diff --git a/packages/webui/src/client/features/settings/contracts/memory-handoff.ts b/packages/webui/src/client/features/settings/contracts/memory-handoff.ts
index 3a6e59b1b..641efd509 100644
--- a/packages/webui/src/client/features/settings/contracts/memory-handoff.ts
+++ b/packages/webui/src/client/features/settings/contracts/memory-handoff.ts
@@ -28,6 +28,43 @@ export interface MemoryHandoff {
   readonly content: string;
 }
 
+/**
+ * What the hand-off still owes the composer.
+ *
+ * The hand-off is one-shot, and so is everything it brings: the file it
+ * attaches and the line it types beside it. The file's own latch is the
+ * composer's consumed seed token; this is the same latch for the line, asked
+ * the same way — with the token the caller has already typed.
+ *
+ * It has to be a latch rather than a write. The line is typed when the
+ * hand-off opens the home surface, but the surface is visited again for every
+ * reason there is — a session, a back, a new task — and a line typed on each
+ * visit replaces what the user has written since.
+ */
+export type WebuiMemoryHandoffPrompt =
+  /** Nothing to type: no hand-off, or this token has already been typed. */
+  | { readonly kind: "none" }
+  /** Type this line, and record the token before doing it. */
+  | { readonly kind: "prompt"; readonly token: string; readonly prompt: string };
+
+/**
+ * Read the hand-off's line, as a decision rather than as a write.
+ *
+ * The caller records the token before it types, so the order the invariant
+ * requires is visible at the call site rather than implied by this function's
+ * internals.
+ */
+export function readWebuiMemoryHandoffPrompt(input: {
+  readonly handoff: MemoryHandoff | undefined;
+  /** The token whose line has already been typed, if any. */
+  readonly consumedToken: string | undefined;
+}): WebuiMemoryHandoffPrompt {
+  const { handoff } = input;
+  if (!handoff) return { kind: "none" };
+  if (input.consumedToken === handoff.token) return { kind: "none" };
+  return { kind: "prompt", token: handoff.token, prompt: MEMORY_HANDOFF_PROMPT };
+}
+
 /**
  * The save predicate, as a decision rather than as component state.
  *
diff --git a/packages/webui/src/client/features/turn/application/turn-commands.ts b/packages/webui/src/client/features/turn/application/turn-commands.ts
index 2bbe04c1e..40d20c51c 100644
--- a/packages/webui/src/client/features/turn/application/turn-commands.ts
+++ b/packages/webui/src/client/features/turn/application/turn-commands.ts
@@ -282,8 +282,15 @@ export interface WebuiSendTurnArgs {
   readonly intent: WebuiSubmissionIntent;
   /** Decided by the owner before any work, so the ticket can say it immediately. */
   readonly admission: WebuiSubmissionAdmission;
-  /** Read the live slice. The home→session migration below changes the key. */
-  readonly readStream?: () => WebuiStreamState;
+  /**
+   * Read the live slice of a record, by the key it is filed under.
+   *
+   * The key is passed in rather than remembered because a first message creates
+   * the session it is sent to: the record moves onto that session, and a reader
+   * bound to the key the turn started from answers about a slot the record has
+   * already left.
+   */
+  readonly readStream?: (sessionKey: string) => WebuiStreamState;
   readonly deps: Omit<WebuiDeliveryDeps, "projection" | "streamState">;
   readonly enqueueMessage?: WebuiClientMessageEnqueuer;
   readonly createSessionWorkspaceDir?: string;
@@ -336,12 +343,25 @@ export function sendWebuiTurn(
   // The bundle is woven here, from the writer this command owns: `createSink`
   // reads the *current* writer, so a turn whose first message created the
   // session mints its lease against the migrated key rather than the home slot.
+  const readSessionStream = args.readStream;
   const turnHandlers: WebuiComposerSubmitHandlers = buildWebuiComposerHandlers({
     createSink: () => writer.createSink(),
     resetStreamForTurn: () => writer.resetStreamForTurn(),
     setRefusal: (refusal) => writer.setStreamRefusal(refusal),
     setSending: (sending) => writer.setTurnSending(sending),
-    ...(args.readStream ? { readStream: args.readStream } : {}),
+    // The live slice, read through the key the turn's record lives under. A
+    // first message creates its session and the record moves onto it, so the
+    // key the turn started from is not the key the record is on any more — and
+    // a reader left on the old key would decide the turn no longer owns the
+    // stream, which is what strands its sending flag.
+    ...(readSessionStream
+      ? {
+          readStream: () =>
+            readSessionStream(
+              createdSessionId ?? args.sessionId ?? WEBUI_HOME_SESSION_KEY,
+            ),
+        }
+      : {}),
     // The draft is consumed by the submission, through the link the assembly
     // installed. No caller supplies a writer.
     //
@@ -447,9 +467,12 @@ export function createWebuiConversationTurnCommands(
     setSending: viewWriter.setSending,
   });
 
