fix(chat): preserve locked message content on unlock

src/data/repositories/chat_local_message_store.ts

@@ -10,7 +10,6 @@ export class ChatLocalMessageStore {
 
   async markMessageUnlocked(
     messageId: string,
-    content: string,
     lockDetail?: ChatLockDetailData,
   ): Promise<Result<void>> {
     return Result.wrap(async () => {
@@ -21,11 +20,10 @@ export class ChatLocalMessageStore {
 
       let changed = false;
       const updatedMessages = localResult.data.map((message) => {
-        if (message.id !== messageId) return message;
+        if (!shouldMarkMessageUnlocked(message, messageId)) return message;
         changed = true;
         return ChatMessage.from({
           ...message.toJson(),
-          content,
           lockDetail: lockDetail ?? {
             ...message.lockDetail,
             locked: false,
@@ -106,3 +104,17 @@ export class ChatLocalMessageStore {
     });
   }
 }
+
+function shouldMarkMessageUnlocked(
+  message: ChatMessage,
+  messageId: string,
+): boolean {
+  if (message.id !== messageId) return false;
+  if (message.role !== "assistant") return false;
+  if (message.lockDetail.locked !== true) return false;
+  return (
+    Boolean(message.image.url) ||
+    message.lockDetail.reason === "private_message" ||
+    message.lockDetail.reason === "voice_message"
+  );
+}

src/data/repositories/chat_repository.ts

@@ -66,12 +66,10 @@ export class ChatRepository implements IChatRepository {
   /** 把本地缓存中的单条锁定消息标记为已解锁。 */
   async markPrivateMessageUnlockedInLocal(
     messageId: string,
-    content: string,
     lockDetail?: ChatLockDetailData,
   ): Promise<Result<void>> {
     return this.localMessages.markMessageUnlocked(
       messageId,
-      content,
       lockDetail,
     );
   }

src/data/repositories/interfaces/ichat_repository.ts

@@ -51,7 +51,6 @@ export interface IChatRepository {
   /** 把本地缓存中的单条锁定消息标记为已解锁。 */
   markPrivateMessageUnlockedInLocal(
     messageId: string,
-    content: string,
     lockDetail?: ChatLockDetailData,
   ): Promise<Result<void>>;
 

src/stores/chat/__tests__/chat-machine.helpers.test.ts

@@ -79,7 +79,7 @@ describe("sendResponseToUiMessage", () => {
       }),
     );
 
-    expect(message.content).toBe("");
+    expect(message.content).toBe("AI reply");
     expect(message.audioUrl).toBe(
       "https://proapi.banlv-ai.com/audio/5198b93c-2915-406a.mp3",
     );
@@ -105,7 +105,7 @@ describe("sendResponseToUiMessage", () => {
       }),
     );
 
-    expect(message.content).toBe("");
+    expect(message.content).toBe("AI reply");
     expect(message.locked).toBe(true);
     expect(message.lockReason).toBe("private_message");
     expect(message.isPrivate).toBe(true);
@@ -293,7 +293,7 @@ describe("localMessagesToUi", () => {
       },
     ]);
 
-    expect(message.content).toBe("");
+    expect(message.content).toBe("hidden voice transcript");
     expect(message.audioUrl).toBe("https://example.com/voice.mp3");
     expect(message.locked).toBe(true);
     expect(message.lockReason).toBe("voice_message");

src/stores/chat/__tests__/chat-machine.transitions.test.ts

@@ -480,7 +480,7 @@ describe("chatMachine transitions", () => {
         historyMessages: [
           {
             id: "msg-private-locked",
-            content: "",
+            content: "Original private message content.",
             isFromAI: true,
             date: "2026-06-29",
             locked: true,
@@ -492,7 +492,7 @@ describe("chatMachine transitions", () => {
         unlockMessageOutput: {
           messageId: "msg-private-locked",
           response: makeUnlockPrivateResponse({
-            content: "This is the unlocked private message.",
+            content: "This response content must be ignored.",
           }),
         },
       }),
@@ -518,7 +518,7 @@ describe("chatMachine transitions", () => {
     expect(actor.getSnapshot().context.messages).toMatchObject([
       {
         id: "msg-private-locked",
-        content: "This is the unlocked private message.",
+        content: "Original private message content.",
         locked: false,
         lockReason: null,
         lockedPrivate: false,
@@ -541,7 +541,7 @@ describe("chatMachine transitions", () => {
           },
           {
             id: "msg-shared-id",
-            content: "",
+            content: "Original AI private message",
             isFromAI: true,
             date: "2026-06-29",
             locked: true,
@@ -553,7 +553,7 @@ describe("chatMachine transitions", () => {
         unlockMessageOutput: {
           messageId: "msg-shared-id",
           response: makeUnlockPrivateResponse({
-            content: "This is the unlocked private message.",
+            content: "This response content must be ignored.",
           }),
         },
       }),
@@ -582,7 +582,7 @@ describe("chatMachine transitions", () => {
       },
       {
         id: "msg-shared-id",
-        content: "This is the unlocked private message.",
+        content: "Original AI private message",
         isFromAI: true,
         locked: false,
         lockReason: null,
@@ -594,6 +594,112 @@ describe("chatMachine transitions", () => {
     actor.stop();
   });
 
