# What I learned counting AI co-authored commits across 26,000 of my own > Source: > Published: 2026-09-20 17:40:26+00:00 I use Claude Code every day, but if you asked me how much of my code I actually write with it, all I had was a feeling. The data was sitting right there in git the whole time: ``` bash $ git log --format='%b' | grep -c 'Co-Authored-By: Claude' 960 ``` 960 out of 1,107 commits in that repo. Across everything I've touched: **10,261 of 26,251 commits — 39%.** I built [a small tool](https://github.com/yosh1/cocommit) to render that as an SVG card for a GitHub profile. The tool is the boring part. What I found while building it is what I actually want to write about. `co-authored-by:` search qualifier The commit search API accepts this: ``` bash $ gh api '/search/commits?q=author:USER+co-authored-by:noreply@anthropic.com&per_page=1' \ --jq '.total_count' ``` It works. It is also documented nowhere — it does not appear in [GitHub's commit search docs](https://docs.github.com/en/search-github/searching-commits). Since "it seems to work" is not evidence, I ran a control (counts move as I commit, so these are one snapshot rather than fixed values): | Query (all with `author:USER` ) | `total_count` | |---|---| | `co-authored-by:noreply@anthropic.com` | 10,261 | | `co-authored-by:copilot@github.com` | 29 | | `zzznotaqualifier:noreply@anthropic.com` | **0** | | no qualifier | 26,251 | An invented qualifier returns zero. Change the value and the count changes. The parser recognizes it. But undocumented means it can vanish without notice, and **the dangerous failure mode isn't returning zero.** If GitHub stops parsing the qualifier, it So the check is on both sides: ``` // Co-authored commits are a strict subset of all commits. A count equal to // the total means the qualifier didn't filter at all. const unusable = (n) => n === 0 || n >= total; ``` This is the one that surprised me, and it's the bug I shipped first. My initial implementation searched `co-authored-by:claude` — the agent's name. Reasonable-looking, and it returns a plausible number. Then I added Cursor and got this: ``` bash $ gh api '/search/commits?q=co-authored-by:cursor+is:public' --jq '.total_count' 10033042 ``` Ten million felt too round. I looked at what was actually matching: ``` bash $ gh api '/search/commits?q=co-authored-by:cursor+is:public&per_page=5' \ --jq '.items[].commit.message' | grep -i co-authored Co-authored-by: Cursor ``` The real trailer uses an address. Searching the *name* matches any co-author who happens to share it. And when I checked my own supposedly-correct Claude numbers: ``` name form : 10,262 email form: 10,255 ``` Seven commits of drift. Looking at what those matched, they carried a second trailer naming a human collaborator — a teammate, counted as an AI, because a name is not an identity. Every agent is now keyed on the address in its trailer. This matters more than it sounds, because some tools put *variable* text in the display name: ``` Co-authored-by: aider (anthropic/claude-sonnet-5) Co-authored-by: aider (ollama/gemma4:e4b-mlx) ``` Aider appends whichever model it used. The name is unstable; the address isn't. I read the trailers off real public commits rather than trusting vendor docs. Here's what nine agents actually write, with the public commit count each one has as of today: | Agent | Trailer address | Public commits | |---|---|---| | Claude | `noreply@anthropic.com` | 89,025,757 | | Cursor | `cursoragent@cursor.com` | 8,374,584 | | Copilot | `copilot@github.com` | 4,046,637 | | Codex | `codex@openai.com` ,`noreply@openai.com` | 1,812,065 | | Devin | `devin-ai-integration[bot]@users.noreply.github.com` | 588,010 | | Gemini | `gemini-code-assist@google.com` + bot address | 290,638 | | Jules | `google-labs-jules[bot]@users.noreply.github.com` | 233,948 | | Aider | `aider@aider.chat` | 133,041 | | Amp | `amp@ampcode.com` | 104,075 | One tool I expected to find had no dedicated trailer at all — searching for it returned only human contributors. Worth checking before you assume. Every image in a README is rewritten through `camo.githubusercontent.com`. People repeat a lot of folklore about what survives that trip, so I read the response headers: ``` content-security-policy: default-src 'none'; img-src data:; style-src 'unsafe-inline' ``` That single line settles it: | JavaScript | **blocked** (`default-src 'none'` ) | | Web fonts | **blocked** — system font stacks or nothing | | External images | **blocked** (`img-src data:` only) | | CSS animation | **allowed** (`style-src 'unsafe-inline'` ) | Animation works, which is fun — until it doesn't. My first version grew the bars from zero: ``` ``` Rasterize that locally and **the bars disappear.** Anything that ignores SMIL sees `height="0"`. Static renderers, social preview generators, and thumbnail pipelines all land there. The fix is to make the resting state the truth and let animation only supply a starting point: ``` ``` Now it animates where animation runs and looks finished everywhere else. There is a test for it, because I will absolutely make this mistake again: ``` js test('animated rendering still declares the finished geometry', () => { const svg = renderCard(sample, { animate: true }); assert.doesNotMatch(svg, /height="0"/); }); ``` I started out planning a github-readme-stats-style URL that returns an SVG. Then I compared the two numbers I could offer: | Scope | AI-written | Total | Share | |---|---|---|---| | including private | 10,261 | 26,251 | **39%** | | public only | 126 | 5,688 | **2%** | Work code lives in private repos. A public-only number isn't a smaller version of the truth, it's a different number — 2% instead of 39%. And commit search only sees repositories the token owner can reach. Other people's *public* commits are searchable, but their private ones never are. So a hosted service can only ever offer the 2% number, no matter how many tokens it pools. Running in the user's own CI solves it completely: their token, their private repos, their number. No server, no one else's PAT to hold. The API shape helps too — I only ever read `total_count`, never enumerate commits. (Which is lucky, since search caps enumeration at 1,000 results while `total_count` stays accurate well past it.) Repository names, commit messages and diffs are never read. Twelve months of history, charted: October 2025: 42 commits. September 2026: 2,067. **A 49x increase**, with the most recent months running above 80%. I knew my workflow had changed. I didn't know it had changed *that* much, and I couldn't have told you so with a number before this. That turned out to be worth more than the card itself. The tool is MIT licensed and has zero dependencies: ``` bash $ GITHUB_TOKEN=ghp_... npx github:yosh1/cocommit --user your-login ``` [https://github.com/yosh1/cocommit](https://github.com/yosh1/cocommit) If your agent isn't in the table, `git log --format='%b' | grep -i co-authored` will show you what it writes — send me the trailer and I'll add it.