feat(web-ai): persist chat history locally

apps/web/src/pages/ai-chat-page.tsx

@@ -19,6 +19,12 @@ import {
   type WebAiChannel,
   WebAiApiError
 } from "@/services/ai-api";
+import {
+  deleteLocalAiChatSession,
+  listLocalAiChatSessions,
+  saveLocalAiChatSession,
+  type LocalAiChatMessageRecord
+} from "@/services/local-ai-chat-repo";
 import type { WebSession } from "@/services/session-storage";
 import { CHANNEL_META, CHANNEL_ORDER } from "@/components/ai/ai-shared";
 
@@ -26,12 +32,7 @@ type AiChatPageProps = {
   session: WebSession;
 };
 
-type AiMessageRecord = {
+type AiMessageRecord = LocalAiChatMessageRecord;
-  id: string;
-  role: "user" | "assistant" | "system";
-  content: string;
-  meta?: string;
-};
 
 function createEmptyMessages(): Record<WebAiChannel, AiMessageRecord[]> {
   return {
@@ -78,6 +79,7 @@ export function AiChatPage({ session }: AiChatPageProps) {
   const [draftMessage, setDraftMessage] = useState("");
   const [sending, setSending] = useState(false);
   const [loadError, setLoadError] = useState<string | null>(null);
+  const [historyLoaded, setHistoryLoaded] = useState(false);
   const messagesEndRef = useRef<HTMLDivElement | null>(null);
 
   const bindingMap = useMemo(() => {
@@ -112,6 +114,68 @@ export function AiChatPage({ session }: AiChatPageProps) {
     void loadBindings();
   }, [loadBindings]);
 
+  useEffect(() => {
+    let cancelled = false;
+
+    async function loadLocalHistory(): Promise<void> {
+      try {
+        const records = await listLocalAiChatSessions(session.user.id);
+        if (cancelled) {
+          return;
+        }
+
+        const nextMessages = createEmptyMessages();
+        const nextSessionIds = createEmptySessionIds();
+
+        for (const record of records) {
+          nextMessages[record.channel] = record.messages;
+          if (record.sessionId) {
+            nextSessionIds[record.channel] = record.sessionId;
+          }
+        }
+
+        setMessagesByChannel(nextMessages);
+        setSessionIds(nextSessionIds);
+      } finally {
+        if (!cancelled) {
+          setHistoryLoaded(true);
+        }
+      }
+    }
+
+    setHistoryLoaded(false);
+    void loadLocalHistory();
+
+    return () => {
+      cancelled = true;
+    };
+  }, [session.user.id]);
+
+  useEffect(() => {
+    if (!historyLoaded) {
+      return;
+    }
+
+    void Promise.all(
+      CHANNEL_ORDER.map(async (channel) => {
+        const messages = messagesByChannel[channel];
+        const sessionId = sessionIds[channel] ?? null;
+
+        if (messages.length === 0 && sessionId === null) {
+          await deleteLocalAiChatSession(session.user.id, channel);
+          return;
+        }
+
+        await saveLocalAiChatSession({
+          userId: session.user.id,
+          channel,
+          sessionId,
+          messages
+        });
+      })
+    );
+  }, [historyLoaded, messagesByChannel, session.user.id, sessionIds]);
+
   useEffect(() => {
     messagesEndRef.current?.scrollIntoView({
       block: "end",

