Claude Sonnet 5.5 (effort default (no --effort flag) · thinking on) on Animate a flickering carved pumpkin on a spooky night in one self-contained HTML file

AClaude Sonnet 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-22 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first tryCompare

Estimated cost: $0.06
Wall time: 20s
Human step-ins: 0
Outcome: Pass

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Exact prompt

# Animate a flickering carved pumpkin on a spooky night in one self-contained HTML file Make a small animated scene: a jack-o'-lantern. 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): `{flame: <number 0..1, the candle brightness now>, pumpkin: {x, y, r}}`. Extra fields are fine. It must describe what is actually drawn. - `pumpkin` is the pumpkin's centre and radius in stage pixels. It is night: keep the page corners and the top-centre edge dark. - 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. `flame_flickers`: across 30 samples over 3 s, `sceneState().flame` stays within 0 to 1, takes at least 6 distinct values (to 3 dp) and spans at least 0.15. 5. `glow_and_night`: the pumpkin (`r` at least 40, centre inside the stage) visibly changes within its box between the first screenshot and a later one over 3 s, and the four page corners and the top centre stay dark (average RGB below 90). 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 jack-o'-lantern 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 over time, the scene behaves as specified (flame flickers; glow and night) 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 flame_flickers glow_and_night no_console_errors

Setup notes: Batch 28 case d03-flickering-jack-o-lantern (offline, synthetic inputs, seed 459430731). 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 0.32 (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-sonnet-5.5: $0.055558. 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: $0.06
Wall time: 20s
Human step-ins: 0
Turns: 3

Model usage
Model	Input tok	Output tok	Cost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5effort default (no --effort flag) · thinking on	58,311	1,875	$0.06

Reproduce this run

Use the use case prompt on the use case page.
Same setup: Claude Sonnet 5.5 (anthropic/claude-sonnet-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 flame_flickers glow_and_night 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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  "stop_reason": "end_turn",
  "session_id": "[REDACTED]",
  "total_cost_usd": 0.0555585,
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   "cache_creation_input_tokens": 7940,
   "cache_read_input_tokens": 50365,
   "output_tokens": 1875,
   "output_tokens_details": {
    "thinking_tokens": 212
   },
   "server_tool_use": {
    "web_search_requests": 0,
    "web_fetch_requests": 0
   },
   "service_tier": "standard",
   "cache_creation": {
    "ephemeral_1h_input_tokens": 7940,
    "ephemeral_5m_input_tokens": 0
   },
   "inference_geo": "global",
   "iterations": [
    {
     "input_tokens": 2,
     "output_tokens": 368,
     "cache_read_input_tokens": 18988,
     "cache_creation_input_tokens": 1491,
     "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 1491
     },
     "type": "message"
    }
   ],
   "speed": "standard",
   "fallback_credit": null
  },
  "modelUsage": {
   "claude-sonnet-5-5": {
    "inputTokens": 6,
    "outputTokens": 1875,
    "cacheReadInputTokens": 50365,
    "cacheCreationInputTokens": 7940,
    "webSearchRequests": 0,
    "costUSD": 0.0555585,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 212,
    "canonicalModel": "claude-sonnet-5-5",
    "provider": "firstParty",
    "costBasis": "list"
   }
  },
  "permission_denials": [],
  "terminal_reason": "completed",
  "fast_mode_state": "off",
  "fast_mode_disabled_reason": "sdk_opt_in_required",
  "subagent_stats": {
   "spawned": 0,
   "requested": {
    "background": 0,
    "foreground": 0,
    "unset": 0
   },
   "started_in_background": 0,
   "max_depth": 0,
   "spawned_by_subagents": 0,
   "completed": 0,
   "failed": 0,
   "killed": {
    "parent": 0,
    "user": 0,
    "system": 0
   },
   "refused": {
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    "concurrency_limit": 0,
    "budget": 0
   },
   "by_type": {}
  },
  "safety_stops": 0,
  "is_error": false,
  "num_turns": 3,
  "subtype": "success",
  "api_error_status": null,
  "result": "I wrote `out/scene.html`, but I haven't opened it in a browser or run any of the six checks against it.\n\nIt's a single 640x400 canvas with the title \"Jack-o'-lantern 366\". It has no external URLs or resources, and the file is small.\n\n- **Flicker:** `sceneState().flame` is a sum of three sine waves, clamped to 0\u20131. The glow behind the pumpkin and the brightness of the carved eyes, nose and mouth both follow it, so the pumpkin's box changes from frame to frame.\n- **Pumpkin:** drawn at centre (320, 220) with radius 110. `sceneState()` reports the same position and radius, since both read the same values.\n- **Darkness:** the page and canvas backgrounds are near-black, and the glow stops at 190 px from the pumpkin centre. The top-centre edge sits about 220 px from it, so it should stay dark. I didn't measure the pixels, though.\n- **Animation:** it redraws on `requestAnimationFrame`.\n\nI didn't add any error handling, so the no-console-errors check rests on the script running cleanly.",
  "ttft_ms": 3780,
  "type": "result",
  "duration_ms": 18978,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 3163,
  "time_to_request_ms": 226,
  "first_content_frame_ms": 3163,
  "queued_turn_count": 0,
  "result_index": 0
 }
]