feat(sync): Phase 2 - multi-relay and complete filters

- Add relay discovery from stored announcements
- Implement FilterService with three-layer strategy
- Support multiple simultaneous relay connections
- Filter batching for large tag sets

1 files changed, 38 insertions, 3 deletions

diff --git a/src/nostr/builder.rs b/src/nostr/builder.rs
index 2284c18..732fd9d 100644
--- a/src/nostr/builder.rs
+++ b/src/nostr/builder.rs
@@ -19,6 +19,7 @@ use crate::nostr::policy::{
     AnnouncementPolicy, AnnouncementResult, PolicyContext, PrEventPolicy, RelatedEventPolicy,
     ReferenceResult, StatePolicy, StateResult,
 };
+use crate::sync::SYNC_SOURCE_ADDR;
 
 /// Type alias for the shared database used by the relay
 pub type SharedDatabase = Arc<dyn NostrDatabase>;
@@ -68,9 +69,39 @@ impl Nip34WritePolicy {
     }
 
     /// Handle repository announcement event
-    async fn handle_announcement(&self, event: &Event) -> PolicyResult {
+    ///
+    /// # Arguments
+    /// * `event` - The announcement event to validate
+    /// * `from_sync` - Whether this event came from GRASP-02 sync (bypasses domain validation)
+    async fn handle_announcement(&self, event: &Event, from_sync: bool) -> PolicyResult {
         let event_id_str = event.id.to_bech32().unwrap_or_else(|_| event.id.to_hex());
 
+        // GRASP-02: Accept Layer 1 events from sync without domain validation
+        // This enables relay discovery chain - synced announcements are stored
+        // for relay URL extraction even if they don't list our domain
+        if from_sync {
+            // Still validate basic structure
+            match RepositoryAnnouncement::from_event(event.clone()) {
+                Ok(_announcement) => {
+                    tracing::debug!(
+                        "Accepted synced repository announcement: {} (domain validation bypassed)",
+                        event_id_str
+                    );
+                    // Don't create bare repository for external announcements
+                    return PolicyResult::Accept;
+                }
+                Err(e) => {
+                    tracing::warn!(
+                        "Rejected malformed synced announcement {}: {}",
+                        event_id_str,
+                        e
+                    );
+                    return PolicyResult::Reject(format!("Failed to parse announcement: {}", e));
+                }
+            }
+        }
+
+        // Normal validation path - requires domain to be listed
         match self.announcement_policy.validate(event).await {
             AnnouncementResult::Accept => {
                 // Parse announcement to get repository details
@@ -256,11 +287,15 @@ impl WritePolicy for Nip34WritePolicy {
     fn admit_event<'a>(
         &'a self,
         event: &'a nostr_relay_builder::prelude::Event,
-        _addr: &'a SocketAddr,
+        addr: &'a SocketAddr,
     ) -> BoxedFuture<'a, PolicyResult> {
         Box::pin(async move {
+            // GRASP-02: Detect sync source for Layer 1 domain validation bypass
+            // Synced events use SYNC_SOURCE_ADDR (127.0.0.2:0) to identify them
+            let from_sync = *addr == SYNC_SOURCE_ADDR;
+
             match event.kind.as_u16() {
-                KIND_REPOSITORY_ANNOUNCEMENT => self.handle_announcement(event).await,
+                KIND_REPOSITORY_ANNOUNCEMENT => self.handle_announcement(event, from_sync).await,
                 KIND_REPOSITORY_STATE => self.handle_state(event).await,
                 KIND_PR | KIND_PR_UPDATE => self.handle_pr_event(event).await,
                 _ => self.handle_related_event(event, "Event").await,