Agent recipe: author a beat-synced montage from the beats CLI output?

[e-jung]

Issue draft — scoping check before PR

Title: Agent recipe: author a beat-synced montage from the beats CLI output?

Body:

The hyperframes beats CLI (#1424) and Studio beat-snapping (#1439) cover beat
detection and manual snapping nicely. What I don't see is any agent-facing
guidance that closes the loop from a detected-beats file to a finished montage —
i.e. "given a folder of photos/videos + beats/<audio>.json, place the cuts on
beats and duck the music under each video clip."

I'd like to add a small docs-only montage skill that teaches an agent:

1. run hyperframes beats → read beats/<audio>.json ({time, strength}[]),
2. place one segment per asset on a beat cadence (every Nth beat),
3. crossfade with the required gsap_exit_missing_hard_kill set,
4. duck #bgm volume under each video clip and lift the clip's own <audio>.

No engine/runtime changes, no new commands — it builds entirely on the shipped
beats CLI and the existing core media/volume contract. Worked example passes
hyperframes lint.

Before I open the PR: is a montage authoring skill something you'd want in-tree,
or would you prefer this as a registry example/recipe instead? Happy to shape it
either way to match how you want montage/music workflows documented.

[e-jung]

The branch is already prepared (one file, skills/montage/SKILL.md, docs-only) and the worked example passes hyperframes lint. Just say the word and I'll open the PR — or close this if it's not a direction you want.

[miguel-heygen]

@e-jung yeah feel free to open the pr

[e-jung]

Opened #1659 with the docs-only skills/montage/SKILL.md — closes the loop from hyperframes beats → beat-synced segment placement → crossfade hard-kills → #bgm ducking under video clips. Worked example passes hyperframes lint (0 errors). Thanks for the green light!

[jrusso1020]

Hey @e-jung we just released our own version of this skill https://github.com/heygen-com/hyperframes/tree/main/skills/music-to-video

We were working on this in a branch when the CLI was already merged

would you mind checking this out to see if it fits your needs?

We had our team take a look at your skill as well to see if there was any parts worth adopting!

[e-jung]

Thanks for the heads-up @jrusso1020! I read through skills/music-to-video — it covers the montage case completely (beat-driven frame cuts, cutting user images/videos in on the grid, BGM-as-spine) and goes well beyond what my docs-only recipe aimed at. The references/montage.md adoption is a nice touch too.

Closing my PR #1659 as superseded — your skill is the right path for anyone in the workflow. Appreciate the team taking a look at mine; glad the montage concept was useful. Nice work on the analyzer + frame-worker pipeline.