feat: add --agent overrides to start/attach

internal/cmd/crew.go

@@ -17,6 +17,7 @@ var (
 	crewDetached      bool
 	crewMessage       string
 	crewAccount       string
+	crewAgentOverride string
 	crewAll           bool
 	crewDryRun        bool
 )
@@ -328,6 +329,7 @@ func init() {
 	crewAtCmd.Flags().BoolVar(&crewNoTmux, "no-tmux", false, "Just print directory path")
 	crewAtCmd.Flags().BoolVarP(&crewDetached, "detached", "d", false, "Start session without attaching")
 	crewAtCmd.Flags().StringVar(&crewAccount, "account", "", "Claude Code account handle to use (overrides default)")
+	crewAtCmd.Flags().StringVar(&crewAgentOverride, "agent", "", "Agent alias to run crew worker with (overrides rig/town default)")
 
 	crewRemoveCmd.Flags().StringVar(&crewRig, "rig", "", "Rig to use")
 	crewRemoveCmd.Flags().BoolVar(&crewForce, "force", false, "Force remove (skip safety checks)")
@@ -350,6 +352,7 @@ func init() {
 
 	crewStartCmd.Flags().BoolVar(&crewAll, "all", false, "Start all crew members in the rig")
 	crewStartCmd.Flags().StringVar(&crewAccount, "account", "", "Claude Code account handle to use")
+	crewStartCmd.Flags().StringVar(&crewAgentOverride, "agent", "", "Agent alias to run crew worker with (overrides rig/town default)")
 
 	crewStopCmd.Flags().StringVar(&crewRig, "rig", "", "Rig to use (filter when using --all)")
 	crewStopCmd.Flags().BoolVar(&crewAll, "all", false, "Stop all running crew sessions")

internal/cmd/crew_at.go

@@ -150,8 +150,11 @@ func runCrewAt(cmd *cobra.Command, args []string) error {
 		// This gives cleaner lifecycle: Claude exits → session ends (no intermediate shell)
 		// Pass "gt prime" as initial prompt so Claude loads context immediately
 		// Export GT_ROLE and BD_ACTOR since tmux SetEnvironment only affects new panes
-		claudeCmd := config.BuildCrewStartupCommand(r.Name, name, r.Path, "gt prime")
+		startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(r.Name, name, r.Path, "gt prime", crewAgentOverride)
-		if err := t.RespawnPane(paneID, claudeCmd); err != nil {
+		if err != nil {
+			return fmt.Errorf("building startup command: %w", err)
+		}
+		if err := t.RespawnPane(paneID, startupCmd); err != nil {
 			return fmt.Errorf("starting claude: %w", err)
 		}
 
@@ -174,8 +177,11 @@ func runCrewAt(cmd *cobra.Command, args []string) error {
 			// Use respawn-pane to replace shell with Claude directly
 			// Pass "gt prime" as initial prompt so Claude loads context immediately
 			// Export GT_ROLE and BD_ACTOR since tmux SetEnvironment only affects new panes
-			claudeCmd := config.BuildCrewStartupCommand(r.Name, name, r.Path, "gt prime")
+			startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(r.Name, name, r.Path, "gt prime", crewAgentOverride)
-			if err := t.RespawnPane(paneID, claudeCmd); err != nil {
+			if err != nil {
+				return fmt.Errorf("building startup command: %w", err)
+			}
+			if err := t.RespawnPane(paneID, startupCmd); err != nil {
 				return fmt.Errorf("restarting claude: %w", err)
 			}
 		}
@@ -185,7 +191,10 @@ func runCrewAt(cmd *cobra.Command, args []string) error {
 	if isInTmuxSession(sessionID) {
 		// We're in the session at a shell prompt - just start the agent directly
 		// Pass "gt prime" as initial prompt so it loads context immediately
-		agentCfg := config.ResolveAgentConfig(townRoot, r.Path)
+		agentCfg, _, err := config.ResolveAgentConfigWithOverride(townRoot, r.Path, crewAgentOverride)
+		if err != nil {
+			return fmt.Errorf("resolving agent: %w", err)
+		}
 		fmt.Printf("Starting %s in current session...\n", agentCfg.Command)
 		return execAgent(agentCfg, "gt prime")
 	}

internal/cmd/crew_lifecycle.go

@@ -338,6 +338,7 @@ func runCrewStart(cmd *cobra.Command, args []string) error {
 		// Set the start.go flags before calling runStartCrew
 		startCrewRig = rigName
 		startCrewAccount = crewAccount
+		startCrewAgentOverride = crewAgentOverride
 
