DrMkdaddy · Sep 23, 2026
@@ -314,6 +314,10 @@
           "type": "boolean",
           "description": "Disable the generation of `GetBody()` and `Get<TypeName>()` getter methods on response objects for `ClientWithResponses`, which are otherwise generated by default."
         },
+        "default-response-error": {
+          "type": "boolean",
+          "description": "Whether the generated response parsing function adds a `default:` case that returns an error for a response whose status code and content type are not matched by any declared case. When false (the default) such a response is returned with no error."
+        },
         "prefer-skip-optional-pointer": {
           "type": "boolean",
           "description": "Allows defining at a global level whether to omit the pointer for a type to indicate that the field/type is optional. This is the same as adding `x-go-type-skip-optional-pointer` to each field (manually, or using an OpenAPI Overlay). A field can set `x-go-type-skip-optional-pointer: false` to still require the optional pointer.",

@@ -146,6 +146,11 @@ output-options:
   client-response-bytes-function: false
   skip-client-response-content-type: false
   skip-response-body-getters: false
+  # When true, the generated response parsing function adds a `default:` case
+  # that returns an error for a response whose status code and content type are
+  # not matched by any declared case. Off by default, which preserves the
+  # existing behaviour of returning such a response with no error.
+  default-response-error: false
   streaming-content-types: []
   # Short names for media types, used in generated type names. Keys are the
   # tag spliced into type names (e.g. the JSON in FindPetsJSONRequestBody),

@@ -0,0 +1,8 @@
+# yaml-language-server: $schema=../../../../../configuration-schema.json
+package: optionsdefaultresponseerrordefault
+output: default_response_error.gen.go
+# default-response-error is left UNSET, so the default behaviour applies: an
+# unmatched response is returned with no error.
+generate:
+  client: true
+  models: true
@@ -0,0 +1,31 @@
+package optionsdefaultresponseerrordefault
+
+import (
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func newResponse(statusCode int, body string) *http.Response {
+	return &http.Response{
+		StatusCode: statusCode,
+		Header:     http.Header{"Content-Type": []string{"application/json"}},
+		Body:       io.NopCloser(strings.NewReader(body)),
+	}
+}
+
+// outputoptions/default-response-error/default: with the option unset, an
+// unmatched response is returned with no error, which is the pre-existing
+// behaviour the option is opt-in to.
+func TestUnmatchedResponseIsNotAnErrorByDefault(t *testing.T) {
+	resp, err := ParseGetThingResponse(newResponse(http.StatusInternalServerError, `{"message":"boom"}`))
+
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+	assert.Nil(t, resp.JSON200)
+	assert.Nil(t, resp.JSON404)
+}
@@ -0,0 +1,9 @@
+// Package optionsdefaultresponseerrordefault checks that, with
+// default-response-error left at its default, the generated Parse<Op>Response
+// function returns an unmatched response with no error, preserving the existing
+// behaviour.
+//
+// outputoptions/default-response-error/default
+package optionsdefaultresponseerrordefault
+
+//go:generate go run github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen --config=config.yaml ../spec.yaml
@@ -0,0 +1,9 @@
+# yaml-language-server: $schema=../../../../../configuration-schema.json
+package: optionsdefaultresponseerrorenabled
+output: default_response_error.gen.go
+generate:
+  client: true
+  models: true
+output-options:
+  # outputoptions/default-response-error/enabled: an unmatched response is an error.
+  default-response-error: true