diff --git a/src/components/ai-edition/LeftPanel.tsx b/src/components/ai-edition/LeftPanel.tsx
index 1942d1da2..2b266ff92 100644
--- a/src/components/ai-edition/LeftPanel.tsx
+++ b/src/components/ai-edition/LeftPanel.tsx
@@ -3,7 +3,8 @@ import { useCallback, useEffect, useRef, useState } from "react";
 import { createPortal } from "react-dom";
 import { toast } from "sonner";
 import { useScopedT } from "@/contexts/I18nContext";
-import { type AxcutAsset, ensureDocument } from "@/lib/ai-edition/schema";
+import type { AxcutAsset } from "@/lib/ai-edition/schema";
+import { applyAgentDocumentIfCurrent } from "@/lib/ai-edition/store/agentDocumentApply";
 import { useProjectStore } from "@/lib/ai-edition/store/projectStore";
 import {
 	useAssetTranscriptions,
@@ -869,15 +870,13 @@ function ChatStripPanel() {
 		scrollRef.current?.scrollTo({ top: scrollRef.current.scrollHeight, behavior: "smooth" });
 	});
 
-	// Apply a document returned by the agent (tool batch or undo). setDocument
-	// pushes the previous doc to the local undo stack (Cmd+Z also works), then
-	// saveDocument persists it to disk.
-	const applyAgentDocument = useCallback(async (doc: unknown) => {
-		const parsed = ensureDocument(doc);
-		const store = useProjectStore.getState();
-		store.setDocument(parsed);
-		await store.saveDocument(parsed);
-	}, []);
+	// Apply a document returned by the agent (tool batch or rewind). Agent turns
+	// supply their starting revision so a concurrent manual edit wins; an explicit
+	// rewind omits it because replacing the live document is the confirmed action.
+	const applyAgentDocument = useCallback(
+		(doc: unknown, expectedRevision?: number) => applyAgentDocumentIfCurrent(doc, expectedRevision),
+		[],
+	);
 
 	const send = async (overrideText?: string) => {
 		const text = (overrideText ?? input).trim();
@@ -928,7 +927,9 @@ function ChatStripPanel() {
 			thinkingRunSessionRef.current = sessionId;
 			// Send the current document snapshot so the agent can run edit tools
 			// against it (P1). Falls back to text-only chat when no doc is open.
-			const documentSnapshot = useProjectStore.getState().document ?? undefined;
+			const snapshot = useProjectStore.getState();
+			const documentSnapshot = snapshot.document ?? undefined;
+			const documentRevision = snapshot.revision;
 			const result = await nativeBridgeClient.aiEdition.chatRun(
 				projectId,
 				sessionId,
@@ -939,7 +940,10 @@ function ChatStripPanel() {
 			if (result.success && assistant) {
 				if (result.document) {
 					try {
-						await applyAgentDocument(result.document);
+						const applyResult = await applyAgentDocument(result.document, documentRevision);
+						if (applyResult === "conflict") {
+							toast.warning(t("chat.agentEditConflict"));
+						}
 					} catch (err) {
 						toast.error(t("chat.applyEditsFailed"), {
 							description: err instanceof Error ? err.message : String(err),
diff --git a/src/i18n/locales/ar/editor.json b/src/i18n/locales/ar/editor.json
index fb3d6875a..580839894 100644
--- a/src/i18n/locales/ar/editor.json
+++ b/src/i18n/locales/ar/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "تعذّر اختيار النموذج",
 		"providerSettings": "إعدادات المزوّد…",
 		"applyEditsFailed": "تعذّر تطبيق تعديلات الوكيل",
+		"agentEditConflict": "لم تُطبَّق تعديلات الوكيل لأن المشروع تغيّر أثناء عمله.",
 		"chatFailed": "فشلت المحادثة",
 		"rewindFailed": "فشلت إعادة الضبط",
 		"rewoundSuccess": "تمت إعادة الضبط إلى بداية تلك الرسالة",
diff --git a/src/i18n/locales/en/editor.json b/src/i18n/locales/en/editor.json
index fe7fe12f9..f3e456c60 100644
