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: 42.8%. Bars are scaled to that peak, not to 100%.
Which agents
| GitHub Copilot | GitHub | 313 | 25.9% |
| Claude Code | Anthropic | 10 | 0.8% |
| OpenAI Codex | OpenAI | 1 | 0.1% |
Verify it yourself
Sample commits that matched. Every one links to GitHub — check the trailers.
879f9867[api] Add program.getResolvedModule and similar (#64247)GitHub Copilot248cd7ff[api] Generate optional protocol properties with `| undefined` so we can sGitHub Copilot8ab45047Add security skill (#64238)GitHub Copilotf802c848Build checker cache keys in an inline buffer with one-shot hashing (microsClaude Codef20c2c2cInline `GetCombinedNodeFlags` and `GetCombinedModifierFlags` bodies (microClaude Codec83522a4Check the arrow-function line-terminator rule without the line map (microsClaude Code71476b44Fix module specifier rename trigger spans (microsoft/typescript-go#4783)OpenAI Codex
What was excluded
| Commits in window | 1,239 |
| Merge commits removed | −1 |
| CI / dependency bots removed | −29 |
| Considered | 1,209 |
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 microsoft/TypeScript