Second recurrence of the same host fault (infra#375; first hit
openbanking-api 2026-09-03, then cobalt-dingo 2026-09-08). golangci-lint
embeds the go/types export-data reader from the Go it was BUILT with, so a
newer GOROOT makes it unable to decode the stdlib:
panic: file requires newer Go version go1.27 (application built with go1.26)
An earlier form printed a typecheck error naming the user's own source file,
which sends people to debug code that is fine. It cost time in two repos before
anyone recognised it as a host fault rather than a repo fault.
CI never sees it — the runner image has matching versions — so it breaks
exactly the local `task check` that AGENT.md requires before every push, and
nothing else. The fix was always one reinstall; the missing thing was the
signal, which is what doctor is for.
Fails open by design: an unparseable version, or no Go at all, is a normal host
and not a fault doctor may assert. Version comparison is major.minor in POSIX
sh rather than sort -V, since this runs on macOS too and the export-data format
is minor-versioned.
Also makes the suite hermetic. The check reads the real host, so on a machine
whose golangci-lint is genuinely stale every unrelated fixture started failing.
The harness now prepends a matching fake pair for the whole file, and only the
four cases that opt in exercise the check.
Verified against koala, which is currently in exactly this state:
FAIL toolchain: golangci-lint built with go1.26.1 but GOROOT is go1.27.0
— lint panics on every Go repo; reinstall it under the current
toolchain (infra#375)
doctor: 25 passed, 0 failed. Full suite green.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>