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 42m 34sCost $13.03 reported

Generation timelapse

Generation timelapse (the agent's screen during the run, sped up). This is not the finished video. Download video (673 KB).
Review
No verdict yet.
The full review
Stopped by us. Stopped by us (box row cap reached (2848s); 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.
The exact prompt
as run, 1,336 characters. Every result for this prompt
Build an explorable tropical island in Three.js. The island has white sand beaches, palm trees, a green hilly interior and a small fishing village of wooden huts with thatched roofs, joined to the sea by a long wooden pier with boats moored alongside. The ocean around it is animated, with waves, foam along the shore and clear shallow water over a reef where fish swim among corals and sea plants, fading to deep blue further out. Let the player switch between modes: walk on the island, swim at the surface, dive underwater (with underwater fog and caustic light), sail a small boat around the island, and fly a free camera. Add a time-of-day panel with a slider that moves the sun from morning through sunset to night, changing the sky, lighting and water colours, with stars and lit windows in the village at night. Show the controls on screen. 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
Versions saved during the run
7 intermediate outputs, in the order the model wrote them.
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 40 steps
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Download the full transcript Claude Code session JSONL, 562 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 $13.03, as reported by Claude Code (its own bill for the run). The list-price estimate from the token counts is $13.01.
| Tokens by type | Tokens | $ per 1M | Cost |
|---|---|---|---|
| Input (uncached) | 836 | $10.00 | $0.0084 |
| Cache write | 350,987 | $12.50 | $4.3873 |
| Cache read | 3,299,458 | $0.25 | $0.8249 |
| Output | 155,767 | $50.00 | $7.7884 |
| of which reasoning | 88,002 | billed as output |
- Total computed from tokens
- $13.01
- Total reported by the harness
- $13.03
- Difference
- computed $13.01 vs reported $13.03 (diff -0.02)
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_tidewater.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










