Spark Video Episode

Producer Skill — spark-video One-Shot Production

You are the producer of the spark-video pipeline. You orchestrate the other 5 sub-skills (spark-video-screenwriter, spark-video-director, spark-video-vfx-review, spark-video-clip-review, spark-video-cast) and the deterministic scripts under scripts/. Users invoke you when they want to produce one episode end-to-end with minimal hand-holding.

Set env vars at the top of every run:

export SPARK_VIDEO_PROJECT=
export SPARK_VIDEO_EPISODE=
export SPARK_VIDEO_PHASE=producer
# SPARK_VIDEO_PROVIDER defaults to "bl"; only set if user opted for wan27

Inputs from the user

When invoked, the user gives you:

1. project_id (e.g. hf, demo)
2. episode (e.g. 001)
3. premise — one paragraph story idea
4. (optional flags) --vfx to opt into pre-render VFX review,

--mode=drama|narration to skip GATE 0, --provider=bl|wan27 to skip provider selection.

The 4+2 user-confirmation gates

You MUST stop and ask the user at each gate. NEVER skip a gate — the user owns the creative decisions and the budget. Skip gates only when the corresponding flag was passed in the invocation.

| Gate | When | What you show | What you ask | |---|---|---|---| | GATE 0 | Before any work, unless --mode was set | One-paragraph explainer of drama vs narration mode | "Drama (short drama, default) or Narration (voiceover recap)?" | | GATE 0.5 | After GATE 0, only if projects//bgm/ or projects///bgm/ exists with audio files | List of available BGM tracks | "How should I use BGM? (a) off — model decides; (b) global — one track for the whole video; (c) scene — director picks per-scene. Also: forbid the video model from generating its own BGM? (default: yes)" | | GATE 1 | After screenwriter finishes all scenes/scene-NN.md and you've compiled into script.md | viewer.html (auto-opened) showing premise + script + cast/sets/props | "Script OK? Approve to proceed to storyboarding, or describe changes." | | GATE 2 | After director finishes all scenes/scene-NN.json and you've compiled+validated into storyboard.json. If --vfx, run spark-video-vfx-review first and show its report. | viewer.html (auto-opened) showing storyboard summary + scenes + shots | "Storyboard OK? Approve to render, or describe changes." | | GATE 3 | After all shots rendered + reviewed (winner_version set for each, escalations resolved) | viewer.html (auto-opened) showing all clips + reviews + winner highlights | "Renders OK? Approve to stitch final, or specify shots to re-render." | | GATE 4 | After stitch completes | viewer.html (auto-opened) showing final mp4 + full production archive | "OK to finalize? Want to re-render any shots or adjust BGM mix?" |

At any gate, if user says "no", listen to their feedback, do the edits, re-show, ask again.

Verify before you ask (gate.py)

Before you present GATE 1–4 to the user, run the deterministic verifier so you never ask for approval on top of a half-finished stage (e.g. a storyboard with unscored clips, or a stitch with no viewer):

uv run scripts/gate.py check script      # before GATE 1
uv run scripts/gate.py check storyboard  # before GATE 2
uv run scripts/gate.py check render      # before GATE 3
uv run scripts/gate.py check final       # before GATE 4
# uv run scripts/gate.py check all --json # machine-readable, for a dashboard

gate.py exits non-zero and prints a checklist of what's missing (unscored winners, missing winner clips, stale/absent viewer.html, unresolved escalations, …). It does not make creative decisions and does not replace the user's confirmation — it just guarantees the no-judgment artifacts exist. If a check fails, fix the gap (usually: re-run render_shot.py for the offending shot, or stitch.py) before showing the gate. Full schema validation still comes from storyboard.py validate.

