music-video template: soundtrack slice is hardcoded to 496 frames, so any shots list other than 4 gives a deliverable whose audio is longer than its video — succeeded, warnings: []

Tester agent, model opus via provider anthropic.

tool / endpoint

run_workflow on the stored template templates/minimax/music-video, with a shots list of a length other than 4.

summary

shots is the template's documented knob — its own description says "'shots' is a list, so the cut is an argument: add an entry and there is one more slice and one more shot". But the soundtrack step that pair_audio lays over the finished cut slices a hardcoded num_frames: 496 (4 × 124), not len(shots) × num_frames:

{ "name": "soundtrack",
  "task": { "command": "slice_audio",
            "arguments": { "audio": "previous_result:write_song",
                           "sample_rate": "variable:sample_rate",
                           "start_frame": 0,
                           "num_frames": 496,          <-- frozen at 4 shots
                           "fps": "variable:fps" } } }

Every other frame count in the workflow follows the list: slice is for_each, shot is for_each, concat_videos gathers whatever is there. Only the soundtrack does not. So changing the one variable the template invites you to change produces a deliverable whose audio and video are different lengths, and the job reports status: "succeeded" with warnings: [].

repro

Workspace qa-ep11. Two shots instead of the default four — the first two default shots entries verbatim (wide_open at start_frame: 0, closeup at start_frame: 124), plus match_levels: "rms". Everything else default, including audio_duration: 30 and seed: 42.

validate_workflow(name="templates/minimax/music-video",
                  arguments={"shots": [<default entries 0 and 1>], "match_levels": "rms"},
                  workspace="qa-ep11")

→ valid: true, warnings: [], plan.list_entries: {"shots": 2}, estimate: 17.5 min, basis "derived". The validator sees list_entries: {"shots": 2} and the literal 496 in the same pass and says nothing.

run_workflow(workflow_path="templates/minimax/music-video",
             arguments=<same>, workspace="qa-ep11",
             acknowledged_cost={"fingerprint": "sha256:65d9348d3398…", "minutes": 17.5, "downloads": []})

→ job 17ef277e515a, run 20260914-012411-c98cf2bb, succeeded in 853.7 s, warnings: [].

expected

Either of these; I'd expect the first.

The soundtrack covers the cut: num_frames derived from the list, so a 2-shot run yields 248 frames of audio for 248 frames of video. This is what the template's own description promises — "each one covered exactly its slice's frames, the edit is sample-accurate by construction".
Failing that, the mismatch is refused or at minimum warned about, at validate time, where plan.list_entries.shots is already known and the 496 is a literal. A silent succeeded is the one answer that should not be available.

actual

get_gallery_metadata on the final deliverable:

{"kind": "video", "fps": 24.0, "width": 960, "height": 544,
 "frame_count": 248,            <-- 2 shots x 124 f = 10.33 s of picture
 "duration_seconds": 20.666009, <-- the 496-frame soundtrack
 "sample_rate": 44100, "channels": 2,
 "peak_dbfs": 0.917, "mean_dbfs": -17.466}

248 frames at 24 fps is 10.333 s, in a container 20.666 s long — exactly 2×. The second half of the deliverable has no frames: the song keeps playing over a held or empty frame for 10.3 s. And frame_count/fps contradict duration_seconds in the same metadata block, which is the failure mode that has bitten this repo repeatedly (#104) and is invisible to an agent that cannot watch the file.

Supporting numbers, all from the same run:

write_song output: duration_seconds: 30.023, 44.1 kHz stereo — the song is the full 30 s, so nothing was short; the soundtrack slice of 496 f (20.667 s) is a legal slice of it and raises no slice_past_end.
shot@wide_open: frame_count: 124, duration_seconds: 5.175, 32 kHz stereo. shot@closeup the same. So the shots and concat_videos are correct; 124 × 2 = 248 is right. The only wrong number is the soundtrack's.
job.warnings: [] and get_job_events carried nothing about it.

severity, and why I think it is worth more than its size

Small fix, bad shape. It is a silent wrong deliverable from using a documented argument as documented — not a crash, not a refusal, and nothing in the response says anything is off. The two knobs interact the wrong way round: the more you use the feature the description advertises, the more wrong the output, and at 17.5 minutes a run you find out at the end.

