Add trim CLI command

internal/config/config.go

@@ -47,6 +47,17 @@ type MergeOptions struct {
 	CoalesceGap           string
 }
 
+// TrimOptions captures raw CLI option values before validation.
+type TrimOptions struct {
+	InputFile    string
+	OutputFile   string
+	ReportFile   string
+	Keep         string
+	Remove       string
+	OutputSchema string
+	AllowEmpty   bool
+}
+
 // Config is the validated runtime configuration for a merge invocation.
 type Config struct {
 	InputFiles             []string
@@ -66,6 +77,17 @@ type Config struct {
 	FillerMaxDuration      float64
 }
 
+// TrimConfig is the validated runtime configuration for a trim invocation.
+type TrimConfig struct {
+	InputFile    string
+	OutputFile   string
+	ReportFile   string
+	Mode         string
+	Selector     string
+	OutputSchema string
+	AllowEmpty   bool
+}
+
 // NewMergeConfig validates raw merge options and returns normalized config.
 func NewMergeConfig(opts MergeOptions) (Config, error) {
 	cfg := Config{
@@ -168,6 +190,63 @@ func NewMergeConfig(opts MergeOptions) (Config, error) {
 	return cfg, nil
 }
 
+// NewTrimConfig validates raw trim options and returns normalized config.
+func NewTrimConfig(opts TrimOptions) (TrimConfig, error) {
+	inputFile := filepath.Clean(strings.TrimSpace(opts.InputFile))
+	if strings.TrimSpace(opts.InputFile) == "" {
+		return TrimConfig{}, errors.New("--input-file is required")
+	}
+	if err := requireFile(inputFile, "--input-file"); err != nil {
+		return TrimConfig{}, err
+	}
+
+	outputFile, err := normalizeOutputPath(opts.OutputFile, "--output-file")
+	if err != nil {
+		return TrimConfig{}, err
+	}
+
+	reportFile := ""
+	if strings.TrimSpace(opts.ReportFile) != "" {
+		reportFile, err = normalizeOutputPath(opts.ReportFile, "--report-file")
+		if err != nil {
+			return TrimConfig{}, err
+		}
+	}
+
+	keep := strings.TrimSpace(opts.Keep)
+	remove := strings.TrimSpace(opts.Remove)
+	if keep == "" && remove == "" {
+		return TrimConfig{}, errors.New("exactly one of --keep or --remove is required")
+	}
+	if keep != "" && remove != "" {
+		return TrimConfig{}, errors.New("--keep and --remove are mutually exclusive")
+	}
+
+	mode := "keep"
+	selector := keep
+	if remove != "" {
+		mode = "remove"
+		selector = remove
+	}
+
+	outputSchema := strings.TrimSpace(opts.OutputSchema)
+	if outputSchema != "" {
+		if err := validateOutputSchema(outputSchema); err != nil {
+			return TrimConfig{}, err
+		}
+	}
+
+	return TrimConfig{
+		InputFile:    inputFile,
+		OutputFile:   outputFile,
+		ReportFile:   reportFile,
+		Mode:         mode,
+		Selector:     selector,
+		OutputSchema: outputSchema,
+		AllowEmpty:   opts.AllowEmpty,
+	}, nil
+}
+
 func parseModuleList(value string) ([]string, error) {
 	value = strings.TrimSpace(value)
 	if value == "" {

internal/config/config_test.go

@@ -612,6 +612,105 @@ func TestCoalesceGapRejectsInvalidOverride(t *testing.T) {
 	}
 }
 
+func TestNewTrimConfigRequiresInputAndOutput(t *testing.T) {
+	dir := t.TempDir()
+	input := writeTempFile(t, dir, "input.json")
+	output := filepath.Join(dir, "trimmed.json")
+
+	_, err := NewTrimConfig(TrimOptions{
+		OutputFile: output,
+		Keep:       "1",
+	})
+	if err == nil || !strings.Contains(err.Error(), "--input-file is required") {
+		t.Fatalf("expected input-file required error, got %v", err)
+	}
+
+	_, err = NewTrimConfig(TrimOptions{
+		InputFile: input,
+		Keep:      "1",
+	})
+	if err == nil || !strings.Contains(err.Error(), "--output-file is required") {
+		t.Fatalf("expected output-file required error, got %v", err)
+	}
+}
+
+func TestNewTrimConfigRequiresExactlyOneSelectorFlag(t *testing.T) {
+	dir := t.TempDir()
+	input := writeTempFile(t, dir, "input.json")
+	output := filepath.Join(dir, "trimmed.json")
+
+	_, err := NewTrimConfig(TrimOptions{
+		InputFile:  input,
+		OutputFile: output,
+	})
+	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",
+	})
+	if err == nil || !strings.Contains(err.Error(), "mutually exclusive") {
+		t.Fatalf("expected mutually exclusive selector error, got %v", err)
+	}
+}
+
+func TestNewTrimConfigAcceptsOutputSchemaOverride(t *testing.T) {
+	dir := t.TempDir()
+	input := writeTempFile(t, dir, "input.json")
+	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,
+	})
+	if err != nil {
+		t.Fatalf("config failed: %v", err)
+	}
+	if cfg.Mode != "remove" {
+		t.Fatalf("mode = %q, want remove", cfg.Mode)
+	}
+	if cfg.Selector != "3-5" {
+		t.Fatalf("selector = %q, want 3-5", cfg.Selector)
+	}
+	if cfg.OutputSchema != OutputSchemaMinimal {
+		t.Fatalf("output schema = %q, want %q", cfg.OutputSchema, OutputSchemaMinimal)
+	}
+	if !cfg.AllowEmpty {
+		t.Fatal("allow empty should be true")
+	}
+	if cfg.ReportFile != reportPath {
+		t.Fatalf("report file = %q, want %q", cfg.ReportFile, reportPath)
+	}
+}
+
+func TestNewTrimConfigRejectsInvalidOutputSchemaOverride(t *testing.T) {
+	dir := t.TempDir()
+	input := writeTempFile(t, dir, "input.json")
+	output := filepath.Join(dir, "trimmed.json")
+
+	_, err := NewTrimConfig(TrimOptions{
+		InputFile:    input,
+		OutputFile:   output,
+		Keep:         "1",
+		OutputSchema: "compact",
+	})
+	if err == nil {
+		t.Fatal("expected output schema validation error")
+	}
+	if !strings.Contains(err.Error(), "--output-schema must be one of") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
 func assertPositiveFloatEnvValidation(t *testing.T, envName string) {
 	t.Helper()