From be211c2ef10405d9b6eda5927658276f2746205c Mon Sep 17 00:00:00 2001
From: Akayashuu <sauvageleo1@gmail.com>
Date: Tue, 4 Aug 2026 19:51:33 +0200
Subject: [PATCH] feat(embeds): surface an embed image's proxy_url
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An embed's image url is wherever the picture really lives — for a link preview
that is a third-party site. Discord mirrors it on its own CDN and reports that
copy as proxy_url. A reader that pins downloads to Discord hosts needs the
mirror, not the original, or every previewed image is off-allowlist.
---
 messages_test.go | 5 ++++-
 types.go         | 9 ++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/messages_test.go b/messages_test.go
index 0cf2195..4ada609 100644
--- a/messages_test.go
+++ b/messages_test.go
@@ -81,7 +81,7 @@ func TestMessagesGetUsesTheDefaultChannel(t *testing.T) {
 func TestMessageDecodesEmbeds(t *testing.T) {
 	s := transport.NewStub().Reply(`{"id":"m1","content":"","embeds":[{
 		"title":"Quest failed","description":"stack trace here","url":"https://example.test/run/1",
-		"image":{"url":"https://cdn.example.test/shot.png"},
+		"image":{"url":"https://cdn.example.test/shot.png","proxy_url":"https://media.discordapp.net/external/shot.png"},
 		"thumbnail":{"url":"https://cdn.example.test/thumb.png"},
 		"fields":[{"name":"env","value":"prod"}]}]}`)
 	got, err := msgs(s, "def").Get(context.Background(), "c", "m1")
@@ -98,6 +98,9 @@ func TestMessageDecodesEmbeds(t *testing.T) {
 	if e.Image == nil || e.Image.URL != "https://cdn.example.test/shot.png" {
 		t.Errorf("image = %+v", e.Image)
 	}
+	if e.Image.ProxyURL != "https://media.discordapp.net/external/shot.png" {
+		t.Errorf("proxy url = %q", e.Image.ProxyURL)
+	}
 	if e.Thumbnail == nil || e.Thumbnail.URL != "https://cdn.example.test/thumb.png" {
 		t.Errorf("thumbnail = %+v", e.Thumbnail)
 	}
diff --git a/types.go b/types.go
index 5adbe20..0957e51 100644
--- a/types.go
+++ b/types.go
@@ -30,10 +30,13 @@ type Attachment struct {
 	Size        int    `json:"size"`
 }
 
-// EmbedMedia is an image carried by an embed. Only the URL is surfaced: it is
-// what a reader needs to fetch the picture.
+// EmbedMedia is an image carried by an embed. URL is where the picture actually
+// lives, which for a link preview is a third-party site; ProxyURL is Discord's
+// own copy of it and is present whenever Discord could fetch it. A reader that
+// only trusts Discord hosts wants ProxyURL, falling back to URL.
 type EmbedMedia struct {
-	URL string `json:"url"`
+	URL      string `json:"url"`
+	ProxyURL string `json:"proxy_url"`
 }
 
 // EmbedField is one name/value pair in an embed's body.