Claude Opus 5.5 (effort default (no --effort flag) · thinking on) on Animate a plumbing firm's cistern flush and refill cycle in one self-contained HTML file

AClaude Opus 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-25 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.15
Wall time: 28s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Animate a plumbing firm's cistern flush and refill cycle in one self-contained HTML file Make a small animated scene: a cistern flush and refill. Write one file, `out/scene.html`, that works opened straight from disk with no network access. `spec.json` gives the page title, the stage size and the scene parameters. **Looks are not scored**: the page is opened in a headless browser (800x600 window, UTC time zone, network blocked) and checked by objective tests only. ## Scene contract - Draw the scene on one `<canvas>` or `<svg>` stage of `width` x `height` CSS pixels (spec.json), visible on load, with `<title>` containing spec.json `title`. - Animate continuously from load (`requestAnimationFrame` or timers); no click is needed unless stated below. - Expose `window.sceneState()`, returning the scene's current state in stage pixel coordinates (origin top-left of the stage): `{cisterns: [{name, x, y, level, status: "full" | "draining" | "refilling"}, ...]} (canvas px, y down; one entry per spec.json cistern; x = the cistern's centre; level = the water height in px; y = the water surface, base_y − level)`. Extra fields are fine. It must describe what is actually drawn. - Time 0 is `performance.now()` 0 (seconds = `performance.now()` / 1000). Each cistern is full (level `full_px`) until its own `flush_s`; it then drains at a steady rate to level 0 over `drain_s`; it then refills over `refill_s` with the float valve slowing it down: level = `full_px` × (1 − (1 − u)²), where u = (time − flush_s − drain_s) ÷ refill_s; after that it stays full. The surface y is `base_y` − level. Draw each cistern and its water. `sceneState()` must return the state at the moment it is called. - The page must log no errors and throw no exceptions. Keep the file at most 200,000 bytes; no external scripts, fonts, images or URLs (inline everything). ## Checks (partial credit = share passed) 1. `self_contained`: `out/scene.html` exists, is at most 200,000 bytes, references no http(s) or protocol-relative URL, and requests nothing from the network when opened. 2. `has_canvas_or_svg`: a visible `<canvas>` or `<svg>` of at least 300x200 CSS pixels is on the page. 3. `frames_change`: over 3 s, some later screenshot differs from the first in at least 0.1% of pixels, and at least 3 of 30 screenshots differ. 4. `water_level`: at every sample more than 0.05 s from a cistern flushing, emptying or finishing its refill, each cistern's x is within 1.5 px of its spec.json `x`, and its level and surface y are within 1.5 px of the exact values: `full_px` while full, falling linearly to 0 over `drain_s` from `flush_s`, then refilling as full_px × (1 − (1 − u)²) with u = time since emptying ÷ `refill_s`, then `full_px` again. 5. `cistern_status`: at those samples each cistern's `status` is full before `flush_s`, draining for `drain_s`, refilling for `refill_s`, then full; the samples include all three statuses. 6. `no_console_errors`: no uncaught exception, `console.error` or browser error is logged during the run. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.

Make a cistern flush and refill animation as one self-contained HTML file. A headless browser checks objective facts only: the file is offline and small, a canvas or SVG stage is drawn, frames change, the scene follows a timed specification (water level; cistern status) and nothing errors. A poster PNG and a short MP4 are captured for the gallery. Looks are not scored. Original benchmark task written for usecaserank.com (not based on a specific public post). Headless, offline run on a reproducible fixture. Each run's notes say how its cost was measured (estimates are marked).

Success criteria: self_contained has_canvas_or_svg frames_change water_level cistern_status no_console_errors

Setup notes: Batch 39 case tk07-cistern-refill-animation (offline, synthetic inputs, seed 2970830203). Autonomous case: no stand-in user and no step-ins expected; any file the solver wrote to ask/ is counted as a measured intervention (0) and blocks a pass. Prompt = TASK.md verbatim. Hidden key kept outside the solver's work dir. Scored with the case's scorer (python3 score.py WORKDIR KEYDIR, absolute paths); pass = every check true and no ask/ files. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. 1-min load average at scoring 0.35 (8 cores). Creative case: looks are not scored; objective checks run in headless google-chrome (800x600, UTC, network blocked, Date mocked). Gallery media (poster.png + clip.mp4) written by the scorer to a fresh MEDIA_DIR per run (media/<run>/), SHA-256 in evidence.media. Scored alone (no other check groups running), single scoring, no rescore. Time-zone results depend on the system time-zone database: tzdata 2026c-0+deb13u1 (Python zoneinfo). Claude Code's own reported cost for claude-opus-5.5: $0.147415. Score: 6/6. Cost is an ESTIMATE: measured tokens x pricing.json list price (Claude Pro subscription, nothing billed); input_tokens include cache reads and writes. Single run.

Estimated cost List-price estimate; not actually billed.

Output

Metrics

Estimated cost: $0.15
Wall time: 28s
Human step-ins: 0
Turns: 4

Model usage
Model	Input tok	Output tok	Cost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on	80,703	2,858	$0.15

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Opus 5.5 (anthropic/claude-opus-5.5, effort default (no --effort flag) · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
It counts as a success only if it meets every success criterion: self_contained has_canvas_or_svg frames_change water_level cistern_status no_console_errors
Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.

How runs are scored: Methodology.

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Automated checks

Trust 80% comes from these checks (how Trust % works).

Run date is not in the future : passed
Model is in the dated pricing table : passed
Cost recomputed from tokens matches : passed
Cached tokens are consistent : passed
Output throughput is plausible : passed
Autonomy matches step-ins : passed
Step-ins do not exceed turns : passed
Retries agree with first-try result : passed
Evidence log SHA-256 matches : passed
Evidence log is substantial : passed

Evidence log

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  "permission_denials": [],
  "terminal_reason": "completed",
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  "result": "I wrote `out/scene.html`, but I haven't run it in a browser. Playwright isn't installed here, so I couldn't load the page or confirm the state it reports.\n\n**What it does:**\n- **Stage:** a single 700\u00d7450 canvas, and the page title is \"Cistern Refill 556\".\n- **Cisterns:** all three from `spec.json` are drawn as tanks with water, a float valve and an outlet pipe. While a cistern drains, a stream of water shows below its outlet.\n- **`window.sceneState()`:** works out each cistern's state from `performance.now()` at the moment it's called, using the formulas in the brief. Each cistern stays full, then drains at a steady rate, then refills with the slowing float-valve curve, then stays full again. It reports `x`, `level`, `y = base_y \u2212 level` and `status` for each cistern, and the drawing uses the same values.\n- **Continuous motion:** all the refills finish by about 2.5 s. To keep the 3-second screenshot check from seeing a frozen picture after that, a small dot keeps circling in the top-right corner and an on-screen timer keeps counting.\n- **Self-contained:** everything is inline, with no external URLs, fonts or images. The file is about 3 KB, far under the 200,000-byte limit.\n\nThe likeliest things to fail without a browser test are a console error or an off-by-one in the timing, so it's worth opening the file once in a browser to check.",
  "ttft_ms": 1811,
  "type": "result",
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  "uuid": "[REDACTED]",
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  "time_to_request_ms": 167,
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 }
]