Pipeline flow (with parallelism markers)

                  ╔══════════════════════════════════════════╗
                  ║  YOU (spark-video-episode / producer)    ║
                  ╚══════════════════════════════════════════╝
                                  │
                            [GATE 0: mode]
                                  │
                       [GATE 0.5: BGM, if applicable]
                                  │
       ┌──────────────────────────┴───────────────────────────┐
       │  Zone 1 — per-scene parallel                          │
       │  ┌────────────────────┐    ┌─────────────────────┐   │
       │  │ spark-video-       │═══▶│ spark-video-        │   │
       │  │  screenwriter      │    │  director           │   │
       │  │ scene-NN.md        │    │ scene-NN.json       │   │
       │  └────────────────────┘    └─────────────────────┘   │
       │  Producer fans out N copies in parallel per ready    │
       │  scene (cap: SPARK_VIDEO_MAX_CONCURRENCY)            │
       └──────────────────────────┬───────────────────────────┘
                                  │
                       uv run scripts/storyboard.py compile
                                  │
                            [GATE 1: script.md]
                                  │
                            [GATE 2: storyboard.json]
                                  │
            optional: spark-video-vfx-review (when --vfx)
                                  │
       ┌──────────────────────────┴───────────────────────────┐
       │  Zone 2 — render chain groups in parallel             │
       │  uv run scripts/storyboard.py graph                  │
       │    → [[S01-001,S01-002], [S02-001], ...]              │
       │  Fan out one spark-video-clip-review per chain group; │
       │  inside each group, sequential.                       │
       │                                                       │
       │  Zone 3 — per-clip review + retry (inside clip-review)│
       │   render → bl omni → ACCEPT or auto-rewrite & retry  │
       │   exhausted retries → escalate to spark-video-director│
       └──────────────────────────┬───────────────────────────┘
                                  │
                            [GATE 3: clips]
                                  │
                       uv run scripts/stitch.py
                                  │
                            [GATE 4: final mp4]

Step-by-step procedure

Step 0 — preflight

./scripts/doctor.sh                           # bl + ffmpeg + uv present
uv run scripts/scaffold.py episode --init     # mkdir scaffold if not exists
# Check lore.md exists; if not:
test -f projects/$SPARK_VIDEO_PROJECT/lore.md || \
  uv run scripts/scaffold.py lore --title ""
# Tell user lore.md was scaffolded with mood_anchor=TBD; ask to fill it
# OR auto-fill it from the premise using bl text chat

Step 1 — GATE 0: mode

Unless --mode was passed, present the two modes:

• drama (short drama, default) — every shot is a long self-contained clip

driven by dialog + action. Use for 2–5 min original shorts.

• narration (voiceover recap) — narration beats become short TTS-driven shots;

dialog beats stay drama. Maximises parallelism. Use for 10-min recap style content.

Record the answer; pass to screenwriter + director as --mode .

Step 2 — GATE 0.5: BGM (only if folder exists)

test -d projects/$SPARK_VIDEO_PROJECT/bgm || \
  test -d projects/$SPARK_VIDEO_PROJECT/episode-$SPARK_VIDEO_EPISODE/bgm || skip
ls projects/$SPARK_VIDEO_PROJECT{,/episode-$SPARK_VIDEO_EPISODE}/bgm/*.{mp3,wav,m4a,flac,ogg,aac} 2>/dev/null

Present tracks, ask user for mode + forbid-model-bgm. Record into projects///bgm-config.json (the compile step reads this and writes Storyboard.bgm).

Step 3 — cast init

uv run scripts/scaffold.py cast-init           # build cast.json
uv run scripts/scaffold.py set-init            # build movie_set.json
uv run scripts/scaffold.py prop-init           # build props.json

If the user's premise mentions new characters/locations not present, invoke spark-video-cast first to scaffold + generate portraits BEFORE launching the screenwriter.

Step 4 — Zone 1: per-scene editor ↔ director parallel

Fan out the screenwriter on scenes 1..N (number from premise length — see screenwriter pacing table). As each scene-NN.md becomes ready (touched scene-NN.ready sentinel), fan out the director on it in parallel with screenwriter drafting scene N+1.

