Function writeChatWithBoundary

src/node/services/historyService.test.ts:809–863

* Helper: write a chat.jsonl file with messages that include a compaction boundary. * Returns { preBoundaryIds, boundaryId, postBoundaryIds }.

(
    cfg: Config,
    workspaceId: string,
    opts: { preBoundaryCount: number; postBoundaryCount: number; epoch?: number }
  )

   * Returns { preBoundaryIds, boundaryId, postBoundaryIds }.
   */
  async function writeChatWithBoundary(
    cfg: Config,
    workspaceId: string,
    opts: { preBoundaryCount: number; postBoundaryCount: number; epoch?: number }
  ) {
    const workspaceDir = cfg.getSessionDir(workspaceId);
    await fs.mkdir(workspaceDir, { recursive: true });

    const epoch = opts.epoch ?? 1;
    const lines: string[] = [];
    const preBoundaryIds: string[] = [];
    const postBoundaryIds: string[] = [];
    let seq = 0;

    // Pre-boundary messages
    for (let i = 0; i < opts.preBoundaryCount; i++) {
      const id = `pre-${i}`;
      preBoundaryIds.push(id);
      lines.push(
        JSON.stringify({
          ...createMuxMessage(id, "user", `message ${i}`, { historySequence: seq++ }),
          workspaceId,
        })
      );
    }

    // Compaction boundary message
    const boundaryId = `boundary-${epoch}`;
    lines.push(
      JSON.stringify({
        ...createMuxMessage(boundaryId, "assistant", "Compaction summary", {
          historySequence: seq++,
          compactionBoundary: true,
          compacted: "user",
          compactionEpoch: epoch,
        }),
        workspaceId,
      })
    );

    // Post-boundary messages
    for (let i = 0; i < opts.postBoundaryCount; i++) {
      const id = `post-${i}`;
      postBoundaryIds.push(id);
      lines.push(
        JSON.stringify({
          ...createMuxMessage(id, "user", `post message ${i}`, { historySequence: seq++ }),
          workspaceId,
        })
      );
    }

    await fs.writeFile(path.join(workspaceDir, "chat.jsonl"), lines.join("\n") + "\n");
    return { preBoundaryIds, boundaryId, postBoundaryIds };
  }

  describe("getHistoryFromLatestBoundary", () => {
    it("should return full history when no boundary exists", async () => {