diff --git a/lib/inbox-listeners.js b/lib/inbox-listeners.js
index 54844c8..5df6ba7 100644
--- a/lib/inbox-listeners.js
+++ b/lib/inbox-listeners.js
@@ -332,16 +332,54 @@ async function logActivity(collections, storeRaw, record) {
 let _apChannelId = null;
 
 /**
- * Look up the ActivityPub channel's ObjectId (cached after first call).
+ * Look up (or auto-create) the ActivityPub channel's ObjectId.
+ * Cached after first successful call.
+ *
+ * The channel is created with `userId: "default"` so it appears in the
+ * Microsub reader UI alongside user-created channels.
+ *
  * @param {object} collections - MongoDB collections
  * @returns {Promise<import("mongodb").ObjectId|null>}
  */
 async function getApChannelId(collections) {
   if (_apChannelId) return _apChannelId;
-  const channel = await collections.microsub_channels?.findOne({
+  if (!collections.microsub_channels) return null;
+
+  let channel = await collections.microsub_channels.findOne({
     uid: "activitypub",
   });
-  _apChannelId = channel?._id || null;
+
+  if (!channel) {
+    // Auto-create the channel with the same fields the Microsub plugin uses
+    const maxOrderDoc = await collections.microsub_channels
+      .find({ userId: "default" })
+      .sort({ order: -1 })
+      .limit(1)
+      .toArray();
+    const order = maxOrderDoc.length > 0 ? maxOrderDoc[0].order + 1 : 0;
+
+    const doc = {
+      uid: "activitypub",
+      name: "Fediverse",
+      userId: "default",
+      order,
+      settings: { excludeTypes: [], excludeRegex: null },
+      createdAt: new Date().toISOString(),
+      updatedAt: new Date().toISOString(),
+    };
+    await collections.microsub_channels.insertOne(doc);
+    channel = doc;
+    console.info("[ActivityPub] Auto-created Microsub channel 'Fediverse'");
+  } else if (!channel.userId) {
+    // Fix existing channel missing userId (created by earlier version)
+    await collections.microsub_channels.updateOne(
+      { _id: channel._id },
+      { $set: { userId: "default" } },
+    );
+    console.info("[ActivityPub] Fixed Microsub channel: set userId to 'default'");
+  }
+
+  _apChannelId = channel._id;
   return _apChannelId;
 }
 
diff --git a/package.json b/package.json
index 4ea84b5..edf9803 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-activitypub",
-  "version": "1.0.16",
+  "version": "1.0.17",
   "description": "ActivityPub federation endpoint for Indiekit via Fedify. Adds full fediverse support: actor, inbox, outbox, followers, following, syndication, and Mastodon migration.",
   "keywords": [
     "indiekit",