One person is driving this. The headline number reflects a single contributor's workflow, not a project-wide shift.
Assisted or autonomous
Assisted — a developer’s identity authored the commit and the agent added itself as co-author. The agent ran git commit during a working session, with a person there. Autonomous — a bot identity is the author, no human in the loop. Across the whole index, 93.7% of agent commits are assisted.
Agent share by month
Peak month: 31%. Bars are scaled to that peak, not to 100%.
Which agents
| Claude Code | Anthropic | 327 | 10.5% |
| GitHub Copilot | GitHub | 2 | 0.1% |
Verify it yourself
Sample commits that matched. Every one links to GitHub — check the trailers.
a844747bgh-117404: Add structured version info for compression modules (GH-150567)Claude Codefd0970c0gh-156713: Fix test_nturl2path for non-UTF-8 filesystem encodings (GH-1574Claude Codeae0d6cc7gh-66172: Don't let a corrupt config file prevent IDLE from starting (#152Claude Code832d5571gh-152068: Reset PyREPL Colors on prompt finish (#152108)GitHub Copilotc8799f13gh-149035: Modernize legacy Python patterns in `Doc/tutorial/stdlib2.rst` GitHub Copilot
What was excluded
| Commits in window | 3,128 |
| Merge commits removed | −3 |
| CI / dependency bots removed | −5 |
| Considered | 3,120 |
Bots are excluded from the denominator entirely. Counting dependabot as “AI-written code” is the fastest way to produce a meaningless number.
How this was measured
Measured over February–August 2026, cloned directly. Detection is deterministic string matching against signatures agents write about themselves — no heuristics, no style analysis. Merge commits and CI bots are excluded from the denominator. The figure is a floor: squash merges strip trailers, so real usage is higher. Contributor counts are aggregate — no individual is named.
Run it yourself: npx qmmit-cli python/cpython