feat(errors): 统一 AppError（Code/Message/Cause/HTTPCode + Wrap %w + HTTPStatus + ToJSON {error:{code,message}}）

internal/errors/http.go

@@ -0,0 +1,45 @@
+package errors
+
+import (
+	stdErrors "errors"
+	"net/http"
+)
+
+// HTTPStatus resolves the HTTP status code for err.
+//
+// If err (or anything wrapped by it) is an AppError with a non-zero HTTPCode,
+// that code is returned; otherwise the fallback is http.StatusInternalServerError
+// (500). New and Wrap propagate the cause's status, so wrapping a sentinel such
+// as ErrNotFound keeps status 404.
+func HTTPStatus(err error) int {
+	var appErr *AppError
+	if stdErrors.As(err, &appErr) && appErr.HTTPCode != 0 {
+		return appErr.HTTPCode
+	}
+	return http.StatusInternalServerError
+}
+
+// ToJSON renders err as an RFC 7807 style error object, aligned with the client
+// API contract {error:{code,message}}.
+//
+// For an AppError (or one wrapped by it) the Code and Message are returned
+// verbatim. For any other error a generic internal error is returned so that
+// internal details are never leaked to the user; the underlying error is kept
+// only in the Cause field for logging.
+func ToJSON(err error) map[string]any {
+	var appErr *AppError
+	if stdErrors.As(err, &appErr) {
+		return map[string]any{
+			"error": map[string]any{
+				"code":    appErr.Code,
+				"message": appErr.Message,
+			},
+		}
+	}
+	return map[string]any{
+		"error": map[string]any{
+			"code":    ErrInternal.Code,
+			"message": ErrInternal.Message,
+		},
+	}
+}