Claude Sonnet 5.5 (effort default (no --effort flag) · thinking on) on Animate hot-air balloons drifting over hills at sunrise 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: $0.05
Wall time: 19s
Human step-ins: 0
Outcome: Pass

Compare with other models on this task →

Exact prompt

# Animate hot-air balloons drifting over hills at sunrise in one self-contained HTML file Make a small animated scene: a hot-air balloons at sunrise. 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): `{balloons: [{x, y}, ...], sun: {x, y}, hills: [ ... one entry per hill ... ]}`. Extra fields are fine. It must describe what is actually drawn. - The sun should still be rising for at least the first 10 s after load. - 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. `balloons_drift`: `sceneState().balloons` has exactly spec.json `balloons` entries and every balloon moves more than 2 px over about 3 s. 5. `sun_rises_over_hills`: the sun's y decreases by more than 0.5 px over about 3 s (it rises), its start is within 60 px of the stage, and `hills` has at least `min_hills` entries. 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 hot-air balloons at sunrise 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 (balloons drift; sun rises over hills) 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 balloons_drift sun_rises_over_hills no_console_errors

Setup notes: Batch 28 case d07-hot-air-balloons-sunrise (offline, synthetic inputs, seed 1415226419). 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 0.57 (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: $0.053118. 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: $0.05
Wall time: 19s
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	58,022	1,722	$0.05

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 balloons_drift sun_rises_over_hills 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.

Was this useful?

⇄ Rerun on another model

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

[
 {
  "duration_api_ms": 17724,
  "stop_reason": "end_turn",
  "session_id": "[REDACTED]",
  "total_cost_usd": 0.053118200000000004,
  "usage": {
   "input_tokens": 6,
   "cache_creation_input_tokens": 7714,
   "cache_read_input_tokens": 50302,
   "output_tokens": 1722,
   "output_tokens_details": {
    "thinking_tokens": 229
   },
   "server_tool_use": {
    "web_search_requests": 0,
    "web_fetch_requests": 0
   },
   "service_tier": "standard",
   "cache_creation": {
    "ephemeral_1h_input_tokens": 7714,
    "ephemeral_5m_input_tokens": 0
   },
   "inference_geo": "global",
   "iterations": [
    {
     "input_tokens": 2,
     "output_tokens": 419,
     "cache_read_input_tokens": 18966,
     "cache_creation_input_tokens": 1287,
     "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 1287
     },
     "type": "message"
    }
   ],
   "speed": "standard",
   "fallback_credit": null
  },
  "modelUsage": {
   "claude-sonnet-5-5": {
    "inputTokens": 6,
    "outputTokens": 1722,
    "cacheReadInputTokens": 50302,
    "cacheCreationInputTokens": 7714,
    "webSearchRequests": 0,
    "costUSD": 0.053118200000000004,
    "contextWindow": 1000000,
    "maxOutputTokens": 128000,
    "thinkingTokens": 229,
    "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": {
    "depth_limit": 0,
    "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 the scene to `out/scene.html`. I haven't opened it in a browser or run any of the six checks, so it is untested.\n\n- **Stage:** one 720x480 canvas (the size from `spec.json`), titled \"Balloon Sunrise 365\". Everything is inline, with no network references.\n- **Sun:** it starts at y=420 and rises 12 px/s until it reaches y=130, which takes about 24 s. That covers the required first 10 s.\n- **Balloons:** four balloons drift sideways at different speeds and wrap around the edges. Each also bobs up and down.\n- **Hills:** three layered hills, matching the minimum of three.\n- **`window.sceneState()`:** it returns `{balloons, sun, hills}` in stage pixels. Each hill entry holds only `base`, `amp` and `y` (equal to `base`), not the drawn outline.\n- **Possible miss:** `sceneState()` returns an empty `balloons` list until the first animation frame has drawn. A check that reads it before that frame would fail.",
  "ttft_ms": 3086,
  "type": "result",
  "duration_ms": 18062,
  "uuid": "[REDACTED]",
  "ttft_stream_ms": 2486,
  "time_to_request_ms": 256,
  "first_content_frame_ms": 2486,
  "queued_turn_count": 0,
  "result_index": 0
 }
]