apps/web/src/services/local-ai-chat-repo.ts

@@ -0,0 +1,91 @@
+import { localDb, type LocalAiChatSessionRecord } from "@/services/local-db";
+import type { WebAiChannel } from "@/services/ai-api";
+
+export type LocalAiChatMessageRecord = {
+  id: string;
+  role: "user" | "assistant" | "system";
+  content: string;
+  meta?: string;
+};
+
+export type SaveLocalAiChatSessionInput = {
+  userId: string;
+  channel: WebAiChannel;
+  sessionId: string | null;
+  messages: LocalAiChatMessageRecord[];
+};
+
+export type LocalAiChatSessionSnapshot = {
+  channel: WebAiChannel;
+  sessionId: string | null;
+  messages: LocalAiChatMessageRecord[];
+};
+
+function createSessionKey(userId: string, channel: WebAiChannel): string {
+  return `${userId}:${channel}`;
+}
+
+function parseMessages(messagesJson: string): LocalAiChatMessageRecord[] {
+  try {
+    const parsed = JSON.parse(messagesJson) as unknown;
+    if (!Array.isArray(parsed)) {
+      return [];
+    }
+
+    return parsed.filter((item): item is LocalAiChatMessageRecord => {
+      if (!item || typeof item !== "object") {
+        return false;
+      }
+
+      const record = item as Record<string, unknown>;
+      return (
+        typeof record["id"] === "string" &&
+        (record["role"] === "user" ||
+          record["role"] === "assistant" ||
+          record["role"] === "system") &&
+        typeof record["content"] === "string" &&
+        (record["meta"] === undefined || typeof record["meta"] === "string")
+      );
+    });
+  } catch {
+    return [];
+  }
+}
+
+function toSnapshot(record: LocalAiChatSessionRecord): LocalAiChatSessionSnapshot {
+  return {
+    channel: record.channel,
+    sessionId: record.sessionId,
+    messages: parseMessages(record.messagesJson)
+  };
+}
+
+export async function listLocalAiChatSessions(
+  userId: string
+): Promise<LocalAiChatSessionSnapshot[]> {
+  const records = await localDb.aiChatSessions.where("userId").equals(userId).toArray();
+  return records.map(toSnapshot);
+}
+
+export async function saveLocalAiChatSession(
+  input: SaveLocalAiChatSessionInput
+): Promise<LocalAiChatSessionRecord> {
+  const record: LocalAiChatSessionRecord = {
+    key: createSessionKey(input.userId, input.channel),
+    userId: input.userId,
+    channel: input.channel,
+    sessionId: input.sessionId,
+    messagesJson: JSON.stringify(input.messages),
+    updatedAt: Date.now()
+  };
+
+  await localDb.aiChatSessions.put(record);
+  return record;
+}
+
+export async function deleteLocalAiChatSession(
+  userId: string,
+  channel: WebAiChannel
+): Promise<void> {
+  await localDb.aiChatSessions.delete(createSessionKey(userId, channel));
+}

apps/web/src/services/local-db.ts

@@ -69,12 +69,22 @@ export type LocalSyncInboxRecord = {
   appliedAt: number | null;
 };
 
+export type LocalAiChatSessionRecord = {
+  key: string;
+  userId: string;
+  channel: "USER_KEY" | "ASTRBOT" | "PUBLIC_POOL";
+  sessionId: string | null;
+  messagesJson: string;
+  updatedAt: number;
+};
+
 class TodoLocalDb extends Dexie {
   declare tasks: Table<LocalTaskRecord, string>;
   declare opLogs: Table<LocalOpLogRecord, string>;
   declare taskDrafts: Table<LocalTaskDraftRecord, string>;
   declare syncStates: Table<LocalSyncStateRecord, string>;
   declare syncInbox: Table<LocalSyncInboxRecord, string>;
+  declare aiChatSessions: Table<LocalAiChatSessionRecord, string>;
 
   constructor() {
     super("todolist-web-db");
@@ -117,11 +127,21 @@ class TodoLocalDb extends Dexie {
           });
       });
 
+    this.version(5).stores({
+      tasks: "&id,userId,status,priority,ddlAt,updatedAt,deletedAt",
+      op_logs: "&opId,entityId,entityType,action,clientTs,syncedAt",
+      task_drafts: "&taskId,userId,updatedAt",
+      sync_states: "&userId,updatedAt,lastSyncedAt",
+      sync_inbox: "&opId,userId,entityId,serverTs,appliedAt",
+      ai_chat_sessions: "&key,userId,channel,updatedAt"
+    });
+
     this.tasks = this.table("tasks");
     this.opLogs = this.table("op_logs");
     this.taskDrafts = this.table("task_drafts");
     this.syncStates = this.table("sync_states");
     this.syncInbox = this.table("sync_inbox");
+    this.aiChatSessions = this.table("ai_chat_sessions");
   }
 }