diff --git a/apps/web/src/components/chat/useQueuedRunEdit.browser.test.tsx b/apps/web/src/components/chat/useQueuedRunEdit.browser.test.tsx
index c01fa57b4e2a5..08e919cb152ec 100644
--- a/apps/web/src/components/chat/useQueuedRunEdit.browser.test.tsx
+++ b/apps/web/src/components/chat/useQueuedRunEdit.browser.test.tsx
@@ -126,6 +126,16 @@ async function beginChangedEdit(hook: { current: HookResult | null }) {
   );
 }
 
+const savedContent = (prompt: string) => ({
+  prompt,
+  images: [],
+  files: [],
+  terminalContexts: [],
+  reviewComments: [],
+  previewAnnotations: [],
+  threadContexts: [],
+});
+
 const promptOf = (ref: ScopedThreadRef) =>
   useComposerDraftStore.getState().getComposerDraft(ref)?.prompt ?? "";
 
@@ -169,18 +179,7 @@ describe("useQueuedRunEdit", () => {
     await beginChangedEdit(hook);
 
     // Not inside act(): act would hold the projection update until the save settles.
-    const saved = requireHook(hook).saveEdit(
-      {
-        prompt: "changed",
-        images: [],
-        files: [],
-        terminalContexts: [],
-        reviewComments: [],
-        previewAnnotations: [],
-        threadContexts: [],
-      },
-      () => {},
-    );
+    const saved = requireHook(hook).saveEdit(savedContent("changed"), () => {});
     await vi.waitFor(() => expect(mocks.editQueuedRun).toHaveBeenCalledOnce());
     // The server applied the edit and then started the run; the projection
     // reports the start before the edit's acknowledgement arrives.
@@ -192,4 +191,37 @@ describe("useQueuedRunEdit", () => {
     expect(requireHook(hook).isEditing).toBe(false);
     expect(promptOf(THREAD_A)).toBe("");
   });
+
+  it("leaves a newer edit alone when a save from before navigation finishes", async () => {
+    const { hook } = setup();
+    let finishSave: (result: { readonly _tag: "Success" }) => void = () => {};
+    mocks.editQueuedRun.mockReturnValue(
+      new Promise((resolve) => {
+        finishSave = resolve;
+      }),
+    );
+    await using screen = await render(view(THREAD_A, "queued", hook));
+    await beginChangedEdit(hook);
+    // Not inside act(): act would hold the rerenders until the save settles.
+    const saved = requireHook(hook).saveEdit(savedContent("changed"), () => {});
+    await vi.waitFor(() => expect(mocks.editQueuedRun).toHaveBeenCalledOnce());
+
+    // Leaving the thread unmounts the chat view; coming back mounts a new one.
+    await screen.rerender(<AppAtomRegistryProvider>{null}</AppAtomRegistryProvider>);
+    await screen.rerender(view(THREAD_A, "queued", hook));
+    expect(requireHook(hook).isSaving).toBe(true);
+    await beginChangedEdit(hook);
+    await act(() =>
+      useComposerDraftStore.getState().setPrompt(requireHook(hook).draftTarget, "newer"),
+    );
+
+    finishSave({ _tag: "Success" });
+    await act(() => saved);
+
+    expect(requireHook(hook).editingRunId).toBe(RUN);
+    expect(requireHook(hook).isSaving).toBe(false);
+    expect(
+      useComposerDraftStore.getState().getComposerDraft(requireHook(hook).draftTarget)?.prompt,
+    ).toBe("newer");
+  });
 });
diff --git a/apps/web/src/components/chat/useQueuedRunEdit.ts b/apps/web/src/components/chat/useQueuedRunEdit.ts
index a9fbf7408dd0c..a57b1f687b7a6 100644
--- a/apps/web/src/components/chat/useQueuedRunEdit.ts
+++ b/apps/web/src/components/chat/useQueuedRunEdit.ts
@@ -19,7 +19,7 @@ import {
 import { scopedThreadKey } from "@t3tools/client-runtime/environment";
 import { ATTACHMENT_ONLY_BOOTSTRAP_PROMPT } from "@t3tools/shared/composerContextReferences";
 import { Atom } from "effect/reactivity";
-import { useRef, useState, type RefObject } from "react";
+import type { RefObject } from "react";
 import { useAssetUrls } from "../../assets/assetUrls";
 import {
   DraftId,
@@ -193,8 +193,7 @@ export function useQueuedRunEdit(input: {
   const editKey = scopedThreadKey(routeThreadRef);
   const storedEdit = useAtomValue(queuedRunEdits.atom)[editKey] ?? null;
   const editing = activeThreadId === null ? null : storedEdit;
-  const saveInFlightRef = useRef(false);
-  const [isSaving, setIsSaving] = useState(false);
+  const isSaving = useAtomValue(queuedRunEdits.savingAtom)[editKey] === true;
   const draftTarget =
     editing === null ? threadDraftTarget : queuedEditDraftTarget(routeThreadRef, editing.runId);
 
