fix(sling): Set hook_bead atomically at polecat spawn time (gt-h46pk)

When slinging work to a rig (auto-spawning a polecat), the hook_bead
is now set atomically during agent bead creation rather than in a
separate updateAgentHookBead call after spawn.

This fixes cross-beads routing issues when town beads (hq-*) are slung
to rig polecats (gt-* agent beads). By setting hook_bead at creation
time within the polecat manager context, the correct beads routing is
used.

Changes:
- Add AddOptions struct with HookBead field to polecat.Manager
- Add AddWithOptions() and RecreateWithOptions() functions
- Pass HookBead through SlingSpawnOptions in cmd/polecat_spawn.go
- Pass beadID as HookBead in cmd/sling.go for rig target spawns

Note: updateAgentHookBead() is kept for non-spawn targets (existing
agents) and formula-on-bead mode (updates hook to wisp root after
creation).

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

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

internal/cmd/polecat_spawn.go

@@ -34,10 +34,11 @@ func (s *SpawnedPolecatInfo) AgentID() string {
 
 // SlingSpawnOptions contains options for spawning a polecat via sling.
 type SlingSpawnOptions struct {
-	Force   bool   // Force spawn even if polecat has uncommitted work
-	Naked   bool   // No-tmux mode: skip session creation
-	Account string // Claude Code account handle to use
-	Create  bool   // Create polecat if it doesn't exist (currently always true for sling)
+	Force    bool   // Force spawn even if polecat has uncommitted work
+	Naked    bool   // No-tmux mode: skip session creation
+	Account  string // Claude Code account handle to use
+	Create   bool   // Create polecat if it doesn't exist (currently always true for sling)
+	HookBead string // Bead ID to set as hook_bead at spawn time (atomic assignment)
 }
 
 // SpawnPolecatForSling creates a fresh polecat and optionally starts its session.
@@ -77,6 +78,12 @@ func SpawnPolecatForSling(rigName string, opts SlingSpawnOptions) (*SpawnedPolec
 
 	// Check if polecat already exists (shouldn't, since we allocated fresh)
 	existingPolecat, err := polecatMgr.Get(polecatName)
+
+	// Build add options with hook_bead set atomically at spawn time
+	addOpts := polecat.AddOptions{
+		HookBead: opts.HookBead,
+	}
+
 	if err == nil {
 		// Exists - recreate with fresh worktree
 		// Check for uncommitted work first
@@ -89,13 +96,13 @@ func SpawnPolecatForSling(rigName string, opts SlingSpawnOptions) (*SpawnedPolec
 			}
 		}
 		fmt.Printf("Recreating polecat %s with fresh worktree...\n", polecatName)
-		if _, err = polecatMgr.Recreate(polecatName, opts.Force); err != nil {
+		if _, err = polecatMgr.RecreateWithOptions(polecatName, opts.Force, addOpts); err != nil {
 			return nil, fmt.Errorf("recreating polecat: %w", err)
 		}
 	} else if err == polecat.ErrPolecatNotFound {
 		// Create new polecat
 		fmt.Printf("Creating polecat %s...\n", polecatName)
-		if _, err = polecatMgr.Add(polecatName); err != nil {
+		if _, err = polecatMgr.AddWithOptions(polecatName, addOpts); err != nil {
 			return nil, fmt.Errorf("creating polecat: %w", err)
 		}
 	} else {

internal/cmd/sling.go

@@ -238,10 +238,11 @@ func runSling(cmd *cobra.Command, args []string) error {
 				// Spawn a fresh polecat in the rig
 				fmt.Printf("Target is rig '%s', spawning fresh polecat...\n", rigName)
 				spawnOpts := SlingSpawnOptions{
-					Force:   slingForce,
-					Naked:   slingNaked,
-					Account: slingAccount,
-					Create:  slingCreate,
+					Force:    slingForce,
+					Naked:    slingNaked,
+					Account:  slingAccount,
+					Create:   slingCreate,
+					HookBead: beadID, // Set atomically at spawn time
 				}
 				spawnInfo, spawnErr := SpawnPolecatForSling(rigName, spawnOpts)
 				if spawnErr != nil {