Batch-request Builder and Result Joiner

• Pinned OpenAI Batch wire subset: unique custom_id, POST, one selected endpoint/model and object body. Local IDs are nonblank strings up to 128 bytes.
• Build sources carry custom_id/body; output adds method/url. Required model and basic messages/input shapes are checked; remaining endpoint/model options are passed through without full compatibility claims. Streaming is rejected.
• Join preserves request order, matches custom_id exactly, labels missing/error/invalid/duplicate rows, keeps duplicate result groups and reports unmatched results. Request validation errors prevent a request/join file export.
• Use combined output/error files for a full join. At most 2,000 rows per source; 1 MiB each, 128 KiB per row. Nothing is uploaded, retried or billed.
• Source: https://developers.openai.com/api/docs/guides/batch
• Original input is preserved. Explicit exports only; nothing is submitted to a provider or training service.
• Submitted input is processed without history. Public release and MCP access remain tracked separately.

Execution budget: 5s; output limit: 4096 KiB. Browser worker startup has a separate 3s allowance.