-  /** The live slice. The home→session migration changes which key this reads. */
+  /** The live slice of a record, read by the key it is filed under. */
+  const readSessionStream = (sessionKey: string): WebuiStreamState =>
+    store.readSession(sessionKey).stream;
+  /** The live slice of this owner's record. */
   const readStream = (): WebuiStreamState =>
-    store.readSession(sessionId ?? WEBUI_HOME_SESSION_KEY).stream;
+    readSessionStream(sessionId ?? WEBUI_HOME_SESSION_KEY);
 
   /**
    * The loop's transports, cut from the slice: an unwired operation is absent,
@@ -595,7 +618,7 @@ export function createWebuiConversationTurnCommands(
         // The UI submits intent only. The execution owner reads the canonical
         // target at invocation time so a stale render cannot choose send vs queue.
         sending: admission.turnLive && decision.kind !== "unsupported" && decision.kind !== "needs-session",
-        readStream,
+        readStream: readSessionStream,
         deps: loopDeps(hold),
         ...(capabilities?.enqueue ? { enqueueMessage: capabilities.enqueue } : {}),
         ...(intent.createSessionWorkspaceDir
diff --git a/packages/webui/src/client/shell/WebuiClientFoundationApp.tsx b/packages/webui/src/client/shell/WebuiClientFoundationApp.tsx
index 74e17733f..762708739 100644
--- a/packages/webui/src/client/shell/WebuiClientFoundationApp.tsx
+++ b/packages/webui/src/client/shell/WebuiClientFoundationApp.tsx
@@ -19,7 +19,7 @@ import { Composer } from "../features/composer/ui/Composer.js";
 import { LeftRail } from "../features/sessions/ui/LeftRail.js";
 import { Transcript } from "../features/transcript/ui/Transcript.js";
 import { UserMenu } from "../features/account/ui/UserMenu.js";
-import { MEMORY_HANDOFF_PROMPT, type MemoryHandoff } from "../features/settings/contracts/memory-handoff.js";
+import { readWebuiMemoryHandoffPrompt, type MemoryHandoff } from "../features/settings/contracts/memory-handoff.js";
 import { WebuiWorkspacePanel } from "../features/workspace/ui/WorkspacePanels.js";
 import { WebuiProgressOverviewPanel } from "../features/workspace/ui/WorkspaceProgressPanel.js";
 import {
@@ -558,15 +558,31 @@ export function WebuiClientFoundationApp(
    * current, so starting from a session would type it somewhere the user never
    * sees. Once no session is selected the key is the home slot, which is the
    * slot on the home surface.
+   *
+   * It is written **once**. The home surface is visited again for every
+   * reason there is — a session, a back, a new task — and a line typed on each
+   * visit replaces what the user has written since. The hand-off's token is
+   * the latch, the same token the attached file is held by.
    */
   const [memoryHandoff, setMemoryHandoff] = useState<MemoryHandoff>();
+  // The token of the hand-off whose line has been typed. A ref, not state: the
+  // latch is a fact about what has been written, not something to render.
+  const handoffPromptToken = useRef<string>();
   const createMemorySession = useCallback((input: MemoryHandoff) => {
     setMemoryHandoff(input);
     startNewTask();
   }, []);
   useEffect(() => {
-    if (!memoryHandoff || selectedSessionId) return;
-    setDraft(MEMORY_HANDOFF_PROMPT);
+    if (selectedSessionId) return;
+    const decision = readWebuiMemoryHandoffPrompt({
+      handoff: memoryHandoff,
+      consumedToken: handoffPromptToken.current,
+    });
+    if (decision.kind === "none") return;
+    // Recorded before the line is typed, so a re-render that runs this effect
+    // again cannot type it a second time.
+    handoffPromptToken.current = decision.token;
+    setDraft(decision.prompt);
   }, [memoryHandoff, selectedSessionId, setDraft]);
 
