feat: bootstrap reusable GoOmni framework

errors/errors.go

@@ -0,0 +1,74 @@
+package apierrors
+
+import (
+	stdErrors "errors"
+	"net/http"
+)
+
+// APIError is the public error shape used by handlers and middleware.
+// Cause is retained for logging and unwrapping, but is never serialized.
+type APIError struct {
+	Status  int
+	Code    string
+	Message string
+	Cause   error
+}
+
+func (e *APIError) Error() string {
+	if e == nil {
+		return ""
+	}
+	if e.Cause != nil {
+		return e.Code + ": " + e.Message + ": " + e.Cause.Error()
+	}
+	return e.Code + ": " + e.Message
+}
+
+func (e *APIError) Unwrap() error {
+	if e == nil {
+		return nil
+	}
+	return e.Cause
+}
+
+// WithCause attaches an internal cause while keeping the public response stable.
+func (e *APIError) WithCause(cause error) *APIError {
+	e.Cause = cause
+	return e
+}
+
+func New(status int, code, message string) *APIError {
+	return &APIError{Status: status, Code: code, Message: message}
+}
+
+func BadRequest(code, message string) *APIError {
+	return New(http.StatusBadRequest, code, message)
+}
+
+func Unauthorized(code, message string) *APIError {
+	return New(http.StatusUnauthorized, code, message)
+}
+
+func Forbidden(code, message string) *APIError {
+	return New(http.StatusForbidden, code, message)
+}
+
+func NotFound(code, message string) *APIError {
+	return New(http.StatusNotFound, code, message)
+}
+
+func Internal(cause error) *APIError {
+	return New(http.StatusInternalServerError, "INTERNAL_ERROR", "internal server error").WithCause(cause)
+}
+
+// From converts any error into the public API error shape.
+func From(err error) *APIError {
+	if err == nil {
+		return nil
+	}
+	var apiErr *APIError
+	if stdErrors.As(err, &apiErr) && apiErr != nil {
+		return apiErr
+	}
+	return Internal(err)
+}