feat(detector): implement nvm-windows detection

[dipto0321]

Changes

• internal/detector/nvm_windows.go (full implementation, //go:build windows):

  • Detect(): platform.LookupManagerBinary("nvm") != "" OR $NVM_HOME env OR $NVM_SYMLINK env (asdf pattern, two-env-var detection)
  • Version(): nvm version, parses the bare semver (e.g., "1.1.12") — upstream's dispatcher calls fmt.Println(NvmVersion) so output has no branding prefix and no v prefix
  • ListInstalled(): nvm list, lines * X.Y.Z (Currently using <arch>-bit executable) (current) / X.Y.Z (others), the trailing (Currently using <arch>-bit executable) suffix is stripped before semver parse; No installations recognized. sentinel filtered out
  • nvmWindowsRoot() helper: $NVM_HOME only — no home-dir fallback because the default location varies between Windows releases and nodeup should not pretend to know
  • nvmWindowsSymlink() helper: $NVM_SYMLINK only (the active-version symlink dir)
  • Mutation methods return ErrNVMWindowsNotImplemented sentinel (asdf pattern)

• internal/detector/nvm_windows_test.go (~30 mocked tests, //go:build windows):

  • parseNVMWindowsVersion: standard output (1.1.12), v-prefixed (v1.1.12), git-describe suffix (1.1.12-4-gabc1234), trailing whitespace (incl. \r\n), empty, whitespace-only, multi-token defensive
  • parseNVMWindowsInstalled: real output (with (Currently using 64-bit executable) suffix), 32-bit marker variant, filters No installations recognized. sentinel, sentinel with leading blank lines, unsorted → sorted ascending, empty stdout, only blank lines, defensive v prefix, skips unparseable lines, \r\n line endings
  • Method tests: Name, Version (success capturing command, v-prefixed, runShell error, empty-output error), ListInstalled (success, empty stdout, runShell error)
  • Detect: no-PATH-no-env, binary-on-PATH (nvm.exe directly since file is Windows-only), honors $NVM_HOME, honors $NVM_SYMLINK, empty env falls through, whitespace-only env falls through
  • MutationMethods_NotImplemented sentinel test
  • nvmWindowsRoot helper: env-precedence, empty-when-unset, whitespace-only-env-falls-through
  • nvmWindowsSymlink helper: env, empty-when-unset, whitespace-only

• internal/detector/registry_windows.go (refactor):

  • Removed the Phase 1 stub NVMWindows type/methods (they live in nvm_windows.go now)
  • All() continues to return NewNVMWindows() as the last entry — behavior unchanged

Design notes

• This is the eighth and final manager in the Phase 1 rollout, completing the internal/detector surface (fnm, nvm, Volta, ASDF, mise, n, Nodenv, NVMWindows).
• nvm-windows is the only Windows-only manager. The build-tag pattern (//go:build windows on both the implementation AND the test file) means the file is excluded from linux/macOS builds. The CI matrix exercises windows-latest so the tests run there.
• The file is build-tagged, so the test code does NOT need a runtime.GOOS switch when constructing the stub nvm.exe binary — that's why nodenv's TestNodenv_Detect_FindsBinaryOnPath runtime.GOOS switch is absent here.
• The detection pattern uses three independent signals: nvm.exe on PATH, $NVM_HOME, and $NVM_SYMLINK. The upstream installer sets $NVM_HOME and $NVM_SYMLINK together at install time, so they typically appear together, but either alone is sufficient — the symlink is the active-version dir, the home is the install root.
• We deliberately do NOT fall back from $NVM_HOME to a hard-coded %APPDATA%\nvm path because that varies between Windows releases (the upstream installer lets the user pick any directory).
• nvm list output strips the v prefix via regex upstream (regexp.MustCompile("v").ReplaceAllString) before printing — so the parser sees bare X.Y.Z. We re-strip a leading v defensively in case a fork skips that step.
• The architecture suffix (32-bit / 64-bit) is hard-coded in upstream's format string (arm64 installs still print 64-bit). We accept both via substring-on-whitespace — the parser doesn't care which bitness the marker uses.
• nvm version aliases (v, -v, --version, -version, --v) all dispatch to the same case in upstream, so we use version as the canonical subcommand.

Verification

• GOOS=windows go build ./... ✅
• GOOS=windows go vet ./... ✅
• GOOS=windows go test -c -o /tmp/detector.test ./internal/detector ✅ (cross-compiles cleanly)
• go test ./... -race (native darwin) ✅ (all 7 prior-manager test suites still pass; nvm-windows tests are excluded by build tag and will run on windows-latest in CI)

[cocogitto-bot]

✔️ 2d1161e - Conventional commits check succeeded.