Add role-based theming with layered config and doctor check

Role themes:
- witness: rust (red/alert)
- refinery: plum (purple)
- crew/polecat: inherit rig theme

Resolution order:
1. Per-rig role override (rig/.gastown/config.json role_themes)
2. Global role default (mayor/town.json theme.role_defaults)
3. Built-in role defaults
4. Rig theme (config or hash-based)

Config schema:
- TownConfig.Theme.RoleDefaults: global role->theme map
- RigConfig.Theme.RoleThemes: per-rig role overrides

Doctor check:
- Detects sessions with outdated theme format (brackets)
- Fixable with 'gt theme apply --all'

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

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

internal/cmd/doctor.go

@@ -61,6 +61,7 @@ func runDoctor(cmd *cobra.Command, args []string) error {
 	d.Register(doctor.NewBranchCheck())
 	d.Register(doctor.NewBeadsSyncOrphanCheck())
 	d.Register(doctor.NewIdentityCollisionCheck())
+	d.Register(doctor.NewThemeCheck())
 
 	// Ephemeral beads checks
 	d.Register(doctor.NewEphemeralExistsCheck())

internal/cmd/theme.go

@@ -137,7 +137,7 @@ func runThemeApply(cmd *cobra.Command, args []string) error {
 		} else if strings.HasPrefix(session, "gt-witness-") {
 			// Witness sessions: gt-witness-<rig>
 			rig = strings.TrimPrefix(session, "gt-witness-")
-			theme = getThemeForRig(rig)
+			theme = getThemeForRole(rig, "witness")
 			worker = "witness"
 			role = "witness"
 		} else {
@@ -157,13 +157,16 @@ func runThemeApply(cmd *cobra.Command, args []string) error {
 			if strings.HasPrefix(workerPart, "crew-") {
 				worker = strings.TrimPrefix(workerPart, "crew-")
 				role = "crew"
+			} else if workerPart == "refinery" {
+				worker = "refinery"
+				role = "refinery"
 			} else {
 				worker = workerPart
 				role = "polecat"
 			}
 
-			// Use configured theme, fall back to hash-based assignment
-			theme = getThemeForRig(rig)
+			// Use role-based theme resolution
+			theme = getThemeForRole(rig, role)
 		}
 
 		// Apply theme and status format
@@ -249,6 +252,55 @@ func getThemeForRig(rigName string) tmux.Theme {
 	return tmux.AssignTheme(rigName)
 }
 
+// getThemeForRole returns the theme for a specific role in a rig.
+// Resolution order:
+// 1. Per-rig role override (rig/.gastown/config.json)
+// 2. Global role default (mayor/town.json)
+// 3. Built-in role defaults (witness=rust, refinery=plum)
+// 4. Rig theme (config or hash-based)
+func getThemeForRole(rigName, role string) tmux.Theme {
+	townRoot, _ := workspace.FindFromCwd()
+
+	// 1. Check per-rig role override
+	if townRoot != "" {
+		configPath := filepath.Join(townRoot, rigName, ".gastown", "config.json")
+		if cfg, err := config.LoadRigConfig(configPath); err == nil {
+			if cfg.Theme != nil && cfg.Theme.RoleThemes != nil {
+				if themeName, ok := cfg.Theme.RoleThemes[role]; ok {
+					if theme := tmux.GetThemeByName(themeName); theme != nil {
+						return *theme
+					}
+				}
+			}
+		}
+	}
+
+	// 2. Check global role default (town config)
+	if townRoot != "" {
+		townConfigPath := filepath.Join(townRoot, "mayor", "town.json")
+		if townCfg, err := config.LoadTownConfig(townConfigPath); err == nil {
+			if townCfg.Theme != nil && townCfg.Theme.RoleDefaults != nil {
+				if themeName, ok := townCfg.Theme.RoleDefaults[role]; ok {
+					if theme := tmux.GetThemeByName(themeName); theme != nil {
+						return *theme
+					}
+				}
+			}
+		}
+	}
+
+	// 3. Check built-in role defaults
+	builtins := config.BuiltinRoleThemes()
+	if themeName, ok := builtins[role]; ok {
+		if theme := tmux.GetThemeByName(themeName); theme != nil {
+			return *theme
+		}
+	}
+
+	// 4. Fall back to rig theme
+	return getThemeForRig(rigName)
+}
+
 // loadRigTheme loads the theme name from rig config.
 func loadRigTheme(rigName string) string {
 	townRoot, err := workspace.FindFromCwd()

internal/config/types.go

@@ -5,10 +5,11 @@ import "time"
 
 // TownConfig represents the main town configuration (mayor/town.json).
 type TownConfig struct {
-	Type      string    `json:"type"`       // "town"
-	Version   int       `json:"version"`    // schema version
-	Name      string    `json:"name"`       // town identifier
-	CreatedAt time.Time `json:"created_at"`
+	Type      string           `json:"type"`            // "town"
+	Version   int              `json:"version"`         // schema version
+	Name      string           `json:"name"`            // town identifier
+	CreatedAt time.Time        `json:"created_at"`
+	Theme     *TownThemeConfig `json:"theme,omitempty"` // global theme settings
 }
 