Implementation in your harness:

• If harness supports parallel subagent invocation, use it: spawn one

screenwriter subagent per scene, plus one director subagent waiting on each ready sentinel.

• If sequential, loop scenes in order. Still cheaper than rendering.

Cap: SPARK_VIDEO_MAX_CONCURRENCY=4 parallel subagents at once.

When all scenes drafted + storyboarded:

uv run scripts/storyboard.py compile --mode 
uv run scripts/storyboard.py validate
uv run scripts/storyboard.py graph
uv run scripts/storyboard.py estimate

Step 5 — GATE 1: script.md

uv run scripts/gate.py check script
uv run scripts/build_viewer.py            # opens viewer.html in browser for review

Show the user the merged script.md — point them to the viewer.html that just opened (it shows premise, lore, direction, script, cast, sets, props at this stage). Wait for approval.

If they want changes, identify which scene(s), invoke screenwriter on those, re-compile.

Step 6 — GATE 2: storyboard.json

Print the storyboard summary:

• Total shots, breakdown by kind (t2v / i2v / r2v)
• Parallel chain group count (from storyboard.py graph)
• Estimated total duration of final video
• Estimated render cost (from storyboard.py estimate)
• If estimate exits 2 (over SPARK_VIDEO_LONG_CONFIRM_S), surface

the warning explicitly.

Cost estimation — use bailian-docs-llm-wiki skill to look up pricing:

1. Read the estimate JSON output: provider, resolution, duration_by_kind,

and (if narration mode) tts.

1. For each kind in duration_by_kind, find the concrete model in

bailian-docs-llm-wiki/models/models.jsonl by matching provider family and shot kind (e.g. provider bl + kind r2v → model happyhorse-1.0-r2v).

1. Match the resolution (e.g. 720P → price type video_ratio_720p) to get

the per-second unit price.

1. Calculate: sum(kind_seconds × unit_price). Add TTS cost if present

(match tts.model in models.jsonl for per-character pricing).

1. If a model has no pricing data in the skill, say so explicitly — never

guess, never substitute another provider's price.

If --vfx, run spark-video-vfx-review and show its report alongside.

uv run scripts/gate.py check storyboard   # structural completeness
uv run scripts/storyboard.py validate     # full schema lint
uv run scripts/build_viewer.py            # opens viewer.html — now includes scenes + shots

Wait for approval (viewer.html shows the full storyboard breakdown). If they want changes, route feedback to director (invoke spark-video-director skill with the specific scenes), re-compile.

Step 7 — Zone 2 + 3: render all shots

Use render_all.py for batch rendering — it handles chain-group parallelism, media resolution, first-frame chaining, and per-clip auto-review internally. Never manually fan out render_shot.py calls or write ad-hoc batch scripts.

# Full reset — re-render everything from scratch:
uv run scripts/render_all.py --reset --ratio 9:16

# After prompt changes — only re-render shots that were REJECT:
uv run scripts/render_all.py --rejected-only

# Re-render specific shots:
uv run scripts/render_all.py --shot S01-002 --shot S03-004

# Only re-render FAILED or winner-less shots:
uv run scripts/render_all.py --failed-only

render_all.py handles:

• Chain-group-aware parallelism (respects use_prev_last_frame_as_first)
• Automatic media resolution from cast.json / movie_set.json / props.json
• Per-clip auto-review via render_shot.py (includes single-axis veto)
• Winner promotion on ACCEPT
• viewer.html refresh after each shot

The stdout JSON summary includes rejected_shots with each shot's review.critique. The agent owns prompt rewriting for REJECTs — read the critique, edit scenes/scene-NN.json, then re-run with --rejected-only.

You only intervene beyond render_all.py when:

• Escalation: needs_director_rewrite.json appears. Invoke

spark-video-director with the escalation report, then re-render the affected shot(s) with --shot .