 		// Use rig/name format for runStartCrew
 		fullName := rigName + "/" + name

internal/cmd/deacon.go

@@ -89,6 +89,8 @@ Stops the current session (if running) and starts a fresh one.`,
 	RunE: runDeaconRestart,
 }
 
+var deaconAgentOverride string
+
 var deaconHeartbeatCmd = &cobra.Command{
 	Use:   "heartbeat [action]",
 	Short: "Update the Deacon heartbeat",
@@ -203,7 +205,6 @@ Examples:
 	RunE: runDeaconStaleHooks,
 }
 
-
 var (
 	triggerTimeout time.Duration
 
@@ -258,6 +259,10 @@ func init() {
 	deaconStaleHooksCmd.Flags().BoolVar(&staleHooksDryRun, "dry-run", false,
 		"Preview what would be unhooked without making changes")
 
+	deaconStartCmd.Flags().StringVar(&deaconAgentOverride, "agent", "", "Agent alias to run the Deacon with (overrides town default)")
+	deaconAttachCmd.Flags().StringVar(&deaconAgentOverride, "agent", "", "Agent alias to run the Deacon with (overrides town default)")
+	deaconRestartCmd.Flags().StringVar(&deaconAgentOverride, "agent", "", "Agent alias to run the Deacon with (overrides town default)")
+
 	rootCmd.AddCommand(deaconCmd)
 }
 
@@ -275,7 +280,7 @@ func runDeaconStart(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("Deacon session already running. Attach with: gt deacon attach")
 	}
 
-	if err := startDeaconSession(t, sessionName); err != nil {
+	if err := startDeaconSession(t, sessionName, deaconAgentOverride); err != nil {
 		return err
 	}
 
@@ -287,7 +292,7 @@ func runDeaconStart(cmd *cobra.Command, args []string) error {
 }
 
 // startDeaconSession creates and initializes the Deacon tmux session.
-func startDeaconSession(t *tmux.Tmux, sessionName string) error {
+func startDeaconSession(t *tmux.Tmux, sessionName, agentOverride string) error {
 	// Find workspace root
 	townRoot, err := workspace.FindFromCwdOrError()
 	if err != nil {
@@ -326,7 +331,11 @@ func startDeaconSession(t *tmux.Tmux, sessionName string) error {
 	// Restarts are handled by daemon via ensureDeaconRunning on each heartbeat
 	// The startup hook handles context loading automatically
 	// Export GT_ROLE and BD_ACTOR in the command since tmux SetEnvironment only affects new panes
-	if err := t.SendKeys(sessionName, config.BuildAgentStartupCommand("deacon", "deacon", "", "")); err != nil {
+	startupCmd, err := config.BuildAgentStartupCommandWithAgentOverride("deacon", "deacon", "", "", agentOverride)
+	if err != nil {
+		return fmt.Errorf("building startup command: %w", err)
+	}
+	if err := t.SendKeys(sessionName, startupCmd); err != nil {
 		return fmt.Errorf("sending command: %w", err)
 	}
 
@@ -394,7 +403,7 @@ func runDeaconAttach(cmd *cobra.Command, args []string) error {
 	if !running {
 		// Auto-start if not running
 		fmt.Println("Deacon session not running, starting...")
-		if err := startDeaconSession(t, sessionName); err != nil {
+		if err := startDeaconSession(t, sessionName, deaconAgentOverride); err != nil {
 			return err
 		}
 	}
@@ -942,4 +951,3 @@ func runDeaconStaleHooks(cmd *cobra.Command, args []string) error {
 
 	return nil
 }
-

internal/cmd/mayor.go

@@ -31,6 +31,8 @@ The Mayor is the global coordinator for Gas Town, running as a persistent
 tmux session. Use the subcommands to start, stop, attach, and check status.`,
 }
 
