ADR 0002: One-Pass Application Body Contract

• Status: Accepted
• Date: 2026-07-18
• Gate: LF-2 before buffered HTTP integration

Decision

Register one llm application handler and delegate to a typed integration. The integration runs pre-body handlers, validates route/method/media type, content encoding, declared length, and deadline, then captures/decompresses one bounded Bytes body exactly once.

If access control appeared earlier in the selected chain, body-aware authorization receives that captured byte sequence before LLM JSON parsing, alias policy, transforms, client selection, or provider work. Parsing and all later content adapters borrow or clone the same immutable Bytes; they do not read the downstream stream again. Every error and downstream disconnect cancels/finalizes the request.

Generic tokenize/detokenize handlers are not assumed to have consumed the body. Content transforms require an explicit LLM adapter.

Evidence

benchmarks/llm-gateway/evidence/body-capture.json records bounded, chunked, one-pass capture and proves authorization precedes parsing while both observe the same digest. The production gateway already demonstrates the relevant ordering in GatewayProxy::request_body_filter; LF-4 must bind this ADR to the new application handler with an integration test.