| --- |
| license: cc-by-4.0 |
| pretty_name: Where Claude Haiku falls behind Opus (163 coding runs, Claude Code, Codex, Antigravity) |
| language: |
| - en |
| tags: |
| - coding-agents |
| - claude |
| - claude-code |
| - codex |
| - gemini |
| - antigravity |
| - benchmark |
| - llm |
| size_categories: |
| - n<1K |
| configs: |
| - config_name: default |
| data_files: ai-coding-limit-line.csv |
| --- |
| |
| # Where Claude Haiku falls behind Opus: 163 coding runs with hidden tests |
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| 163 headless runs (plus 11 excluded) of Claude Code (Haiku 5.5, Sonnet 5.5, Opus 5.5), Codex (gpt-6-luna) and Antigravity CLI (Gemini 4 Argon) on six levels of coding tasks, measured 2026-10-23 to 24 on one Windows 11 laptop. |
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| Page, tables and method: https://tokensave.app/data/ai-coding-limit-line · DOI [10.5281/zenodo.23600477](https://doi.org/10.5281/zenodo.23600477) · License: CC BY 4.0 |
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|  |
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| ## Key findings |
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| - Levels 2 to 5 (apps from a spec, and an existing 1,032-line app with six symptom-only bugs plus three features): Haiku, Sonnet and Opus got full marks on all 21 runs each, Gemini 18/18, Codex 17/20. |
| - Level 6, three real bugs fixed in the [marked](https://github.com/markedjs/marked) Markdown parser in Sep to Oct 2026: the easy and medium bugs were solved by almost every run. No run fully fixed the hard one (7-case upstream test), but the models split: Sonnet passed 6 of 7 in 8 of 10 runs, Opus in 6 of 10, Haiku in 1 of 10. The missed cases are code spans containing a backtick, which the bug report did not mention. |
| - Letting the agents run the tests (dependencies preinstalled, `node`, `npm test`/`npm run`, read-only git allowed; 5 runs per Claude model) did not change the cases passed. Fewer runs broke other code with tests (2 of 15 without, one Opus run left marked unable to load; 0 of 15 with), but with so few runs that gap could be chance. Codex was also run with tests allowed, but its Windows sandbox blocked esbuild in all 5 runs (excluded). |
| - Average API cost per run (Claude Code's own figure): Haiku $0.026, Sonnet $0.19, Opus $0.45. |
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| ## Files |
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| Prompts, checkers, reference solutions and every run log are in the GitHub folder: https://github.com/johnisking/token-cost-by-language/tree/main/limit-line |
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| - `ai-coding-limit-line.csv` / `.json`: one row per run (score, full marks, seconds, tokens, cost, notes; level 5 and 6 detail columns). `excluded` marks runs stopped by the harness or by quota. |
| - `prompts/`: every prompt (tier2 to tier5b, tier6_t1 to t3, and tier6_t3_dev for the tests-allowed runs). |
| - `checkers/`: the hidden-test checkers (Playwright, Python) and the tier-6 scorer. `ref/`, `tier5a/`, `tier5b/`: reference solutions, the planted-bug base app and broken variants used to validate the checkers. |
| - `results/`: raw checker output per level. |
| - `runs/<tool>[dev]_t<level>_r<n>/` (`dev` = tests allowed): each run's log (`run.jsonl` or `run.json`), `seconds.txt` and the code it produced (`work/`; for level 6 only `work/src`). The PC user name is replaced by USER. |
| - `build_dataset.py`: builds the CSV/JSON from the results and logs. |
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| ## Notes |
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| - Level 6 scoring: a clean checkout of the commit before the upstream fix plus only the run's `src/`, the upstream fix's spec file added, then marked's spec suite. 1 point if the hidden spec passes and no other spec test newly fails. |
| - Antigravity's headless mode ends a turn at the first denied command. Gemini runs used read-only allow-rules; the level 6 runs were repeated with full permissions (`geminifull_*`, run by the owner). |
| - Few runs per cell at the higher levels (1 to 5); see the page for all limitations. |
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