Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) on Animate a mass on a damped spring released from rest in one self-contained HTML file

AClaude Haiku 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-23 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.0095
Wall time: 42s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Animate a mass on a damped spring released from rest in one self-contained HTML file Make a small animated scene: a damped mass-spring oscillator. 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): `{x: <displacement of the mass from rest, px, positive = stretched>, v: <velocity, px/s>}`. Extra fields are fine. It must describe what is actually drawn. - Time 0 is `performance.now()` 0 (seconds = `performance.now()` / 1000). Treat px as the length unit for displacement (the dynamics only need the rate constants: damping rate = damping_ns_per_m / (2 × mass_kg), natural frequency = √(k_n_per_m / mass_kg)). The mass is released from rest, so its velocity at time 0 is 0. Draw the spring from a fixed anchor to the mass, `rest_length_px` long at rest. `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. `damped_position`: at every sample, `x` is within 1.5 px of the exact displacement of a damped mass-spring released from rest at `x0_px` at time 0 (mass `mass_kg`, stiffness `k_n_per_m`, damping `damping_ns_per_m`). 5. `damped_velocity`: at every sample, `v` is within 3 px/s + 2% of `x0_px` × the damped angular frequency of the exact velocity. 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 damped mass-spring oscillator 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 (damped position; damped velocity) 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: Passes the case's automated scorer (hidden tests / answer key, run after the agent finished).

Setup notes: Batch 31 case ta07-damped-spring-oscillator (offline, synthetic inputs, seed 1149829800). 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 0.29 (8 cores). Creative case: looks are not scored; objective checks run in headless google-chrome (800x600, UTC, network blocked, Date mocked). Gallery media (3 s capture: poster.png + clip.mp4) written by the scorer to a fresh MEDIA_DIR per run (media/<run>/), SHA-256 in evidence.media; a single failed scene check is rescored once (both recorded in 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-haiku-5.5: $0.009494. 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: $0.0095
Wall time: 42s
Human step-ins: 0
Turns: 8

Model usage
Model	Input tok	Output tok	Cost
AClaude Haiku 5.5anthropic/claude-haiku-5.5effort default (no --effort flag) · thinking on	204,289	8,261	$0.0095

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Haiku 5.5 (anthropic/claude-haiku-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: Passes the case's automated scorer (hidden tests / answer key, run after the agent finished).
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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    "thinkingTokens": 2794,
    "canonicalModel": "claude-haiku-5-5",
    "provider": "firstParty",
    "costBasis": "list"
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  },
  "permission_denials": [],
  "terminal_reason": "completed",
  "fast_mode_state": "off",
  "fast_mode_disabled_reason": "sdk_opt_in_required",
  "subagent_stats": {
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   "requested": {
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  "safety_stops": 0,
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  "subtype": "success",
  "api_error_status": null,
  "result": "The scene is written to `out/scene.html`. It's a 4.5 KB self-contained page with a canvas and no external references. I checked it in headless Chrome, but not against the full test harness.\n\n- **Physics:** \u03b3 = 0.4 s\u207b\u00b9, \u03c9\u2080 = 5 rad/s, \u03c9_d \u2248 4.984 rad/s. The closed-form position and velocity for release from rest at 110 px are used directly. A numerical derivative of x(t) matches v(t) to about 5e-8.\n- **`sceneState()`:** it reads `performance.now()/1000` at call time and returns `{x, v}` plus some extra fields. In a headless Chrome probe with 31 samples over 3 s, the maximum error against the exact solution was 0 px for x and 0 px/s for v. The probe also saw no uncaught errors.\n- **Drawing:** the spring runs from a fixed anchor at the top to the mass, with rest length 256 px. The drawn mass position is `REST_Y + x`, so it matches the reported state. The mass stays inside the 400 px stage at full amplitude.\n- **Choices:** I inlined the spec values as constants because a `file://` page can't fetch `spec.json`. I also set the canvas backing store to the device pixel ratio, with CSS size fixed at 640\u00d7400.\n\nThe Chrome run printed dbus errors on stderr. They come from the sandbox's Chrome, not the page, and the page itself logged nothing.",
  "ttft_ms": 1265,
  "type": "result",
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  "uuid": "[REDACTED]",
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  "time_to_request_ms": 223,
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 }
]