Make AI Short Skill for Claude

make-ai-short — generative shorts, end to end

The pixels come from a video model; Remotion only composites clips + captions. Proven on

blue-man #1 "The Door". Sibling of /make-short (100% TSX) — same discipline, plus three

gates TSX never needed: cost stated before generating, **character locked from

character.json, loop pinned via end-frame conditioning**.

Run everything from the repo root. Needs FAL_KEY (clips + images) and ELEVENLABS_API_KEY

(voice) in .env.

The three iron rules

• NEVER generate a character from text twice. ai-shorts/<char>/character.json +

character.png is the locked reference. Every still that needs the character is

gen_image.py --ref character.png; every clip is image-to-video from a frame that already

contains him. If a character sheet doesn't exist yet, making ONE (and getting the user's

eye on it) is its own step before anything else.

• STATE THE COST BEFORE SPENDING IT. Derived, not quoted: Seedance 1080p audio-off =

h×w×24×dur/1024 tokens × $1.2/1M ≈ $0.0583/s (fal pricing API validated 2026-07-14 —

see ai-shorts/IDEAS.md for the full table + the Wan/Veo-Lite traps). Always

generate_audio:false — voice is ElevenLabs, sound is our SFX pipeline.

• Loop by CONSTRAINT, not luck. Shot 1's true frame 0 (extracted from the clip, not the

prompt image) is the loop target. The final shot passes it as end_image_url

(Seedance/Kling), and the composition settles onto that exact still over the last ~10

frames (LoopSettle pattern in remotion/src/shots/ai-1/Ai1Door.tsx).

Artifact contract

ai-shorts/<name>/
  script.md · beats.json      — same contract as /make-short (vo[] with real word times)
  character.json              — THE LOCKED REFERENCE (+ video_model block = the picked model)
  shots/NN-slug.png           — per-shot START frame (gen_image.py --ref character.png [--ref scene])
  shots/NN-slug.json          — gen_clip sidecar (model, payload, request id)
  shots/upload-urls.json      — fal storage urls (uploads are reusable across re-rolls)
  voice/ · sfx-plan.json · output/                                          [voice/output gitignored]
remotion/src/shots/ai-N/      — composition + vo.gen.ts
media/projects/<name>/        — THE clip copies for staticFile() (committed — pixels are
                                not reproducible; shots/*.mp4 working copies are gitignored)

Order of operations (voice before pixels)

• Script — script.md + beats.json. Hook composed at frame 0; thesis should WANT the loop

(blue-man #1: "arrival is a myth" → ending = walking toward the same door). ~80-100 words,

2.5-2.7 wps windows. No engagement-CTA outro, ever — end on the payoff, loop is the ending.

• Voice FIRST — python tools/gen_voice.py --beats ... --emit-ts remotion/src/shots/ai-N/vo.gen.ts

(George JBFqnCBsd6RMkjVDRZzb + eleven_v3 tags for narrators). Real word times decide the

shot windows; Seedance takes integer 4-12s durations, so round shot lengths UP from windows.

• Start frames — one per shot, python tools/gen_image.py --model pro --aspect 9:16 --ref character.png

(+ the shot-1 scene still as a 2nd ref when a location/prop must match across shots).

QA every PNG before any video call — this is where drift is cheap to fix.

• Watch hands, clothing details, proportions — name them explicitly in the prompt on re-rolls.
• Geometry must be walkable (the shot-6 lesson, cost 2 re-rolls): with an end-frame pin,

the start frame must let the motion REACH the end state by walking forward — if the end

frame's character is CLOSER to camera than the start's, the model spawns a clone instead.

Start him larger/nearer than the end state so forward motion shrinks him into it.

• Clips — state the total derived cost, then python tools/gen_clip.py per shot in parallel

(`--set image_url=<fal storage url> --set 'duration="N"' --set resolution=1080p

--set generate_audio=false, final shot --set end_image_url=<frame0 url>`). Upload refs

once via bakeoff_clip.upload_ref; keep urls in shots/upload-urls.json.

Prompt every clip with: exact character phrase + "EXACTLY ONE character in the scene for

the entire shot" (clones are the #1 failure) + camera move + "no morphing" + style line.

• Clip QA, frame by frame — start/mid/end strip per clip + a side-by-side of the final

clip's last frame vs the loop target. Re-roll failures (state the re-roll cost); a 5s

1080p re-roll is ~$0.29 — cheap next to shipping a clone.

• Composition — Sequences of OffthreadVideo over ONE timeline, ~8-frame crossfade

underlaps (clips are ~1s longer than their windows — that's the slack), Captions +

ProgressBar at root, LoopSettle dissolve at the tail. Copy final clips to

media/projects/<name>/. npm run gen, frames.mjs at boundaries + heroes, READ every PNG,

then render-all --scale=1 and mux voice.wav.

• SFX — /suggest-sfx flow. Gappy-VO calibration (blue-man #1): cues in VO gaps get no

masking and no duck — they need ~7-8 dB LESS than the dense-narration table (gap

whooshes -9..-13, not -3..-5). Verify with volumedetect RMS against a speech-mean

reference; hero layer may kiss voice level once. Audition mix awaits the user's ear

(hard gate).

• Save back — catalog used_in, beats.json real timings (gen_voice writes them), sidecars

committed, cost ledger in the final report.

Done =

character consistent in every frame of every clip (frame-by-frame QA'd) · loop verified

(last frame vs frame 0 side-by-side) · captions on real word times · costs stated before each

spend and totalled after · SFX audition rendered, awaiting the user's ear · no CTA outro.