fix: discover skills under .github/skills/ directory

Closes #52

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: spboyer

internal/discovery/discovery.go

@@ -46,8 +46,8 @@ func Discover(root string) ([]DiscoveredSkill, error) {
 			return nil // skip inaccessible entries
 		}
 
-		// Skip hidden directories
-		if info.IsDir() && strings.HasPrefix(info.Name(), ".") {
+		// Skip hidden directories, except .github
+		if info.IsDir() && strings.HasPrefix(info.Name(), ".") && info.Name() != ".github" {
 			return filepath.SkipDir
 		}
 

internal/discovery/discovery_test.go

@@ -229,3 +229,55 @@ func TestFilterWithEval(t *testing.T) {
 		t.Errorf("expected no-eval, got %s", withoutEval[0].Name)
 	}
 }
+
+func TestDiscoverGitHubSkillsDir(t *testing.T) {
+	// Discover() finds skills under .github/skills/
+	root := t.TempDir()
+
+	setupSkillDir(t, filepath.Join(root, ".github", "skills", "github-skill"))
+	setupEvalFile(t, filepath.Join(root, ".github", "skills", "github-skill", "eval.yaml"))
+
+	skills, err := Discover(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(skills) != 1 {
+		t.Fatalf("expected 1 skill, got %d", len(skills))
+	}
+	if skills[0].Name != "github-skill" {
+		t.Errorf("expected github-skill, got %s", skills[0].Name)
+	}
+	if !skills[0].HasEval() {
+		t.Error("github-skill should have eval")
+	}
+}
+
+func TestDiscoverOtherHiddenDirsStillSkipped(t *testing.T) {
+	// .github is exempted, but other hidden dirs (.hidden, .secret) are still skipped
+	root := t.TempDir()
+
+	// .github/skills/ should be found
+	setupSkillDir(t, filepath.Join(root, ".github", "skills", "github-skill"))
+	setupEvalFile(t, filepath.Join(root, ".github", "skills", "github-skill", "eval.yaml"))
+
+	// .hidden/ should be skipped
+	setupSkillDir(t, filepath.Join(root, ".hidden", "secret-skill"))
+	setupEvalFile(t, filepath.Join(root, ".hidden", "secret-skill", "eval.yaml"))
+
+	// .secret/ should be skipped
+	setupSkillDir(t, filepath.Join(root, ".secret", "another-skill"))
+	setupEvalFile(t, filepath.Join(root, ".secret", "another-skill", "eval.yaml"))
+
+	skills, err := Discover(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(skills) != 1 {
+		t.Fatalf("expected 1 skill (.github only), got %d", len(skills))
+	}
+	if skills[0].Name != "github-skill" {
+		t.Errorf("expected github-skill, got %s", skills[0].Name)
+	}
+}

internal/workspace/workspace.go

@@ -118,20 +118,38 @@ func DetectContext(dir string, opts ...DetectOption) (*WorkspaceContext, error)
 
 	// 3. Check for configured skills subdirectory with SKILL.md children
 	skillsDir := filepath.Join(absDir, o.skillsDir)
+	var skills []SkillInfo
 	if isDir(skillsDir) {
-		skills := scanForSkills(skillsDir)
-		if len(skills) > 0 {
-			return &WorkspaceContext{
-				Type:     ContextMultiSkill,
-				Root:     absDir,
-				Skills:   skills,
-				EvalsDir: o.evalsDir,
-			}, nil
+		skills = scanForSkills(skillsDir)
+	}
+
+	// 3b. Also check .github/skills/ directory (GitHub Copilot convention)
+	githubSkillsDir := filepath.Join(absDir, ".github", "skills")
+	if isDir(githubSkillsDir) {
+		githubSkills := scanForSkills(githubSkillsDir)
+		// Merge with configured skills, deduplicating by name (configured wins)
+		existingNames := make(map[string]bool)
+		for _, s := range skills {
+			existingNames[s.Name] = true
 		}
+		for _, s := range githubSkills {
+			if !existingNames[s.Name] {
+				skills = append(skills, s)
+			}
+		}
+	}
+
+	if len(skills) > 0 {
+		return &WorkspaceContext{
+			Type:     ContextMultiSkill,
+			Root:     absDir,
+			Skills:   skills,
+			EvalsDir: o.evalsDir,
+		}, nil
 	}
 
