feat(sling): Support batch slinging multiple beads to a rig

Allows slinging multiple beads in a single command:
  gt sling gt-abc gt-def gt-ghi gastown

Each bead gets its own freshly spawned polecat. This parallelizes
work dispatch without running gt sling N times manually.

Changes:
- Updated Args from RangeArgs(1,2) to MinimumNArgs(1)
- Added batch mode detection when len(args)>2 and last arg is a rig
- Added runBatchSling() to handle multiple beads with progress tracking

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

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

internal/cmd/sling.go

@@ -84,8 +84,14 @@ Compare:
   gt sling <bead>     # Attach + start now (keep context)
   gt handoff <bead>   # Attach + restart (fresh context)
 
-The propulsion principle: if it's on your hook, YOU RUN IT.`,
+The propulsion principle: if it's on your hook, YOU RUN IT.
-	Args: cobra.RangeArgs(1, 2),
+
+Batch Slinging:
+  gt sling gt-abc gt-def gt-ghi gastown   # Sling multiple beads to a rig
+
+  When multiple beads are provided with a rig target, each bead gets its own
+  polecat. This parallelizes work dispatch without running gt sling N times.`,
+	Args: cobra.MinimumNArgs(1),
 	RunE: runSling,
 }
 
@@ -146,6 +152,16 @@ func runSling(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("--var cannot be used with --on (formula-on-bead mode doesn't support variables)")
 	}
 
+	// Batch mode detection: multiple beads with rig target
+	// Pattern: gt sling gt-abc gt-def gt-ghi gastown
+	// When len(args) > 2 and last arg is a rig, sling each bead to its own polecat
+	if len(args) > 2 {
+		lastArg := args[len(args)-1]
+		if rigName, isRig := IsRigName(lastArg); isRig {
+			return runBatchSling(args[:len(args)-1], rigName, townBeadsDir)
+		}
+	}
+
 	// --quality is shorthand for formula-on-bead with polecat workflow
 	// Convert: gt sling gp-abc greenplace --quality=shiny
 	// To:      gt sling mol-polecat-shiny --on gt-abc gastown
@@ -1233,3 +1249,150 @@ func createAutoConvoy(beadID, beadTitle string) (string, error) {
 
