Motion Choreographer

motion-choreographer

Turn an approved still + the 12-block scene blueprint into a provider-tuned motion prompt that the target video adapter consumes. Camera choreography, primary subject motion, secondary environment motion, physics constraints, and — when the adapter declares audio: native — a synchronized audio direction block. Reads adapter capabilities from adapter-contract.md; never speaks to a network API.

When to use

• An image is locked (operator picked one candidate via operator-pick.sh) and the next step is motion + audio direction for the video adapter.
• The blueprint exists in scenes/<id>/blueprint.json but the motion prompt has not been emitted yet.
• A provider switch (Veo → Kling, Sora → Higgsfield) requires the same scene retuned for the new adapter's capability profile.

Do NOT use when:

• The blueprint is still prose only — run scene-expander → parse-blueprint.sh first.
• No still has been locked — the operator-selection checkpoint must complete first.
• The output is a still graphic — canvas-design.

Procedure

Step 0: Inspect

1. Read scenes/<id>/blueprint.json — fail loud if missing.
2. Read scenes/<id>/selection.json — fail loud if missing; the locked image path is required as the motion anchor.
3. Read the target adapter's capability via scripts/ai-video/adapters/<id>.sh capability. Cache audio=* for Step 3.
4. If a character.json lock exists, load it verbatim — identity tokens are immutable.
5. Continuous take or connector asked for? Read the model's start_frame / end_frame first — scripts/ai-video/adapters/<id>.sh capability --model <m>. null is unknown, never true. A model that cannot frame-lock is declined with a one-line why, never substituted in (adapter-contract.md#end_image).

Step 1: Camera choreography

Emit a CAMERA MOTION block with the move type, distance, speed in seconds, and start-end framing.

• Move types: lock-off, pan, tilt, dolly-in, dolly-out, truck, pedestal, push, pull, handheld, gimbal-glide, crane, whip.
• Speed in seconds per beat (0.4s push, hold 1.6s, 0.4s pull).
• Start and end framing named (MS → CU, WS → MS).

Blueprint intent-class decoding — the blueprint CAMERA block names one of six provider-agnostic intent classes; map it to the move types above before encoding:

Adapter quirks (per-provider encoding of the mapped move):

• Veo — accepts named moves; prefers ≤ 8s clips.
• Kling — motion intensity 0–1 token; map our speed to that.
• Sora — natural-language move + duration; no token.
• Higgsfield — preset-driven; pick the preset that matches the move; record the preset id in the motion prompt.
• LENS handling — blueprint mm + aperture translate to the provider's nearest lens / FOV idiom; never forward raw mm to a provider that lacks lens grammar.
• DURATION handling — the blueprint value is free; clamp to the provider ceiling here and record the clamp in review.md (a silent clamp is a drift bug).

Step 2: Primary + secondary motion

Two blocks:

1. PRIMARY MOTION — what the subject does, beat-counted, with physics anchors (mass, contact points, momentum). Reuse ACTION from the blueprint; refine for the adapter's preferred verb density.
2. SECONDARY MOTION — what the world does (hair, fabric, foliage, water, dust, particles, breath). One layer per line.

Step 3: Audio direction (conditional)

If adapter capability is audio: native AND the blueprint's audio.enable_native_audio is true:

Emit an AUDIO DIRECTION block with:

• DIALOGUE TIMING — speaker @ 0.4s: "line" per dialogue entry.
• AMBIENT LAYERS — copy from blueprint; one layer per line.
• SYNC CUES — which action beat maps to which audio cue (footstep @ 1.2s, door close @ 2.1s).

If adapter capability is audio: none:

• Emit a # AUDIO: ffmpeg-mux fallback comment with the blueprint's audio paths queued for stitch-time mux.
• Set enable_native_audio: false in the motion-prompt JSON.
• Blueprint carries DIALOGUE → the mux fallback cannot speak text lines. Emit a mandatory AUDIO DOWNGRADE warning block in motion-prompt.txt AND adapter-notes.md listing every dialogue line that will not render. The decision whether that is acceptable belongs to the orchestrator gate (adapter-contract § Audio ownership) — this skill translates, it never validates, and it NEVER silently strips dialogue.

Step 4: Physics constraints

Emit PHYSICS — a short list of what the model must respect: gravity direction, contact friction, fluid behavior, hair / cloth inertia, lens parallax. Single line per constraint.

Step 5: Emit motion-prompt JSON

Write scenes/<id>/motion-prompt.json with the adapter-contract stdin shape. The orchestrator pipes this into the video adapter's submit subcommand.

Step 6: Validate

1. JSON parses (jq .).
2. requires.audio_native is consistent with the chosen adapter's capability.
3. Duration in the motion prompt matches blueprint duration ±0.
4. Identity tokens (if character.json exists) are verbatim.

Output format

1. scenes/<id>/motion-prompt.json — adapter-contract stdin.
2. scenes/<id>/motion-prompt.txt — labeled prose blocks (CAMERA MOTION · PRIMARY MOTION · SECONDARY MOTION · AUDIO DIRECTION · PHYSICS) for operator review.
3. scenes/<id>/adapter-notes.md — which adapter, which capability, which preset / model, with rationale.

Gotcha

• The model wants to "improve" the blueprint's SUBJECT block — identity tokens are immutable; refuse the temptation.
• Picking audio: native on an adapter that returns audio: none produces silent video — always read capability first, never guess from the adapter name.
• Higgsfield preset id must be recorded; otherwise the rerun drifts to whichever preset the model picks on the next call.
• Sora durations > 8s often degrade — clamp at the adapter table limit; surface the clamp to the operator.

Do NOT

• Do NOT emit motion prompts for an adapter whose capability you did not query this turn.
• Do NOT skip the still-locked check — motion direction without an anchored image diverges on every call.
• Do NOT paraphrase identity tokens from character.json.
• Do NOT call any network API — this skill is provider-tuning prose only.

Policies

Paths, enforcement model, and the full set: the media policy preamble.

Motion prompts inherit every constraint the upstream blueprint carries. Before emitting provider-tuned prose:

• disclosure — every distributed clip carries the non-removable AI-generation disclosure; refuse adapter flags that would suppress it.
• transparency — provider provenance (C2PA / SynthID) is preserved; refuse re-encode flags whose effect is to strip provenance.
• voice-cloning — when the motion prompt requests audio: native narration in a named voice.
• brand-impersonation — when the motion prompt copies a recognised brand's chyron / mascot / signature transition.

Refuse-and-surface; the motion prompt cannot launder a policy gap upstream skills should have caught.