Method getMessagesForCompactionEpoch

src/node/services/historyService.ts:882–944

(
    workspaceId: string,
    metadata: CompactionCompletionMetadata
  )

  }

  async getMessagesForCompactionEpoch(
    workspaceId: string,
    metadata: CompactionCompletionMetadata
  ): Promise<Result<{ messages: MuxMessage[]; summary: MuxMessage }>> {
    assert(
      typeof workspaceId === "string" && workspaceId.trim().length > 0,
      "workspaceId is required"
    );
    assert(
      metadata.workspaceId === workspaceId,
      "compaction metadata workspace must match request"
    );
    assert(
      isNonNegativeInteger(metadata.summaryHistorySequence),
      "summaryHistorySequence must be a non-negative integer"
    );

    try {
      const messages: MuxMessage[] = [];
      let summary: MuxMessage | undefined;
      const lowerBound = metadata.previousBoundaryHistorySequence;
      const seenHistorySequences = new Set<number>();

      // The just-compacted epoch can straddle chat-archive.jsonl and chat.jsonl after
      // sealed-history rotation, so scan the full logical history under the workspace
      // lock; otherwise a concurrent boundary rotation can move rows between files mid-scan.
      const iteration = await this.fileLocks.withLock(workspaceId, () =>
        this.iterateFullHistory(workspaceId, "forward", (chunk) => {
          for (const message of chunk) {
            const sequence = message.metadata?.historySequence;
            if (!isNonNegativeInteger(sequence)) continue;
            if (seenHistorySequences.has(sequence)) continue;
            seenHistorySequences.add(sequence);

            if (
              sequence === metadata.summaryHistorySequence &&
              message.id === metadata.summaryMessageId
            ) {
              summary = message;
              continue;
            }

            if (sequence >= metadata.summaryHistorySequence) continue;
            if (lowerBound !== undefined && sequence <= lowerBound) continue;
            if (message.id === metadata.compactionRequestMessageId) continue;
            if (isDurableContextBoundaryMarker(message)) continue;
            messages.push(message);
          }
        })
      );
      if (!iteration.success) {
        return Err(`Failed to read compaction epoch messages: ${iteration.error}`);
      }

      if (summary === undefined) {
        return Err(`Compaction summary not found: ${metadata.summaryMessageId}`);
      }