/creating-video

name: creating-video
description: "Create video from prompts by overseeing multi-clip AI generation end to end: write a shot list, generate each scene with Gemini Omni Flash (via the Cloudflare AI Gateway), review the results, and assemble them into a finished cut. Use when the user asks to make/generate a video, a short film, an animatic, or a multi-scene clip from a script or idea; when they mention Omni, Veo, text-to-video, or image-to-video; or when acting as the editing/director agent over generated footage. Triggers on 'make a video', 'generate a clip', 'short film', 'video from this script', 'turn this into a video', 'omni', 'veo', 'text to video', 'storyboard to video'. For transcoding/trimming/merging/GIF/subtitles use processing-video; for reading or summarizing existing video content use parsing-video."
metadata:
  version: 0.2.1

Creating Video

Claude cannot render video itself, but it can direct a generator. This skill drives a multi-clip pipeline — **script → per-scene generation → review → assembly** — with Claude as the editing agent overseeing continuity and cut.

Requires `ffmpeg`/`ffprobe` and Cloudflare AI Gateway creds (`/mnt/project/proxy.env`).

**Default model: Gemini Omni Flash** (`gemini-omni-flash-preview`, Interactions API) — Google's own guidance as of 2026-07. It beats Veo on character consistency, reference-image control, text rendering, and conversational editing, and generates faster (~30–90 s/clip vs 1–3 min). Fall back to **Veo 3.1** (`scripts/veo_generate.py`, kept intact) only for scene extension, first+last-frame interpolation, or legacy pipelines — Omni supports neither.

The five stages

1. **Shot list** — break the story into beats, up to 10 s each, one prompt per shot. 2. **Generate** — `scripts/omni_generate.py`, run detached. 3. **Review** — `parsing-video` on each clip **and** on the assembled cut. 4. **Assemble** — `scripts/assemble.py`, run detached. 5. **Iterate** — re-review, then **edit** failing scenes conversationally (cheaper and more stable than regenerating from scratch).

Stage 2 — Generation (Omni via Cloudflare AI Gateway)

Auth is CF AI Gateway BYOK: `proxy.env` supplies `CF_ACCOUNT_ID`, `CF_GATEWAY_ID`, `CF_API_TOKEN`; the Google key lives *inside* the gateway. Both the interactions call and the `files/{id}:download` retrieval route through it (verified 2026-07-20).

**Run detached.** The Interactions API is *synchronous* — the HTTP call holds open for the whole generation (~30–90 s/clip). `bash_tool` caps at ~50 s. Launch and adaptive-wait on the `DONE` sentinel:

# prompts.json = {"1": "...", "2": {"text": "...", "images": ["ref0.png"]}, ...}
set -a; . /mnt/project/proxy.env; set +a
(setsid python3 scripts/omni_generate.py prompts.json --out omni/ \
    --negative "on-screen watermark" &)
# then, in a separate call:
timeout 45 sh -c 'while [ ! -f omni/DONE ]; do sleep 3; done'; cat omni/generate.log

**Gotchas (all verified 2026-07-20 — the script already handles them):**

• **No dry run exists.** Even `input:""` returns 200 and bills a full

generation (~58k video output tokens). Every request costs money; never "validate" with a throwaway call.

• No `negativePrompt` parameter (Veo had one; Omni 400s on unsupported

params). `--negative` folds into the prompt as "Do not include: X."

• Videos >4MB need `delivery:"uri"` → poll `files/{id}` to ACTIVE → download

via the gateway. The script always uses uri delivery, inline base64 as fallback.

• Output is up to 10 s 1280×720 mp4 with synchronized audio + SynthID

watermark. No video extension, no first↔last-frame interpolation, no multi-video referencing — those are Veo territory.

• The egress proxy 503s on cold start → retry with backoff.

**Omni defaults to multi-shot.** Left alone it invents its own cuts inside a clip, which fights a shot-list pipeline. Every per-scene prompt should say "single continuous shot" / "no scene cuts" unless the beat wants internal cuts.

Stage 3 — Review (use the parsing-video skill)

Contact-sheet **each clip and the assembled cut**. Per-clip sheets miss cross-clip continuity; the full-cut sheet is where character drift, prop jumps, and logic breaks show up in one read (Oskar, 2026-07-18: review the whole assembly, not just scenes). Scan every sheet against the **continuity checklist**:

• **Character** — same face/hair/wardrobe across every shot they appear in.
• **Prop** — same identity, size, color, and attachment point shot to shot.
• **Physical logic** — is the world coherent (a window must be open before a bird

lands on the sill)?

• **Action completeness** — is the key action actually *shown*, not cut around?

Stage 4 — Assembly (`scripts/assemble.py`)

Trims each clip to its beat, crossfades, drops audio by default, optionally burns an overlay word, and holds the final frame so the ending lands.

(setsid python3 scripts/assemble.py omni/scene_1.mp4 ... omni/scene_6.mp4 \
    --out film.mp4 --tail-hold 1.3 &)

Run detached too — six trims plus a 30 s stitch exceed the bash ceiling on the single-core container. Diagnosed: abrupt ending → `--tail-hold`; jarring cuts between independently generated ambiences → audio dropped by default (`--keep-audio` to `acrossfade` instead).

Stage 5 — Iterate by editing, not regenerating

`results.json` stores each scene's `interaction_id`. A failed detail (wrong color, unwanted object, lighting) is a one-line conversational edit that preserves everything else:

python3 scripts/omni_generate.py --edit <interaction_id> \
    "Make the scarf red. Keep everything else the same." --out omni/scene_3_v2.mp4

Simple edit prompts work best; append "Keep everything else the same." Reserve full regeneration for scenes whose composition or action is wrong. (Editing requires `store=true`, the script's default.)

Prompt craft — continuity is the hard part

The failure modes below came from real crits on 2026-07-18 (Veo era). Omni narrows several of t