feat: Add charmbracelet TUI for gt feed (gt-u7dxq)

- Add bubbletea and bubbles dependencies
- Create internal/tui/feed package with:
  - model.go: Main bubbletea model with agent tree and event stream
  - view.go: Rendering logic with lipgloss styling
  - keys.go: Vim-style key bindings (j/k, tab, /, q)
  - styles.go: Color palette and component styles
  - events.go: Event source from bd activity
- Update gt feed to use TUI by default (--plain for text mode)
- TUI features: agent tree by role, event stream, keyboard nav

Closes gt-be0as, gt-lexye, gt-1uhmj

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/feed.go

@@ -7,9 +7,12 @@ import (
 	"strings"
 	"syscall"
 
+	tea "github.com/charmbracelet/bubbletea"
 	"github.com/spf13/cobra"
 	"github.com/steveyegge/gastown/internal/tmux"
+	"github.com/steveyegge/gastown/internal/tui/feed"
 	"github.com/steveyegge/gastown/internal/workspace"
+	"golang.org/x/term"
 )
 
 var (
@@ -21,6 +24,7 @@ var (
 	feedRig      string
 	feedNoFollow bool
 	feedWindow   bool
+	feedPlain    bool
 )
 
 func init() {
@@ -34,6 +38,7 @@ func init() {
 	feedCmd.Flags().StringVar(&feedType, "type", "", "Filter by event type (create, update, delete, comment)")
 	feedCmd.Flags().StringVar(&feedRig, "rig", "", "Run from specific rig's beads directory")
 	feedCmd.Flags().BoolVarP(&feedWindow, "window", "w", false, "Open in dedicated tmux window (creates 'feed' window)")
+	feedCmd.Flags().BoolVar(&feedPlain, "plain", false, "Use plain text output (bd activity) instead of TUI")
 }
 
 var feedCmd = &cobra.Command{
@@ -42,15 +47,16 @@ var feedCmd = &cobra.Command{
 	Short:   "Show real-time activity feed from beads",
 	Long: `Display a real-time feed of issue and molecule state changes.
 
-This command wraps 'bd activity' to show mutations as they happen,
-providing visibility into workflow progress across Gas Town.
+By default, launches an interactive TUI dashboard with:
+  - Agent tree (top): Shows all agents organized by role with latest activity
+  - Event stream (bottom): Chronological feed you can scroll through
+  - Vim-style navigation: j/k to scroll, tab to switch panels, q to quit
 
-By default, streams in follow mode. Use --no-follow to show events once.
+Use --plain for simple text output (wraps bd activity).
 
 Tmux Integration:
   Use --window to open the feed in a dedicated tmux window named 'feed'.
   This creates a persistent window you can cycle to with C-b n/p.
-  If the window already exists, switches to it.
 
 Event symbols:
   +  created/bonded  - New issue or molecule created
@@ -60,12 +66,10 @@ Event symbols:
   ⊘  deleted         - Issue removed
 
 Examples:
-  gt feed                       # Stream all events (default: --follow)
+  gt feed                       # Launch TUI dashboard
+  gt feed --plain               # Plain text output (bd activity)
   gt feed --window              # Open in dedicated tmux window
-  gt feed -w                    # Short form of --window
-  gt feed --no-follow           # Show last 100 events and exit
   gt feed --since 1h            # Events from last hour
-  gt feed --mol gt-xyz          # Filter by issue prefix
   gt feed --rig gastown         # Use gastown rig's beads`,
 	RunE: runFeed,
 }
@@ -112,7 +116,14 @@ func runFeed(cmd *cobra.Command, args []string) error {
 		return runFeedInWindow(workDir, bdArgs)
 	}
 
-	// Standard mode: exec bd activity directly
+	// Use TUI by default if running in a terminal and not --plain
+	useTUI := !feedPlain && term.IsTerminal(int(os.Stdout.Fd()))
+
+	if useTUI {
+		return runFeedTUI(workDir)
+	}
+
+	// Plain mode: exec bd activity directly
 	return runFeedDirect(workDir, bdArgs)
 }
 
@@ -167,6 +178,28 @@ func runFeedDirect(workDir string, bdArgs []string) error {
 	return syscall.Exec(bdPath, fullArgs, os.Environ())
 }
 
+// runFeedTUI runs the interactive TUI feed.
+func runFeedTUI(workDir string) error {
+	// Create event source from bd activity
+	source, err := feed.NewBdActivitySource(workDir)
+	if err != nil {
+		return fmt.Errorf("creating event source: %w", err)
+	}
+	defer source.Close()
+
+	// Create model and connect event source
+	m := feed.NewModel()
+	m.SetEventChannel(source.Events())
+
+	// Run the TUI
+	p := tea.NewProgram(m, tea.WithAltScreen())
+	if _, err := p.Run(); err != nil {
+		return fmt.Errorf("running TUI: %w", err)
+	}
+
+	return nil
+}
+
 // runFeedInWindow opens the feed in a dedicated tmux window.
 func runFeedInWindow(workDir string, bdArgs []string) error {
 	// Check if we're in tmux