Function writeMergedMailboxStateFile

src/proxy/mailbox/state.js:157–195

* Merge a partial state write with the latest on-disk state. * * Callers pass the keys they intentionally changed. Secret-bearing keys are * only written when they are in `updatedKeys`, so an old long-running * MailboxStore cannot overwrite a fresher Hub-rotated or divergence-cleared * secret t

(stateFile, nextState, updatedKeys)

 * @returns {Record<string, unknown>}
 */
function writeMergedMailboxStateFile(stateFile, nextState, updatedKeys) {
  const releaseLock = acquireStateFileLock(stateFile);
  try {
    const next = isPlainState(nextState) ? nextState : {};
    const disk = readMailboxStateFile(stateFile);
    const hasDiskState = isPlainState(disk);
    const merged = hasDiskState ? { ...disk } : {};
    const updatedSet = updatedKeys ? new Set(Array.from(updatedKeys)) : null;
    const keys = updatedSet ? Array.from(updatedSet) : Object.keys(next);
    const touchesNodeSecretTuple = keys.some((key) => MAILBOX_NODE_SECRET_TUPLE_KEY_SET.has(key));
    const preserveDiskNodeSecretTuple = touchesNodeSecretTuple
      && hasDiskState
      && isHubRotatedNodeSecretState(disk)
      && !isFullNodeSecretTupleUpdate(updatedSet);

    for (const key of keys) {
      if (MAILBOX_NODE_SECRET_STATE_KEY_SET.has(key) && hasDiskState && (!updatedSet || !updatedSet.has(key))) {
        continue;
      }
      if (
        MAILBOX_NODE_SECRET_TUPLE_KEY_SET.has(key) &&
        preserveDiskNodeSecretTuple &&
        !canApplyPartialNodeSecretTupleWrite(key, disk, next)
      ) {
        continue;
      }
      if (!Object.prototype.hasOwnProperty.call(next, key)) {
        delete merged[key];
        continue;
      }
      merged[key] = next[key];
    }

    replaceStateFile(stateFile, merged);
    return merged;
  } finally {
    releaseLock();
  }
}

module.exports = {
  PRIVATE_DIR_MODE,