feat(nudge): Add gt nudge command for reliable Claude session messaging

Encapsulates tmux send-keys with: literal mode, 500ms debounce, separate Enter.
Tested and reliable. Updates spawn.go to use NudgeSession.

Related: gt-1hf, gt-lz2

🤖 Generated with Claude Code

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

internal/cmd/nudge.go

@@ -0,0 +1,52 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+	"github.com/steveyegge/gastown/internal/tmux"
+)
+
+func init() {
+	rootCmd.AddCommand(nudgeCmd)
+}
+
+var nudgeCmd = &cobra.Command{
+	Use:   "nudge <session> <message>",
+	Short: "Send a message to a Claude session reliably",
+	Long: `Sends a message to a tmux session running Claude Code.
+
+Uses a reliable delivery pattern:
+1. Sends text in literal mode (-l flag)
+2. Waits 500ms for paste to complete
+3. Sends Enter as a separate command
+
+This is the ONLY way to send messages to Claude sessions.
+Do not use raw tmux send-keys elsewhere.`,
+	Args: cobra.ExactArgs(2),
+	RunE: runNudge,
+}
+
+func runNudge(cmd *cobra.Command, args []string) error {
+	session := args[0]
+	message := args[1]
+
+	t := tmux.NewTmux()
+
+	// Verify session exists
+	exists, err := t.HasSession(session)
+	if err != nil {
+		return fmt.Errorf("checking session: %w", err)
+	}
+	if !exists {
+		return fmt.Errorf("session %q not found", session)
+	}
+
+	// Send message with reliable pattern
+	if err := t.NudgeSession(session, message); err != nil {
+		return fmt.Errorf("nudging session: %w", err)
+	}
+
+	fmt.Printf("✓ Nudged %s\n", session)
+	return nil
+}

internal/cmd/spawn.go

@@ -338,11 +338,11 @@ func runSpawn(cmd *cobra.Command, args []string) error {
 		style.Bold.Render("✓"),
 		style.Dim.Render(fmt.Sprintf("gt session at %s/%s", rigName, polecatName)))
 
-	// Send direct nudge to start working - don't rely on hooks or witness coordination
+	// Send direct nudge to start working using reliable NudgeSession
 	// The polecat has a work assignment in its inbox; just tell it to check
 	sessionName := sessMgr.SessionName(polecatName)
 	nudgeMsg := fmt.Sprintf("You have a work assignment. Run 'gt mail inbox' to see it, then start working on issue %s.", assignmentID)
-	if err := t.SendKeysDebounced(sessionName, nudgeMsg, 500); err != nil {
+	if err := t.NudgeSession(sessionName, nudgeMsg); err != nil {
 		fmt.Printf("  %s\n", style.Dim.Render(fmt.Sprintf("Warning: could not nudge polecat: %v", err)))
 	} else {
 		fmt.Printf("  %s\n", style.Dim.Render("Polecat nudged to start working"))