+  it("keeps image message text empty after a single image unlock succeeds", async () => {
+    const actor = createActor(
+      createTestChatMachine({
+        historyMessages: [
+          {
+            id: "msg-image-locked",
+            content: "",
+            isFromAI: true,
+            date: "2026-06-29",
+            imageUrl: "https://example.com/locked.jpg",
+            imagePaywalled: true,
+            locked: true,
+            lockReason: "image",
+          },
+        ],
+        unlockMessageOutput: {
+          messageId: "msg-image-locked",
+          response: makeUnlockPrivateResponse({
+            content: "This text should not render below the image.",
+          }),
+        },
+      }),
+    ).start();
+
+    actor.send({ type: "ChatUserLogin", token: "token" });
+    await waitFor(actor, (snapshot) =>
+      snapshot.matches({ userSession: "ready" }),
+    );
+
+    actor.send({
+      type: "ChatUnlockMessageRequested",
+      messageId: "msg-image-locked",
+      kind: "image",
+    });
+
+    await waitFor(actor, (snapshot) =>
+      snapshot.matches({ userSession: "ready" }),
+    );
+
+    expect(actor.getSnapshot().context.messages).toMatchObject([
+      {
+        id: "msg-image-locked",
+        content: "",
+        imageUrl: "https://example.com/locked.jpg",
+        imagePaywalled: false,
+        locked: false,
+        lockReason: null,
+      },
+    ]);
+
+    actor.stop();
+  });
+
+  it("keeps voice message content unchanged after unlock succeeds", async () => {
+    const actor = createActor(
+      createTestChatMachine({
+        historyMessages: [
+          {
+            id: "msg-voice-locked",
+            content: "Original voice transcript.",
+            isFromAI: true,
+            date: "2026-06-29",
+            audioUrl: "https://example.com/voice.mp3",
+            locked: true,
+            lockReason: "voice_message",
+            privateMessageHint: "A voice message is waiting.",
+          },
+        ],
+        unlockMessageOutput: {
+          messageId: "msg-voice-locked",
+          response: makeUnlockPrivateResponse({
+            content: "This response content must be ignored.",
+          }),
+        },
+      }),
+    ).start();
+
+    actor.send({ type: "ChatUserLogin", token: "token" });
+    await waitFor(actor, (snapshot) =>
+      snapshot.matches({ userSession: "ready" }),
+    );
+
+    actor.send({
+      type: "ChatUnlockMessageRequested",
+      messageId: "msg-voice-locked",
+      kind: "voice",
+    });
+
+    await waitFor(actor, (snapshot) =>
+      snapshot.matches({ userSession: "ready" }),
+    );
+
+    expect(actor.getSnapshot().context.messages).toMatchObject([
+      {
+        id: "msg-voice-locked",
+        content: "Original voice transcript.",
+        audioUrl: "https://example.com/voice.mp3",
+        locked: false,
+        lockReason: null,
+        privateMessageHint: null,
+      },
+    ]);
+
+    actor.stop();
+  });
+
   it("requests payment when single message unlock lacks credits", async () => {
     const actor = createActor(
       createTestChatMachine({

src/stores/chat/chat-message-mappers.ts

@@ -31,7 +31,6 @@ export function localMessagesToUi(
       content: m.content,
       isFromAI: m.role === "assistant",
       hasImage: Boolean(m.image?.url),
-      lockDetail: m.lockDetail,
     }),
     isFromAI: m.role === "assistant",
     date: messageDateFromCreatedAt(m.createdAt),
@@ -51,7 +50,6 @@ export function sendResponseToUiMessage(response: ChatSendResponse): UiMessage {
       content: response.reply,
       isFromAI: true,
       hasImage: Boolean(response.image.url),
-      lockDetail: response.lockDetail,
     }),
     isFromAI: true,
     date: todayString(new Date(response.timestamp)),
@@ -70,12 +68,7 @@ function getAiMessageDisplayContent(input: {
   content: string;
   isFromAI: boolean;
   hasImage?: boolean;
-  lockDetail?: {
-    showContent: boolean;
-    reason: string | null;
-  };
 }): string {
-  if (input.lockDetail?.showContent === false) return "";
   return input.isFromAI && input.hasImage ? "" : input.content;
 }
 

src/stores/chat/chat-unlock-flow.ts

@@ -63,7 +63,6 @@ export const chatUnlockActors = {
       if (unlockResult.data.unlocked) {
         const markResult = await chatRepo.markPrivateMessageUnlockedInLocal(
           input.messageId,
-          unlockResult.data.content,
           unlockResult.data.lockDetail,
         );
         if (Result.isErr(markResult)) {

src/stores/chat/chat-unlock-helpers.ts

@@ -18,14 +18,8 @@ export function applySingleUnlockOutput(
   return messages.map((message) => {
     if (!shouldApplySingleUnlock(message, output.messageId)) return message;
 
-    const nextContent =
-      output.response.content.length > 0
-        ? output.response.content
-        : message.content;
-
     return {
       ...message,
-      content: nextContent,
       locked: output.response.lockDetail.locked,
       lockReason: output.response.lockDetail.reason,
       imagePaywalled: message.imageUrl