 	// 4. Scan immediate children of dir for SKILL.md
-	skills := scanForSkills(absDir)
+	skills = scanForSkills(absDir)
 	if len(skills) > 0 {
 		return &WorkspaceContext{
 			Type:     ContextMultiSkill,

internal/workspace/workspace_test.go

@@ -426,3 +426,101 @@ func TestFindEval_WithCustomEvalsDir(t *testing.T) {
 		t.Errorf("expected %q, got %q", expected, evalPath)
 	}
 }
+
+func TestDetectContext_GitHubSkillsDir(t *testing.T) {
+	// Skills in .github/skills/ are auto-discovered
+	root := t.TempDir()
+	writeFile(t, filepath.Join(root, ".github", "skills", "github-skill", "SKILL.md"), skillMD("github-skill"))
+
+	ctx, err := DetectContext(root)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if ctx.Type != ContextMultiSkill {
+		t.Fatalf("expected ContextMultiSkill, got %d", ctx.Type)
+	}
+	if len(ctx.Skills) != 1 {
+		t.Fatalf("expected 1 skill, got %d", len(ctx.Skills))
+	}
+	if ctx.Skills[0].Name != "github-skill" {
+		t.Errorf("expected 'github-skill', got %q", ctx.Skills[0].Name)
+	}
+}
+
+func TestDetectContext_BothSkillsDirs(t *testing.T) {
+	// Skills in both skills/ and .github/skills/ are merged
+	root := t.TempDir()
+	writeFile(t, filepath.Join(root, "skills", "regular-skill", "SKILL.md"), skillMD("regular-skill"))
+	writeFile(t, filepath.Join(root, ".github", "skills", "github-skill", "SKILL.md"), skillMD("github-skill"))
+
+	ctx, err := DetectContext(root)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if ctx.Type != ContextMultiSkill {
+		t.Fatalf("expected ContextMultiSkill, got %d", ctx.Type)
+	}
+	if len(ctx.Skills) != 2 {
+		t.Fatalf("expected 2 skills, got %d", len(ctx.Skills))
+	}
+
+	names := map[string]bool{}
+	for _, s := range ctx.Skills {
+		names[s.Name] = true
+	}
+	if !names["regular-skill"] || !names["github-skill"] {
+		t.Errorf("expected skills regular-skill and github-skill, got %v", names)
+	}
+}
+
+func TestDetectContext_GitHubSkillsDirDedup(t *testing.T) {
+	// Same skill name in both dirs: configured skills/ wins
+	root := t.TempDir()
+	writeFile(t, filepath.Join(root, "skills", "shared-name", "SKILL.md"), skillMD("shared-name"))
+	writeFile(t, filepath.Join(root, ".github", "skills", "shared-name", "SKILL.md"), skillMD("shared-name"))
+
+	ctx, err := DetectContext(root)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if ctx.Type != ContextMultiSkill {
+		t.Fatalf("expected ContextMultiSkill, got %d", ctx.Type)
+	}
+	if len(ctx.Skills) != 1 {
+		t.Fatalf("expected 1 skill (deduped), got %d", len(ctx.Skills))
+	}
+	if ctx.Skills[0].Name != "shared-name" {
+		t.Errorf("expected 'shared-name', got %q", ctx.Skills[0].Name)
+	}
+	// Verify that skills/ directory won (not .github/skills/)
+	expectedDir := filepath.Join(root, "skills", "shared-name")
+	if ctx.Skills[0].Dir != expectedDir {
+		t.Errorf("expected dir %q (configured should win), got %q", expectedDir, ctx.Skills[0].Dir)
+	}
+}
+
+func TestDetectContext_GitHubSkillsDirWithCustomOverride(t *testing.T) {
+	// Custom paths.skills + .github/skills/ both work
+	root := t.TempDir()
+	writeFile(t, filepath.Join(root, "my-skills", "custom-skill", "SKILL.md"), skillMD("custom-skill"))
+	writeFile(t, filepath.Join(root, ".github", "skills", "github-skill", "SKILL.md"), skillMD("github-skill"))
+
+	ctx, err := DetectContext(root, WithSkillsDir("my-skills"))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if ctx.Type != ContextMultiSkill {
+		t.Fatalf("expected ContextMultiSkill, got %d", ctx.Type)
+	}
+	if len(ctx.Skills) != 2 {
+		t.Fatalf("expected 2 skills, got %d", len(ctx.Skills))
+	}
+
+	names := map[string]bool{}
+	for _, s := range ctx.Skills {
+		names[s.Name] = true
+	}
+	if !names["custom-skill"] || !names["github-skill"] {
+		t.Errorf("expected skills custom-skill and github-skill, got %v", names)
+	}
+}