A small group is using agents. Adoption has spread beyond one person but is not project-wide.
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: 50%. Bars are scaled to that peak, not to 100%.
Which agents
| Claude Code | Anthropic | 95 | 18.2% |
| GitHub Copilot | GitHub | 9 | 1.7% |
Verify it yourself
Sample commits that matched. Every one links to GitHub — check the trailers.
5725da19Honour an explicit select slug on a tab (#4601)Claude Code39316fc2Add agent actions to the prompt block (#4610)Claude Codec08d05adFix select filters on table and cards blocks (#4608)Claude Code1dccf8f0Fix table-of-contents page group's first item cut off after navigation (RNGitHub Copilot98b2df42Add sendFeedback MCP tool for reporting documentation findings (#4384)GitHub Copilot8bfced2eAdd negotiator for markdown acceptance in middleware (#4238)GitHub Copilot
What was excluded
| Commits in window | 522 |
| Merge commits removed | −0 |
| CI / dependency bots removed | −0 |
| Considered | 522 |
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 GitbookIO/gitbook