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📝 WalkthroughWalkthroughStatic playback now uses stable reservation keys, PostgreSQL coordination, device-aware aliases, legacy duplicate reconciliation, and selected-media recovery. CI adds PostgreSQL-backed race tests and reservation benchmarks. ChangesStatic playback session coordination
Estimated code review effort: 4 (Complex) | ~45 minutes Merge Risk: 🟠 High · up to Concurrent playback and recovery requests can lose durable state, affect another device’s playback, or start the wrong media file. These issues should be fixed before merge. Sequence Diagram(s)sequenceDiagram
participant Client
participant HandleVideoStream
participant CompatPlaybackStore
participant PostgreSQL
participant UpstreamPlayback
Client->>HandleVideoStream: send static playback request
HandleVideoStream->>CompatPlaybackStore: reserve static playback session
CompatPlaybackStore->>PostgreSQL: lock and create or reuse session
PostgreSQL-->>CompatPlaybackStore: return durable session
CompatPlaybackStore-->>HandleVideoStream: return reserved session
HandleVideoStream->>UpstreamPlayback: start or attach playback
Suggested reviewers: 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 23.08% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 39 functions across 7 files. (1 skipped: 1 unsupported.)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Inline comments:
In `@internal/jellycompat/playback_sessions_postgres.go`:
- Around line 930-938: Update the caller’s pending-update handling in Update so
consumePendingUpdates is invoked only when the update result has both a non-nil
committed session and err == nil. Preserve the authoritative-session return path
for errUpstreamReplaced in updateDB without consuming or dropping pending
closures when the transaction rolls back.
In `@internal/jellycompat/streams.go`:
- Around line 2026-2030: Update the fallback resolution around
FindFinalizableByClientPlaySessionID so that when req.DeviceId is present, only
a session with the exact matching client device is accepted; reject legacy
sessions with an empty or different ClientDeviceID rather than allowing progress
or stop reports to proceed. Add a regression test covering an empty-device
legacy session.
- Line 3113: In the HandleVideoStream flow, assign ps.SelectedMediaFileID from
matched.FileID before calling GetOrCreateStatic so concurrent reservation checks
see the selected source. Keep the existing staticPlaybackKey assignment and
reservation behavior unchanged.
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Run ID: 2c618d08-02e4-4073-99f9-5a215493cb84
📒 Files selected for processing (8)
.github/workflows/ci.ymlinternal/jellycompat/playback_report_liveness_test.gointernal/jellycompat/playback_sessions.gointernal/jellycompat/playback_sessions_postgres.gointernal/jellycompat/playback_sessions_postgres_test.gointernal/jellycompat/playback_static_directplay_test.gointernal/jellycompat/playback_static_duplicates.gointernal/jellycompat/streams.go
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This was referenced Sep 3, 2026
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Problem
Related issue: #922. Companion reporting PR: #924.
During live playback verification, I saw duplicate Activity rows for what appeared to be one Jellyfin-compatible client play. Matching titles alone were not enough to merge them: they could have represented separate devices, plays, profiles, or media editions.
The static path had a concrete creation race. Parallel
Static=truerequests could both miss the session lookup and create different compatibility records before either attached its native playback session. Subsequent progress/recovery lookups could then be ambiguous. A separate recovery risk was selecting the first media source after the originally selected edition had been lost from the lookup context.Solution
Reserve one static playback identity atomically
A static reservation is keyed by the authenticated compatibility token, profile, explicit device identity, client play ID, content item, and selected source. The fields are framed before hashing; a title or route by itself is never the deduplication key.
GetOrCreateStaticis implemented by both stores.PostgreSQL's advisory-lock documentation describes why a transaction-scoped lock fits this reservation: release follows transaction completion, including rollback, rather than depending on a later application unlock.
Preserve the winning native-session attachment across API instances
The existing native attachment path already checks which upstream session it observed before creating a replacement. The durable update layer could swallow that closure's
errUpstreamReplacedrejection after another API instance won, leaving the stale writer believing its speculative attachment succeeded.I now return that specific rejection with the authoritative locked row, replace the speculative cached state with the winner, and do not queue the losing closure for a later persistence retry. Unrelated pending updates survive a rejected attachment transaction and are consumed only after a successful commit. The caller can follow its existing losing-attachment cleanup/adoption path. Other update-error behavior is unchanged.
This is covered by a real-PostgreSQL regression using two independent durable stores with stale cached state, followed by a fresh third store. All must retain the same winner, and the losing store must have no queued attachment retry.
Resolve recovery by device and selected edition
SelectedMediaFileIDin the reservation before native attachment. A concurrent range request with an omitted source or item-as-source alias therefore retains the selected edition even during that attachment window.Reconcile only provable legacy duplicates
Legacy repair is deliberately narrower than new reservation:
The oldest record is the stable canonical mapping. The other records are retained with a terminal/superseded marker; unknown JSON fields are preserved. Superseded records cannot return through stream lookup, terminal finalization, or restart recovery. Repair does not manufacture a stop/scrobble event or manually delete playback history.
