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fix(engine): play() resumes a forward-only source instead of looping on a rejected rewind - #15
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Quick104 merged 5 commits intoOct 14, 2026
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A forward-only source (one chunked response with no ranges, a sequential origin, a one-shot custom reader) has one read position. Three paths tried to move it, and each ended the session: the reposition flushes the packets the demuxer has queued, the reader cannot rewind to read them again, libavformat reports "partial file", and the read loop stops. - load with a start position: the software host no longer seeks. A start inside the clock anchor's 2 s tolerance is reached by decoding forward from the stream origin; a later one is dropped and playback begins at the origin. A host resuming a server-seeked progressive stream hit the seek on every resume, because the server starts the stream at the preceding keyframe and asks the player to skip the pre-roll. - seek: rejected at the engine with the new SeekEvent.Rejection.sourceNotSeekable, before the target is clamped to the container's duration or published. The host refuses too, before any decoder or queue is disturbed. - play: no rewind to zero. A fragmented MP4 served as one response reports its first fragment as the duration, so the playhead read as parked at the end and the first play after a pause ended playback. Seekable and live sources are unchanged. The audio-only host still repositions a forward-only source. Refs Silo-Server/silo-apple#656 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Check name Status Explanation Linked Issues check Check skipped because no linked issues were found for this pull request. Out of Scope Changes check Check skipped because no linked issues were found for this pull request. Title check The title clearly and concisely describes the main change: preventing repeated rejected rewinds so play() resumes forward-only sources. Description check The description directly explains the forward-only playback issue, the engine and software reload changes, testing, and documented behavior.
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Docstring coverage is 5.56% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 18 functions across 6 files. (2 skipped: 2 unsupported.)
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Review comments at @Sources/AetherEngine/AetherEngine.swift:
- Around line 5059-5064: Update the forward-only refusal guard in the seek flow
to close an in-flight deferred ticket with a rejected result when replay is
refused. Preserve the standalone emitSeekRejected behavior when no deferred
ticket is active.
Review comments at @Sources/AetherEngine/SeekEvent.swift:
- Line 46: Update the release notes for the public `SeekEvent.Rejection`
addition to identify `sourceNotSeekable` as a source-breaking change for
exhaustive switches and document that clients must handle the new case; follow
the existing `.ended` note for `PlaybackState` in `CHANGELOG.md`.
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CHANGELOG.mdSources/AetherEngine/AetherEngine.swiftSources/AetherEngine/Native/SoftwarePlaybackHost.swiftSources/AetherEngine/SeekEvent.swiftTests/AetherEngineTests/SeekToEndOfMediaTests.swiftTests/AetherEngineTests/SoftwareHostForwardOnlyStartTests.swift
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… its replay A seek stashed during load is replayed once the session settles, with its deferred ticket still open. The forward-only rejection returned without closing it, so isSeeking stayed latched over a session that played on. Close the ticket with the rejection; a seek with no stash still gets the standalone event. Also say in the changelog that SeekEvent.Rejection.sourceNotSeekable is a new public case an exhaustive switch has to handle. Refs Silo-Server/silo-apple#656 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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… would (Sodalite#173) The first round ended a cancelled load with a host stop(), which dropped the native host and AVPlayer (Silo-Server#15) and an AE#158 handover item that the next load's own teardown would have kept, so every zap that cancelled a load lost AVPlayer reuse. The cancelled generation is now ended with the supersede teardown (native host and handover item kept, panel mode kept, no audio-session release) plus the published reset to .idle. A load following an AE#629 rebuild no longer cancels the rebuild's Task, which the retained-reader branch never observed; it ends the rebuild's generation instead, and the rebuild unwinds at its own checkpoints. A load cancelled before it began withdraws a reroute's superuser404notfound#361 continuation, and AVIOReader no longer logs streaming mode for a closed size ladder. