Adds the spec for running one build against two Jellyfin generations, plus the
research report that establishes what actually differs — with a source URL per
claim, and an explicit section for what could NOT be established.
The framing the spec started from was wrong, which is the most useful thing here:
Jellyfin 11.0 does not exist and never did. With 12.0 the project dropped the
leading "10" from its scheme, so what would have been 10.12.0 shipped as 12.0
and the server reports Version: "12.0.0". The two live generations are 10.11.x
and 12.x — one release-branch step apart, not two majors. 12.0 became stable
on 2026-09-08.
The delta turned out far smaller than assumed, and almost none of it is a
version branch:
- X-Emby-Authorization and the api_key query parameter are disabled by default
in 12.0, including on upgraded servers via a migration. This is the one
genuinely breaking change, and the fix is a rename: Authorization and ApiKey
are ungated on both generations.
- GetItems now defaults recursive to true for a library parent with
IncludeItemTypes, so the same request returns a different result set. Fixed
by stating Recursive explicitly.
- The /Users/{userId}/... family survives. Six routes were removed in total;
none are ones this client calls.
- BaseItemDto is purely additive. DeviceProfile, PlaybackInfo and
PublicSystemInfo are byte-identical between the two tags.
The generalisable lesson, recorded in the spec: most of a version delta is fixed
by writing the request correctly for both generations rather than by branching
on the version. A flag is a silent branch that outlives the reason it was added.
Allocates UR-085, IR-035, JA-037, DR-279..DR-288 and IT-019..IT-026. DR-287 and
DR-288 did not exist when the spec was written — they are what the research
turned up.
Also corrects docs/specs/README.md, whose "next free requirement ids" line was
stale by five, two and forty-seven.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dtourolleandClaude Opus 5
b1844f673e