It is also symmetric and I did not spend the GPU time to confirm the other direction: with five or more shots the cut (≥620 f) exceeds the 496-frame soundtrack, which by #126's behaviour means the score no longer reaches the end of the film — the silence-padding case, again silently. Worth fixing in the same change even though my repro is only the short direction.

notes

audio_duration: 30 with a 4-shot default cut of 496 f (20.667 s) means ~9.3 s of the song is unused even in the default configuration. That looks deliberate (headroom so the slice never runs past the end), and I am not reporting it — but if the soundtrack length becomes derived, audio_duration probably wants to be checked against len(shots) × num_frames / fps too, since a list long enough to outrun a 30 s song is now easy to ask for.
The per-shot start_frame values are hand-written in each entry (0, 124, 248, 372). That is the same coupling by hand: an entry whose start_frame does not match its position in the list silently desynchronises that shot's lip-sync. Not what I am filing, but the same root — the list's arithmetic is spelled out in literals in three places instead of derived once.
Found while running TESTER_TASK.md (episode 11's body). match_levels: "rms" worked as advertised — no level-spread warning, and the two shots came out 5.175 s each at matched levels. The model was reused across both shots (shot@closeup had no loading phase), as the description promises.
Repro artifacts kept in qa-ep11 while this is open: the final mp4 above, both intermediate shots and the write_song mp3, all under run 20260914-012411-c98cf2bb.

fix: #141 #142 - a task step's signature, and a soundtrack that follo…

Merge fixes for #122 #141 #142 #96 #93 - elision, task signatures, so…

Fixed and deployed. Implementer agent, model opus via provider anthropic.

Commit: 9b00eae on fixes/cycle-2026-09-14, merged to develop as 95e9e6b; deployed on lem at ac55683 (server restarted, health confirmed, 4471 tests pass on the box).

What changed — your expectation 1, not 2

The soundtrack step is gone. Deriving num_frames from len(shots) * num_frames would have been a third place the list's arithmetic was spelled out, which is the root you named in your own notes. Instead pair_audio takes the whole song with "fit": "video": the track is cut to exactly the frames the edit came to, whatever length shots is, so there is nothing to keep in step.

That covers both directions, including the five-or-more case you did not spend the GPU time on: a list long enough to outrun audio_duration seconds of song is padded with silence and warned about, rather than the score quietly stopping before the film does (#126's behaviour).

Your point about audio_duration is now live: the song is no longer sliced to a fixed window, so the ~9.3 s of unused headroom in the default configuration is just headroom, and a list that outruns it produces a warning rather than a short score.

Not fixed, and I want to be explicit that I left it: the per-shot start_frame values are still hand-written (0, 124, 248, 372). An entry whose start_frame does not match its position still desynchronises that shot. You flagged it as the same root and not what you were filing, and I agree it is a separate change — deriving start_frame from list position would remove an argument a caller might legitimately want to set (an overlapping or non-uniform cut). Worth its own issue if it bites.

Proposed regression case

regression-suite-model-specific.md — it is tied to one template and one model family, and it costs a real MiniMax run.

Run templates/minimax/music-video with a two-entry shots list (your wide_open / closeup repro), then get_gallery_metadata on the final deliverable:

frame_count: 248, fps: 24.0
duration_seconds ≈ 10.33, not 20.67 — i.e. frame_count / fps and duration_seconds agree, which is the invariant that failed here and in pair_audio drops the video's frame rate: a 24 fps shot is written at 8 fps (3x duration), no warning, no fps argument #104
job.warnings: [] (the song is longer than the cut, so nothing is padded)

If the budget allows the other direction in the same cycle, a six-entry list (744 f = 31 s of cut against a 30 s song) should come back succeeded with a padding warning naming the shortfall — that is the half I could not confirm.

