The Rulebook Said More Than the Merge Script Allowed

Which dependency updates may an AI agent merge without a human looking? I thought I knew. In my last post on it I praised the merge script, merge-pr.ts, the program agents merge through. It lets an agent merge a library bump only if Dependabot (GitHub's update bot) opened it from this repo, it touches just the dependency files, and the version stays within the same major number (a 0.x library counts a minor step as a major one, since 0.4 to 0.5 may break things). What I hadn't read was the repo's written decision, ADR-0004 (an ADR is a short record of a decision; this one says which changes need a human to merge them). It said: "A minor or patch version bump can be merged by an agent, even though it changes package.json". Any agent, any bump. The script was stricter than the repo's own written rules.

The part that got me is how often that was noticed. The repo has a scheduled agent that audits the docs for drift, and issue #2395, filed at 01:01 UTC on the 22nd, says it had named this mismatch twice and filed nothing. Its session logs are the records agents write about their own runs. The one from the 16th calls the mismatch "tracked in" #1889 and ends "No issue filed." The one from the 20th says ADR-0004 and the human-merge rule (the list of files only a person may merge) "say any minor/patch bump may be agent-merged but merge-pr.ts only allows same-repo Dependabot bumps". The issue's guess is that issue #1889, "Decide how Dependabot PRs get merged", sounded close enough that the runs took it as already covering the gap. The check that finally filed it was another scheduled run, one that reviews how the auditors behave.

Then came the choice, which I'd have botched. Either widen the script so agents can merge their own small bumps, or narrow the ADR to what the script does. I'd have widened it; more code feels like progress. PR #2406 did the opposite. Per its description the owner picked "change the ADR to match the code, with no code changes", and it merged at 08:11 UTC, seven hours after the issue. The ADR now says an agent may merge a minor or patch bump that Dependabot opens from this repo, "if it changes only package.json and the lockfile and stays within each package's major" (the lockfile is the file that pins every library's exact version). That is the 0.x rule from above, now written into the ADR. The short summary of it that agents are handed at the start of every session stops at "only package.json and the lockfile" and leaves the major-version clause to the full ADR.

I like that the safer direction won: agents are now allowed less than the old text promised, and nobody had to write new code to get there. What keeps me up is the count. The rulebook was wrong while two audits read it and moved on, and it took a third process, one that watches the auditors, to write it down. I can only hope the answer is not "nobody".