 // RigsConfig represents the rigs registry (mayor/rigs.json).
@@ -64,6 +65,10 @@ type ThemeConfig struct {
 
 	// Custom overrides the palette with specific colors.
 	Custom *CustomTheme `json:"custom,omitempty"`
+
+	// RoleThemes overrides themes for specific roles in this rig.
+	// Keys: "witness", "refinery", "crew", "polecat"
+	RoleThemes map[string]string `json:"role_themes,omitempty"`
 }
 
 // CustomTheme allows specifying exact colors for the status bar.
@@ -72,6 +77,23 @@ type CustomTheme struct {
 	FG string `json:"fg"` // Foreground color (hex or tmux color name)
 }
 
+// TownThemeConfig represents global theme settings (mayor/config.json).
+type TownThemeConfig struct {
+	// RoleDefaults sets default themes for roles across all rigs.
+	// Keys: "witness", "refinery", "crew", "polecat"
+	RoleDefaults map[string]string `json:"role_defaults,omitempty"`
+}
+
+// BuiltinRoleThemes returns the default themes for each role.
+// These are used when no explicit configuration is provided.
+func BuiltinRoleThemes() map[string]string {
+	return map[string]string{
+		"witness":  "rust",  // Red/rust - watchful, alert
+		"refinery": "plum",  // Purple - processing, refining
+		// crew and polecat use rig theme by default (no override)
+	}
+}
+
 // MergeQueueConfig represents merge queue settings for a rig.
 type MergeQueueConfig struct {
 	// Enabled controls whether the merge queue is active.

internal/doctor/theme_check.go

@@ -0,0 +1,116 @@
+package doctor
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+
+	"github.com/steveyegge/gastown/internal/tmux"
+)
+
+// ThemeCheck verifies tmux sessions have correct themes applied.
+type ThemeCheck struct {
+	FixableCheck
+}
+
+// NewThemeCheck creates a new theme check.
+func NewThemeCheck() *ThemeCheck {
+	return &ThemeCheck{
+		FixableCheck: FixableCheck{
+			BaseCheck: BaseCheck{
+				CheckName:        "themes",
+				CheckDescription: "Check tmux session theme configuration",
+			},
+		},
+	}
+}
+
+// Run checks if tmux sessions have themes applied correctly.
+func (c *ThemeCheck) Run(ctx *CheckContext) *CheckResult {
+	t := tmux.NewTmux()
+
+	// List all sessions
+	sessions, err := t.ListSessions()
+	if err != nil {
+		// No tmux server or error - not a problem, just skip
+		return &CheckResult{
+			Name:    c.Name(),
+			Status:  StatusOK,
+			Message: "No tmux sessions running",
+		}
+	}
+
+	// Check for Gas Town sessions
+	var gtSessions []string
+	for _, s := range sessions {
+		if strings.HasPrefix(s, "gt-") {
+			gtSessions = append(gtSessions, s)
+		}
+	}
+
+	if len(gtSessions) == 0 {
+		return &CheckResult{
+			Name:    c.Name(),
+			Status:  StatusOK,
+			Message: "No Gas Town sessions running",
+		}
+	}
+
+	// Check if sessions have proper status-left format (no brackets = new format)
+	var needsUpdate []string
+	for _, session := range gtSessions {
+		statusLeft, err := getSessionStatusLeft(session)
+		if err != nil {
+			continue
+		}
+		// Old format had brackets like [Mayor] or [gastown/crew]
+		if strings.Contains(statusLeft, "[") && strings.Contains(statusLeft, "]") {
+			needsUpdate = append(needsUpdate, session)
+		}
+	}
+
+	if len(needsUpdate) > 0 {
+		details := make([]string, len(needsUpdate))
+		for i, s := range needsUpdate {
+			details[i] = fmt.Sprintf("Needs update: %s", s)
+		}
+		return &CheckResult{
+			Name:    c.Name(),
+			Status:  StatusWarning,
+			Message: fmt.Sprintf("%d session(s) have outdated theme format", len(needsUpdate)),
+			Details: details,
+			FixHint: "Run 'gt theme apply --all' or 'gt doctor --fix'",
+		}
+	}
+
+	return &CheckResult{
+		Name:    c.Name(),
+		Status:  StatusOK,
+		Message: fmt.Sprintf("%d session(s) have correct themes", len(gtSessions)),
+	}
+}
+
+// Fix applies themes to all sessions.
+func (c *ThemeCheck) Fix(ctx *CheckContext) error {
+	cmd := exec.Command("gt", "theme", "apply", "--all")
+	cmd.Dir = ctx.TownRoot
+	return cmd.Run()
+}
+
+// getSessionStatusLeft retrieves the status-left setting for a tmux session.
+func getSessionStatusLeft(session string) (string, error) {
+	cmd := exec.Command("tmux", "show-options", "-t", session, "status-left")
+	output, err := cmd.Output()
+	if err != nil {
+		return "", err
+	}
+	// Parse: status-left "value"
+	line := strings.TrimSpace(string(output))
+	if idx := strings.Index(line, "\""); idx != -1 {
+		end := strings.LastIndex(line, "\"")
+		if end > idx {
+			return line[idx+1 : end], nil
+		}
+	}
+	return line, nil
+}