diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index 6ca93979e30..188de637b37 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -909,7 +909,12 @@ export namespace SessionPrompt {
           title: "",
           metadata,
           output: truncated.content,
-          attachments,
+          attachments: attachments.map((attachment) => ({
+            ...attachment,
+            id: Identifier.ascending("part"),
+            sessionID: ctx.sessionID,
+            messageID: input.processor.message.id,
+          })),
           content: result.content, // directly return content to preserve ordering when outputting to model
         }
       }