fix: enable Layer 3 sync by adding root events to pending queue

When root events (issues/patches) are received via self-subscription,
handle_root_event() was only updating the repo_sync_index directly.
This caused process_batch() to early-return when pending.is_empty(),
so Layer 3 filters for comments/replies were never created.

The fix adds root events to both:
1. repo_sync_index (for immediate availability)
2. pending queue (to trigger Layer 3 filter creation in next batch)

Critical: The pending entry must include relays from repo_sync_index
so derive_relay_targets() knows where to send Layer 3 subscriptions.

The Layer 3 test now verifies that events sent BEFORE the subscription
is established are still synced - proving subscriptions without 'since'
correctly fetch historical events.

Enabled 4 previously ignored Layer 3 tests:
- test_live_sync_layer3_events
- test_layer3_sync_with_lowercase_e_tag
- test_layer3_sync_with_uppercase_e_tag
- test_layer3_sync_with_q_tag

1 files changed, 25 insertions, 7 deletions

diff --git a/src/sync/self_subscriber.rs b/src/sync/self_subscriber.rs
index 27e7e64..f83b081 100644
--- a/src/sync/self_subscriber.rs
+++ b/src/sync/self_subscriber.rs
@@ -167,13 +167,14 @@ impl SelfSubscriber {
                     }
                 } else {
                     // For root event kinds (1617, 1618, 1619, 1621),
-                    // process them to update the RepoSyncIndex
+                    // process them to update the RepoSyncIndex AND add to pending
+                    // for Layer 3 filter creation
                     tracing::trace!(
                         kind = %event.kind,
                         event_id = %event.id,
                         "Received root event"
                     );
-                    self.handle_root_event(&event).await;
+                    self.handle_root_event(&event, pending).await;
                 }
                 LoopControl::Continue
             }
@@ -375,8 +376,9 @@ impl SelfSubscriber {
     /// Handle a root event (1617/1618/1619/1621)
     ///
     /// Extracts the 'a' tag to find the repo addressable reference,
-    /// then updates the RepoSyncIndex with the event ID.
-    async fn handle_root_event(&self, event: &Event) {
+    /// then updates the RepoSyncIndex with the event ID AND adds to pending
+    /// so that Layer 3 filters will be created in the next batch.
+    async fn handle_root_event(&self, event: &Event, pending: &mut PendingUpdates) {
         // Extract 'a' tag to find the repo addressable reference
         let repo_a_tag = event.tags.iter().find(|tag| {
             let tag_vec = tag.as_slice();
@@ -406,15 +408,31 @@ impl SelfSubscriber {
             }
         };
 
-        // Look up repo in repo_sync_index
+        // Look up repo in repo_sync_index - add root event directly and also to pending
         let mut index = self.repo_sync_index.write().await;
         if let Some(repo_sync) = index.get_mut(&repo_ref) {
-            // Add event.id to root_events set
+            // Add event.id to root_events set in the index (immediate availability)
             repo_sync.root_events.insert(event.id);
+            
+            // Clone the relays before releasing the lock - Layer 3 filters need to be
+            // sent to the same relays as Layer 2 filters for this repo
+            let relays = repo_sync.relays.clone();
+            
+            // Release lock before modifying pending
+            drop(index);
+            
+            // Also add root event to pending - this ensures batch processing runs
+            // and creates Layer 3 filters for events referencing this root event.
+            // CRITICAL: Include relays so derive_relay_targets knows where to send filters!
+            let mut root_events = HashSet::new();
+            root_events.insert(event.id);
+            pending.add_repo(repo_ref.clone(), relays.clone(), root_events);
+            
             tracing::debug!(
                 event_id = %event.id,
                 repo_ref = %repo_ref,
-                "Added root event to repo"
+                relay_count = relays.len(),
+                "Added root event to index and pending for Layer 3 filter creation"
             );
         } else {
             tracing::debug!(