Function appendTranscriptEvents

packages/core/src/interaction/session-transcript.ts:60–90

(
  projectRoot: string,
  sessionId: string,
  buildEvents: (context: {
    readonly events: ReadonlyArray<TranscriptEvent>;
    readonly nextSeq: number;
  }) => ReadonlyArray<TranscriptEvent> | Promise<ReadonlyArray<TranscriptEvent>>,
)

}

export async function appendTranscriptEvents(
  projectRoot: string,
  sessionId: string,
  buildEvents: (context: {
    readonly events: ReadonlyArray<TranscriptEvent>;
    readonly nextSeq: number;
  }) => ReadonlyArray<TranscriptEvent> | Promise<ReadonlyArray<TranscriptEvent>>,
): Promise<TranscriptEvent[]> {
  const key = `${projectRoot}:${sessionId}`;
  const previous = appendQueues.get(key) ?? Promise.resolve();
  let result: TranscriptEvent[] = [];

  const next = previous.then(async () => {
    const events = await readTranscriptEvents(projectRoot, sessionId);
    const nextSeq = events.reduce((max, event) => Math.max(max, event.seq), 0) + 1;
    const built = await buildEvents({ events, nextSeq });
    result = built.map((event) => TranscriptEventSchema.parse(event));
    if (result.length === 0) return;

    await mkdir(sessionsDir(projectRoot), { recursive: true });
    await appendFile(
      transcriptPath(projectRoot, sessionId),
      `${result.map((event) => JSON.stringify(event)).join("\n")}\n`,
      "utf-8",
    );
  });

  appendQueues.set(key, next.catch(() => undefined));
  await next;
  return result;
}

function transcriptRoleForMessage(message: AgentMessage): TranscriptRole | null {
  if (!message || typeof message !== "object" || !("role" in message)) return null;