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Claude Haiku 5.5 (effort default (no --effort flag) · thinking on) on Fix three bugs in a Python repo so its tests pass

AClaude Haiku 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-16 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first try
Estimated cost
$0.0032
Wall time
10s
Human step-ins
0
Outcome
Pass

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Summary

Exact prompt

You are working on the repository in ./repo. Fix the three bugs described in repo/ISSUES.md in textstats.py. Run the existing tests (python3 -m unittest in repo) and make sure they pass. Do not change function names or signatures.

Task prompt given to the agent (headless, offline, synthetic fixture inputs): You are working on the repository in ./repo. Fix the three bugs described in repo/ISSUES.md in textstats.py. Run the existing tests (python3 -m unittest in repo) and make sure they pass. Do not change function names or signatures. Inspired by https://x.com/bnjmn_marie/status/2089775546943312076 (unverified; not checked with the author). This is an independent re-run on a reproducible synthetic task; it does not report or reproduce the original post's numbers. Cost shown is a list-price API-equivalent estimate (run on a Claude Pro subscription, not billed).

Success criteria: All automated rubric checks pass: hidden test test_avg; hidden test test_mc; hidden test test_wc.

Setup notes: Cost is an ESTIMATE: Claude Code's list-price API-equivalent figure. The run used a Claude Pro subscription, so nothing was billed. input_tokens = all input incl. cache-creation and cache-read tokens; cached_tokens = cache reads (subset of input). Claude Code's cost bills cache writes at the 1h cache-write premium, so it can differ from a flat input-price recompute. Web disabled; tools Read/Write/Edit/Glob/Grep/Bash; single run; scored automatically (3/3 checks).

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost
$0.0032
Wall time
10s
Human step-ins
0
Turns
5
Model usage
ModelInput tokOutput tokCost
AClaude Haiku 5.5anthropic/claude-haiku-5.5effort default (no --effort flag) · thinking on98,9151,330$0.0032

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: All automated rubric checks pass: hidden test test_avg; hidden test test_mc; hidden test test_wc.
  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

Trust 80% comes from these checks (how Trust % works).

Evidence log
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 "result": "All three bugs in `ISSUES.md` are fixed in `textstats.py`, and `python3 -m unittest` now passes all 3 tests (it failed 2 failures and 1 error before the change). No function names or signatures changed.\n\n1. **`word_count`**: it now uses `text.split()` instead of `text.split(\" \")`, so runs of spaces, tabs and newlines count as separators.\n2. **`avg_word_length`**: returns `0.0` when there are no words, instead of dividing by zero.\n3. **`most_common`**: lowercases the text before tokenizing, so \"The the THE\" counts as one word. Ties are broken alphabetically, and empty or word-less text returns `None`.\n\nSpot checks: `word_count('a\\tb\\nc  d')` gives 4, `word_count('')` gives 0, `most_common('b A a B')` gives `'a'`.\n\nThe repo isn't a git repository, so I didn't commit anything.",
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