Go Ecosystem Upgrade

A protocol for bumping, migrating, and releasing Go library versions across many consumer projects without repeating the same expensive mistakes. Every rule below exists because a real session burned hours (or shipped broken code) by violating it. The #1 most repeated failure across every report: build-only verification — running go build instead of go test ./... and skipping behavioral checks. Compilation proves nothing about behavior.

When this skill activates

You're about to change a version number in one or more Go projects. That covers:

• Single-library bump: go get github.com/foo/bar@v1.2.0 across N consumers
• Toolchain pin: every go.mod declares go 1.26 (or a specific patch)
• Major-version migration: module path changes (v2 → v3), breaking API migrations
• Ecosystem-wide sweep: bump ALL dependencies in ALL repos
• Library release: cut tags, push to the module proxy, verify consumers resolve them
• Vendor sync: go mod vendor after a bump, or eliminating vendor/ via Nix
• Diagnostic: a bump broke things, a tag is poisoned, go.sum won't verify