Files
hermes-agent/tests/gateway
gshall 6210642297 fix(signal): detect M4A-branded voice notes so iOS audio reaches STT
iOS Signal delivers voice notes as MP4-container AAC carrying an audio
ftyp brand ("M4A "). `_guess_extension()` returned ".mp4" for every
`ftyp` file regardless of brand, so those attachments were cached as
documents instead of audio and STT rejected the upload:

    API error: Error code: 400 - Invalid file format.
    Supported formats: ['flac','m4a','mp3','mp4','mpeg','mpga','oga',
    'ogg','wav','webm']

Read the 4-byte brand at offset 8 and return ".m4a" for audio brands
("M4A ", "M4B ") so they satisfy `_is_audio_ext()` and route to
`cache_audio_from_bytes()`. Video brands (isom/mp42/avc1/qt) still
return ".mp4".

This mirrors the existing brand/form-type disambiguation already used
in this function for RIFF (WEBP vs WAVE) and for ADTS AAC vs MP3.

Verified against a real iOS Signal voice note: pre-fix the upload was
rejected with the 400 above; post-fix the same bytes transcribe
successfully.
2026-07-28 11:52:44 -07:00
..