diff --git a/internal/config/config_test.go b/internal/config/config_test.go
index 905651a..02f19eb 100644
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@@ -538,15 +538,9 @@ func TestCoalesceGapUsesValidOverride(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "merged.json")
 
-	cfg, err := NewMergeConfig(MergeOptions{
-		InputFiles:            []string{input},
-		OutputFile:            output,
-		InputReader:           DefaultInputReader,
-		OutputModules:         DefaultOutputModules,
-		PreprocessingModules:  DefaultPreprocessingModules,
-		PostprocessingModules: DefaultPostprocessingModules,
-		CoalesceGap:           "1.5",
-	})
+	opts := validMergeOptions(input, output)
+	opts.CoalesceGap = "1.5"
+	cfg, err := NewMergeConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -560,15 +554,9 @@ func TestCoalesceGapAllowsZero(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "merged.json")
 
-	cfg, err := NewMergeConfig(MergeOptions{
-		InputFiles:            []string{input},
-		OutputFile:            output,
-		InputReader:           DefaultInputReader,
-		OutputModules:         DefaultOutputModules,
-		PreprocessingModules:  DefaultPreprocessingModules,
-		PostprocessingModules: DefaultPostprocessingModules,
-		CoalesceGap:           "0",
-	})
+	opts := validMergeOptions(input, output)
+	opts.CoalesceGap = "0"
+	cfg, err := NewMergeConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -593,15 +581,9 @@ func TestCoalesceGapRejectsInvalidOverride(t *testing.T) {
 			input := writeTempFile(t, dir, "input.json")
 			output := filepath.Join(dir, "merged.json")
 
-			_, err := NewMergeConfig(MergeOptions{
-				InputFiles:            []string{input},
-				OutputFile:            output,
-				InputReader:           DefaultInputReader,
-				OutputModules:         DefaultOutputModules,
-				PreprocessingModules:  DefaultPreprocessingModules,
-				PostprocessingModules: DefaultPostprocessingModules,
-				CoalesceGap:           test.value,
-			})
+			opts := validMergeOptions(input, output)
+			opts.CoalesceGap = test.value
+			_, err := NewMergeConfig(opts)
 			if err == nil {
 				t.Fatal("expected error")
 			}
@@ -639,20 +621,16 @@ func TestNewTrimConfigRequiresExactlyOneSelectorFlag(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "trimmed.json")
 
-	_, err := NewTrimConfig(TrimOptions{
-		InputFile:  input,
-		OutputFile: output,
-	})
+	opts := validTrimOptions(input, output)
+	opts.Keep = ""
+	_, err := NewTrimConfig(opts)
 	if err == nil || !strings.Contains(err.Error(), "exactly one of --keep or --remove is required") {
 		t.Fatalf("expected missing selector error, got %v", err)
 	}
 
-	_, err = NewTrimConfig(TrimOptions{
-		InputFile:  input,
-		OutputFile: output,
-		Keep:       "1",
-		Remove:     "2",
-	})
+	opts = validTrimOptions(input, output)
+	opts.Remove = "2"
+	_, err = NewTrimConfig(opts)
 	if err == nil || !strings.Contains(err.Error(), "mutually exclusive") {
 		t.Fatalf("expected mutually exclusive selector error, got %v", err)
 	}
@@ -664,14 +642,13 @@ func TestNewTrimConfigAcceptsOutputSchemaOverride(t *testing.T) {
 	output := filepath.Join(dir, "trimmed.json")
 	reportPath := filepath.Join(dir, "report.json")
 
-	cfg, err := NewTrimConfig(TrimOptions{
-		InputFile:    input,
-		OutputFile:   output,
-		ReportFile:   reportPath,
-		Remove:       "3-5",
-		OutputSchema: OutputSchemaMinimal,
-		AllowEmpty:   true,
-	})
+	opts := validTrimOptions(input, output)
+	opts.Keep = ""
+	opts.Remove = "3-5"
+	opts.ReportFile = reportPath
+	opts.OutputSchema = OutputSchemaMinimal
+	opts.AllowEmpty = true
+	cfg, err := NewTrimConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -697,12 +674,9 @@ func TestNewTrimConfigTreatsWhitespaceReportFileAsOmitted(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "trimmed.json")
 
-	cfg, err := NewTrimConfig(TrimOptions{
-		InputFile:  input,
-		OutputFile: output,
-		Keep:       "1",
-		ReportFile: "  \t  ",
-	})
+	opts := validTrimOptions(input, output)
+	opts.ReportFile = "  \t  "
+	cfg, err := NewTrimConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -716,12 +690,9 @@ func TestNewTrimConfigRejectsInvalidOutputSchemaOverride(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "trimmed.json")
 
-	_, err := NewTrimConfig(TrimOptions{
-		InputFile:    input,
-		OutputFile:   output,
-		Keep:         "1",
-		OutputSchema: "compact",
-	})
+	opts := validTrimOptions(input, output)
+	opts.OutputSchema = "compact"
+	_, err := NewTrimConfig(opts)
 	if err == nil {
 		t.Fatal("expected output schema validation error")
 	}
@@ -750,10 +721,8 @@ func TestNewNormalizeConfigRequiresOutputFile(t *testing.T) {
 	dir := t.TempDir()
 	input := writeTempFile(t, dir, "input.json")
 