+var mayorAgentOverride string
+
 var mayorStartCmd = &cobra.Command{
 	Use:   "start",
 	Short: "Start the Mayor session",
@@ -84,6 +86,10 @@ func init() {
 	mayorCmd.AddCommand(mayorStatusCmd)
 	mayorCmd.AddCommand(mayorRestartCmd)
 
+	mayorStartCmd.Flags().StringVar(&mayorAgentOverride, "agent", "", "Agent alias to run the Mayor with (overrides town default)")
+	mayorAttachCmd.Flags().StringVar(&mayorAgentOverride, "agent", "", "Agent alias to run the Mayor with (overrides town default)")
+	mayorRestartCmd.Flags().StringVar(&mayorAgentOverride, "agent", "", "Agent alias to run the Mayor with (overrides town default)")
+
 	rootCmd.AddCommand(mayorCmd)
 }
 
@@ -101,7 +107,7 @@ func runMayorStart(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("Mayor session already running. Attach with: gt mayor attach")
 	}
 
-	if err := startMayorSession(t, sessionName); err != nil {
+	if err := startMayorSession(t, sessionName, mayorAgentOverride); err != nil {
 		return err
 	}
 
@@ -113,7 +119,7 @@ func runMayorStart(cmd *cobra.Command, args []string) error {
 }
 
 // startMayorSession creates and initializes the Mayor tmux session.
-func startMayorSession(t *tmux.Tmux, sessionName string) error {
+func startMayorSession(t *tmux.Tmux, sessionName, agentOverride string) error {
 	// Find workspace root
 	townRoot, err := workspace.FindFromCwdOrError()
 	if err != nil {
@@ -139,8 +145,11 @@ func startMayorSession(t *tmux.Tmux, sessionName string) error {
 	// Use SendKeysDelayed to allow shell initialization after NewSession
 	// Export GT_ROLE and BD_ACTOR in the command since tmux SetEnvironment only affects new panes
 	// Mayor uses default runtime config (empty rigPath) since it's not rig-specific
-	claudeCmd := config.BuildAgentStartupCommand("mayor", "mayor", "", "")
+	startupCmd, err := config.BuildAgentStartupCommandWithAgentOverride("mayor", "mayor", "", "", agentOverride)
-	if err := t.SendKeysDelayed(sessionName, claudeCmd, 200); err != nil {
+	if err != nil {
+		return fmt.Errorf("building startup command: %w", err)
+	}
+	if err := t.SendKeysDelayed(sessionName, startupCmd, 200); err != nil {
 		return fmt.Errorf("sending command: %w", err)
 	}
 
@@ -208,7 +217,7 @@ func runMayorAttach(cmd *cobra.Command, args []string) error {
 	if !running {
 		// Auto-start if not running
 		fmt.Println("Mayor session not running, starting...")
-		if err := startMayorSession(t, sessionName); err != nil {
+		if err := startMayorSession(t, sessionName, mayorAgentOverride); err != nil {
 			return err
 		}
 	}

internal/cmd/start.go

@@ -25,8 +25,10 @@ import (
 
 var (
 	startAll               bool
+	startAgentOverride     string
 	startCrewRig           string
 	startCrewAccount       string
+	startCrewAgentOverride string
 	shutdownGraceful       bool
 	shutdownWait           int
 	shutdownAll            bool
@@ -104,9 +106,11 @@ Examples:
 func init() {
 	startCmd.Flags().BoolVarP(&startAll, "all", "a", false,
 		"Also start Witnesses and Refineries for all rigs")
+	startCmd.Flags().StringVar(&startAgentOverride, "agent", "", "Agent alias to run Mayor/Deacon with (overrides town default)")
 
 	startCrewCmd.Flags().StringVar(&startCrewRig, "rig", "", "Rig to use")
 	startCrewCmd.Flags().StringVar(&startCrewAccount, "account", "", "Claude Code account handle to use")
+	startCrewCmd.Flags().StringVar(&startCrewAgentOverride, "agent", "", "Agent alias to run crew worker with (overrides rig/town default)")
 	startCmd.AddCommand(startCrewCmd)
 
 	shutdownCmd.Flags().BoolVarP(&shutdownGraceful, "graceful", "g", false,
@@ -155,7 +159,7 @@ func runStart(cmd *cobra.Command, args []string) error {
 	fmt.Printf("Starting Gas Town from %s\n\n", style.Dim.Render(townRoot))
 
