Method migrateWorkspaceId

src/node/services/historyService.ts:2000–2050

* Migrate all messages in chat.jsonl to use a new workspace ID * This is used during workspace rename to update the workspaceId field in all historical messages * IMPORTANT: Should be called AFTER the session directory has been renamed

(oldWorkspaceId: string, newWorkspaceId: string)

   * IMPORTANT: Should be called AFTER the session directory has been renamed
   */
  async migrateWorkspaceId(oldWorkspaceId: string, newWorkspaceId: string): Promise<Result<void>> {
    return this.fileLocks.withLock(newWorkspaceId, async () => {
      try {
        // Migrate the sealed archive first so a crash mid-migration never leaves
        // the active file pointing at a stale-ID archive.
        const archiveMessages = await this.readArchivedHistory(newWorkspaceId);
        if (archiveMessages.length > 0) {
          await writeFileAtomic(
            this.getChatArchivePath(newWorkspaceId),
            this.serializeHistoryEntries(archiveMessages, newWorkspaceId)
          );
        }

        // Read messages from the NEW workspace location (directory was already renamed).
        // Structural rewrite requires full file content.
        const messages = await this.readChatHistory(newWorkspaceId);
        if (messages.length === 0) {
          // No active messages to migrate, just transfer the sequence counter.
          // Floor it with the archive max: an archive-only session (active file
          // deleted/truncated) renamed in a fresh process has no cached counter,
          // and seeding 0 would reuse archived historySequence values.
          const oldCounter = this.sequenceCounters.get(oldWorkspaceId) ?? 0;
          const archiveFloor = (await this.getArchiveTailMaxSequence(newWorkspaceId)) + 1;
          this.sequenceCounters.set(newWorkspaceId, Math.max(oldCounter, archiveFloor));
          this.sequenceCounters.delete(oldWorkspaceId);
          return Ok(undefined);
        }

        // Rewrite all messages with new workspace ID
        const newHistoryPath = this.getChatHistoryPath(newWorkspaceId);
        const historyEntries = this.serializeHistoryEntries(messages, newWorkspaceId);

        // Atomic write prevents corruption if app crashes mid-write
        await writeFileAtomic(newHistoryPath, historyEntries);

        // Transfer sequence counter to new workspace ID
        const oldCounter = this.sequenceCounters.get(oldWorkspaceId) ?? 0;
        this.sequenceCounters.set(newWorkspaceId, oldCounter);
        this.sequenceCounters.delete(oldWorkspaceId);

        log.debug(
          `Migrated ${messages.length} messages from ${oldWorkspaceId} to ${newWorkspaceId}`
        );

        return Ok(undefined);
      } catch (error) {
        const message = getErrorMessage(error);
        return Err(`Failed to migrate workspace ID: ${message}`);
      }
    });
  }
}