Keep the playlist context
A URI named chunk-900.ts does not prove that its HLS media sequence number is 900. RFC 8216 does not require the number to appear in the URI. A filename can reflect an encoder counter, a clock, a storage convention or an opaque identifier.
In an invented snapshot whose MEDIA-SEQUENCE is 50, the first listed segment has sequence 50, even if its filename contains 900. The next listed media segment has sequence 51. Save the tag and ordered entries together; a directory listing cannot reconstruct all of that context.
Compare two snapshots
Suppose the next snapshot starts at sequence 52. Check which earlier entries were removed and which new entries appeared, using their ordered positions and resolved resource identities. A jump in a filename suffix is not sufficient evidence that the manifest skipped a playable segment.
Keep the fetch time and playlist URL with each snapshot. Comparing two differently cached responses as though they were consecutive origin updates can create a false regression. When reporting an apparent reversal, include response freshness information and the actual bodies.
Handle restarts deliberately
After an origin or packager restart, inspect sequence continuity, media identity and timeline state separately. Reusing a familiar filename while changing its bytes can introduce a cache problem even when the sequence tag moves forward. Renaming a resource also does not automatically repair an inconsistent timeline.
For a release record, preserve the before-and-after snapshots rather than a screenshot of one filename. That small artifact allows another reviewer to reproduce the reasoning. It contains no need for private credentials; remove access-bearing query parameters before sharing it.
Questions answered
Must the segment URI contain its sequence number?
No. Read the media sequence tag and the segment's position in that playlist.
Does a numeric filename gap prove missing media?
No. First compare the ordered playlist entries and the actual resources they identify.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.