 	// Start core agents (Mayor and Deacon)
-	if err := startCoreAgents(t); err != nil {
+	if err := startCoreAgents(t, startAgentOverride); err != nil {
 		return err
 	}
 
@@ -182,7 +186,7 @@ func runStart(cmd *cobra.Command, args []string) error {
 }
 
 // startCoreAgents starts Mayor and Deacon sessions.
-func startCoreAgents(t *tmux.Tmux) error {
+func startCoreAgents(t *tmux.Tmux, agentOverride string) error {
 	// Get session names
 	mayorSession := getMayorSessionName()
 	deaconSession := getDeaconSessionName()
@@ -193,7 +197,7 @@ func startCoreAgents(t *tmux.Tmux) error {
 		fmt.Printf("  %s Mayor already running\n", style.Dim.Render("○"))
 	} else {
 		fmt.Printf("  %s Starting Mayor...\n", style.Bold.Render("→"))
-		if err := startMayorSession(t, mayorSession); err != nil {
+		if err := startMayorSession(t, mayorSession, agentOverride); err != nil {
 			return fmt.Errorf("starting Mayor: %w", err)
 		}
 		fmt.Printf("  %s Mayor started\n", style.Bold.Render("✓"))
@@ -205,7 +209,7 @@ func startCoreAgents(t *tmux.Tmux) error {
 		fmt.Printf("  %s Deacon already running\n", style.Dim.Render("○"))
 	} else {
 		fmt.Printf("  %s Starting Deacon...\n", style.Bold.Render("→"))
-		if err := startDeaconSession(t, deaconSession); err != nil {
+		if err := startDeaconSession(t, deaconSession, agentOverride); err != nil {
 			return fmt.Errorf("starting Deacon: %w", err)
 		}
 		fmt.Printf("  %s Deacon started\n", style.Bold.Render("✓"))
@@ -799,8 +803,11 @@ func runStartCrew(cmd *cobra.Command, args []string) error {
 		if !t.IsClaudeRunning(sessionID) {
 			// Claude has exited, restart it with "gt prime" as initial prompt
 			fmt.Printf("Session exists, restarting Claude...\n")
-			claudeCmd := config.BuildCrewStartupCommand(rigName, name, r.Path, "gt prime")
+			startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(rigName, name, r.Path, "gt prime", startCrewAgentOverride)
-			if err := t.SendKeys(sessionID, claudeCmd); err != nil {
+			if err != nil {
+				return fmt.Errorf("building startup command: %w", err)
+			}
+			if err := t.SendKeys(sessionID, startupCmd); err != nil {
 				return fmt.Errorf("restarting claude: %w", err)
 			}
 		} else {
@@ -833,8 +840,11 @@ func runStartCrew(cmd *cobra.Command, args []string) error {
 
 		// Start claude with skip permissions and proper env vars for seance
 		// Pass "gt prime" as initial prompt so context is loaded immediately
-		claudeCmd := config.BuildCrewStartupCommand(rigName, name, r.Path, "gt prime")
+		startupCmd, err := config.BuildCrewStartupCommandWithAgentOverride(rigName, name, r.Path, "gt prime", startCrewAgentOverride)
-		if err := t.SendKeys(sessionID, claudeCmd); err != nil {
+		if err != nil {
+			return fmt.Errorf("building startup command: %w", err)
+		}
+		if err := t.SendKeys(sessionID, startupCmd); err != nil {
 			return fmt.Errorf("starting claude: %w", err)
 		}
 

internal/config/loader_test.go

@@ -1035,6 +1035,89 @@ func TestBuildPolecatStartupCommandWithAgentOverride(t *testing.T) {
 	}
 }
 
