From d7ef3610f7e408246c294b4cc2f4f4a8709a4d17 Mon Sep 17 00:00:00 2001
From: Virgil <virgil@lethean.io>
Date: Thu, 2 Apr 2026 03:38:34 +0000
Subject: [PATCH] fix(response): attach meta to all json responses

Co-Authored-By: Virgil <virgil@lethean.io>
---
 middleware_test.go | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 response_meta.go   | 19 +++++++++++++++++-
 2 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/middleware_test.go b/middleware_test.go
index 6bcaa9d..58d9c43 100644
--- a/middleware_test.go
+++ b/middleware_test.go
@@ -84,6 +84,18 @@ func (g autoErrorResponseMetaTestGroup) RegisterRoutes(rg *gin.RouterGroup) {
 	})
 }
 
+type plusJSONResponseMetaTestGroup struct{}
+
+func (g plusJSONResponseMetaTestGroup) Name() string     { return "plus-json-response-meta" }
+func (g plusJSONResponseMetaTestGroup) BasePath() string { return "/v1" }
+func (g plusJSONResponseMetaTestGroup) RegisterRoutes(rg *gin.RouterGroup) {
+	rg.GET("/plus-json", func(c *gin.Context) {
+		c.Header("Content-Type", "application/problem+json")
+		c.Status(http.StatusOK)
+		_, _ = c.Writer.Write([]byte(`{"success":true,"data":"ok"}`))
+	})
+}
+
 // ── Bearer auth ─────────────────────────────────────────────────────────
 
 func TestBearerAuth_Bad_MissingToken(t *testing.T) {
@@ -357,6 +369,43 @@ func TestResponseMeta_Good_AttachesMetaToErrorResponses(t *testing.T) {
 	}
 }
 
+func TestResponseMeta_Good_AttachesMetaToPlusJSONContentType(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	e, _ := api.New(
+		api.WithRequestID(),
+		api.WithResponseMeta(),
+	)
+	e.Register(plusJSONResponseMetaTestGroup{})
+
+	h := e.Handler()
+	w := httptest.NewRecorder()
+	req, _ := http.NewRequest(http.MethodGet, "/v1/plus-json", nil)
+	req.Header.Set("X-Request-ID", "client-id-plus-json-meta")
+	h.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d", w.Code)
+	}
+
+	if got := w.Header().Get("Content-Type"); got != "application/problem+json" {
+		t.Fatalf("expected Content-Type to be preserved, got %q", got)
+	}
+
+	var resp api.Response[string]
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("unmarshal error: %v", err)
+	}
+	if resp.Meta == nil {
+		t.Fatal("expected Meta to be present")
+	}
+	if resp.Meta.RequestID != "client-id-plus-json-meta" {
+		t.Fatalf("expected request_id=%q, got %q", "client-id-plus-json-meta", resp.Meta.RequestID)
+	}
+	if resp.Meta.Duration == "" {
+		t.Fatal("expected duration to be populated")
+	}
+}
+
 // ── CORS ────────────────────────────────────────────────────────────────
 
 func TestCORS_Good_PreflightAllOrigins(t *testing.T) {
diff --git a/response_meta.go b/response_meta.go
index 5ff1d2f..0ca66bd 100644
--- a/response_meta.go
+++ b/response_meta.go
@@ -7,6 +7,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"io"
+	"mime"
 	"net"
 	"net/http"
 	"strconv"
@@ -184,10 +185,26 @@ func refreshResponseMetaBody(body []byte, meta *Meta) []byte {
 }
 
 func shouldAttachResponseMeta(contentType string, body []byte) bool {
-	if !strings.Contains(contentType, "application/json") {
+	if !isJSONContentType(contentType) {
 		return false
 	}
 
 	trimmed := bytes.TrimSpace(body)
 	return len(trimmed) > 0 && trimmed[0] == '{'
 }
+
+func isJSONContentType(contentType string) bool {
+	if strings.TrimSpace(contentType) == "" {
+		return false
+	}
+
+	mediaType, _, err := mime.ParseMediaType(contentType)
+	if err != nil {
+		mediaType = strings.TrimSpace(contentType)
+	}
+	mediaType = strings.ToLower(mediaType)
+
+	return mediaType == "application/json" ||
+		strings.HasSuffix(mediaType, "+json") ||
+		strings.HasSuffix(mediaType, "/json")
+}