feat: reserve built-in agent slash commands

agent/skills.go

@@ -325,6 +325,31 @@ func (c *SkillCatalog) Diagnostics() []error {
 	return append([]error(nil), c.diagnostics...)
 }
 
+// ExcludeNames removes skills whose names are reserved by a caller. It returns
+// the excluded names in sorted order.
+func (c *SkillCatalog) ExcludeNames(names []string) []string {
+	if c == nil {
+		return nil
+	}
+	reserved := make(map[string]struct{}, len(names))
+	for _, name := range names {
+		name = strings.TrimPrefix(strings.ToLower(strings.TrimSpace(name)), "/")
+		if name != "" {
+			reserved[name] = struct{}{}
+		}
+	}
+	var excluded []string
+	for name := range c.skills {
+		if _, ok := reserved[name]; !ok {
+			continue
+		}
+		delete(c.skills, name)
+		excluded = append(excluded, name)
+	}
+	sort.Strings(excluded)
+	return excluded
+}
+
 func (c *SkillCatalog) Load(name string) (Skill, error) {
 	name = strings.TrimSpace(name)
 	if !skillName.MatchString(name) {

agent/skills_test.go

@@ -257,6 +257,30 @@ func TestLoadDefaultSkillsPrecedenceAndCollisions(t *testing.T) {
 	}
 }
 
+func TestSkillCatalogExcludeNames(t *testing.T) {
+	dir := t.TempDir()
+	for _, name := range []string{"release-notes", "system", "exit"} {
+		writeCatalogSkill(t, dir, name, "instructions")
+	}
+	catalog, err := DiscoverSkills(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if got, want := strings.Join(catalog.ExcludeNames([]string{"/system", "EXIT"}), ","), "exit,system"; got != want {
+		t.Fatalf("excluded skills = %q, want %q", got, want)
+	}
+	if _, err := catalog.Load("system"); err == nil {
+		t.Fatal("excluded system skill should not load")
+	}
+	if _, err := catalog.Load("exit"); err == nil {
+		t.Fatal("excluded exit skill should not load")
+	}
+	if _, err := catalog.Load("release-notes"); err != nil {
+		t.Fatalf("non-conflicting skill should remain available: %v", err)
+	}
+}
+
 func TestSkillContentListsDirectoryAndResources(t *testing.T) {
 	root := t.TempDir()
 	skillDir := filepath.Join(root, "pdf-processing")

cmd/agent_tui.go

@@ -87,6 +87,9 @@ func GenerateAgentTUI(cmd *cobra.Command, client *api.Client, opts agentTUIOptio
 	if err != nil {
 		return fmt.Errorf("load agent skills: %w", err)
 	}
+	if ignored := skillCatalog.ExcludeNames(agentchat.BuiltinSlashCommandNames()); len(ignored) > 0 {
+		fmt.Fprintf(os.Stderr, "\033[1mwarning:\033[0m ignoring agent skill(s): %s\n", strings.Join(ignored, ", "))
+	}
 	for _, diagnostic := range skillCatalog.Diagnostics() {
 		fmt.Fprintf(os.Stderr, "\033[1mwarning:\033[0m ignored invalid agent skill: %v\n", diagnostic)
 	}

cmd/agent_tui_test.go

@@ -95,6 +95,39 @@ func TestAgentSkillSystemContextRequiresAvailableEnabledSkillTool(t *testing.T)
 	}
 }
 
+func TestAgentSkillCommandCollisionsAreIgnored(t *testing.T) {
+	dir := t.TempDir()
+	for _, name := range []string{"release-notes", "system", "exit"} {
+		if err := os.Mkdir(filepath.Join(dir, name), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		content := "---\nname: " + name + "\ndescription: Test skill.\n---\nInstructions."
+		if err := os.WriteFile(filepath.Join(dir, name, "SKILL.md"), []byte(content), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	catalog, err := coreagent.DiscoverSkills(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ignored := catalog.ExcludeNames(agentchat.BuiltinSlashCommandNames())
+	if got, want := strings.Join(ignored, ", "), "exit, system"; got != want {
+		t.Fatalf("ignored skills = %q, want %q", got, want)
+	}
+	if _, err := catalog.Load("release-notes"); err != nil {
+		t.Fatalf("non-conflicting skill should remain available: %v", err)
+	}
+	if context := catalog.SystemContext(); !strings.Contains(context, "release-notes: Test skill.") || strings.Contains(context, "system: Test skill.") || strings.Contains(context, "exit: Test skill.") {
+		t.Fatalf("skill context = %q", context)
+	}
+	for _, name := range []string{"system", "exit"} {
+		if _, err := catalog.Load(name); err == nil {
+			t.Fatalf("conflicting skill %q should be ignored", name)
+		}
+	}
+}
+
 func TestAgentSelectionItemsUseLaunchSections(t *testing.T) {
 	items := agentSelectionItems([]agentchat.ModelOption{
 		{Name: "glm-5.2:cloud", Description: "cloud", Recommended: true, Cloud: true},

cmd/tui/chat/input.go

@@ -64,6 +64,24 @@ var chatSlashCommands = []chatSlashCommand{
 	{name: "/save", usage: "/save <filename>", description: "save request JSON; saved as <filename>.json"},
 }
 
+// BuiltinSlashCommandNames returns the names reserved by built-in slash
+// commands, including aliases.
+func BuiltinSlashCommandNames() []string {
+	names := make(map[string]struct{})
+	for _, command := range chatSlashCommands {
+		names[strings.TrimPrefix(command.name, "/")] = struct{}{}
+		for _, alias := range command.aliases {
+			names[strings.TrimPrefix(alias, "/")] = struct{}{}
+		}
+	}
+	reserved := make([]string, 0, len(names))
+	for name := range names {
+		reserved = append(reserved, name)
+	}
+	sort.Strings(reserved)
+	return reserved
+}
+
 func (m *chatModel) handleSubmit() (tea.Model, tea.Cmd) {
 	m.syncInputPlaceholders()
 	input := strings.TrimSpace(string(m.input))