If source identity is missing, contradictory, or unavailable, historical rows remain untouched. Explicit device identity can still resolve the current play without guessing what those older records meant. This was important in the live case: unproven old records were not merged to make the dashboard count look better.
Scope and rollout
This is the Jellyfin-compatible static-session lifecycle contribution, not the dashboard vocabulary change. It needs no new schema migration; the added fields live in the existing compatibility-session JSON. Reporting/output-format changes are isolated in #924.
Native Android/Apple decoder advertisement, V3 planning, transcoding policy, and the successful Original HTTP playback path are unchanged. This does not require a new native client build. No deployment configuration or unrelated production-fork changes are included.
Reservation prevention requires the participating API instances to run the new static path. An older instance can still create an unreserved row during a mixed-version rollout; the conservative legacy rules are not a promise to identify every such historical duplicate.
The equivalent static reservation/device/edition behavior was tested on the deployed fork. The cross-instance stale-attachment correction and the pre-attachment edition/device-fallback edge-case fixes added during upstream review are new to this contribution, not claimed as a new production deployment. The working production server was not changed while preparing these PRs.
Validation
Latest follow-up:
a6dfa3924a5c013103939a53dcfc30cb316bdd43. The new edition-reservation and device-fallback regressions failed before their fixes and now pass with the nearby targeted tests. The full upstream CI rerun for this head is pending; the previously completed gate is recorded below.Full upstream repository CI passed on
437a56b13e3a2f9030d9a397e387d49a2af6fb5a:make test-go.make test-web: 358 test files, 3,062 tests passed.go test -race. This is additional coverage beyond the normal suite, whose database-dependent tests otherwise skip without a test DSN.Actual database regression output:
The focused in-memory/static/report tests also passed locally; heavy builds and the full gate ran on GitHub-hosted runners, not the Mac or production server. No production database was used for the tests or benchmarks.
The targeted regressions cover:
These concurrency assertions test identity correctness; they are not measurements of client playback startup.
The final review additionally found that a rejected attachment could incorrectly consume unrelated pending updates. A new regression checks rollback retention and a later successful retry. The follow-up correction at
437a56b1passed the full upstream CI gate, including the new rollback-retention test. The benchmark below retains its exact original measured commit; it is not relabeled as a later measurement.Reservation microbenchmarks
Measured on the exact contribution commit
c9a34f3152b6f3dbd053cb1401cab8ffb6f7ee1bby GitHub Actions / Go: Go 1.26.4, Linux/amd64, AMD EPYC 7763 host CPU, benchmark suffix-4, PostgreSQL 17 in a disposable local service container. Five 250 ms benchmark samples per case, not five playback attempts.In-memory lookup scaling (one block ≈ 0.5 µs/op; same 0–12 µs scale):
The durable median is 1.196 ms/op for reservation reuse, including the transaction, lock, exact lookup, decoding and cache revalidation. It is not FFmpeg startup or client first frame. The memory cases measure a scan in a populated store; the durable case has one reservation and is not a thousand-row database/load test. These are measurements of the new correctness path, not a claimed speedup over the previous non-atomic path.
Actual CI benchmark output (all samples)
Wider playback work and startup evidence
The linked reporting PR contains the complete sanitized pipeline history, timing table, and references to merged Android #250, #262, #268, #275, #282, #284 and related server work. Those changes are present in the published Android build 16 release; this compatibility-session fix does not claim authorship of other contributors' work or make Android decoding depend on Jellyfin-compatible session reservations.
The live viewer's approximately five-second-to-one–two-second improvement and no-buffering feedback remains an attributed observation. The same-file retained build 16 sample records 3,917 ms for client plan installation to first frame and 21 ms for server session/transport commit. Those are different timer scopes. This PR makes no one–two second startup performance claim.
Review, risks and limits
The adversarial review traced reservation through storage, native attachment, cached state, progress/stop resolution, source selection, and restart handling. It found the swallowed cross-instance attachment rejection; this PR fixes it and adds the regression described above. I checked token/profile/device/source separation, lock framing, expiry/terminal state, missing metadata, failure behavior, and legacy records that must not be guessed away. The repository's automatic CodeRabbit review also identified the pre-attachment selected-source gap and unscoped legacy-device fallback. I verified both with failing regressions before applying the focused fixes; review suggestions were not accepted without checking the actual paths.
The in-memory reservation lookup remains linear in the active store size. The durable query is bounded by the existing token index, not a new global scan or migration. Benchmark results characterize those paths; they do not establish production throughput, cross-region database latency, or end-to-end playback speed.
Ambiguous historical records may remain visible until normal lifecycle expiry. That is safer than merging distinct plays or choosing a different edition. No account names, IP addresses, media titles, real session/device IDs, paths, credentials, or private logs are included.
AI Disclosure
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