--- a/src/i18n/locales/en/editor.json
+++ b/src/i18n/locales/en/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Could not select model",
 		"providerSettings": "Provider settings…",
 		"applyEditsFailed": "Could not apply the agent's edits",
+		"agentEditConflict": "Agent edits were not applied because the project changed while it was working.",
 		"chatFailed": "Chat failed",
 		"rewindFailed": "Rewind failed",
 		"rewoundSuccess": "Rewound to the start of that message",
diff --git a/src/i18n/locales/es/editor.json b/src/i18n/locales/es/editor.json
index efc550fa7..8f318607f 100644
--- a/src/i18n/locales/es/editor.json
+++ b/src/i18n/locales/es/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "No se pudo seleccionar el modelo",
 		"providerSettings": "Configuración del proveedor…",
 		"applyEditsFailed": "No se pudieron aplicar las ediciones del agente",
+		"agentEditConflict": "Las ediciones del agente no se aplicaron porque el proyecto cambió mientras trabajaba.",
 		"chatFailed": "Error en el chat",
 		"rewindFailed": "Error al rebobinar",
 		"rewoundSuccess": "Rebobinado al inicio de ese mensaje",
diff --git a/src/i18n/locales/fr/editor.json b/src/i18n/locales/fr/editor.json
index 152b139d9..d856bed1b 100644
--- a/src/i18n/locales/fr/editor.json
+++ b/src/i18n/locales/fr/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Impossible de sélectionner le modèle",
 		"providerSettings": "Réglages du fournisseur…",
 		"applyEditsFailed": "Impossible d'appliquer les modifications de l'agent",
+		"agentEditConflict": "Les modifications de l'agent n'ont pas été appliquées, car le projet a changé pendant son travail.",
 		"chatFailed": "Échec du chat",
 		"rewindFailed": "Échec du retour en arrière",
 		"rewoundSuccess": "Retour au début de ce message effectué",
diff --git a/src/i18n/locales/it/editor.json b/src/i18n/locales/it/editor.json
index 8462d90a4..cac82dd73 100644
--- a/src/i18n/locales/it/editor.json
+++ b/src/i18n/locales/it/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Impossibile selezionare il modello",
 		"providerSettings": "Impostazioni provider…",
 		"applyEditsFailed": "Impossibile applicare le modifiche dell'agente",
+		"agentEditConflict": "Le modifiche dell'agente non sono state applicate perché il progetto è cambiato durante l'elaborazione.",
 		"chatFailed": "Chat non riuscita",
 		"rewindFailed": "Riavvolgimento non riuscito",
 		"rewoundSuccess": "Riavvolto all'inizio di quel messaggio",
diff --git a/src/i18n/locales/ja-JP/editor.json b/src/i18n/locales/ja-JP/editor.json
index 0ec709cce..71c7db5e1 100644
--- a/src/i18n/locales/ja-JP/editor.json
+++ b/src/i18n/locales/ja-JP/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "モデルを選択できませんでした",
 		"providerSettings": "プロバイダー設定…",
 		"applyEditsFailed": "エージェントの編集を適用できませんでした",
+		"agentEditConflict": "エージェントの処理中にプロジェクトが変更されたため、編集は適用されませんでした。",
 		"chatFailed": "チャットに失敗しました",
 		"rewindFailed": "巻き戻しに失敗しました",
 		"rewoundSuccess": "そのメッセージの先頭まで巻き戻しました",
diff --git a/src/i18n/locales/ko-KR/editor.json b/src/i18n/locales/ko-KR/editor.json
index f6abeea22..3713c0161 100644
--- a/src/i18n/locales/ko-KR/editor.json
+++ b/src/i18n/locales/ko-KR/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "모델을 선택할 수 없습니다",
 		"providerSettings": "제공업체 설정…",
 		"applyEditsFailed": "에이전트의 편집을 적용할 수 없습니다",
+		"agentEditConflict": "에이전트가 작업하는 동안 프로젝트가 변경되어 편집 내용이 적용되지 않았습니다.",
 		"chatFailed": "채팅 실패",
 		"rewindFailed": "되감기 실패",
 		"rewoundSuccess": "해당 메시지 시작 지점으로 되감았습니다",
diff --git a/src/i18n/locales/pt-BR/editor.json b/src/i18n/locales/pt-BR/editor.json