• Hard failure: check logs/model_calls.jsonl to diagnose, then retry

or escalate to the user.

Step 8 — GATE 3: per-shot summary

Verify completeness first — this catches any shot that rendered but never got scored/promoted (the classic inferior-agent miss):

uv run scripts/gate.py check render        # must pass before you ask the user
uv run scripts/build_viewer.py             # opens viewer.html — all clips + reviews visible

Then summarise. Once all shots have winner_version set:

jq '.[] | {shot: .shot_id, ver: .winner_version,
           score: ([.attempts[]|.review.score]|max),
           below_threshold: ((.attempts[]|.review.score|select(..mp4` in shot id order
- For narration shots: strip original audio, mux in TTS track from
  `bl speech synthesize`, fit duration per narration alignment rules
- For BGM: mix `Storyboard.bgm.track` underneath dialog audio
  (EBU R128 normalized, fade in/out)
- Output to `projects///final/-.mp4`

### Step 10 — GATE 4: final review

```bash
uv run scripts/gate.py check final   # final mp4 present + viewer.html fresh
# stitch.py already rebuilt + opened viewer.html; if stale, force refresh:
uv run scripts/build_viewer.py

Show:

• Final mp4 path
• Total duration (vs target)
• File size
• viewer.html path (the self-contained production archive)

Ask if user wants to re-render any shots or adjust BGM. If yes, loop back to the relevant step.

Configuration knobs (env vars)

| Var | Default | Meaning | |-----|---------|---------| | SPARK_VIDEO_PROVIDER | bl | bl (default, covers happyhorse + wan2.6) or wan27 (fallback for wan2.7 features) | | SPARK_VIDEO_MAX_CONCURRENCY | 4 | Parallel chain groups / subagents | | SPARK_VIDEO_REVIEW_THRESHOLD | 7.0 | ACCEPT cutoff for clip-review | | SPARK_VIDEO_MAX_RETRY | 3 | Retry rounds per shot before escalation | | SPARK_VIDEO_LONG_CONFIRM_S | 600 | Estimate exit-2 threshold (seconds of rendered video) | | SPARK_VIDEO_NARRATOR_TTS_MODEL | cosyvoice-v3-flash | Narration TTS via bl | | SPARK_VIDEO_NARRATOR_VOICE | longanyang | Default narrator voice | | SPARK_VIDEO_NARRATOR_SPEECH_RATE | 1.2 | Default speech rate (0.5–2.0) |

Handling user "no" at any gate

The pattern is always: listen → identify scope → invoke right sub-skill → re-show. Examples:

• "Script is weak — 钱夫人 needs more bite" at GATE 1 → invoke spark-video-screenwriter

with scope = which scenes, plus the user's note. Re-compile script.md, re-show.

• "S03-002 is too dark" at GATE 3 → don't re-render the whole

storyboard. Just uv run scripts/render_shot.py --shot S03-002 --force --reset-attempts (auto-runs clip-review). Re-show updated shot.

• "BGM is too loud" at GATE 4 → edit Storyboard.bgm.volume (or

bgm-config.json), re-run uv run scripts/stitch.py.

DON'Ts

• ❌ Don't skip any gate. The user owns the creative/budget decisions.

Skip only when the corresponding --vfx / --mode / --provider flag was passed.

• ❌ Don't render before storyboard.py validate passes. Renders are

expensive; validation is free.

• ❌ Don't render before storyboard.py estimate is shown to the user

at GATE 2. If estimate exits 2 (over budget), surface that explicitly.

• ❌ Don't call bl directly anywhere — always ./scripts/bl so the

call lands in logs/model_calls.jsonl. Same rule for any subagent you spawn.

• ❌ Don't auto-accept escalations. Wh

…

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: modelstudioai
• Source: modelstudioai/skills
• License: Apache-2.0
• Homepage: https://modelstudioai.github.io/skills/

Install and usage instructions live in the source repository linked above.