Nobody versions their agent configs, and everybody pays for it. The
config files that steer AI agents in your repos are infrastructure:
they change behavior, they break silently, and they interact with
external tools whose formats move. Infrastructure without versioning
means every incident is an archaeology project. Here is the minimal
discipline that fixes it.
Three properties make agent configs version-critical in a way ordinary
docs are not:
One version for the whole config set, bumped on every deliberate
change:
Where the version lives: a header comment in AGENTS.md and a
VERSION entry in the changelog. One grep finds it.
Not "updated rules", the entry says what an agent will do differently:
## [2.1.0], 2026-09-14
### Added
- Migration safety rules: forward-only, expand/contract, batch backfills.
### Changed
- Test naming rule now scoped to test globs (was always-on), always-on budget drops ~15 lines.
### Fixed
- 20-testing.mdc frontmatter had `alwaysApply: true` defeating the glob.
Six months later, "why does the agent stop-and-plan now?" has a
greppable answer.
One line per release: which upstream tool documentation the configs
were validated against, dated. When Cursor changes frontmatter
semantics and your rules misbehave, the compatibility record tells you
whether your files predate the change. This is the artifact nobody
keeps and everyone eventually needs.
The update path matters more than the version number:
Once configs have versions, changelogs, compatibility records, and an
update procedure, they have become.. packages. The logical endpoint is
to consume them like packages: versioned kits, installed per repo,
updated by deliberate bump, local customizations living in a documented
layer. That is the model AgentConfig Studio ships, semver releases, a
changelog with behavior-level entries, a COMPATIBILITY.md matrix per
release, and an idempotent installer so the update is one command and
the rollback is a re-install of the previous version.
If you'd rather not assemble this by hand: AgentConfig Studio on Gumroad ships this as version-pinned, validator-tested kits for 12 stacks. The complete Next.js/TypeScript kit is free (MIT) if you want to inspect the structure first.