feat(go-config): multi-format codecs, envc CLI, fixtures, ASRs

- Module github.com/eslider/go-config with env/yaml/json/ini packages
- internal: source, keymap, merge, structconv, bytesutil
- cmd/envc: convert, get, merge
- docs/asr ASR-0001..0008, README/CHANGELOG/AGENTS refresh
- golangci-lint v2 config; tests + fixtures

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

env/codec_test.go

@@ -0,0 +1,125 @@
+package env
+
+import (
+	"context"
+	"testing"
+
+	"github.com/eslider/go-config/testfixtures"
+)
+
+type identityRoot struct {
+	Service svc `mapstructure:"service"`
+}
+
+type svc struct {
+	Name       string
+	Subservice sub `mapstructure:"subservice"`
+	Database   db  `mapstructure:"database"`
+}
+
+type sub struct {
+	Name    string
+	Key     string
+	Timeout int
+	Enabled bool
+}
+
+type db struct {
+	URL      string
+	PoolSize int `mapstructure:"poolsize"`
+}
+
+func TestCodec_IdentityEnvFixture(t *testing.T) {
+	c := New(WithBytes(testfixtures.Load(t, "identity", "service.env")))
+	var got identityRoot
+	if err := c.Unmarshal(&got); err != nil {
+		t.Fatal(err)
+	}
+	assertIdentity(t, got)
+}
+
+func assertIdentity(t *testing.T, got identityRoot) {
+	t.Helper()
+	if got.Service.Name != "my-service" {
+		t.Fatalf("Name=%q", got.Service.Name)
+	}
+	if got.Service.Subservice.Name != "abc" || got.Service.Subservice.Key != "abs" {
+		t.Fatalf("sub %+v", got.Service.Subservice)
+	}
+	if got.Service.Subservice.Timeout != 30 || !got.Service.Subservice.Enabled {
+		t.Fatalf("sub scalars %+v", got.Service.Subservice)
+	}
+	if got.Service.Database.URL != "postgres://localhost:5432/db" || got.Service.Database.PoolSize != 10 {
+		t.Fatalf("db %+v", got.Service.Database)
+	}
+}
+
+func TestCodec_MultiSourceLastWins(t *testing.T) {
+	c := New(
+		WithBytes(testfixtures.Load(t, "merge", "defaults.env")),
+		WithBytes(testfixtures.Load(t, "merge", "overlay.env")),
+	)
+	m, err := c.Map(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := m["service"].(map[string]any)["subservice"].(map[string]any)["name"]; got != "overlay-name" {
+		t.Fatalf("subservice.name = %v", got)
+	}
+}
+
+func TestCodec_WithCurrentEnvironment(t *testing.T) {
+	t.Setenv("SERVICE_KEY", "abc")
+	t.Setenv("SERVICE_PORT", "8080")
+
+	var cfg struct {
+		Service struct {
+			Key  string `mapstructure:"key"`
+			Port int    `mapstructure:"port"`
+		} `mapstructure:"service"`
+	}
+	c := New(WithCurrentEnvironment())
+	if err := c.Unmarshal(&cfg); err != nil {
+		t.Fatal(err)
+	}
+	if cfg.Service.Key != "abc" || cfg.Service.Port != 8080 {
+		t.Fatalf("%+v", cfg)
+	}
+}
+
+func TestCodec_WithTrimWeaklyTyped(t *testing.T) {
+	t.Setenv("NAME", "  x  ")
+	var cfg struct{ Name string }
+	c := New(WithCurrentEnvironment(), WithTrim(true))
+	if err := c.Unmarshal(&cfg); err != nil {
+		t.Fatal(err)
+	}
+	if cfg.Name != "x" {
+		t.Fatalf("%q", cfg.Name)
+	}
+}
+
+func TestCodec_WithWeaklyTypedOff(t *testing.T) {
+	t.Setenv("PORT", "8080")
+	var cfg struct{ Port int }
+	c := New(WithCurrentEnvironment(), WithWeaklyTyped(false))
+	if err := c.Unmarshal(&cfg); err == nil {
+		t.Fatal("expected error")
+	}
+}
+
+func TestCodec_WithTagName(t *testing.T) {
+	t.Setenv("DATABASE_URL", "postgres://x")
+	var cfg struct {
+		DB struct {
+			URL string `mapstructure:"url"`
+		} `mapstructure:"database" env:"database"`
+	}
+	c := New(WithCurrentEnvironment(), WithTagName("env"))
+	if err := c.Unmarshal(&cfg); err != nil {
+		t.Fatal(err)
+	}
+	if cfg.DB.URL != "postgres://x" {
+		t.Fatalf("%q", cfg.DB.URL)
+	}
+}