index 71af170d5..526e773d0 100644
--- a/src/i18n/locales/pt-BR/editor.json
+++ b/src/i18n/locales/pt-BR/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Não foi possível selecionar o modelo",
 		"providerSettings": "Configurações do provedor…",
 		"applyEditsFailed": "Não foi possível aplicar as edições do agente",
+		"agentEditConflict": "As edições do agente não foram aplicadas porque o projeto mudou durante o processamento.",
 		"chatFailed": "Falha no chat",
 		"rewindFailed": "Falha ao rebobinar",
 		"rewoundSuccess": "Rebobinado até o início dessa mensagem",
diff --git a/src/i18n/locales/ru/editor.json b/src/i18n/locales/ru/editor.json
index 451c4d062..133f860c2 100644
--- a/src/i18n/locales/ru/editor.json
+++ b/src/i18n/locales/ru/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Не удалось выбрать модель",
 		"providerSettings": "Настройки провайдера…",
 		"applyEditsFailed": "Не удалось применить правки агента",
+		"agentEditConflict": "Правки агента не применены, потому что проект изменился во время его работы.",
 		"chatFailed": "Ошибка чата",
 		"rewindFailed": "Ошибка отката",
 		"rewoundSuccess": "Откат к началу этого сообщения выполнен",
diff --git a/src/i18n/locales/tr/editor.json b/src/i18n/locales/tr/editor.json
index becba505e..c9677158a 100644
--- a/src/i18n/locales/tr/editor.json
+++ b/src/i18n/locales/tr/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Model seçilemedi",
 		"providerSettings": "Sağlayıcı ayarları…",
 		"applyEditsFailed": "Aracının düzenlemeleri uygulanamadı",
+		"agentEditConflict": "Aracı çalışırken proje değiştiği için düzenlemeleri uygulanmadı.",
 		"chatFailed": "Sohbet başarısız oldu",
 		"rewindFailed": "Geri sarma başarısız oldu",
 		"rewoundSuccess": "O mesajın başına geri sarıldı",
diff --git a/src/i18n/locales/vi/editor.json b/src/i18n/locales/vi/editor.json
index 8fa562492..7b7187cd3 100644
--- a/src/i18n/locales/vi/editor.json
+++ b/src/i18n/locales/vi/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "Không thể chọn mô hình",
 		"providerSettings": "Cài đặt nhà cung cấp…",
 		"applyEditsFailed": "Không thể áp dụng chỉnh sửa của tác nhân",
+		"agentEditConflict": "Các chỉnh sửa của tác nhân không được áp dụng vì dự án đã thay đổi trong lúc xử lý.",
 		"chatFailed": "Trò chuyện thất bại",
 		"rewindFailed": "Tua lại thất bại",
 		"rewoundSuccess": "Đã tua lại đến đầu tin nhắn đó",
diff --git a/src/i18n/locales/zh-CN/editor.json b/src/i18n/locales/zh-CN/editor.json
index dd629f57f..1ee47890d 100644
--- a/src/i18n/locales/zh-CN/editor.json
+++ b/src/i18n/locales/zh-CN/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "无法选择模型",
 		"providerSettings": "提供方设置…",
 		"applyEditsFailed": "无法应用代理的编辑",
+		"agentEditConflict": "代理工作期间项目已更改，因此未应用代理的编辑。",
 		"chatFailed": "聊天失败",
 		"rewindFailed": "回退失败",
 		"rewoundSuccess": "已回退到该消息的开头",
diff --git a/src/i18n/locales/zh-TW/editor.json b/src/i18n/locales/zh-TW/editor.json
index 865096d0f..75259b9b3 100644
--- a/src/i18n/locales/zh-TW/editor.json
+++ b/src/i18n/locales/zh-TW/editor.json
@@ -235,6 +235,7 @@
 		"selectModelFailed": "無法選擇模型",
 		"providerSettings": "提供者設定…",
 		"applyEditsFailed": "無法套用代理的編輯",
+		"agentEditConflict": "代理執行期間專案已變更，因此未套用代理的編輯。",
 		"chatFailed": "聊天失敗",
 		"rewindFailed": "倒轉失敗",
 		"rewoundSuccess": "已倒轉至該訊息的開頭",
diff --git a/src/lib/ai-edition/store/agentDocumentApply.test.ts b/src/lib/ai-edition/store/agentDocumentApply.test.ts
new file mode 100644
index 000000000..fd38ad0ee
--- /dev/null
+++ b/src/lib/ai-edition/store/agentDocumentApply.test.ts
@@ -0,0 +1,67 @@
+// @vitest-environment jsdom
