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Claude Sonnet 5.5 (effort default (no --effort flag) · thinking on) on Refactor a legacy freight tariff into structured output while preserving its quirks for old orders

AClaude Sonnet 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
$0.07
Wall time
22s
Human step-ins
0
Outcome
Pass

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Summary

Exact prompt

# Refactor a legacy freight tariff without changing old invoices `legacy/tariff.py` is a 2019 script that prints one total per order from a pipe-separated file (`python legacy/tariff.py orders.txt`). Old invoices depend on its **exact** output, quirks included. Write `solve.py` (Python 3 standard library only): `python solve.py input.json answer.json`, where `input.json` has `orders` (each `id`, `date`, `zone`, `kg`, `declared`, `flags`; `orders.txt` holds the same orders in the legacy format). **The `legacy/` directory is deleted before scoring**, so `solve.py` must not import or run it. Fresh order sets are generated. ## Required behaviour 1. Orders dated **before 2027-01-01**: reproduce the legacy script exactly. That covers its `total` string and its `ERROR zone` cases, and every intermediate value as the legacy code computes it: billable kg, the rate it uses, base (after the express doubling), fuel, insurance, discount and the remote charge. Floating-point and formatting quirks included. 2. Orders dated **on or after 2027-01-01** follow the same legacy calculation, except: a. the zone rate is always the order's own zone rate (A, B or C; zone is case-insensitive), with no weight-based switch; any other zone is an error; b. flag `H` (hazmat) adds a flat 15.00 after everything else (not discounted). Before 2027 `H` is ignored, like any unknown flag. 3. Output per order, in input order: `{"id", "billable_kg", "rate", "base", "fuel", "insurance", "discount", "remote", "hazmat", "total"}` with numbers as JSON numbers and `total` as the string the legacy code would print (`"%.2f"`). An error order is `{"id", "error": "zone"}`. `hazmat` is 0 for orders without it, and `remote` is 9.99 or 0. ## answer.json `{"quotes": [...]}` ## Scoring Hidden checks (partial credit; all must pass; values must be equal exactly): `legacy_totals_preserved`, `legacy_breakdown` (pre-2027 orders), `new_rules_totals`, `new_rules_breakdown` (2027+ orders) on the given orders; `fresh_run_1`, `fresh_run_2` (all fields, all orders). 30-second limit per run.

A 'clean' rewrite with exact decimal rounding, or one that fixes the zone bug everywhere, breaks old totals; the legacy file is removed before scoring, so it must be reimplemented. 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: 1. legacy_totals_preserved 2. legacy_breakdown 3. new_rules_totals 4. new_rules_breakdown 5. fresh_run_1 6. fresh_run_2

Setup notes: Use Case Scout batch 12 case m09-legacy-freight-refactor (offline, synthetic fixture). Prepared with batch12/prepare.sh; hidden key/checker kept outside the agent's work dir (temp dir during the run). Prompt = TASK.md verbatim. Scored with the case's scorer: `python score.py WORKDIR KEYDIR` (python3, run from the case dir). Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. 1-min load average at scoring 0.33 (8 cores). Claude Code's own reported cost for claude-sonnet-5.5: $0.070744. 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
$0.07
Wall time
22s
Human step-ins
0
Turns
4
Model usage
ModelInput tokOutput tokCost
AClaude Sonnet 5.5anthropic/claude-sonnet-5.5effort default (no --effort flag) · thinking on83,3832,394$0.07

Reproduce this run

  1. Use the use case prompt on the use case page.
  2. 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.
  3. It counts as a success only if it meets every success criterion: 1. legacy_totals_preserved 2. legacy_breakdown 3. new_rules_totals 4. new_rules_breakdown 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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  "result": "I wrote `solve.py` in the working directory. It doesn't import or run anything from `legacy/`.\n\nI compared it against the legacy script on the pre-2027 orders in `input.json`. All 55 of them match: the same `total` strings and the same zone errors. The other 15 orders are dated 2027 or later, so there was nothing to compare them against. I checked only the totals and error cases, not the intermediate values (billable kg, rate, base and so on). I also didn't time it, though there are only 70 orders.\n\nTwo legacy quirks are kept for pre-2027 orders:\n- **Unknown zones:** an unknown zone with a billable weight over 30 kg gets the B rate instead of an error. Only unknown zones up to 30 kg give the `ERROR zone` result.\n- **Discount flags:** if an order has more than one `D` flag, the last one wins.\n\nFor 2027 and later, the zone must be A, B or C (case-insensitive). The rate is always that zone's own rate, and flag `H` adds a flat 15.00 after everything else.",
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 }
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