feat: add TOML codec and envc format support

New toml package (pelletier/go-toml/v2) matching yaml/json options and merge flow.
envc convert/get/merge accept --from/--to toml; fixture and CLI tests; docs refresh.

Co-authored-by: Cursor <cursoragent@cursor.com>

cmd/envc/convert.go

@@ -11,6 +11,7 @@ import (
 	"github.com/eslider/go-config/ini"
 	"github.com/eslider/go-config/internal/bytesutil"
 	libjson "github.com/eslider/go-config/json"
+	"github.com/eslider/go-config/toml"
 	"github.com/eslider/go-config/yaml"
 	yaml3 "gopkg.in/yaml.v3"
 )
@@ -19,8 +20,8 @@ import (
 func RunConvert(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	fs := flag.NewFlagSet("convert", flag.ContinueOnError)
 	fs.SetOutput(stderr)
-	from := fs.String("from", "", "source format: yaml|json|ini|env")
-	to := fs.String("to", "", "target format: yaml|json|ini|env")
+	from := fs.String("from", "", "source format: yaml|json|toml|ini|env")
+	to := fs.String("to", "", "target format: yaml|json|toml|ini|env")
 	input := fs.String("input", "-", "input path, URL, or - for stdin")
 	output := fs.String("output", "-", "output path or - for stdout")
 	if err := fs.Parse(args); err != nil {
@@ -75,6 +76,8 @@ func loadMapFromBytes(ctx context.Context, format string, b []byte) (map[string]
 		return ini.New(ini.WithBytes(b)).Map(ctx)
 	case "env":
 		return env.New(env.WithBytes(b)).Map(ctx)
+	case "toml":
+		return toml.New(toml.WithBytes(b)).Map(ctx)
 	default:
 		return nil, fmt.Errorf("unknown format %q", format)
 	}
@@ -90,6 +93,8 @@ func marshalMap(format string, m map[string]any) ([]byte, error) {
 		return ini.New().Marshal(m)
 	case "env":
 		return env.New().Marshal(m)
+	case "toml":
+		return toml.New().Marshal(m)
 	default:
 		return nil, fmt.Errorf("unknown format %q", format)
 	}

cmd/envc/convert_test.go

@@ -8,6 +8,18 @@ import (
 	"testing"
 )
 
+func TestRunConvert_TOMLToJSON(t *testing.T) {
+	var stdout, stderr bytes.Buffer
+	stdin := strings.NewReader("[app]\nport = 8080\n")
+	code := RunConvert([]string{"--from", "toml", "--to", "json", "--input", "-"}, stdin, &stdout, &stderr)
+	if code != 0 {
+		t.Fatalf("stderr: %s", stderr.String())
+	}
+	if !strings.Contains(stdout.String(), `"port"`) || !strings.Contains(stdout.String(), "8080") {
+		t.Fatalf("out: %s", stdout.String())
+	}
+}
+
 func TestRunConvert_YAMLToJSON(t *testing.T) {
 	var stdout, stderr bytes.Buffer
 	stdin := strings.NewReader("a: 1\n")

cmd/envc/doc.go

@@ -1,3 +1,3 @@
 // Command envc converts, queries, and merges configuration between env, YAML,
-// JSON, and INI formats.
+// JSON, TOML, and INI formats.
 package main

cmd/envc/get.go

@@ -16,7 +16,7 @@ import (
 func RunGet(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	fs := flag.NewFlagSet("get", flag.ContinueOnError)
 	fs.SetOutput(stderr)
-	from := fs.String("from", "", "format: yaml|json|ini|env")
+	from := fs.String("from", "", "format: yaml|json|toml|ini|env")
 	path := fs.String("path", "", "dot-separated path (e.g. service.subservice.name)")
 	if err := fs.Parse(args); err != nil {
 		return 2

cmd/envc/main.go

@@ -16,7 +16,7 @@ var (
 
 // printUsage writes the root help text to w.
 func printUsage(w io.Writer) {
-	_, _ = io.WriteString(w, `envc — convert, query, and merge configuration across env, YAML, JSON, and INI.
+	_, _ = io.WriteString(w, `envc — convert, query, and merge configuration across env, YAML, JSON, TOML, and INI.
 
 Usage:
   envc <command> [arguments]

cmd/envc/merge.go

@@ -15,8 +15,8 @@ import (
 func RunMerge(args []string, stdin io.Reader, stdout, stderr io.Writer) int {
 	fs := flag.NewFlagSet("merge", flag.ContinueOnError)
 	fs.SetOutput(stderr)
-	from := fs.String("from", "", "input format: yaml|json|ini|env")
-	to := fs.String("to", "", "output format: yaml|json|ini|env")
+	from := fs.String("from", "", "input format: yaml|json|toml|ini|env")
+	to := fs.String("to", "", "output format: yaml|json|toml|ini|env")
 	output := fs.String("output", "-", "output path or - for stdout")
 	if err := fs.Parse(args); err != nil {
 		return 2