Add --lean flag for simplified TUI mode

cmd/root/new.go

@@ -80,10 +80,10 @@ func (f *newFlags) runNewCommand(cmd *cobra.Command, args []string) error {
 
 	sess := session.New(sessOpts...)
 
-	return runTUI(ctx, rt, sess, nil, nil, appOpts...)
+	return runTUI(ctx, rt, sess, nil, nil, nil, appOpts...)
 }
 
-func runTUI(ctx context.Context, rt runtime.Runtime, sess *session.Session, spawner tui.SessionSpawner, cleanup func(), opts ...app.Opt) error {
+func runTUI(ctx context.Context, rt runtime.Runtime, sess *session.Session, spawner tui.SessionSpawner, cleanup func(), tuiOpts []tui.Option, opts ...app.Opt) error {
 	if gen := rt.TitleGenerator(); gen != nil {
 		opts = append(opts, app.WithTitleGenerator(gen))
 	}
@@ -106,7 +106,7 @@ func runTUI(ctx context.Context, rt runtime.Runtime, sess *session.Session, spaw
 		cleanup = func() {}
 	}
 	wd, _ := os.Getwd()
-	model := tui.New(ctx, spawner, a, wd, cleanup)
+	model := tui.New(ctx, spawner, a, wd, cleanup, tuiOpts...)
 
 	p := tea.NewProgram(model, tea.WithContext(ctx), tea.WithFilter(filter))
 	coalescer.SetSender(p.Send)

cmd/root/run.go

@@ -60,6 +60,7 @@ type runExecFlags struct {
 
 	// Run only
 	hideToolResults bool
+	lean            bool
 
 	// globalPermissions holds the user-level global permission checker built
 	// from user config settings. Nil when no global permissions are configured.
@@ -117,6 +118,7 @@ func addRunOrExecFlags(cmd *cobra.Command, flags *runExecFlags) {
 	_ = cmd.PersistentFlags().MarkHidden("memprofile")
 	cmd.PersistentFlags().BoolVar(&flags.forceTUI, "force-tui", false, "Force TUI mode even when not in a terminal")
 	_ = cmd.PersistentFlags().MarkHidden("force-tui")
+	cmd.PersistentFlags().BoolVar(&flags.lean, "lean", false, "Use a simplified TUI with minimal chrome")
 	cmd.PersistentFlags().BoolVar(&flags.sandbox, "sandbox", false, "Run the agent inside a Docker sandbox (requires Docker Desktop with sandbox support)")
 	cmd.PersistentFlags().StringVar(&flags.sandboxTemplate, "template", "", "Template image for the sandbox (passed to docker sandbox create -t)")
 	cmd.MarkFlagsMutuallyExclusive("fake", "record")
@@ -275,7 +277,7 @@ func (f *runExecFlags) runOrExec(ctx context.Context, out *cli.Printer, args []s
 	}
 
 	sessStore := rt.SessionStore()
-	return runTUI(ctx, rt, sess, f.createSessionSpawner(agentSource, sessStore), initialTeamCleanup, opts...)
+	return runTUI(ctx, rt, sess, f.createSessionSpawner(agentSource, sessStore), initialTeamCleanup, f.tuiOpts(), opts...)
 }
 
 func (f *runExecFlags) loadAgentFrom(ctx context.Context, agentSource config.Source) (*teamloader.LoadResult, error) {
@@ -454,7 +456,16 @@ func (f *runExecFlags) launchTUI(ctx context.Context, out *cli.Printer, rt runti
 		return err
 	}
 
-	return runTUI(ctx, rt, sess, nil, nil, opts...)
+	return runTUI(ctx, rt, sess, nil, nil, f.tuiOpts(), opts...)
+}
+
+// tuiOpts returns the TUI options derived from the current flags.
+func (f *runExecFlags) tuiOpts() []tui.Option {
+	var opts []tui.Option
+	if f.lean {
+		opts = append(opts, tui.WithLeanMode())
+	}
+	return opts
 }
 
 func (f *runExecFlags) buildAppOpts(args []string) ([]app.Opt, error) {

pkg/tui/page/chat/chat.go

@@ -139,7 +139,8 @@ type chatPage struct {
 	sessionState *service.SessionState
 
 	// State
-	working bool
+	working  bool
+	leanMode bool
 
 	msgCancel       context.CancelFunc
 	streamCancelled bool
@@ -174,6 +175,16 @@ type chatPage struct {
 func (p *chatPage) computeSidebarLayout() sidebarLayout {
 	innerWidth := p.width - appPaddingHorizontal
 
+	// Lean mode: no sidebar at all
+	if p.leanMode {
+		return sidebarLayout{
+			mode:       sidebarCollapsedNarrow,
+			innerWidth: innerWidth,
+			chatWidth:  innerWidth,
+			chatHeight: max(1, p.height),
+		}
+	}
+
 	var mode sidebarLayoutMode
 	switch {
 	case p.width >= minWindowWidth && !p.sidebar.IsCollapsed():
@@ -300,7 +311,7 @@ func getEditorDisplayNameFromEnv(visual, editorEnv string) string {
 }
 
 // New creates a new chat page
-func New(a *app.App, sessionState *service.SessionState) Page {
+func New(a *app.App, sessionState *service.SessionState, opts ...PageOption) Page {
 	p := &chatPage{
 		sidebar:      sidebar.New(sessionState),
 		messages:     messages.New(sessionState),
@@ -309,9 +320,23 @@ func New(a *app.App, sessionState *service.SessionState) Page {
 		sessionState: sessionState,
 	}
 
+	for _, opt := range opts {
+		opt(p)
+	}
+
 	return p
 }
 
+// PageOption configures a chat page.
+type PageOption func(*chatPage)
+
+// WithLeanMode creates a lean chat page with no sidebar.
+func WithLeanMode() PageOption {
+	return func(p *chatPage) {
+		p.leanMode = true
+	}
+}
+
 // Init initializes the chat page
 func (p *chatPage) Init() tea.Cmd {
 	var cmds []tea.Cmd
@@ -518,19 +543,26 @@ func (p *chatPage) View() string {
 		bodyContent = lipgloss.JoinHorizontal(lipgloss.Left, chatView, toggleCol, sidebarView)
 
 	case sidebarCollapsed, sidebarCollapsedNarrow:
-		sidebarRendered := p.renderCollapsedSidebar(sl)
-
-		chatView := styles.ChatStyle.
-			Height(sl.chatHeight).
-			Width(sl.innerWidth).
-			Render(messagesView)
-
-		bodyContent = lipgloss.JoinVertical(lipgloss.Top, sidebarRendered, chatView)
+		if p.leanMode {
+			// Lean mode: no sidebar header, no fixed height
+			bodyContent = styles.ChatStyle.
+				Width(sl.innerWidth).
+				Render(messagesView)
+		} else {
+			sidebarRendered := p.renderCollapsedSidebar(sl)
+			chatView := styles.ChatStyle.
+				Height(sl.chatHeight).
+				Width(sl.innerWidth).
+				Render(messagesView)
+			bodyContent = lipgloss.JoinVertical(lipgloss.Top, sidebarRendered, chatView)
+		}
 	}
 
-	return styles.AppStyle.
-		Height(p.height).
-		Render(bodyContent)
+	appStyle := styles.AppStyle
+	if !p.leanMode {
+		appStyle = appStyle.Height(p.height)
+	}
+	return appStyle.Render(bodyContent)
 }
 
 // renderSidebarHandle renders the sidebar toggle/resize handle.