fix custom type management

pkg/app/setup_custom.go

@@ -17,7 +17,7 @@ import (
 // that overloads *config.AppConfig. Will perform normal env
 // substitutions for AppConfig, but env overrides for custom type
 // are up to the caller.
-func MustLoadConfigInto[T interface{ *config.AppConfig }](ctx context.Context, into T) (context.Context, T) {
+func MustLoadConfigInto[T any](ctx context.Context, into T) (context.Context, T) {
 	// Step 1: Check our custom type for required *config.AppConfig
 	if err := HasAppConfig(into); err != nil {
 		panic(err)

pkg/config/ctx.go

@@ -3,6 +3,7 @@ package config
 import (
 	"context"
 	"errors"
+	"reflect"
 )
 
 type appConfigKey uint8
@@ -15,22 +16,18 @@ func (ac *AppConfig) AddToCtx(ctx context.Context) context.Context {
 }
 
 // Add to Ctx for custom type that embeds AppConfig
-func AddToContextFor[T interface {
-	*AppConfig
-}](ctx context.Context, cfg T) context.Context {
+func AddToContextFor[T any](ctx context.Context, cfg T) context.Context {
 	return context.WithValue(ctx, appConfigCtxKey, cfg)
 }
 
 // FromCtxFor retrieves custom config that embeds AppConfig from context
-func FromCtxFor[T interface {
-	*AppConfig
-}](ctx context.Context) (T, error) {
+func FromCtxFor[T any](ctx context.Context) (*T, error) {
 	ctxData := ctx.Value(appConfigCtxKey)
 	if ctxData == nil {
 		return nil, errors.New("no config found in context")
 	}
 
-	cfg, ok := ctxData.(T)
+	cfg, ok := ctxData.(*T)
 	if !ok {
 		return nil, errors.New("invalid config stored in context")
 	}
@@ -39,9 +36,7 @@ func FromCtxFor[T interface {
 }
 
 // MustFromCtxFor retrieves custom config that embeds AppConfig from context, or panics if not found.
-func MustFromCtxFor[T interface {
-	*AppConfig
-}](ctx context.Context) T {
+func MustFromCtxFor[T any](ctx context.Context) *T {
 	cfg, err := FromCtxFor[T](ctx)
 	if err != nil {
 		panic(err)
@@ -59,16 +54,38 @@ func MustFromCtx(ctx context.Context) *AppConfig {
 }
 
 // FromCtx retrieves the AppConfig from the context.
+// It handles both direct *AppConfig and custom types that embed *AppConfig.
 func FromCtx(ctx context.Context) (*AppConfig, error) {
 	ctxData := ctx.Value(appConfigCtxKey)
 	if ctxData == nil {
 		return nil, errors.New("no config found in context")
 	}
 
-	cfg, ok := ctxData.(*AppConfig)
-	if !ok {
-		return nil, errors.New("invalid config stored in context")
-	}
-
+	// Try direct type assertion first
+	if cfg, ok := ctxData.(*AppConfig); ok {
 		return cfg, nil
 	}
+
+	// Try to extract *AppConfig from a custom type that embeds it
+	v := reflect.ValueOf(ctxData)
+	if v.Kind() != reflect.Pointer || v.IsNil() {
+		return nil, errors.New("invalid config stored in context: must be a non-nil pointer")
+	}
+
+	v = v.Elem()
+	if v.Kind() != reflect.Struct {
+		return nil, errors.New("invalid config stored in context: must be a pointer to a struct")
+	}
+
+	// Look for *AppConfig field
+	for i := range v.NumField() {
+		field := v.Field(i)
+		if field.Type() == reflect.TypeFor[*AppConfig]() {
+			if appConfig, ok := field.Interface().(*AppConfig); ok {
+				return appConfig, nil
+			}
+		}
+	}
+
+	return nil, errors.New("no *AppConfig found in context value")
+}