fix(mastodon-api): DM response "no data" — return full serialized status

The minimal bare JSON returned for visibility=direct DMs caused clients
(Phanpy, Elk) to show "no data" — they expect a full Mastodon Status
entity. Fix: build a proper ap_timeline document, store it with
visibility=direct (home/public timelines already exclude direct items),
and serialize it via serializeStatus() before returning. Also store the
DM in ap_notifications for the thread view as before.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/mastodon/routes/statuses.js

@@ -284,12 +284,14 @@ router.post("/api/v1/statuses", async (req, res, next) => {
       });
       console.info(`[Mastodon API] Sent DM to ${recipientActorUrl}`);
 
-      // Store in ap_notifications so it appears in the DM thread view
+      const now = new Date().toISOString();
+      const hostname = new URL(publicationUrl).hostname;
+      const profile = await collections.ap_profile.findOne({});
+
+      // Store in ap_notifications for the DM thread view
       try {
         const ap_notifications = collections.ap_notifications;
         if (ap_notifications) {
-          const hostname = new URL(publicationUrl).hostname;
-          const profile = await collections.ap_profile.findOne({});
           await addNotification({ ap_notifications }, {
             uid: noteId.href,
             url: noteId.href,
@@ -303,23 +305,54 @@ router.post("/api/v1/statuses", async (req, res, next) => {
             actorHandle: `@${handle}@${hostname}`,
             inReplyTo: inReplyTo || null,
             content: { text: (statusText || "").trim(), html: (statusText || "").trim() },
-            published: new Date().toISOString(),
-            createdAt: new Date().toISOString(),
+            published: now,
+            createdAt: now,
           });
         }
       } catch (storeError) {
-        console.warn("[Mastodon API] Failed to store outbound DM:", storeError.message);
+        console.warn("[Mastodon API] Failed to store outbound DM in notifications:", storeError.message);
       }
 
-      // Return a minimal status object so the client doesn't error
-      return res.json({
-        id: noteId.href,
-        created_at: new Date().toISOString(),
-        content: (statusText || "").trim(),
-        visibility: "direct",
+      // Store in ap_timeline with visibility=direct so serializeStatus can
+      // produce a full Mastodon status object. Home/public timelines already
+      // exclude direct-visibility items (visibility: { $nin: ["direct"] }).
+      const timelineItem = {
+        uid: noteId.href,
         url: noteId.href,
-        account: { acct: handle },
+        type: "note",
+        visibility: "direct",
+        content: {
+          text: (statusText || "").trim(),
+          html: (statusText || "").trim(),
+        },
+        author: {
+          name: profile?.name || handle,
+          url: actorUri.href,
+          photo: profile?.icon || "",
+          handle: `@${handle}@${hostname}`,
+        },
+        published: now,
+        createdAt: now,
+        inReplyTo: inReplyTo || null,
+        category: [],
+        counts: { likes: 0, boosts: 0, replies: 0 },
+      };
+
+      try {
+        await addTimelineItem(collections.ap_timeline, timelineItem);
+      } catch (storeError) {
+        console.warn("[Mastodon API] Failed to store outbound DM in timeline:", storeError.message);
+      }
+
+      // Return a full serialized status so clients (Phanpy, Elk) can render it
+      const status = serializeStatus(timelineItem, {
+        baseUrl,
+        favouritedIds: new Set(),
+        rebloggedIds: new Set(),
+        bookmarkedIds: new Set(),
+        pinnedIds: new Set(),
       });
+      return res.json(status);
     }
     // ── End DM path ───────────────────────────────────────────────────────────