-	_, err := NewNormalizeConfig(NormalizeOptions{
-		InputFile:     input,
-		OutputModules: DefaultOutputModules,
-	})
+	opts := validNormalizeOptions(input, "")
+	_, err := NewNormalizeConfig(opts)
 	if err == nil {
 		t.Fatal("expected output-file required error")
 	}
@@ -768,11 +737,8 @@ func TestNewNormalizeConfigResolvesOutputSchemaDefaultAndEnv(t *testing.T) {
 	output := filepath.Join(dir, "normalized.json")
 
 	t.Setenv(OutputSchemaEnv, "")
-	cfg, err := NewNormalizeConfig(NormalizeOptions{
-		InputFile:     input,
-		OutputFile:    output,
-		OutputModules: DefaultOutputModules,
-	})
+	opts := validNormalizeOptions(input, output)
+	cfg, err := NewNormalizeConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -781,11 +747,7 @@ func TestNewNormalizeConfigResolvesOutputSchemaDefaultAndEnv(t *testing.T) {
 	}
 
 	t.Setenv(OutputSchemaEnv, OutputSchemaMinimal)
-	cfg, err = NewNormalizeConfig(NormalizeOptions{
-		InputFile:     input,
-		OutputFile:    output,
-		OutputModules: DefaultOutputModules,
-	})
+	cfg, err = NewNormalizeConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -799,12 +761,9 @@ func TestNewNormalizeConfigRejectsInvalidOutputSchema(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "normalized.json")
 
-	_, err := NewNormalizeConfig(NormalizeOptions{
-		InputFile:     input,
-		OutputFile:    output,
-		OutputSchema:  "compact",
-		OutputModules: DefaultOutputModules,
-	})
+	opts := validNormalizeOptions(input, output)
+	opts.OutputSchema = "compact"
+	_, err := NewNormalizeConfig(opts)
 	if err == nil {
 		t.Fatal("expected output schema error")
 	}
@@ -818,11 +777,9 @@ func TestNewNormalizeConfigRejectsUnknownOutputModule(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "normalized.json")
 
-	_, err := NewNormalizeConfig(NormalizeOptions{
-		InputFile:     input,
-		OutputFile:    output,
-		OutputModules: "json,yaml",
-	})
+	opts := validNormalizeOptions(input, output)
+	opts.OutputModules = "json,yaml"
+	_, err := NewNormalizeConfig(opts)
 	if err == nil {
 		t.Fatal("expected output module error")
 	}
@@ -836,12 +793,9 @@ func TestNewNormalizeConfigTreatsWhitespaceReportFileAsOmitted(t *testing.T) {
 	input := writeTempFile(t, dir, "input.json")
 	output := filepath.Join(dir, "normalized.json")
 
-	cfg, err := NewNormalizeConfig(NormalizeOptions{
-		InputFile:     input,
-		OutputFile:    output,
-		ReportFile:    "\n\t ",
-		OutputModules: DefaultOutputModules,
-	})
+	opts := validNormalizeOptions(input, output)
+	opts.ReportFile = "\n\t "
+	cfg, err := NewNormalizeConfig(opts)
 	if err != nil {
 		t.Fatalf("config failed: %v", err)
 	}
@@ -870,14 +824,7 @@ func assertPositiveFloatEnvValidation(t *testing.T, envName string) {
 			input := writeTempFile(t, dir, "input.json")
 			output := filepath.Join(dir, "merged.json")
 
-			_, err := NewMergeConfig(MergeOptions{
-				InputFiles:            []string{input},
-				OutputFile:            output,
-				InputReader:           DefaultInputReader,
-				OutputModules:         DefaultOutputModules,
-				PreprocessingModules:  DefaultPreprocessingModules,
-				PostprocessingModules: DefaultPostprocessingModules,
-			})
+			_, err := NewMergeConfig(validMergeOptions(input, output))
 			if err == nil {
 				t.Fatal("expected error")
 			}
@@ -888,6 +835,33 @@ func assertPositiveFloatEnvValidation(t *testing.T, envName string) {
 	}
 }
 
+func validMergeOptions(inputFile string, outputFile string) MergeOptions {
+	return MergeOptions{
+		InputFiles:            []string{inputFile},
+		OutputFile:            outputFile,
+		InputReader:           DefaultInputReader,
+		OutputModules:         DefaultOutputModules,
+		PreprocessingModules:  DefaultPreprocessingModules,
+		PostprocessingModules: DefaultPostprocessingModules,
+	}
+}
+
+func validTrimOptions(inputFile string, outputFile string) TrimOptions {
+	return TrimOptions{
+		InputFile:  inputFile,
+		OutputFile: outputFile,
+		Keep:       "1",
+	}
+}
+
+func validNormalizeOptions(inputFile string, outputFile string) NormalizeOptions {
+	return NormalizeOptions{
+		InputFile:     inputFile,
+		OutputFile:    outputFile,
+		OutputModules: DefaultOutputModules,
+	}
+}
+
 func writeTempFile(t *testing.T, dir string, name string) string {
 	t.Helper()