fix: honor witness role start_command

internal/witness/manager.go

@@ -16,6 +16,7 @@ import (
 	"github.com/steveyegge/gastown/internal/session"
 	"github.com/steveyegge/gastown/internal/tmux"
 	"github.com/steveyegge/gastown/internal/util"
+	"github.com/steveyegge/gastown/internal/workspace"
 )
 
 // Common errors
@@ -175,6 +176,18 @@ func (m *Manager) Start(foreground bool, agentOverride string) error {
 	theme := tmux.AssignTheme(m.rig.Name)
 	_ = t.ConfigureGasTownSession(sessionID, theme, m.rig.Name, "witness", "witness")
 
+	roleConfig, err := m.roleConfig()
+	if err != nil {
+		_ = t.KillSession(sessionID)
+		return err
+	}
+
+	townRoot := m.townRoot()
+	// Apply role config env vars if present (non-fatal).
+	for key, value := range roleConfigEnvVars(roleConfig, townRoot, m.rig.Name) {
+		_ = t.SetEnvironment(sessionID, key, value)
+	}
+
 	// Update state to running
 	now := time.Now()
 	w.State = StateRunning
@@ -191,10 +204,10 @@ func (m *Manager) Start(foreground bool, agentOverride string) error {
 	// NOTE: No gt prime injection needed - SessionStart hook handles it automatically
 	// Export GT_ROLE and BD_ACTOR in the command since tmux SetEnvironment only affects new panes
 	// Pass m.rig.Path so rig agent settings are honored (not town-level defaults)
-	command, err := config.BuildAgentStartupCommandWithAgentOverride("witness", bdActor, m.rig.Path, "", agentOverride)
+	command, err := buildWitnessStartCommand(m.rig.Path, m.rig.Name, townRoot, agentOverride, roleConfig)
 	if err != nil {
 		_ = t.KillSession(sessionID)
-		return fmt.Errorf("building startup command: %w", err)
+		return err
 	}
 	// Wait for shell to be ready before sending keys (prevents "can't find pane" under load)
 	if err := t.WaitForShellReady(sessionID, 5*time.Second); err != nil {
@@ -233,6 +246,48 @@ func (m *Manager) Start(foreground bool, agentOverride string) error {
 	return nil
 }
 
+func (m *Manager) roleConfig() (*beads.RoleConfig, error) {
+	beadsPath := m.rig.BeadsPath()
+	beadsDir := beads.ResolveBeadsDir(beadsPath)
+	bd := beads.NewWithBeadsDir(beadsPath, beadsDir)
+	roleConfig, err := bd.GetRoleConfig(beads.RoleBeadIDTown("witness"))
+	if err != nil {
+		return nil, fmt.Errorf("loading witness role config: %w", err)
+	}
+	return roleConfig, nil
+}
+
+func (m *Manager) townRoot() string {
+	townRoot, err := workspace.Find(m.rig.Path)
+	if err != nil || townRoot == "" {
+		return m.rig.Path
+	}
+	return townRoot
+}
+
+func roleConfigEnvVars(roleConfig *beads.RoleConfig, townRoot, rigName string) map[string]string {
+	if roleConfig == nil || len(roleConfig.EnvVars) == 0 {
+		return nil
+	}
+	expanded := make(map[string]string, len(roleConfig.EnvVars))
+	for key, value := range roleConfig.EnvVars {
+		expanded[key] = beads.ExpandRolePattern(value, townRoot, rigName, "", "witness")
+	}
+	return expanded
+}
+
+func buildWitnessStartCommand(rigPath, rigName, townRoot, agentOverride string, roleConfig *beads.RoleConfig) (string, error) {
+	if roleConfig != nil && roleConfig.StartCommand != "" {
+		return beads.ExpandRolePattern(roleConfig.StartCommand, townRoot, rigName, "", "witness"), nil
+	}
+	bdActor := fmt.Sprintf("%s/witness", rigName)
+	command, err := config.BuildAgentStartupCommandWithAgentOverride("witness", bdActor, rigPath, "", agentOverride)
+	if err != nil {
+		return "", fmt.Errorf("building startup command: %w", err)
+	}
+	return command, nil
+}
+
 // Stop stops the witness.
 func (m *Manager) Stop() error {
 	w, err := m.loadState()

internal/witness/manager_test.go

@@ -0,0 +1,38 @@
+package witness
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/steveyegge/gastown/internal/beads"
+)
+
+func TestBuildWitnessStartCommand_UsesRoleConfig(t *testing.T) {
+	roleConfig := &beads.RoleConfig{
+		StartCommand: "exec run --town {town} --rig {rig} --role {role}",
+	}
+
+	got, err := buildWitnessStartCommand("/town/rig", "gastown", "/town", "", roleConfig)
+	if err != nil {
+		t.Fatalf("buildWitnessStartCommand: %v", err)
+	}
+
+	want := "exec run --town /town --rig gastown --role witness"
+	if got != want {
+		t.Errorf("buildWitnessStartCommand = %q, want %q", got, want)
+	}
+}
+
+func TestBuildWitnessStartCommand_DefaultsToRuntime(t *testing.T) {
+	got, err := buildWitnessStartCommand("/town/rig", "gastown", "/town", "", nil)
+	if err != nil {
+		t.Fatalf("buildWitnessStartCommand: %v", err)
+	}
+
+	if !strings.Contains(got, "GT_ROLE=witness") {
+		t.Errorf("expected GT_ROLE=witness in command, got %q", got)
+	}
+	if !strings.Contains(got, "BD_ACTOR=gastown/witness") {
+		t.Errorf("expected BD_ACTOR=gastown/witness in command, got %q", got)
+	}
+}