Fix duplicate mention handling in remote posts

Prevents database constraint violations when a remote post mentions
the same user multiple times by adding onConflictDoNothing to the
mentions insert operation. Also improves error logging in the
federation refresh endpoint.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dahlia

CHANGES.md

@@ -6,6 +6,9 @@ Version 0.6.3
 
 To be released.
 
+ -  Fixed a bug where remote posts mentioning the same user multiple times
+    could not be retrieved due to database constraint violations.
+
 
 Version 0.6.2
 -------------

src/federation/post.ts

@@ -381,6 +381,9 @@ export async function persistPost(
           accountId: account.id,
           postId: post.id,
         })
+        .onConflictDoNothing({
+          target: [mentions.accountId, mentions.postId],
+        })
         .returning();
       mentionRows.push(...result);
     }

src/pages/federation.tsx

@@ -7,6 +7,9 @@ import federation from "../federation";
 import { persistAccount } from "../federation/account";
 import { isPost, persistPost } from "../federation/post";
 import { loginRequired } from "../login";
+import { getLogger } from "@logtape/logtape";
+
+const logger = getLogger(["hollo", "pages", "federation"]);
 
 const data = new Hono();
 
@@ -155,7 +158,9 @@ data.post("/refresh", async (c) => {
         await persistPost(db, object, c.req.url, { ...fedCtx, documentLoader });
         return c.redirect("/federation?done=refresh:post");
       }
-    } catch {}
+    } catch (error) {
+      logger.error("Failed to refresh: {error}", { error });
+    }
   }
   return c.redirect("/federation?error=refresh");
 });