+func TestBuildAgentStartupCommandWithAgentOverride(t *testing.T) {
+	townRoot := t.TempDir()
+
+	if err := os.MkdirAll(filepath.Join(townRoot, "mayor"), 0755); err != nil {
+		t.Fatalf("MkdirAll: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(townRoot, "mayor", "town.json"), []byte("{}"), 0600); err != nil {
+		t.Fatalf("WriteFile town.json: %v", err)
+	}
+
+	townSettings := NewTownSettings()
+	townSettings.DefaultAgent = "gemini"
+	if err := SaveTownSettings(TownSettingsPath(townRoot), townSettings); err != nil {
+		t.Fatalf("SaveTownSettings: %v", err)
+	}
+
+	originalWd, _ := os.Getwd()
+	t.Cleanup(func() { _ = os.Chdir(originalWd) })
+	if err := os.Chdir(townRoot); err != nil {
+		t.Fatalf("Chdir: %v", err)
+	}
+
+	t.Run("empty override uses default agent", func(t *testing.T) {
+		cmd, err := BuildAgentStartupCommandWithAgentOverride("mayor", "mayor", "", "", "")
+		if err != nil {
+			t.Fatalf("BuildAgentStartupCommandWithAgentOverride: %v", err)
+		}
+		if !strings.Contains(cmd, "GT_ROLE=mayor") {
+			t.Fatalf("expected GT_ROLE export in command: %q", cmd)
+		}
+		if !strings.Contains(cmd, "BD_ACTOR=mayor") {
+			t.Fatalf("expected BD_ACTOR export in command: %q", cmd)
+		}
+		if !strings.Contains(cmd, "gemini --approval-mode yolo") {
+			t.Fatalf("expected gemini command in output: %q", cmd)
+		}
+	})
+
+	t.Run("override switches agent", func(t *testing.T) {
+		cmd, err := BuildAgentStartupCommandWithAgentOverride("mayor", "mayor", "", "", "codex")
+		if err != nil {
+			t.Fatalf("BuildAgentStartupCommandWithAgentOverride: %v", err)
+		}
+		if !strings.Contains(cmd, "codex") {
+			t.Fatalf("expected codex command in output: %q", cmd)
+		}
+	})
+}
+
+func TestBuildCrewStartupCommandWithAgentOverride(t *testing.T) {
+	townRoot := t.TempDir()
+	rigPath := filepath.Join(townRoot, "testrig")
+
+	townSettings := NewTownSettings()
+	if err := SaveTownSettings(TownSettingsPath(townRoot), townSettings); err != nil {
+		t.Fatalf("SaveTownSettings: %v", err)
+	}
+
+	if err := SaveRigSettings(RigSettingsPath(rigPath), NewRigSettings()); err != nil {
+		t.Fatalf("SaveRigSettings: %v", err)
+	}
+
+	cmd, err := BuildCrewStartupCommandWithAgentOverride("testrig", "max", rigPath, "gt prime", "gemini")
+	if err != nil {
+		t.Fatalf("BuildCrewStartupCommandWithAgentOverride: %v", err)
+	}
+	if !strings.Contains(cmd, "GT_ROLE=crew") {
+		t.Fatalf("expected GT_ROLE export in command: %q", cmd)
+	}
+	if !strings.Contains(cmd, "GT_RIG=testrig") {
+		t.Fatalf("expected GT_RIG export in command: %q", cmd)
+	}
+	if !strings.Contains(cmd, "GT_CREW=max") {
+		t.Fatalf("expected GT_CREW export in command: %q", cmd)
+	}
+	if !strings.Contains(cmd, "BD_ACTOR=testrig/crew/max") {
+		t.Fatalf("expected BD_ACTOR export in command: %q", cmd)
+	}
+	if !strings.Contains(cmd, "gemini --approval-mode yolo") {
+		t.Fatalf("expected gemini command in output: %q", cmd)
+	}
+}
+
 func TestLoadRuntimeConfigFromSettings(t *testing.T) {
 	// Create temp rig with custom runtime config
 	dir := t.TempDir()