fix: auto-configure sync-branch for rig beads

New rigs now get sync-branch: beads-sync in their .beads/config.yaml
automatically. This enables multi-clone coordination for polecats,
crew members, and refinery.

Also added gt doctor check (beads-sync-branch) to verify existing rigs
have sync-branch configured, with --fix support.

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

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

internal/cmd/doctor.go

@@ -55,6 +55,7 @@ func runDoctor(cmd *cobra.Command, args []string) error {
 	// Register built-in checks
 	d.Register(doctor.NewDaemonCheck())
 	d.Register(doctor.NewBeadsDatabaseCheck())
+	d.Register(doctor.NewBeadsSyncBranchCheck())
 
 	// Run checks
 	var report *doctor.Report

internal/doctor/beads_sync_check.go

@@ -0,0 +1,110 @@
+package doctor
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// BeadsSyncBranchCheck verifies that rig-level beads have sync-branch configured.
+// Rig beads need sync-branch for multi-clone coordination (polecats, crew, etc.)
+// Town-level beads should NOT have sync-branch (single clone, commits to main).
+type BeadsSyncBranchCheck struct {
+	FixableCheck
+}
+
+// NewBeadsSyncBranchCheck creates a new sync-branch configuration check.
+func NewBeadsSyncBranchCheck() *BeadsSyncBranchCheck {
+	return &BeadsSyncBranchCheck{
+		FixableCheck: FixableCheck{
+			BaseCheck: BaseCheck{
+				CheckName:        "beads-sync-branch",
+				CheckDescription: "Verify rig beads have sync-branch configured",
+			},
+		},
+	}
+}
+
+// Run checks if rig-level beads have sync-branch properly configured.
+func (c *BeadsSyncBranchCheck) Run(ctx *CheckContext) *CheckResult {
+	// Only check if a rig is specified
+	if ctx.RigName == "" {
+		return &CheckResult{
+			Name:    c.Name(),
+			Status:  StatusOK,
+			Message: "No rig specified, skipping rig beads sync-branch check",
+		}
+	}
+
+	// Check rig-level beads config
+	rigBeadsDir := filepath.Join(ctx.RigPath(), ".beads")
+	configPath := filepath.Join(rigBeadsDir, "config.yaml")
+
+	content, err := os.ReadFile(configPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return &CheckResult{
+				Name:    c.Name(),
+				Status:  StatusWarning,
+				Message: "No .beads/config.yaml in rig",
+				FixHint: "Run 'bd init' in the rig directory",
+			}
+		}
+		return &CheckResult{
+			Name:    c.Name(),
+			Status:  StatusError,
+			Message: "Could not read .beads/config.yaml: " + err.Error(),
+		}
+	}
+
+	// Check for sync-branch setting
+	if !strings.Contains(string(content), "sync-branch:") {
+		return &CheckResult{
+			Name:    c.Name(),
+			Status:  StatusWarning,
+			Message: "Rig beads missing sync-branch configuration",
+			Details: []string{
+				"Rig: " + ctx.RigName,
+				"Rig beads need sync-branch for multi-clone coordination",
+				"Without this, polecats and crew members can't share beads",
+			},
+			FixHint: "Run 'gt doctor --fix' or add 'sync-branch: beads-sync' to .beads/config.yaml",
+		}
+	}
+
+	return &CheckResult{
+		Name:    c.Name(),
+		Status:  StatusOK,
+		Message: "Rig beads sync-branch is configured",
+	}
+}
+
+// Fix adds sync-branch to the rig beads config.
+func (c *BeadsSyncBranchCheck) Fix(ctx *CheckContext) error {
+	if ctx.RigName == "" {
+		return nil
+	}
+
+	rigBeadsDir := filepath.Join(ctx.RigPath(), ".beads")
+	configPath := filepath.Join(rigBeadsDir, "config.yaml")
+
+	content, err := os.ReadFile(configPath)
+	if err != nil {
+		return err
+	}
+
+	// Check if already configured
+	if strings.Contains(string(content), "sync-branch:") {
+		return nil
+	}
+
+	// Append sync-branch setting
+	f, err := os.OpenFile(configPath, os.O_APPEND|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = f.WriteString("sync-branch: beads-sync\n")
+	return err
+}

internal/rig/manager.go

@@ -329,6 +329,7 @@ func (m *Manager) initAgentStates(rigPath string) error {
 }
 
 // initBeads initializes the beads database at rig level.
+// Rig beads use sync-branch for multi-clone coordination (polecats, crew, etc.)
 func (m *Manager) initBeads(rigPath, prefix string) error {
 	beadsDir := filepath.Join(rigPath, ".beads")
 	if err := os.MkdirAll(beadsDir, 0755); err != nil {
@@ -341,10 +342,20 @@ func (m *Manager) initBeads(rigPath, prefix string) error {
 	if err := cmd.Run(); err != nil {
 		// bd might not be installed or --no-agents not supported, create minimal structure
 		configPath := filepath.Join(beadsDir, "config.yaml")
-		configContent := fmt.Sprintf("prefix: %s\n", prefix)
+		// Rig beads need sync-branch for multi-clone coordination
+		configContent := fmt.Sprintf("prefix: %s\nsync-branch: beads-sync\n", prefix)
 		if writeErr := os.WriteFile(configPath, []byte(configContent), 0644); writeErr != nil {
 			return writeErr
 		}
+	} else {
+		// bd init succeeded, but we still need to add sync-branch
+		// Append to config.yaml (bd init doesn't set sync-branch by default)
+		configPath := filepath.Join(beadsDir, "config.yaml")
+		f, err := os.OpenFile(configPath, os.O_APPEND|os.O_WRONLY, 0644)
+		if err == nil {
+			defer f.Close()
+			f.WriteString("sync-branch: beads-sync\n")
+		}
 	}
 	return nil
 }