asset_engine consumer needed to render kokoro-captioned, whose wire
shape is a JSON envelope carrying base64-encoded audio plus a
structured timestamps array. Modeling it as response.type=json
would force either a per-service-id renderer (forbidden by
brief §1.7) or extending the closed response-type vocabulary
(forbidden by brief §2.2 without a coordinated bump).
Resolution (per althing thread 01KRCF4W66X3): keep response.type
closed at the existing six values and decompose at the response
*field* level instead — the same flexibility seam already used by
mime / mime_from_field / output_field. Adds three optional keys:
- audio_field: JSON key holding base64-encoded audio bytes
- audio_format_field: JSON key holding the decoded audio MIME
- timestamps_field: JSON key holding a structured timestamps array
(independent of type, declared by any service emitting time-
aligned markers)
Validators in CatalogResponse enforce sane combinations:
- audio_field requires response.type=audio
- audio_field forbids mime_from_field
- audio_format_field requires audio_field
This is additive and backward-compatible — no catalog_version bump,
existing services parse unchanged. CATALOG-CONTRACT.md updated with
the new rows in the response-field table and a versioning-policy
row codifying that adding optional keys to response: doesn't bump.
kokoro-captioned re-shaped to use the new schema:
response:
type: audio
audio_field: audio
audio_format_field: audio_format
timestamps_field: timestamps
And marked status: experimental until the asset_engine consumer's
audio-with-timestamps renderer ships.
JSON Schema regenerated to reflect the new Pydantic shape.
Pydantic-model side of this change lives in the asset_engine repo
at src/asset_engine/catalog.py — committed there separately.
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