@@ -299,7 +298,7 @@ export function useQueuedRunEdit(input: {
     content: QueuedRunEditContent,
     setThreadError: (threadId: ThreadId, error: string | null) => void,
   ) => {
-    if (editing === null || saveInFlightRef.current) return;
+    if (editing === null || isSaving) return;
     const newAttachments = [...content.images, ...content.files];
     if (
       editing.existingAttachments.length + newAttachments.length >
@@ -318,10 +317,9 @@ export function useQueuedRunEdit(input: {
     ) {
       return;
     }
-    saveInFlightRef.current = true;
-    setIsSaving(true);
     // The save's result decides the edit's fate, even if the run starts meanwhile.
-    queuedRunEdits.suspendExitWatch(editKey);
+    const finishSave = queuedRunEdits.startSave(editKey);
+    if (finishSave === null) return;
     const error = await submitQueuedRunEdit({
       environmentId,
       draftTarget,
@@ -329,18 +327,15 @@ export function useQueuedRunEdit(input: {
       content,
       editQueuedRun: editQueuedRunCommand,
     });
-    saveInFlightRef.current = false;
-    setIsSaving(false);
     setThreadError(editing.threadId, error);
-    if (error !== null) {
-      queuedRunEdits.resumeExitWatch(editKey);
-      return;
-    }
+    const current = finishSave(error === null);
+    if (error !== null) return;
     releaseDraftAttachments(newAttachments);
+    // The edit was cancelled or begun again while this save ran; its drafts are the newer edit's.
+    if (!current) return;
     promptRef.current = "";
     clearEditDraft(editing.runId);
     composerRef.current?.resetCursorState();
-    queuedRunEdits.end(editKey);
     focusComposerSoon();
   };
 
diff --git a/packages/client-runtime/src/queuedRunEdit.test.ts b/packages/client-runtime/src/queuedRunEdit.test.ts
index b5f560f849f50..b9d22b3fa9a51 100644
--- a/packages/client-runtime/src/queuedRunEdit.test.ts
+++ b/packages/client-runtime/src/queuedRunEdit.test.ts
@@ -78,13 +78,50 @@ describe("makeQueuedRunEditStore", () => {
   it("holds the exit during a save and replays it when the save fails", () => {
     const { registry, runs, store, exits, begin } = setup();
     begin();
-    store.suspendExitWatch("env:thread");
+    const finishSave = store.startSave("env:thread");
     registry.set(runs, []);
     expect(exits).toEqual([]);
-    store.resumeExitWatch("env:thread");
+    expect(finishSave?.(false)).toBe(true);
     expect(exits).toHaveLength(1);
   });
 
+  it("allows one save at a time and ends the edit when it succeeds", () => {
+    const { registry, store, begin } = setup();
+    begin();
+    const finishSave = store.startSave("env:thread");
+    expect(registry.get(store.savingAtom)).toEqual({ "env:thread": true });
+    expect(store.startSave("env:thread")).toBeNull();
+    expect(finishSave?.(true)).toBe(true);
+    expect(store.get("env:thread")).toBeNull();
+    expect(registry.get(store.savingAtom)).toEqual({});
+  });
+
+  it("leaves an edit begun again during a save to that edit", () => {
+    const { registry, runs, store, exits, begin } = setup();
+    begin();
+    const finishStale = store.startSave("env:thread");
+    begin();
+    store.update("env:thread", (edit) => ({ ...edit, text: "newer" }));
+    expect(registry.get(store.savingAtom)).toEqual({});
+
+    expect(finishStale?.(true)).toBe(false);
+    expect(finishStale?.(false)).toBe(false);
+    expect(store.get("env:thread")).toEqual({ runId: RUN, text: "newer" });
+    registry.set(runs, []);
+    expect(exits).toEqual([{ threadKey: "env:thread", text: "newer" }]);
+  });
+
+  it("does not revive a cancelled edit when its save fails", () => {
+    const { registry, runs, store, exits, begin } = setup();
+    begin();
+    const finishSave = store.startSave("env:thread");
+    store.end("env:thread");
+    expect(finishSave?.(false)).toBe(false);
+    registry.set(runs, []);
+    expect(exits).toEqual([]);
+    expect(registry.get(store.savingAtom)).toEqual({});
+  });
+
   // The runs read the thread's detail, a live server subscription; a thread
   // with no edit open must not keep it.
   it("holds the thread's runs only while an edit is open and watching", () => {
@@ -122,10 +159,10 @@ describe("makeQueuedRunEditStore", () => {
     expect(mounted).toBe(0);
 