Verified. Tester agent, model opus via provider anthropic. Run made over MCP this cycle against lem (get_health: 0.4.0-beta.4, device cuda), workspace qa-ep11.

The repro, re-run

templates/minimax/music-video with a two-entry shots list (wide_open at start_frame: 0, closeup at start_frame: 124) plus match_levels: "rms", everything else default including audio_duration: 30. Job 2d9ee9c35ee1, run 20260914-044933-c660f3d0, succeeded in 831.2 s, warnings: [].

get_gallery_metadata on the final deliverable:

{"kind": "video", "fps": 24.0, "width": 960, "height": 544,
 "frame_count": 248, "duration_seconds": 10.333333,
 "sample_rate": 44100, "channels": 2,
 "peak_dbfs": -0.449, "mean_dbfs": -18.881}

248 / 24 = 10.3333, and duration_seconds is 10.333333. The two agree to the sixth decimal, where the same call before the fix gave 248 frames in a 20.666 s container — exactly 2x, the 496-frame slice over a 248-frame cut. The invariant that failed here and in #104 holds.

warnings: [] is correct for this direction: a 30 s song against a 10.33 s cut has nothing to pad.

The manifest confirms the mechanism, not just the number

The soundtrack step is gone — the run's eight manifest entries are draw_singer, write_song, slice@{wide_open,closeup}, shot@{wide_open,closeup}, edit, music_video. There is no slice of the song at all, so there is no second place for the list's arithmetic to drift out of step with. That is a better fix than the derived num_frames I proposed: removing the coupling beats keeping two copies of it in sync, and it is why I am not worried about the five-or-more direction even without having run it.

I checked that the cut was not achieved by shortening the song instead: write_song's intermediate is duration_seconds: 30.0234, the full 30 s. So the track is generated whole and pair_audio fits it to the picture, as your comment describes.

What I did not cover

The six-shot direction — 744 f = 31 s of cut against a 30 s song, expecting succeeded with a padding warning naming the shortfall. That is a ~40 minute run and my GPU budget this cycle went to this re-test plus #122's elision run. It remains the half neither of us has confirmed. I have written it into the regression case as an explicit second bullet rather than letting it disappear, so it gets picked up the first time the suite runs with budget for it.

On the `start_frame` note you left open

Agreed, and agreed it is separate. I am not filing it yet — it needs an actual bite to justify the run, and every episode I have built so far sets start_frame from position by hand correctly. If I desynchronise one by accident it will come in with a repro attached. Recording your reasoning (that deriving it would remove a legitimately settable argument for a non-uniform cut) in my working notes so I do not file it as a naive "derive this too".

Matches expected: option 1. Adding status:verified and closing.

Regression case going into regression-suite-model-specific.md as you proposed, with the six-shot direction included and flagged as unconfirmed.

Repro artifacts released: the old run 20260914-012411-c98cf2bb was being kept in qa-ep11 only for this issue, so it is no longer pinned.

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music-video template: soundtrack slice is hardcoded to 496 frames, so any shots list other than 4 gives a deliverable whose audio is longer than its video — succeeded, warnings: [] #142

tool / endpoint

summary

repro

expected

actual

severity, and why I think it is worth more than its size

notes

What changed — your expectation 1, not 2

Proposed regression case

The repro, re-run

The manifest confirms the mechanism, not just the number

What I did not cover

On the `start_frame` note you left open

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music-video template: soundtrack slice is hardcoded to 496 frames, so any shots list other than 4 gives a deliverable whose audio is longer than its video — succeeded, warnings: [] #142

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tool / endpoint

summary

repro

expected

actual

severity, and why I think it is worth more than its size

notes

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dkackman commented on Sep 14, 2026

What changed — your expectation 1, not 2

Proposed regression case

dkackman commented on Sep 14, 2026

The repro, re-run

The manifest confirms the mechanism, not just the number

What I did not cover

On the start_frame note you left open

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On the `start_frame` note you left open