Function getCompactionMetadataToPreserve

src/node/services/historyService.ts:44–96

(
  workspaceId: string,
  existingMessage: MuxMessage,
  incomingMessage: MuxMessage
)

}

function getCompactionMetadataToPreserve(
  workspaceId: string,
  existingMessage: MuxMessage,
  incomingMessage: MuxMessage
): Partial<MuxMetadata> | null {
  const existingMetadata = existingMessage.metadata;
  if (existingMetadata?.compactionBoundary !== true) {
    return null;
  }

  if (existingMessage.role !== "assistant") {
    // Self-healing read path: boundary metadata on non-assistant rows is invalid.
    log.warn("Skipping malformed persisted compaction boundary during history update", {
      workspaceId,
      messageId: existingMessage.id,
      reason: "compactionBoundary set on non-assistant message",
    });
    return null;
  }

  if (incomingMessage.role !== "assistant") {
    return null;
  }

  if (!hasDurableCompactionBoundary(existingMetadata)) {
    // Self-healing read path: malformed boundary metadata should not be propagated.
    log.warn("Skipping malformed persisted compaction boundary during history update", {
      workspaceId,
      messageId: existingMessage.id,
      reason: "compactionBoundary missing valid compacted+compactionEpoch metadata",
    });
    return null;
  }

  if (hasDurableCompactionBoundary(incomingMessage.metadata)) {
    return null;
  }

  const preserved: Partial<MuxMetadata> = {
    compacted: existingMetadata.compacted,
    compactionBoundary: true,
    compactionEpoch: existingMetadata.compactionEpoch,
  };

  if (
    isCompactionSummaryMetadata(existingMetadata.muxMetadata) &&
    !isCompactionSummaryMetadata(incomingMessage.metadata?.muxMetadata)
  ) {
    preserved.muxMetadata = existingMetadata.muxMetadata;
  }

  return preserved;
}
/**
 * HistoryService - Manages chat history persistence and sequence numbering
 *