Method _updateLogFile

packages/core/src/core/logger.ts:163–227

(
    entryToAppend: LogEntry,
  )

  }

  private async _updateLogFile(
    entryToAppend: LogEntry,
  ): Promise<LogEntry | null> {
    if (!this.logFilePath) {
      console.debug('Log file path not set. Cannot persist log entry.');
      throw new Error('Log file path not set during update attempt.');
    }

    let currentLogsOnDisk: LogEntry[];
    try {
      currentLogsOnDisk = await this._readLogFile();
    } catch (readError) {
      console.debug(
        'Critical error reading log file before append:',
        readError,
      );
      throw readError;
    }

    // Determine the correct messageId for the new entry based on current disk state for its session
    const sessionLogsOnDisk = currentLogsOnDisk.filter(
      (e) => e.sessionId === entryToAppend.sessionId,
    );
    const nextMessageIdForSession =
      sessionLogsOnDisk.length > 0
        ? Math.max(...sessionLogsOnDisk.map((e) => e.messageId)) + 1
        : 0;

    // Update the messageId of the entry we are about to append
    entryToAppend.messageId = nextMessageIdForSession;

    // Check if this entry (same session, same *recalculated* messageId, same content) might already exist
    // This is a stricter check for true duplicates if multiple instances try to log the exact same thing
    // at the exact same calculated messageId slot.
    const entryExists = currentLogsOnDisk.some(
      (e) =>
        e.sessionId === entryToAppend.sessionId &&
        e.messageId === entryToAppend.messageId &&
        e.timestamp === entryToAppend.timestamp && // Timestamps are good for distinguishing
        e.message === entryToAppend.message,
    );

    if (entryExists) {
      console.debug(
        `Duplicate log entry detected and skipped: session ${entryToAppend.sessionId}, messageId ${entryToAppend.messageId}`,
      );
      this.logs = currentLogsOnDisk; // Ensure in-memory is synced with disk
      return null; // Indicate that no new entry was actually added
    }

    currentLogsOnDisk.push(entryToAppend);

    try {
      await fs.writeFile(
        this.logFilePath,
        JSON.stringify(currentLogsOnDisk, null, 2),
        'utf-8',
      );