Cinematic transition endpoints all return 500 (broken geq filter expr) — blocks Studio-native transitions

[nanxingw]

Summary

All four cinematic transition endpoints return HTTP 500 with an ffmpeg filter error, so transitions cannot be applied through the documented API. Because these are the only Studio-native way to render cinematic transitions, and Studio is the user's direct visual entry point, an agent is forced to hand-roll ffmpeg outside the composition — which then can't be represented in composition.yaml or shown/rendered by Studio.

Affected endpoints

• POST /api/transitions/glitch
• POST /api/transitions/light-leak
• POST /api/transitions/domain-warp
• POST /api/transitions/grav-lens

All four fail identically.

Repro

curl -X POST http://localhost:3271/api/transitions/glitch \
  -H "Content-Type: application/json" \
  -d '{"workId":"<id>","clipARelative":"assets/clips/a.mp4","clipBRelative":"assets/clips/b.mp4","outputFilename":"t.mp4","clipADuration":4.3,"transitionDuration":0.4}'

Inputs verified valid: both clips exist, 1080x1920, clipA duration 4.29s (> transitionDuration).

Actual result

HTTP 500
{"error":"glitch-cut transition: ffmpeg exit null\n
[Parsed_geq_3 @ ...] [Eval @ ...] Undefined constant or missing '(' in 't*200)*15,0)),Y)'\n
[AVFilterGraph @ ...] Error initializing filters\n","errorCode":"transition_failed"}

The ffmpeg geq expression the endpoint builds is malformed — an unbalanced/undefined expression around 't*200)*15,0)),Y)' — so filtergraph init fails before any frame is written (ffmpeg exit null). light-leak / domain-warp / grav-lens all hit the same transition_failed path.

Impact

• Transitions are completely unusable via the API on this build.
• Studio (the user's visual entry point) cannot show or render cinematic transitions, since the only supported path is broken.
• Agents must fall back to hand-rolled ffmpeg xfade/flash/glitch, whose results live outside composition.yaml (the schema has no representation for these baked transitions/reframes), breaking WYSIWYG between the timeline and the exported video.

Suggested fix

Audit the geq expression construction in the transition renderer (the glitch RGB-shift / scanline expr looks like the culprit — a missing min(/max( open-paren or an unescaped comma inside the geq string). Add a smoke test that renders each of the four transitions on two solid-color clips in CI so a broken filter expr fails fast.

Environment

• autoviral 0.1.11, backend on :3271
• macOS (Apple Silicon), ffmpeg from Homebrew