feat: Update how messages load and sync, allow plugins to import messages

toju-app/src/app/infrastructure/persistence/README.md

@@ -57,7 +57,7 @@ The persisted `rooms` store is a local cache of room metadata. Channel topology
 
 ### Browser (IndexedDB)
 
-All operations run inside IndexedDB transactions in the renderer thread. The browser backend resolves the active database name from the logged-in user, reusing a legacy shared database only when it already belongs to that same account. Queries like `getMessages` pull all messages for a room via the `roomId` index, sort them by timestamp in JS, then apply limit/offset. Deleted messages are normalised on read (content replaced with a sentinel string).
+All operations run inside IndexedDB transactions in the renderer thread. The browser backend resolves the active database name from the logged-in user, reusing a legacy shared database only when it already belongs to that same account. Queries like `getMessages` pull all messages for a room via the `roomId` index, optionally filter to a text channel, sort them by timestamp in JS, then apply limit/offset. Deleted messages are normalised on read (content replaced with a sentinel string).
 
 ```mermaid
 sequenceDiagram
@@ -66,11 +66,11 @@ sequenceDiagram
     participant BDB as BrowserDatabaseService
     participant IDB as IndexedDB
 
-    Eff->>DB: getMessages(roomId, 50)
-    DB->>BDB: getMessages(roomId, 50)
+    Eff->>DB: getMessages(roomId, 50, 0, channelId?)
+    DB->>BDB: getMessages(roomId, 50, 0, channelId?)
     BDB->>IDB: tx.objectStore("messages")<br/>.index("roomId").getAll(roomId)
     IDB-->>BDB: Message[]
-    Note over BDB: Sort by timestamp, slice, normalise
+    Note over BDB: Optional channel filter, sort, slice, normalise
     BDB-->>DB: Message[]
     DB-->>Eff: Message[]
 ```

toju-app/src/app/infrastructure/persistence/browser-database.service.ts

@@ -70,12 +70,28 @@ export class BrowserDatabaseService {
    * @param roomId - Target room.
    * @param limit  - Maximum number of messages to return.
     * @param offset - Number of newer messages to skip (for pagination).
+   * @param channelId - Optional channel scope; 'general' includes null/empty.
+   * @param beforeTimestamp - Optional cursor; only messages strictly older
+   *                          than this timestamp are returned. Used for
+   *                          scroll-up history pagination.
    */
-  async getMessages(roomId: string, limit = 100, offset = 0): Promise<Message[]> {
+  async getMessages(
+    roomId: string,
+    limit = 100,
+    offset = 0,
+    channelId?: string,
+    beforeTimestamp?: number
+  ): Promise<Message[]> {
     const allRoomMessages = await this.getAllFromIndex<Message>(
       STORE_MESSAGES, 'roomId', roomId
     );
-    const sortedMessages = allRoomMessages.sort((first, second) => first.timestamp - second.timestamp);
+    const scopedMessages = channelId
+      ? allRoomMessages.filter((message) => (message.channelId || 'general') === channelId)
+      : allRoomMessages;
+    const cursorFiltered = beforeTimestamp === undefined
+      ? scopedMessages
+      : scopedMessages.filter((message) => message.timestamp < beforeTimestamp);
+    const sortedMessages = cursorFiltered.sort((first, second) => first.timestamp - second.timestamp);
     const endIndex = Math.max(sortedMessages.length - offset, 0);
     const startIndex = Math.max(endIndex - limit, 0);
     const messages = sortedMessages.slice(startIndex, endIndex);

toju-app/src/app/infrastructure/persistence/database.service.ts

@@ -49,8 +49,19 @@ export class DatabaseService {
   /** Persist a single chat message. */
   saveMessage(message: Message) { return this.backend.saveMessage(message); }
 
-  /** Retrieve the latest messages for a room with optional pagination. */
-  getMessages(roomId: string, limit = 100, offset = 0) { return this.backend.getMessages(roomId, limit, offset); }
+  /** Retrieve the latest messages for a room or channel with optional pagination.
+   *
+   * When `beforeTimestamp` is provided, only messages strictly older than that
+   * timestamp are returned. This is how scroll-up history loading paginates
+   * backwards through the DB without holding the whole history in memory.
+   */
+  getMessages(
+    roomId: string,
+    limit = 100,
+    offset = 0,
+    channelId?: string,
+    beforeTimestamp?: number
+  ) { return this.backend.getMessages(roomId, limit, offset, channelId, beforeTimestamp); }
 
   /** Retrieve messages newer than a given timestamp for a room. */
   getMessagesSince(roomId: string, sinceTimestamp: number) { return this.backend.getMessagesSince(roomId, sinceTimestamp); }

toju-app/src/app/infrastructure/persistence/electron-database.service.ts

@@ -42,9 +42,21 @@ export class ElectronDatabaseService {
    * @param roomId - Target room.
    * @param limit  - Maximum number of messages to return.
     * @param offset - Number of newer messages to skip (for pagination).
+   * @param channelId - Optional channel scope; 'general' includes null/empty.
+   * @param beforeTimestamp - Optional cursor; only messages strictly older
+   *                          than this timestamp are returned (scroll-up paging).
    */
-  getMessages(roomId: string, limit = 100, offset = 0): Promise<Message[]> {
-    return this.api.query<Message[]>({ type: 'get-messages', payload: { roomId, limit, offset } });
+  getMessages(
+    roomId: string,
+    limit = 100,
+    offset = 0,
+    channelId?: string,
+    beforeTimestamp?: number
+  ): Promise<Message[]> {
+    return this.api.query<Message[]>({
+      type: 'get-messages',
+      payload: { roomId, limit, offset, channelId, beforeTimestamp }
+    });
   }
 
   getMessagesSince(roomId: string, sinceTimestamp: number): Promise<Message[]> {