test: Add test coverage for 16 files (40.3% → 45.5%) (#463)

* test: Add test coverage for 16 files (40.3% -> 45.5%)

Add comprehensive tests for previously untested packages:
- internal/agent/state_test.go
- internal/cmd/errors_test.go
- internal/crew/types_test.go
- internal/doctor/errors_test.go
- internal/dog/types_test.go
- internal/mail/bd_test.go
- internal/opencode/plugin_test.go
- internal/rig/overlay_test.go
- internal/runtime/runtime_test.go
- internal/session/town_test.go
- internal/style/style_test.go
- internal/ui/markdown_test.go
- internal/ui/terminal_test.go
- internal/wisp/io_test.go
- internal/wisp/types_test.go
- internal/witness/types_test.go

style_test.go uses func(...string) to match lipgloss variadic Render signature.

* fix(lint): remove unused error return from buildCVSummary

buildCVSummary always returned nil for its error value, causing
golangci-lint to fail with "result 1 (error) is always nil".

The function handles errors internally by returning partial data,
so the error return was misleading. Removed it and updated caller.

internal/session/town_test.go

@@ -0,0 +1,93 @@
+package session
+
+import (
+	"testing"
+)
+
+func TestTownSessions(t *testing.T) {
+	sessions := TownSessions()
+
+	if len(sessions) != 3 {
+		t.Errorf("TownSessions() returned %d sessions, want 3", len(sessions))
+	}
+
+	// Verify order is correct (Mayor, Boot, Deacon)
+	expectedOrder := []string{"Mayor", "Boot", "Deacon"}
+	for i, s := range sessions {
+		if s.Name != expectedOrder[i] {
+			t.Errorf("TownSessions()[%d].Name = %q, want %q", i, s.Name, expectedOrder[i])
+		}
+		if s.SessionID == "" {
+			t.Errorf("TownSessions()[%d].SessionID should not be empty", i)
+		}
+	}
+}
+
+func TestTownSessions_SessionIDFormats(t *testing.T) {
+	sessions := TownSessions()
+
+	for _, s := range sessions {
+		if s.SessionID == "" {
+			t.Errorf("TownSession %q has empty SessionID", s.Name)
+		}
+		// Session IDs should follow a pattern
+		if len(s.SessionID) < 4 {
+			t.Errorf("TownSession %q SessionID %q is too short", s.Name, s.SessionID)
+		}
+	}
+}
+
+func TestTownSession_StructFields(t *testing.T) {
+	ts := TownSession{
+		Name:      "Test",
+		SessionID: "test-session",
+	}
+
+	if ts.Name != "Test" {
+		t.Errorf("TownSession.Name = %q, want %q", ts.Name, "Test")
+	}
+	if ts.SessionID != "test-session" {
+		t.Errorf("TownSession.SessionID = %q, want %q", ts.SessionID, "test-session")
+	}
+}
+
+func TestTownSession_CanBeCreated(t *testing.T) {
+	// Test that TownSession can be created with any values
+	tests := []struct {
+		name      string
+		sessionID string
+	}{
+		{"Mayor", "hq-mayor"},
+		{"Boot", "hq-boot"},
+		{"Custom", "custom-session"},
+	}
+
+	for _, tt := range tests {
+		ts := TownSession{
+			Name:      tt.name,
+			SessionID: tt.sessionID,
+		}
+		if ts.Name != tt.name {
+			t.Errorf("TownSession.Name = %q, want %q", ts.Name, tt.name)
+		}
+		if ts.SessionID != tt.sessionID {
+			t.Errorf("TownSession.SessionID = %q, want %q", ts.SessionID, tt.sessionID)
+		}
+	}
+}
+
+func TestTownSession_ShutdownOrder(t *testing.T) {
+	// Verify that shutdown order is Mayor -> Boot -> Deacon
+	// This is critical because Boot monitors Deacon
+	sessions := TownSessions()
+
+	if sessions[0].Name != "Mayor" {
+		t.Errorf("First session should be Mayor, got %q", sessions[0].Name)
+	}
+	if sessions[1].Name != "Boot" {
+		t.Errorf("Second session should be Boot, got %q", sessions[1].Name)
+	}
+	if sessions[2].Name != "Deacon" {
+		t.Errorf("Third session should be Deacon, got %q", sessions[2].Name)
+	}
+}