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { createEmptyDocument } from "../schema";
+import { applyAgentDocumentIfCurrent } from "./agentDocumentApply";
+import { useProjectStore } from "./projectStore";
+
+const saveMock = vi.hoisted(() => vi.fn());
+
+vi.mock("@/native/client", () => ({
+	nativeBridgeClient: {
+		aiEdition: { save: saveMock },
+	},
+}));
+
+describe("applyAgentDocumentIfCurrent", () => {
+	beforeEach(() => {
+		useProjectStore.getState().clear();
+		saveMock.mockReset();
+	});
+
+	it("applies an agent result when the document revision is unchanged", async () => {
+		const before = createEmptyDocument({ projectId: "project_1", title: "Before" });
+		const agentResult = {
+			...before,
+			project: { ...before.project, title: "Agent edit" },
+		};
+		useProjectStore.setState({ projectId: "project_1", document: before, revision: 4 });
+		saveMock.mockImplementation(async (document) => ({ success: true, document }));
+
+		await expect(applyAgentDocumentIfCurrent(agentResult, 4)).resolves.toBe("applied");
+
+		expect(saveMock).toHaveBeenCalledOnce();
+		expect(useProjectStore.getState().document?.project.title).toBe("Agent edit");
+	});
+
+	it("preserves a manual edit made after the agent snapshot", async () => {
+		const before = createEmptyDocument({ projectId: "project_1", title: "Before" });
+		const agentResult = {
+			...before,
+			project: { ...before.project, title: "Agent edit" },
+		};
+		useProjectStore.setState({ projectId: "project_1", document: before, revision: 4 });
+		useProjectStore.getState().setDocument({
+			...before,
+			project: { ...before.project, title: "Manual edit" },
+		});
+
+		await expect(applyAgentDocumentIfCurrent(agentResult, 4)).resolves.toBe("conflict");
+
+		expect(saveMock).not.toHaveBeenCalled();
+		expect(useProjectStore.getState().document?.project.title).toBe("Manual edit");
+	});
+
+	it("allows an explicit rewind to replace the current revision", async () => {
+		const current = createEmptyDocument({ projectId: "project_1", title: "Current" });
+		const checkpoint = {
+			...current,
+			project: { ...current.project, title: "Checkpoint" },
+		};
+		useProjectStore.setState({ projectId: "project_1", document: current, revision: 9 });
+		saveMock.mockImplementation(async (document) => ({ success: true, document }));
+
+		await expect(applyAgentDocumentIfCurrent(checkpoint)).resolves.toBe("applied");
+
+		expect(useProjectStore.getState().document?.project.title).toBe("Checkpoint");
+	});
+});
diff --git a/src/lib/ai-edition/store/agentDocumentApply.ts b/src/lib/ai-edition/store/agentDocumentApply.ts
new file mode 100644
index 000000000..c2a0a1e5e
--- /dev/null
+++ b/src/lib/ai-edition/store/agentDocumentApply.ts
@@ -0,0 +1,26 @@
+import { ensureDocument } from "../schema";
+import { useProjectStore } from "./projectStore";
+
+export type AgentDocumentApplyResult = "applied" | "conflict";
+
+/**
+ * Apply a full document returned by the agent only if the live editor is still
+ * on the revision used to start that agent turn.
+ *
+ * `expectedRevision` is omitted for explicit rewind operations, where replacing
+ * the current document is the action the user just confirmed.
+ */
+export async function applyAgentDocumentIfCurrent(
+	document: unknown,
+	expectedRevision?: number,
+): Promise<AgentDocumentApplyResult> {
+	const store = useProjectStore.getState();
+	if (expectedRevision !== undefined && store.revision !== expectedRevision) {
+		return "conflict";
+	}
+
+	const parsed = ensureDocument(document);
+	store.setDocument(parsed);
+	await store.saveDocument(parsed);
+	return "applied";
+}