 	return convoyID, nil
 }
+
+// runBatchSling handles slinging multiple beads to a rig.
+// Each bead gets its own freshly spawned polecat.
+func runBatchSling(beadIDs []string, rigName string, townBeadsDir string) error {
+	// Validate all beads exist before spawning any polecats
+	for _, beadID := range beadIDs {
+		if err := verifyBeadExists(beadID); err != nil {
+			return fmt.Errorf("bead '%s' not found", beadID)
+		}
+	}
+
+	if slingDryRun {
+		fmt.Printf("%s Batch slinging %d beads to rig '%s':\n", style.Bold.Render("🎯"), len(beadIDs), rigName)
+		for _, beadID := range beadIDs {
+			fmt.Printf("  Would spawn polecat for: %s\n", beadID)
+		}
+		if slingNaked {
+			fmt.Printf("  --naked: would skip tmux sessions\n")
+		}
+		return nil
+	}
+
+	fmt.Printf("%s Batch slinging %d beads to rig '%s'...\n", style.Bold.Render("🎯"), len(beadIDs), rigName)
+
+	// Track results for summary
+	type slingResult struct {
+		beadID   string
+		polecat  string
+		success  bool
+		errMsg   string
+	}
+	results := make([]slingResult, 0, len(beadIDs))
+
+	// Spawn a polecat for each bead and sling it
+	for i, beadID := range beadIDs {
+		fmt.Printf("\n[%d/%d] Slinging %s...\n", i+1, len(beadIDs), beadID)
+
+		// Check bead status
+		info, err := getBeadInfo(beadID)
+		if err != nil {
+			results = append(results, slingResult{beadID: beadID, success: false, errMsg: err.Error()})
+			fmt.Printf("  %s Could not get bead info: %v\n", style.Dim.Render("✗"), err)
+			continue
+		}
+
+		if info.Status == "pinned" && !slingForce {
+			results = append(results, slingResult{beadID: beadID, success: false, errMsg: "already pinned"})
+			fmt.Printf("  %s Already pinned (use --force to re-sling)\n", style.Dim.Render("✗"))
+			continue
+		}
+
+		// Spawn a fresh polecat
+		spawnOpts := SlingSpawnOptions{
+			Force:    slingForce,
+			Naked:    slingNaked,
+			Account:  slingAccount,
+			Create:   slingCreate,
+			HookBead: beadID, // Set atomically at spawn time
+		}
+		spawnInfo, err := SpawnPolecatForSling(rigName, spawnOpts)
+		if err != nil {
+			results = append(results, slingResult{beadID: beadID, success: false, errMsg: err.Error()})
+			fmt.Printf("  %s Failed to spawn polecat: %v\n", style.Dim.Render("✗"), err)
+			continue
+		}
+
+		targetAgent := spawnInfo.AgentID()
+		hookWorkDir := spawnInfo.ClonePath
+
+		// Auto-convoy: check if issue is already tracked
+		if !slingNoConvoy {
+			existingConvoy := isTrackedByConvoy(beadID)
+			if existingConvoy == "" {
+				convoyID, err := createAutoConvoy(beadID, info.Title)
+				if err != nil {
+					fmt.Printf("  %s Could not create auto-convoy: %v\n", style.Dim.Render("Warning:"), err)
+				} else {
+					fmt.Printf("  %s Created convoy 🚚 %s\n", style.Bold.Render("→"), convoyID)
+				}
+			} else {
+				fmt.Printf("  %s Already tracked by convoy %s\n", style.Dim.Render("○"), existingConvoy)
+			}
+		}
+
+		// Hook the bead
+		hookCmd := exec.Command("bd", "update", beadID, "--status=hooked", "--assignee="+targetAgent)
+		hookCmd.Env = append(os.Environ(), "BEADS_DIR="+townBeadsDir)
+		if hookWorkDir != "" {
+			hookCmd.Dir = hookWorkDir
+		}
+		hookCmd.Stderr = os.Stderr
+		if err := hookCmd.Run(); err != nil {
+			results = append(results, slingResult{beadID: beadID, polecat: spawnInfo.PolecatName, success: false, errMsg: "hook failed"})
+			fmt.Printf("  %s Failed to hook bead: %v\n", style.Dim.Render("✗"), err)
+			continue
+		}
+
+		fmt.Printf("  %s Work attached to %s\n", style.Bold.Render("✓"), spawnInfo.PolecatName)
+
+		// Log sling event
+		actor := detectActor()
+		_ = events.LogFeed(events.TypeSling, actor, events.SlingPayload(beadID, targetAgent))
+
+		// Update agent bead state
+		updateAgentHookBead(targetAgent, beadID, hookWorkDir, townBeadsDir)
+
+		// Store args if provided
+		if slingArgs != "" {
+			if err := storeArgsInBead(beadID, slingArgs); err != nil {
+				fmt.Printf("  %s Could not store args: %v\n", style.Dim.Render("Warning:"), err)
+			}
+		}
+
+		// Nudge the polecat
+		if spawnInfo.Pane != "" {
+			if err := injectStartPrompt(spawnInfo.Pane, beadID, slingSubject, slingArgs); err != nil {
+				fmt.Printf("  %s Could not nudge (agent will discover via gt prime)\n", style.Dim.Render("○"))
+			} else {
+				fmt.Printf("  %s Start prompt sent\n", style.Bold.Render("▶"))
+			}
+		}
+
+		results = append(results, slingResult{beadID: beadID, polecat: spawnInfo.PolecatName, success: true})
+	}
+
+	// Wake witness and refinery once at the end
+	wakeRigAgents(rigName)
+
+	// Print summary
+	successCount := 0
+	for _, r := range results {
+		if r.success {
+			successCount++
+		}
+	}
+
+	fmt.Printf("\n%s Batch sling complete: %d/%d succeeded\n", style.Bold.Render("📊"), successCount, len(beadIDs))
+	if successCount < len(beadIDs) {
+		for _, r := range results {
+			if !r.success {
+				fmt.Printf("  %s %s: %s\n", style.Dim.Render("✗"), r.beadID, r.errMsg)
+			}
+		}
+	}
+
+	return nil
+}