The pre-fix wrapper at stacks/ace-step/infer-api.py returned a JSON
{output_path: "..."} reference to a file written inside the
container at /app/outputs/. That path was unreachable from outside
the container — every consumer got 134 bytes of JSON-pretending-to-
be-WAV instead of audio. Surfaced by the asset_engine consumer's
end-to-end smoke (althing thread 01KRCJF7NGMXYE9F62Q1A6KFD4 msg 5);
my own earlier smoke missed it because I checked HTTP=200 and stopped
reading instead of inspecting the response body.
Wrapper now reads back the file the pipeline writes and streams the
bytes via fastapi.responses.Response with media_type set from the
audio_format request field (audio/wav | audio/mpeg | audio/flac).
The in-container path is exposed via X-Output-Path header for log
correlation but is no longer load-bearing.
Verified end-to-end against live ace-step on irv-ml1:
POST /generate -> HTTP 200 in 80s
content-type: audio/wav
content-length: 945226
x-output-path: /app/outputs/output_cfe87d1d....wav
$ file response.wav
RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit,
stereo 48000 Hz
Catalog: ace-step bumped version 3 -> 4. Dropped
response.output_field (no longer applicable). reproducibility.notes
expanded to record both the v2 18-arg-tuple fix and this v4
inline-streaming change so the history is auditable from the
catalog itself.
Stale ACEStepOutput Pydantic model left in infer-api.py for now —
unused but small; future cleanup.
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