   const handleWorkspaceSubagentClick = useCallback(
diff --git a/packages/webui/test/unit/conversation-turn-commands.test.ts b/packages/webui/test/unit/conversation-turn-commands.test.ts
index e7dd17464..eb367c254 100644
--- a/packages/webui/test/unit/conversation-turn-commands.test.ts
+++ b/packages/webui/test/unit/conversation-turn-commands.test.ts
@@ -16,6 +16,7 @@ import { createWebuiSessionStore } from "../../src/client/application/session-st
 import { createWebuiSessionScopeManager } from "../../src/client/conversation/session-scope.js";
 import { createWebuiDeliveryDisposers } from "../../src/client/features/turn/application/delivery-disposers.js";
 import { WEBUI_HOME_SESSION_KEY } from "../../src/client/application/state.js";
+import type { WebuiStreamFrame } from "../../src/shared/contracts/stream.js";
 
 /** A resume that never settles: the attachment's lease stays claimed. */
 const openStream = () => new Promise<never>(() => undefined);
@@ -169,6 +170,113 @@ describe("the conversation turn commands", () => {
   });
 });
 
+describe("a first message on the home surface", () => {
+  const createSession = async () => ({ sessionId: "s-created" });
+
+  it("clears the sending flag on the session the message created", async () => {
+    // The first message has no session yet, so the turn creates one and its
+    // record moves onto it. The flag the composer renders from lives on that
+    // record, and the turn's own cleanup has to read it there: a reader still
+    // looking at the home slot would decide the turn no longer owns the
+    // stream, skip the cleanup, and leave the send button as a stop button —
+    // which swallows the next message into the queue.
+    const store = createWebuiSessionStore();
+    const commands = createWebuiConversationTurnCommands({
+      store,
+      sessionId: undefined,
+      capabilities: {
+        createSession: createSession as never,
+        send: (async (
+          _request: unknown,
+          onFrame: (frame: WebuiStreamFrame) => void,
+        ) => {
+          onFrame({
+            cursor: "c1",
+            dataJson: JSON.stringify({
+              type: 2,
+              agent_message: { msg_id: "m1", msg_content: "hi" },
+            }),
+          });
+          onFrame({ cursor: "c2", dataJson: "[DONE]" });
+        }) as never,
+      },
+      taskSessions: {
+        creationPending: () => false,
+        submit: async () => {
+          // The creation moves the home record onto the session it created,
+          // so the home slot is empty by the time the turn settles.
+          store.transferSession(WEBUI_HOME_SESSION_KEY, "s-created", {
+            expectSourceIncarnation: store.readHomeIncarnation(),
+          });
+          return {
+            kind: "created" as const,
+            sessionId: "s-created",
+            selected: true,
+          };
+        },
+      },
+    });
+
+    const ticket = commands.send({ message: "hello" });
+    await ticket?.completion;
+
+    expect(store.readSession("s-created").sending).toBe(false);
+    expect(store.readSession("s-created").stream.phase).toBe("done");
+  });
+
+  it("sends the next message instead of queueing it", async () => {
+    // The same defect, seen from the composer: a sending flag left standing
+    // makes the next submission look like a turn that is already live, so it
+    // is queued rather than sent.
+    const store = createWebuiSessionStore();
+    const enqueueMessage = vi.fn(async () => undefined);
+    const sendMessage = vi.fn(
+      async (
+        _request: unknown,
+        onFrame: (frame: WebuiStreamFrame) => void,
+      ) => {
+        onFrame({ cursor: "c1", dataJson: "[DONE]" });
+      },
+    );
+    const capabilities = {
+      createSession: createSession as never,
+      send: sendMessage as never,
+      enqueue: enqueueMessage as never,
+    };
+    const taskSessions = {
+      creationPending: () => false,
+      submit: async () => ({
+        kind: "created" as const,
+        sessionId: "s-created",