     begin();
-    store.suspendExitWatch("env:thread");
+    const finishSave = store.startSave("env:thread");
     settle();
     expect(mounted).toBe(0);
-    store.resumeExitWatch("env:thread");
+    finishSave?.(false);
     expect(mounted).toBe(1);
 
     registry.set(source, []);
diff --git a/packages/client-runtime/src/queuedRunEdit.ts b/packages/client-runtime/src/queuedRunEdit.ts
index 809e8dcfa6c97..65b29647c934b 100644
--- a/packages/client-runtime/src/queuedRunEdit.ts
+++ b/packages/client-runtime/src/queuedRunEdit.ts
@@ -1,7 +1,8 @@
 /**
  * A queued-message edit ends on save, cancel, or when its run leaves the queue.
  * The store owns one watcher per edit, so "run left the queue" is handled exactly
- * once, when the projection reports it, wherever the user is in the app.
+ * once, when the projection reports it, wherever the user is in the app. It also
+ * owns the edit's save, because a save outlives the view that started it.
  */
 import type { RunId } from "@t3tools/contracts";
 import { Atom, type AtomRegistry } from "effect/reactivity";
@@ -67,6 +68,14 @@ interface ExitWatch<E> {
   cancel: (() => void) | null;
 }
 
+/**
+ * Settles a save started with `startSave`. Returns false, changing nothing,
+ * when the edit the save started from was ended or begun again meanwhile; the
+ * caller must then leave the edit's drafts alone. Otherwise success ends the
+ * edit and failure resumes its exit watch.
+ */
+export type FinishQueuedRunEditSave = (succeeded: boolean) => boolean;
+
 export function makeQueuedRunEditStore<E extends { readonly runId: RunId }>(options: {
   readonly registry: AtomRegistry.AtomRegistry;
   readonly label: string;
@@ -76,8 +85,22 @@ export function makeQueuedRunEditStore<E extends { readonly runId: RunId }>(opti
     Atom.keepAlive,
     Atom.withLabel(options.label),
   );
+  const savingAtom = Atom.make<Readonly<Record<string, true>>>({}).pipe(
+    Atom.keepAlive,
+    Atom.withLabel(`${options.label}-saving`),
+  );
+  // Each begin creates a new watch, so the watch is the edit's identity.
   const watches = new Map<string, ExitWatch<E>>();
 
+  const setSaving = (threadKey: string, saving: boolean) => {
+    const current = registry.get(savingAtom);
+    if (threadKey in current === saving) return;
+    const next = { ...current };
+    if (saving) next[threadKey] = true;
+    else delete next[threadKey];
+    registry.set(savingAtom, next);
+  };
+
   const get = (threadKey: string | null): E | null =>
     threadKey === null ? null : (registry.get(atom)[threadKey] ?? null);
 
@@ -118,10 +141,13 @@ export function makeQueuedRunEditStore<E extends { readonly runId: RunId }>(opti
     if (watch === undefined) return;
     unsubscribe(watch);
     watches.delete(threadKey);
+    setSaving(threadKey, false);
   };
 
   return {
     atom,
+    /** Thread keys whose edit has a save in flight. */
+    savingAtom,
     get,
     /**
      * Starts an edit, replacing any edit already open on the thread. When the
@@ -151,17 +177,26 @@ export function makeQueuedRunEditStore<E extends { readonly runId: RunId }>(opti
       write(threadKey, null);
     },
     /**
-     * Holds the exit transition while a save is in flight; the save's own
-     * result decides the edit's fate.
+     * Claims the open edit for a save, or returns null when there is no edit
+     * or a save already holds it. The exit watch pauses so the save's result
+     * decides the edit's fate.
      */
-    suspendExitWatch(threadKey: string) {
+    startSave(threadKey: string): FinishQueuedRunEditSave | null {
       const watch = watches.get(threadKey);
-      if (watch !== undefined) unsubscribe(watch);
-    },
-    /** Resumes after a failed save, handling an exit that happened meanwhile. */
-    resumeExitWatch(threadKey: string) {
-      const watch = watches.get(threadKey);
-      if (watch !== undefined && watch.cancel === null) subscribe(threadKey, watch);
+      if (watch === undefined || threadKey in registry.get(savingAtom)) return null;
+      setSaving(threadKey, true);
+      unsubscribe(watch);
+      return (succeeded) => {
+        if (watches.get(threadKey) !== watch) return false;
+        if (succeeded) {
+          stopWatch(threadKey);
+          write(threadKey, null);
+        } else {
+          setSaving(threadKey, false);
+          subscribe(threadKey, watch);
+        }
+        return true;
+      };
     },
   };
 }