Review follow-ups before QA:
- Editor: getMediaIncompatibilityReason rejects a PDF on non-document content types, so the schedule gate and variant auto-snap match the backend rule (compliance i18n in en/es/pt-BR)
- MCP UpdatePostTool: validate effective content_type vs stored media on schedule, closing the schedule-without-content_type gap; share entriesForUpdate/errorsFor with the API path
- Tests: Platform allowedMediaTypes contains Document, URL-attach of a PDF (LinkedIn ok / TikTok rejected), multi-platform PDF rejection, document init-failure/missing-URN, Page publisher PROCESSING_FAILED