### JPEG AI — a byte-exact codestream→RGB decoder (`jpegai_decode::decode`)

- `wai::jpegai_decode::decode(codestream, &DecoderWeights, &NormTables) -> Rgb`
  reconstructs an ISO/IEC 6048 JPEG-AI codestream to RGB through a fully
  integer entropy front end and a deterministic value/synthesis/post-filter
  path — one pinned reconstruction, reproducible byte-for-byte on every machine,
  so the decoded pixels have a portable hash. No per-image fixtures: every
  per-image quantity is derived from the bitstream; only checkpoint constants
  come from a sink-supplied model bundle.
- Determinism profile: the entropy decode (mANS), the dequant, and the derived
  entropy inputs (skip mask, σ index, RVS band, dequant gain) are integer-exact
  against the reference; the PTQ value/synthesis stages are deterministic and
  land within 1 LSB of the ISO reference decoder. Distinct from the in-house
  `wai.neural.int_*` codecs (all-i64, hash-portable): this decodes a published
  external standard's codestream deterministically.
- Modules: `jpegai_decode` (the composed entry point) over `jpegai_bitstream`,
  `jpegai_mans`, `jpegai_pipeline`, `jpegai_synthesis`, `jpegai_icci`
  (feature `neural_int`). Inputs are regenerable via
  `tools/wai_jpegai_build_e2e_inputs.py` from the JPEG-AI reference-software
  assets, which are kept locally and are not in this repository; the extraction is
  published under WAI's versioned models root (`jpegai/v1/`). The whole chain —
  codestream → RGB — is exercised end to end against the reference PNG by
  `wai-jpegai-e2e.yml`, which fetches those inputs pinned by SHA-256.

