aitools: lint nits + Windows-safe acceptance script

- libs/aitools/installer/installer.go: alternateVariantKey uses
  strings.CutSuffix (modernize lint hint).
- libs/aitools/installer/uninstall.go: drop the redundant `name := raw`
  copy of the loop variable (copyloopvar lint hint; Go 1.22+ semantics).
- acceptance/experimental/aitools/skills/*/script: stub the Claude Code
  install dir under "${USERPROFILE:-$HOME}/.claude". On Windows the
  acceptance harness sets USERPROFILE (Go's os.UserHomeDir backing var
  on that platform), not HOME, so the previous `$HOME/.claude` wrote to
  the wrong path and the cli reported "No supported coding agents
  detected." The fallback keeps Linux/macOS behavior unchanged.

Co-authored-by: Isaac

Author: jamesbroadhead

acceptance/experimental/aitools/skills/install-experimental-empty/script

@@ -1,4 +1,8 @@
-mkdir -p "$HOME/.claude"
+# Stub a Claude Code install under the harness-set home dir so agent
+# detection picks it up. On Windows the harness sets USERPROFILE (Go's
+# os.UserHomeDir backing var on that platform), not HOME — use USERPROFILE
+# when set, fall back to HOME for Linux/macOS.
+mkdir -p "${USERPROFILE:-$HOME}/.claude"
 
 title "--experimental against a manifest with no experimental skills logs a nudge"
 trace $CLI experimental aitools install --global --experimental

acceptance/experimental/aitools/skills/install-specific/script

@@ -1,4 +1,8 @@
-mkdir -p "$HOME/.claude"
+# Stub a Claude Code install under the harness-set home dir so agent
+# detection picks it up. On Windows the harness sets USERPROFILE (Go's
+# os.UserHomeDir backing var on that platform), not HOME — use USERPROFILE
+# when set, fall back to HOME for Linux/macOS.
+mkdir -p "${USERPROFILE:-$HOME}/.claude"
 
 title "install only one specific stable skill via --skills"
 trace $CLI experimental aitools install --global --skills test-stable-a

acceptance/experimental/aitools/skills/install/script

@@ -1,5 +1,8 @@
-# Fake a Claude Code installation so agent detection picks it up.
-mkdir -p "$HOME/.claude"
+# Stub a Claude Code install under the harness-set home dir so agent
+# detection picks it up. On Windows the harness sets USERPROFILE (Go's
+# os.UserHomeDir backing var on that platform), not HOME — use USERPROFILE
+# when set, fall back to HOME for Linux/macOS.
+mkdir -p "${USERPROFILE:-$HOME}/.claude"
 
 title "stable-only install (no --experimental flag) installs 1 skill"
 trace $CLI experimental aitools install --global

libs/aitools/installer/installer.go

@@ -49,8 +49,8 @@ func manifestHasExperimental(m *Manifest) bool {
 // variant when a skill transitions between experimental and stable
 // upstream.
 func alternateVariantKey(key string) string {
-	if strings.HasSuffix(key, experimentalSuffix) {
-		return strings.TrimSuffix(key, experimentalSuffix)
+	if base, ok := strings.CutSuffix(key, experimentalSuffix); ok {
+		return base
 	}
 	return key + experimentalSuffix
 }

libs/aitools/installer/uninstall.go

@@ -63,16 +63,15 @@ func UninstallSkillsOpts(ctx context.Context, opts UninstallOptions) error {
 	var toRemove []string
 	if len(opts.Skills) > 0 {
 		seen := make(map[string]bool)
-		for _, raw := range opts.Skills {
+		for _, name := range opts.Skills {
 			// Accept either variant: if the literal name isn't installed but
 			// the alternate variant is, use the alternate. This makes uninstall
 			// resilient to the experimental↔stable transition.
-			name := raw
 			if _, ok := state.Skills[name]; !ok {
 				if alt := alternateVariantKey(name); state.Skills[alt] != "" {
 					name = alt
 				} else {
-					return fmt.Errorf("skill %q is not installed", raw)
+					return fmt.Errorf("skill %q is not installed", name)
 				}
 			}
 			if seen[name] {