gitnexus-impact-analysis — Claude Code skill: what breaks when you

What gitnexus-impact-analysis does

The skill answers questions like whether it is safe to change a function and who calls it. It walks the dependency graph upstream and sorts results by depth: d=1 are direct callers that will break, d=2 are indirectly affected, d=3 may need testing. It also checks affected execution flows and recent edits through a git diff.

It runs through the MCP tools impact and detect_changes, with CLI fallbacks node .gitnexus/run.cjs impact <symbol> --direction upstream --repo . and node .gitnexus/run.cjs detect-changes --scope all --repo .. Before the first call the skill wants list_repos {} to bind the repository. Once more than one repository is indexed, repo is required on every call: with a default configured in the MCP policy an omitted repo resolves to that default silently, and the answer describes the wrong code. If the intended repository is unclear, the skill says to stop and ask.

Worktrees are the sharp edge. detect_changes takes worktree when your edits live in a linked worktree the MCP server was not started from: the server only auto-detects a worktree when launched inside one, otherwise git diff runs against another checkout and reports zero changed symbols. That zero looks exactly like a real clean result, so check that the diffed checkout is the one you edited. The partial and truncated flags mean the result is incomplete and the check should be re-run.