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Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) on Tide height by rule of twelfths and cosine, with under-keel clearance windows

AClaude Haiku 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-20 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first try
Estimated cost
$0.0083
Wall time
37s
Human step-ins
0
Outcome
Pass

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Summary

Exact prompt

# Tide height by rule of twelfths and cosine, and under-keel clearance `input.json` (synthetic, not for navigation) gives two consecutive tide events `event1` and `event2` (`time_min` minutes, `height_m`; either rising or falling), `chart_depth_m`, the boat's `draft_m`, required `min_ukc_m`, `need_minutes`, and `queries` (minutes). Write `solve.py` (Python 3 standard library only); `python solve.py input.json answer.json` writes `answer.json` and `tide.svg`. Fresh inputs are used too. ## Rules Let T = event2 time - event1 time and f = (t - event1 time) / T clamped to [0, 1]. Height = h1 + (h2 - h1) * F(f). - **Twelfths**: split [0, 1] into 6 equal parts; cumulative fractions at the part boundaries are 0, 1, 3, 6, 9, 11, 12 twelfths; interpolate linearly inside a part. - **Cosine**: F(f) = (1 - cos(pi * f)) / 2. - Under-keel clearance UKC = chart_depth + height(twelfths) - draft. A query is `safe` if UKC >= min_ukc. `required_height_m` = draft + min_ukc - chart_depth. - Safe window (per method): scan whole minutes t from event1 to event2 inclusive; a run is consecutive minutes with height >= required height. Report the first run whose length end - start (minutes) is >= `need_minutes` as `{"start", "end"}` (first and last safe minute), or null. - `max_method_diff_m`: the largest |twelfths - cosine| over those whole minutes. Use a 1e-9 tolerance on the >= comparisons. Round heights and UKC to 3 decimals. ## Visual output: tide.svg Static, self-contained SVG (root `<svg>`, no scripts, images, links or external assets; renders headless) with `<polyline id="tide-twelfths">`, `<polyline id="tide-cosine">` and `<line id="min-depth-line">` at the required height. The drawing itself is not graded. ## answer.json `{"required_height_m", "queries": [{"t", "twelfths", "cosine", "ukc", "safe"}, ...], "window_twelfths", "window_cosine", "max_method_diff_m"}` ## Scoring Hidden checks (partial credit; all must pass): `query_heights`, `safe_windows` (exact), `method_difference`, `tide_svg_static` (tide.svg exists, follows the static rules, has the ids/tags above), `fresh_run_1`, `fresh_run_2`. Numbers within 0.0015. 60-second limit per run.

Piecewise twelfths interpolation vs the cosine curve on rising and falling tides, a clamped fraction, a minute-by-minute run search with a length rule, and exact window endpoints. 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).

Benchmark code for comparing AI models, not navigation or safety software.

Success criteria: 1. query_heights 2. safe_windows 3. method_difference 4. tide_svg_static 5. fresh_run_1 6. fresh_run_2

Setup notes: Use Case Scout batch 10 case k05-tide-underkeel-clearance (offline fixture). Prepared with batch10/prepare.sh; hidden key/tests kept outside the agent's work dir. Prompt = TASK.md verbatim. Scored with the scout's scorer: `python score.py WORKDIR KEYDIR`. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. Visual output (tide.svg) rendered offline to PNG with google-chrome headless, network blocked, 1280x800 at ~3 s after load. Claude Code's own reported cost for claude-haiku-5.5: $0.008301. 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.

Metrics

Estimated cost
$0.0083
Wall time
37s
Human step-ins
0
Turns
5
Model usage
ModelInput tokOutput tokCost
AClaude Haiku 5.5anthropic/claude-haiku-5.5effort default (no --effort flag) · thinking on120,7048,035$0.0083

Reproduce this run

  1. Use the use case prompt on the use case page.
  2. 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.
  3. It counts as a success only if it meets every success criterion: 1. query_heights 2. safe_windows 3. method_difference 4. tide_svg_static 5. fresh_run_1 6. fresh_run_2
  4. 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

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Evidence log
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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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  "result": "`solve.py` is written and runs in about 0.02 s on the given input. It produces `answer.json` and `tide.svg`, and the SVG parses as valid XML.\n\nFor `input.json`:\n- **Required height:** 1.54 m.\n- **Safe window, twelfths:** minutes 722 to 937.\n- **Safe window, cosine:** minutes 722 to 937.\n- **Max method difference:** 0.05 m.\n- **Queries:** the 597 query is unsafe (UKC 0.02), the 767 query is safe (UKC 0.995), and the rest are as expected.\n\nI spot-checked the twelfths height at t=628 by hand (1.049 m) and the window start at t=722 against the 1.54 m threshold. I also ran a falling-tide fresh input (3.1 m to 0.5 m) to confirm the falling case produces a sensible window.\n\nChoices I made where the spec was open:\n- **`tide.svg` location:** it is written next to `answer.json`, so `python solve.py input.json answer.json` puts it in the current directory.\n- **Safety test:** `safe` and the window use the unrounded height against the required height with the 1e-9 tolerance. Heights and UKC are rounded to 3 decimals only in the output.\n- **UKC and `safe`:** both use the rule-of-twelfths height, as the spec's UKC formula says.\n- **Window end:** a qualifying run is reported with its true end minute, not the minute where it first reached the required length.\n- **Degenerate input:** if the two events share a time, the fraction is set to 0 before the event and 1 at or after it.\n\nThis is not a git repository, so I did not commit anything.",
  "ttft_ms": 1431,
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  "time_to_request_ms": 274,
  "first_content_frame_ms": 1310,
  "queued_turn_count": 0,
  "result_index": 0
 }
]

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