Claude Fable 5.1 in Claude Code 2.1.280
skills off
The model's own page, run in a sandboxed frame only when you ask (a page that needs its own origin opens in a new tab on a separate demo site). Phones get a full-screen player capped at 1.5x pixel density (2x on larger screens) so it stays smooth; the original page runs uncapped. It starts in its auto-tour (T switches to play mode on a keyboard).
drawing unverified.
Wall time 43m 04sCost $12.85 reported

Generation timelapse

Generation timelapse (the agent's screen during the run, sped up). This is not the finished video. Download video (487 KB).
Review
No verdict yet.
The full review
Stopped by us. Stopped by us (box row cap reached (2861s); stopped by the box lane so the run ships as partial); not a model failure.
Scores
Not scored: only runs that finished on their own are scored.
Downloads
Files actually published for this run. Original output, site-made previews and post-run conversions are labelled separately.
- HTML project entry point
- Project source (.zip)
- Run capture video
- Generation timelapse
- Poster / render by this site (WebP)
- Scrubbed run transcript
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
- Additional project file
The exact prompt
as run, 1,341 characters. Every result for this prompt
Build an interactive Three.js scene of a single red Japanese maple (momiji) standing on a small rocky island in a still, misty lake. Its leaves are deep autumn red and orange; some drift down onto the water, where they float and leave gentle ripples. Low mist hangs over the lake and soft mountain silhouettes fade into the haze behind. A stone lantern stands beside the tree with a warm flame inside. Let the viewer interact: dragging across the water stirs the floating leaves and sends ripples through them, clicking the lantern makes it swing so its light sways across the water, and a dial turns the time of day from dawn through day and dusk to moonlight, changing the sky, the colour of the mist, the lighting and the reflections, with the moon and its reflection at night. Keep the mood calm and painterly, with a light wind moving the branches. Everything is built in code from Three.js geometry, shaders and materials; no external models or textures. Build it as index.html (plus any local asset files you create) in the current directory. Three.js may load from a pinned CDN. You may serve it locally and open it in headless chromium (/usr/bin/chromium, software WebGL, no GPU) to screenshot and inspect your own output, and iterate on your own before finishing. Close any browser you open as soon as you've taken your screenshot.
How it was made
Step by step
The prompt, every agent turn and tool call (tool name and a one-line summary; inputs and outputs are not shown), then the final message. The full machine-format transcript is published as a scrubbed download.
Show all 39 steps
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Download the full transcript Claude Code session JSONL, 554 KB. Scrubbed: anything that looks like a key, token, e-mail address or phone number is replaced, and account details and the test machine's file paths are removed.
Cost breakdown
Headline cost $12.85, as reported by Claude Code (its own bill for the run). The list-price estimate from the token counts is $12.89.
| Tokens by type | Tokens | $ per 1M | Cost |
|---|---|---|---|
| Input (uncached) | 744 | $10.00 | $0.0074 |
| Cache write | 241,138 | $12.50 | $3.0142 |
| Cache read | 2,140,913 | $0.25 | $0.5352 |
| Output | 186,645 | $50.00 | $9.3323 |
| of which reasoning | 133,235 | billed as output |
- Total computed from tokens
- $12.89
- Total reported by the harness
- $12.85
- Difference
- computed $12.89 vs reported $12.85 (diff +0.04)
Claude Code 2.1.280 reported its own total; token counts x list prices shown beside it.
Prices: Project price table (vendor list prices), 2026-09-22.
Run notes
- frozen prompt (rewritten): engine/prompts_rewritten/threejs_momijigari.txt: written by us from the recorded description (zero results)
- plain wave-1-equivalent cc_config copy (settings.json + .claude.json; no ECC files)
- Mode: interactive TUI in tmux (160x48), inside bubblewrap sandbox
- Context setting: 1M ([1m] model name)
- Isolation audit: outside paths seen

