spawn: Notify Witness instead of direct nudge

- Remove hacky 5-second delay from spawn
- Send SPAWN notification to Witness after starting polecat session
- Witness uses AI to monitor polecat startup and nudge when ready
- Added SPAWN REQUEST PROCESSING section to Witness template

This implements event-driven polecat readiness detection (gt-hb0).

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

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

internal/cmd/spawn.go

@@ -337,20 +337,31 @@ func runSpawn(cmd *cobra.Command, args []string) error {
 		style.Bold.Render("✓"),
 		style.Dim.Render(fmt.Sprintf("gt session at %s/%s", rigName, polecatName)))
 
-	// TODO: Proper solution requires Witness/Deacon to monitor polecat startup
-	// and detect when Claude is ready using AI intelligence. See gt-polecat-ready issue.
-	// For now, use a fixed delay - SessionStart hook runs gt prime which tells polecat
-	// to check mail, but we also send an explicit instruction as backup.
-	sessionName := sessMgr.SessionName(polecatName)
-	time.Sleep(5 * time.Second)
+	// Notify Witness about the spawn - Witness will monitor startup and nudge when ready
+	witnessAddr := fmt.Sprintf("%s/witness", rigName)
+	spawnNotification := &mail.Message{
+		To:      witnessAddr,
+		From:    "mayor/",
+		Subject: fmt.Sprintf("SPAWN: %s starting on %s", polecatName, assignmentID),
+		Body: fmt.Sprintf(`Polecat spawn notification.
 
-	// Send work instruction - backup in case SessionStart hook doesn't trigger action
-	workInstruction := "Check your inbox with `gt mail inbox` and begin working on your assigned issue."
-	if err := t.SendKeys(sessionName, workInstruction); err != nil {
-		fmt.Printf("  %s\n", style.Dim.Render(fmt.Sprintf("Warning: could not send work instruction: %v", err)))
+Polecat: %s
+Issue: %s
+Session: %s
+
+Please monitor this polecat's startup. When Claude is ready (you can see the prompt
+in the tmux session), send a nudge to start working:
+
+    tmux send-keys -t %s "Check your inbox with 'gt mail inbox' and begin working." Enter
+
+The polecat has a work assignment in its inbox.`, polecatName, assignmentID, sessMgr.SessionName(polecatName), sessMgr.SessionName(polecatName)),
 	}
 
-	fmt.Printf("  %s\n", style.Dim.Render("Work instruction sent to polecat"))
+	if err := router.Send(spawnNotification); err != nil {
+		fmt.Printf("  %s\n", style.Dim.Render(fmt.Sprintf("Warning: could not notify witness: %v", err)))
+	} else {
+		fmt.Printf("  %s\n", style.Dim.Render("Witness notified to monitor startup"))
+	}
 
 	return nil
 }

internal/templates/roles/witness.md.tmpl

@@ -102,6 +102,57 @@ gt mail delete <message-id>
 
 ---
 
+## 🚀 SPAWN REQUEST PROCESSING
+
+When you receive a message with subject containing "SPAWN:":
+
+This means a new polecat was just spawned and needs monitoring until it starts working.
+
+### Step 1: Parse the Spawn Info
+Extract from the message:
+- Polecat name
+- Issue ID
+- Session name (e.g., `gt-{{ .RigName }}-<polecat>`)
+
+### Step 2: Monitor Startup
+Check if Claude is ready by looking at the session:
+```bash
+gt session capture {{ .RigName }}/<polecat> -n 20
+```
+
+Look for signs Claude is ready:
+- The Claude Code banner is visible
+- A prompt line starting with `>` is visible
+- No "loading" or initialization messages
+
+### Step 3: Nudge to Start Working
+Once Claude appears ready, send the work instruction:
+```bash
+tmux send-keys -t gt-{{ .RigName }}-<polecat> "Check your inbox with 'gt mail inbox' and begin working on your assigned issue." Enter
+```
+
+### Step 4: Verify Work Started
+After nudging, check the session again:
+```bash
+gt session capture {{ .RigName }}/<polecat> -n 30
+```
+
+Look for signs the polecat is working:
+- Running `gt mail inbox`
+- Reading the work assignment
+- Starting to work on the issue
+
+### Step 5: Acknowledge
+Delete the spawn notification once the polecat is working:
+```bash
+gt mail delete <message-id>
+```
+
+**Note**: If the polecat doesn't respond after 2-3 nudges, it may be stuck.
+Escalate to Mayor or try restarting the session.
+
+---
+
 ## 🔍 HEALTH CHECK PROTOCOL
 
 Periodically check polecat health: