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/style/style_test.go

@@ -0,0 +1,169 @@
+package style
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"testing"
+)
+
+func TestStyleVariables(t *testing.T) {
+	// Test that all style variables render non-empty output
+	tests := []struct {
+		name   string
+		render func(...string) string
+	}{
+		{"Success", Success.Render},
+		{"Warning", Warning.Render},
+		{"Error", Error.Render},
+		{"Info", Info.Render},
+		{"Dim", Dim.Render},
+		{"Bold", Bold.Render},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.render == nil {
+				t.Errorf("Style variable %s should not be nil", tt.name)
+			}
+			// Test that Render works
+			result := tt.render("test")
+			if result == "" {
+				t.Errorf("Style %s.Render() should not return empty string", tt.name)
+			}
+		})
+	}
+}
+
+func TestPrefixVariables(t *testing.T) {
+	// Test that all prefix variables are non-empty
+	tests := []struct {
+		name   string
+		prefix string
+	}{
+		{"SuccessPrefix", SuccessPrefix},
+		{"WarningPrefix", WarningPrefix},
+		{"ErrorPrefix", ErrorPrefix},
+		{"ArrowPrefix", ArrowPrefix},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.prefix == "" {
+				t.Errorf("Prefix variable %s should not be empty", tt.name)
+			}
+		})
+	}
+}
+
+func TestPrintWarning(t *testing.T) {
+	// Capture stdout
+	oldStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	PrintWarning("test warning: %s", "value")
+
+	w.Close()
+	os.Stdout = oldStdout
+
+	// Read captured output
+	var buf bytes.Buffer
+	io.Copy(&buf, r)
+	output := buf.String()
+
+	if output == "" {
+		t.Error("PrintWarning() should produce output")
+	}
+
+	// Check that warning message is present
+	if !bytes.Contains(buf.Bytes(), []byte("test warning: value")) {
+		t.Error("PrintWarning() output should contain the warning message")
+	}
+}
+
+func TestPrintWarning_NoFormatArgs(t *testing.T) {
+	oldStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	PrintWarning("simple warning")
+
+	w.Close()
+	os.Stdout = oldStdout
+
+	var buf bytes.Buffer
+	io.Copy(&buf, r)
+	output := buf.String()
+
+	if output == "" {
+		t.Error("PrintWarning() should produce output")
+	}
+
+	if !bytes.Contains(buf.Bytes(), []byte("simple warning")) {
+		t.Error("PrintWarning() output should contain the message")
+	}
+}
+
+func TestStyles_RenderConsistently(t *testing.T) {
+	// Test that styles consistently render non-empty output
+	testText := "test message"
+
+	styles := map[string]func(...string) string{
+		"Success": Success.Render,
+		"Warning": Warning.Render,
+		"Error":   Error.Render,
+		"Info":    Info.Render,
+		"Dim":     Dim.Render,
+		"Bold":    Bold.Render,
+	}
+
+	for name, renderFunc := range styles {
+		t.Run(name, func(t *testing.T) {
+			result := renderFunc(testText)
+			if result == "" {
+				t.Errorf("Style %s.Render() should not return empty string", name)
+			}
+			// Result should be different from input (has styling codes)
+			// except possibly for some edge cases
+		})
+	}
+}
+
+func TestMultiplePrintWarning(t *testing.T) {
+	// Test that multiple warnings can be printed
+	oldStdout := os.Stdout
+	r, w, _ := os.Pipe()
+	os.Stdout = w
+
+	for i := 0; i < 3; i++ {
+		PrintWarning("warning %d", i)
+	}
+
+	w.Close()
+	os.Stdout = oldStdout
+
+	var buf bytes.Buffer
+	io.Copy(&buf, r)
+	_ = buf.String() // ensure buffer is read
+
+	// Should have 3 lines
+	lineCount := 0
+	for _, b := range buf.Bytes() {
+		if b == '\n' {
+			lineCount++
+		}
+	}
+
+	if lineCount != 3 {
+		t.Errorf("Expected 3 lines of output, got %d", lineCount)
+	}
+}
+
+func ExamplePrintWarning() {
+	// This example demonstrates PrintWarning usage
+	fmt.Print("Example output:\n")
+	PrintWarning("This is a warning message")
+	PrintWarning("Warning with value: %d", 42)
+}