TV playback parity on Media3 with the Back-button state machine #34

Part of putdotio/putio-ios#14 (W4 — Android TV parity). Blocked by putdotio/putio-ios#33; playback model putdotio/putio-sdk-kotlin#23. Closes putdotio/putio-ios#9 (UI-1528).

Outcome

Playback parity with the RN app's custom Android TV controls (17–31), adapted to Media3 and the current Android TV design contract, plus the Back-button state machine putdotio/putio-ios#9 demands. HLS/MP4 ship first; libVLC remains post-v1 under putdotio/putio-ios#52.

Scope

• Player with custom controls overlay: ~3s auto-hide, any-key reveal, raw filename title chrome; Language only when >1 audio track, Subtitles only when tracks exist, Speed always (0.25–2x, resets per file)
• Resume is a play-time M3 text/progress dialog, never a poster and never an in-app Continue Watching shelf: show the raw filename and LinearProgressIndicator; stack full-width pill buttons; prefer Continue; Start from the beginning resets to zero
• Show resume only when duration and saved start_from are positive; progress previews the focused choice; Back leaves playback, as the RN prompt does (fix(playback): clear finished positions, resume audio silently, stop forcing landscape #266)
• Start-from write-back remains throttled + debounced with a final flush; never write per progress tick
• Subtitles: embedded + sidecar, autoselect gated by dont_autoselect_subtitles, MP4 label rewriting; audio-language picker; respect user subtitle style settings
• Seek: D-pad accumulating press-count scrubbing (15s × count), auto-pause while scrubbing + resume on commit, FF/REW focus capture
• Back-button state machine (Dismiss playback overlays before exiting on TV Back #9): Back with any overlay/picker/seek mode open dismisses the topmost layer preserving time/pause/tracks/focus; Back with nothing open exits playback. Uniform across all overlays; Fire TV remote must never skip straight out
• HLS/MP4 selection from user config via the SDK playback source; tv-native's default buffer (Android TV has no buffer setting); conversion starts automatically on open, with the interstitial (feat(playback): start MP4 conversion on opening a video that needs it #260); typed recoverable media errors; MediaSession for system controls
• Fire TV hardware smoke for remote/back behavior

Remaining: L6: Fire TV remote smoke and oracle 17–31 capture parity (#51); putdotio/putio-ios#9 on Fire TV.

Acceptance criteria

• Playback captures match oracle 17–31 route/state names
• A recording proves Continue preferred, Start from beginning, Back-to-saved-position, scrub/pickers, and the overlay Back sequence
• chore(env): hardcode 1Password vault/item; rename helper script putio-ios#9's contract is demonstrated on Fire TV
• DoD: ./gradlew verify, both flavor assembles, TV harness proof, and published recordings pass