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Main now covers two of the three paths this branch changed, so the conflicts resolve to main's side: - seek: main rejects a seek on a forward-only VOD with the same SeekEvent.Rejection.sourceNotSeekable and closes a stashed seek (c3183ee), and its Demuxer refuses the reposition itself, keeping the probe's packets (19ee344). The engine guard, the host refusal and the duplicate enum case are dropped. - load: main clears the start position of a forward-only VOD before any host loads, so the software host's start plan never saw a start. The plan and its tests are dropped. The play() rewind is still missing on main and follows in the next commit. Refs Silo-Server/silo-apple#656 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…g it A fragmented MP4 served as one response reports its first fragment as the container duration. Past it the playhead reads as parked at the end, so play() asked for a rewind to 0, seek(to:) rejected it as sourceNotSeekable, and play() asked again: thousands of rejected seeks a second while playback stayed paused. shouldRewindBeforePlay now skips a source that cannot be repositioned. The rule comes from one place, sourceIsForwardOnly, which canSeek and seek(to:) also read, so the native sequential-origin path is covered as well as the software one. Refs Silo-Server/silo-apple#656 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…uild keeps seekability play() rewound a VOD parked at its end and then called itself again. When seek(to:) rejected the rewind nothing moved, and the same rewind was asked for without end: an errored session parked at its end (noActiveSession) looped exactly as a forward-only source did. The rewind task now resumes the transport once, and drops it when a newer load has started. After an audio switch or reload on the software path isSourceSeekable stayed nil: stopInternal cleared it and only loadNative set it back. canSeek then read false on a seekable source, and a forward-only source lost its forward-only handling. loadSoftware republishes what the host opened, snapshotted in load() like the native session's. Also: shouldRewindBeforePlay takes a required sourceIsForwardOnly, so a new caller cannot fall back to the rewinding default, and the README's end-of-media note says a forward-only source resumes in place. Refs Silo-Server/silo-apple#656 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Main has moved under this branch. Upstream 7.31.0 (c3183ee) already rejects a seek on a forward-only VOD with the same SeekEvent.Rejection.sourceNotSeekable and closes a stashed seek. The same release clears the start position of a forward-only VOD before any host loads. Main's Demuxer also refuses the reposition itself now and keeps the probe's packets (19ee344). So the seek and load halves of this PR are already on main, and the branch conflicts in all four source files and the changelog.
What main still lacks is the play() fix, and the loop there is worse than the description says. I'm merging main into this branch, keeping main's side of the seek and load paths, and reworking the play fix on top, so there's no need to change anything yourself. Findings are on the lines below. Two more have no line in this diff:
- Major: a software rebuild drops
isSourceSeekable.stopInternal()sets it to nil, and onlyloadNativesets it back (AetherEngine+Loading.swift,isSourceSeekable = session.openedSourceIsSeekable). After an audio switch or reload on the software path,canSeekreads false on a seekable source, and a forward-only source loses its forward-only handling until the next load. I'm fixing this on the branch:loadSoftwarerepublishes the seekability the host snapshotted when it opened the source. - Minor: README contract.
README.mdsaysplay()rewinds a VOD parked at its final frame. A forward-only source now resumes in place instead. I'm updating that note.
Review by Claude Code (claude-opus-5-5), with a cross-provider pass by Codex (gpt-6.1-sol).
