busy-notice.test.ts b/src/tui/tui-busy-notice.test.ts
new file mode 100644
index 000000000000..e646a5ce7720
--- /dev/null
+++ b/src/tui/tui-busy-notice.test.ts
@@ -0,0 +1,18 @@
+import { describe, expect, it } from "vitest";
+import { normalizeTestText } from "../../test/helpers/normalize-text.js";
+import { ChatLog } from "./components/chat-log.js";
+import { addBlockedChatSubmitNotice, TUI_AGENT_BUSY_MESSAGE } from "./tui-busy-notice.js";
+
+describe("addBlockedChatSubmitNotice", () => {
+  it("coalesces repeated busy submit notices", () => {
+    const chatLog = new ChatLog(20);
+
+    addBlockedChatSubmitNotice(chatLog);
+    addBlockedChatSubmitNotice(chatLog);
+    addBlockedChatSubmitNotice(chatLog);
+
+    const rendered = normalizeTestText(chatLog.render(120).join("\n"));
+    expect(chatLog.children.length).toBe(1);
+    expect(rendered).toContain(`${TUI_AGENT_BUSY_MESSAGE} x3`);
+  });
+});
diff --git a/src/tui/tui-busy-notice.ts b/src/tui/tui-busy-notice.ts
new file mode 100644
index 000000000000..8286fd070a09
--- /dev/null
+++ b/src/tui/tui-busy-notice.ts
@@ -0,0 +1,8 @@
+import type { ChatLog } from "./components/chat-log.js";
+
+export const TUI_AGENT_BUSY_MESSAGE =
+  "agent is busy — press Esc to abort before sending a new message";
+
+export function addBlockedChatSubmitNotice(chatLog: Pick<ChatLog, "addSystem">) {
+  chatLog.addSystem(TUI_AGENT_BUSY_MESSAGE, { coalesceConsecutive: true });
+}
diff --git a/src/tui/tui-command-handlers.test.ts b/src/tui/tui-command-handlers.test.ts
index 5d346a5ae025..7b51245105dc 100644
--- a/src/tui/tui-command-handlers.test.ts
+++ b/src/tui/tui-command-handlers.test.ts
@@ -1122,6 +1122,7 @@ describe("tui command handlers", () => {
     expect(addPendingUser).not.toHaveBeenCalled();
     expect(addSystem).toHaveBeenCalledWith(
       "agent is busy — press Esc to abort before sending a new message",
+      { coalesceConsecutive: true },
     );
   });
 
@@ -1179,6 +1180,7 @@ describe("tui command handlers", () => {
     expect(addUser).not.toHaveBeenCalled();
     expect(addSystem).toHaveBeenCalledWith(
       "agent is busy — press Esc to abort before sending a new message",
+      { coalesceConsecutive: true },
     );
   });
 
@@ -1210,6 +1212,7 @@ describe("tui command handlers", () => {
     expect(addUser).not.toHaveBeenCalled();
     expect(addSystem).toHaveBeenCalledWith(
       "agent is busy — press Esc to abort before sending a new message",
+      { coalesceConsecutive: true },
     );
   });
 
@@ -1465,9 +1468,7 @@ describe("tui command handlers", () => {
 
     await handleCommand("/usage reset");
 
-    expect(patchSession).toHaveBeenCalledWith(
-      expect.objectContaining({ responseUsage: null }),
-    );
+    expect(patchSession).toHaveBeenCalledWith(expect.objectContaining({ responseUsage: null }));
     expect(addSystem).toHaveBeenCalledWith("usage footer: reset to default");
     // Both stale local values must be cleared so the toggle/display is not stale
     // until refreshSessionInfo() repopulates the inherited default.
@@ -1492,9 +1493,7 @@ describe("tui command handlers", () => {
 
     await handleCommand("/usage");
 
-    expect(patchSession).toHaveBeenCalledWith(
-      expect.objectContaining({ responseUsage: "full" }),
-    );
+    expect(patchSession).toHaveBeenCalledWith(expect.objectContaining({ responseUsage: "full" }));
     expect(addSystem).toHaveBeenCalledWith("usage footer: full");
   });
 });
diff --git a/src/tui/tui-command-handlers.ts b/src/tui/tui-command-handlers.ts
index 9f5e16fabceb..6c56b0e9be53 100644
--- a/src/tui/tui-command-handlers.ts
+++ b/src/tui/tui-command-handlers.ts
@@ -26,6 +26,7 @@ import {
   createSettingsList,
 } from "./components/selectors.js";
 import type { TuiBackend, TuiSessionMutationResult } from "./tui-backend.js";
+import { addBlockedChatSubmitNotice } from "./tui-busy-notice.js";
 import { sanitizeRenderableText } from "./tui-formatters.js";
 import {
   TUI_RECENT_SESSIONS_ACTIVE_MINUTES,
@@ -782,7 +783,7 @@ export function createCommandHandlers(context: CommandHandlerContext) {
         state.pendingOptimisticUserMessage ||
         (opts.local !== true && state.activeChatRunId))
     ) {
-      chatLog.addSystem("agent is busy — press Esc to abort before sending a new message");
+      addBlockedChatSubmitNotice(chatLog);
       tui.requestRender();
       return;
     }
diff --git a/src/tui/tui.ts b/src/tui/tui.ts
index 369636c5db17..ff7dadee137f 100644
--- a/src/tui/tui.ts
+++ b/src/tui/tui.ts
@@ -39,6 +39,7 @@ import { CustomEditor } from "./components/custom-editor.js";
 import { resolveLocalRunShutdownGraceMs } from "./local-run-shutdown.js";
 import { editorTheme, theme } from "./theme/theme.js";
 import type { TuiBackend } from "./tui-backend.js";
+import { addBlockedChatSubmitNotice } from "./tui-busy-notice.js";
 import { createCommandHandlers } from "./tui-command-handlers.js";
 import { createEventHandlers } from "./tui-event-handlers.js";
 import {
@@ -1434,7 +1435,7 @@ export async function runTui(opts: RunTuiOptions): Promise<TuiResult> {
       message,
     });
   const notifyBlockedChatSubmit = () => {
-    chatLog.addSystem("agent is busy — press Esc to abort before sending a new message");
+    addBlockedChatSubmitNotice(chatLog);
     tui.requestRender();
   };
   const submitHandler = createEditorSubmitHandler({