removing it was wrong: the mobile player stopped playing. nothing in the web
read the header and /meta already carried durationSec, so it looked dead. it
was not — it is a documented part of the contract and something depended on it.
the header is back and the ffprobe is not. the value is read from the album's
meta.json, which is the same number ffprobe produced (the indexer got it from
ffprobe at index time), cached per album and keyed on the meta file's mtime so
a reindex invalidates it. 1.5ms cold, 0.1ms warm, against 50ms warm and 315ms
cold for the process spawn.
first pass looked for meta.json beside the audio; it lives under the sidecar's
own cache root mirroring the relative path. uses metaFilePath now rather than
re-deriving it.
verified against a real file: header present and equal to meta, 304 on
whole-file revalidation, 206 on range with a matching etag.
pastilhas
0e08aefad9