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Quick104
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Review summaryMain already covers the seek and load halves of this PR (upstream 7.31.0, c3183ee; the Reviewed head: 6ae175a (main 23889c5 merged in at da4de17). Addressed on this branch
VerificationOn a 60 s fragmented MP4 served as one chunked response without ranges (reported duration 2.08 s), pause then Remaining (not fixed here, all predate this PR)
Checks
VerdictFit: 9/10 · Readiness: 8/10 — conditional (assuming CI is green)
Review by Claude Code (claude-opus-5-5), with a cross-provider pass by Codex (gpt-6.1-sol). |
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Move the AetherEngine pin to b0712217, Silo-Server/AetherEngine#15. On a forward-only source parked past its container duration, play() asked for a rewind to 0, seek(to:) rejected it, and play() asked again without end while playback stayed paused. The engine now resumes a forward-only source in place, asks for one rewind per press on any other source, and republishes source seekability after a software-path rebuild. No package-graph change: b0712217 is the previous pin plus that commit. The notices and bundled acknowledgements record the new revision and the engine PR, and the reviewed build-input and selector snapshots are refreshed for the new project.yml. Refs #656 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Summary
play()on a forward-only source parked past its reported duration never resumes. A fragmented MP4 served as one chunked response with no ranges (Silo's server remux) reports its first fragment as the container duration, about 2 to 4 s. Past that pointplay()treats the playhead as parked at the end (superuser404notfound#164) and asks for a rewind to 0.seek(to:)rejects it assourceNotSeekable, andplay()asks again, tens of thousands of times a second, while playback stays paused. Silo's Apple client hits this on the first play after a pause on every "Server Remux" title.Related issue: Silo-Server/silo-apple#656 (issues are disabled on this repository; that issue has the logs and the trace).
The first version of this PR also stopped seeks and start-position seeks on a forward-only source. Main now does both: upstream 7.31.0 (c3183ee) rejects the seek with the same
SeekEvent.Rejection.sourceNotSeekableand clears the start position in the engine, and itsDemuxerrefuses the reposition and keeps the probe's packets (19ee344). The branch merges main and keeps main's side of those paths.What changed
play()resumes where it is. One property,sourceIsForwardOnly, now decides this forplay(),canSeekand theseek(to:)rejection, so the native sequential-origin path that main promotes this source to is covered too.play()resumes the transport instead of calling itself again, so a rejected or superseded rewind can no longer loop (an errored session parked at its end looped the same way). The resume is skipped when a newer load has started.isSourceSeekablestayed nil, because only the native path set it back.canSeekread false on a seekable source, and a forward-only source lost its forward-only handling.loadSoftwarenow republishes what the host opened.play()behavior.Seekable and live sources rewind and resume as before. A forward-only source genuinely paused at its end no longer rewinds, because it cannot.
Test plan
swift test, Xcode 27): a 60 s fragmented MP4 built like a server remux, served from loopback as one chunked 200 with noContent-Lengththat ignoresRange. libavformat reports 2.08 s. Load, play past 4 s, pause,play():playOnForwardOnlySourceDoesNotRewindandplayRewindsOncePerPressdrive the realplay(). Each fails with its fix reverted.Evidence: https://evidence.siloserver.org/r/aetherengine/pr-15-play-rewind/
Follow-ups (not in this PR)
sourceNotSeekablerejection the host never asked for, and the start-at-0 safeguard no longer runs.duration(progress, the Loopback-HLS: the final segment of a long 4K DV title never completes at EOM — AVPlayer parks ~0.1s from the end (WaitingToMinimizeStalls) → -12889; resuming into the tail can't start a master superuser404notfound/AetherEngine#169 tail-park end synthesis) may misread it. Not verified.Checklist
CHANGELOG.mdupdatedfeat(...),fix(...),chore(...))No public API change:
SeekEvent.Rejection.sourceNotSeekablealready exists on main.AI Disclosure
play()fix and added the rebuild republish, with read-only Claude subagent finders and a cross-provider review by Codex (gpt-6.1-sol).🤖 Generated with Claude Code
Note
Stop rewinding forward-only sources on play and republish seekability after software loads
sourceIsForwardOnly, a shared classification for sources declared sequential or probed as unseekable. It now drivescanSeek,seekrejection, and the end-of-media rewind decision.playissues at most one rewind per press, resumes only when the load generation is still active, and directly resumes forward-only sources instead of attempting a rejected seek to zero. The recursive retry after a rewind is removed.SoftwarePlaybackHostrecords the opened source's seekability, andloadSoftwarerepublishes it after rebuilds such as audio switches.canSeekandseeknow reject any non-live source known to be unseekable, not only ones declared sequential;playno longer retries rewinds, so playback resumption depends on the single same-generation seek inAetherEngine.swift.Macroscope summarized 6ae175a.