+        selected: true,
+      }),
+    };
+    const home = createWebuiConversationTurnCommands({
+      store,
+      sessionId: undefined,
+      capabilities,
+      taskSessions,
+    });
+
+    await home.send({ message: "first" })?.completion;
+
+    // The created session is the one the user is now in, so the next message
+    // is sent from it.
+    const inSession = createWebuiConversationTurnCommands({
+      store,
+      sessionId: "s-created",
+      capabilities,
+      taskSessions,
+    });
+    const second = inSession.send({ message: "second" });
+
+    expect(second?.admission).toEqual({ kind: "dispatching" });
+    await second?.completion;
+    expect(sendMessage).toHaveBeenCalledTimes(2);
+    expect(enqueueMessage).not.toHaveBeenCalled();
+  });
+});
+
 describe("recheck and gap recovery are the command set's, not the view's", () => {
   const busy = { turnId: "t-1", busyReason: "turn" as const, locallyOwned: false };
   const tick = () => new Promise((resolve) => setTimeout(resolve, 0));
diff --git a/packages/webui/test/unit/personalization-settings.test.tsx b/packages/webui/test/unit/personalization-settings.test.tsx
index 206393320..b3831a4e3 100644
--- a/packages/webui/test/unit/personalization-settings.test.tsx
+++ b/packages/webui/test/unit/personalization-settings.test.tsx
@@ -41,6 +41,7 @@ import {
   MEMORY_HANDOFF_PROMPT,
   formatMemoryTimestamp,
   isMemorySaveable,
+  readWebuiMemoryHandoffPrompt,
 } from "../../src/client/features/settings/contracts/memory-handoff.js";
 import { resolveEditorSeed } from "../../src/client/features/settings/ui/GlobalInstructionsSection.js";
 import { isProfileSaveable } from "../../src/client/features/settings/ui/UserProfileSection.js";
@@ -172,6 +173,55 @@ describe("「在会话中创建」 hand-off", () => {
     // the file identity.
     expect(MEMORY_HANDOFF_PROMPT).toBe("我想调整下这个记忆文件");
   });
+
+  it("types the line once, not on every visit to the home surface", () => {
+    const handoff = {
+      token: "t1",
+      fileName: "memory.md",
+      mimeType: "text/markdown",
+      sizeBytes: 12,
+      content: "x",
+    };
+    // The first visit types it.
+    expect(readWebuiMemoryHandoffPrompt({ handoff, consumedToken: undefined })).toEqual({
+      kind: "prompt",
+      token: "t1",
+      prompt: MEMORY_HANDOFF_PROMPT,
+    });
+    // The second visit must not. The home slot holds what the user has
+    // written since, and a line typed again replaces it.
+    expect(readWebuiMemoryHandoffPrompt({ handoff, consumedToken: "t1" })).toEqual({
+      kind: "none",
+    });
+    // A hand-off of its own still types, whatever was typed before.
+    expect(
+      readWebuiMemoryHandoffPrompt({
+        handoff: { ...handoff, token: "t2" },
+        consumedToken: "t1",
+      }),
+    ).toEqual({ kind: "prompt", token: "t2", prompt: MEMORY_HANDOFF_PROMPT });
+    // No hand-off, nothing to type.
+    expect(
+      readWebuiMemoryHandoffPrompt({ handoff: undefined, consumedToken: undefined }),
+    ).toEqual({ kind: "none" });
+  });
+
+  it("keeps the shell from typing the line a second time", () => {
+    // The decision is only half of the fix: the shell has to ask it, and has
+    // to keep the token it typed. An effect cannot be reached by a static
+    // render — this package has no DOM framework — so the wiring is read off
+    // the source, the way the rail's own wiring is.
+    const frame = readFileSync(
+      new URL("../../src/client/shell/WebuiClientFoundationApp.tsx", import.meta.url),
+      "utf8",
+    );
+    expect(frame).toMatch(/readWebuiMemoryHandoffPrompt\(\{/u);
+    expect(frame).toMatch(/consumedToken: handoffPromptToken\.current/u);
+    expect(frame).toMatch(/handoffPromptToken\.current = decision\.token/u);
+    // A direct write of the constant is what put the line back into the slot
+    // on every visit; it must not come back.
+    expect(frame).not.toMatch(/setDraft\(MEMORY_HANDOFF_PROMPT\)/u);
+  });
 });
 
 describe("the delete confirmation's copy", () => {