harness/ — cross-implementation conformance runner

Drives every reference implementation in impl/ against the corpus (test-vectors/v1/conformance-corpus.json) via the subprocess contract: a length-prefixed JSON request {op, in} on stdin → {out | error | skipped} on stdout.

• adapters/<lang>/ — per-language conformance adapters (10 languages).
• runner/ — the Go runner that spawns an adapter, feeds it the corpus, and grades the responses (golden-match / MUST-reject / case-insensitive comparison).
• INSTRUCTIONS.md, CONFORMANCE-README.md — the harness contract and how to run it.

A consuming product's own conformance gate (an in-process conformance test driving its vendored impl against a pinned corpus copy) lives in that product; this directory is the cross-implementation runner for the reference impls themselves.