fix: Tighten overseer validation, document fallback behavior

internal/cmd/mail.go

@@ -719,6 +719,10 @@ func detectSender() string {
 // detectSenderFromRole builds an address from the GT_ROLE and related env vars.
 // GT_ROLE can be either a simple role name ("crew", "polecat") or a full address
 // ("gastown/crew/joe") depending on how the session was started.
+//
+// If GT_ROLE is a simple name but required env vars (GT_RIG, GT_POLECAT, etc.)
+// are missing, falls back to cwd-based detection. This could return "overseer"
+// if cwd doesn't match any known agent path - a misconfigured agent session.
 func detectSenderFromRole(role string) string {
 	rig := os.Getenv("GT_RIG")
 

internal/config/overseer.go

@@ -74,9 +74,14 @@ func SaveOverseerConfig(path string, config *OverseerConfig) error {
 
 // validateOverseerConfig validates an OverseerConfig.
 func validateOverseerConfig(c *OverseerConfig) error {
+	// Type must be "overseer" (allow empty for backwards compat on load, set on save)
 	if c.Type != "overseer" && c.Type != "" {
 		return fmt.Errorf("%w: expected type 'overseer', got '%s'", ErrInvalidType, c.Type)
 	}
+	// Ensure type is set for saving
+	if c.Type == "" {
+		c.Type = "overseer"
+	}
 	if c.Version > CurrentOverseerVersion {
 		return fmt.Errorf("%w: got %d, max supported %d", ErrInvalidVersion, c.Version, CurrentOverseerVersion)
 	}