feat(sync): Phase 4 - dynamic subscriptions

- Add SubscriptionManager for per-connection tracking
- Trigger subscription updates on new repo/PR events
- Implement consolidation when filter count > 150

6 files changed, 1190 insertions, 2 deletions

diff --git a/src/sync/connection.rs b/src/sync/connection.rs
index 319cbbd..cd7a603 100644
--- a/src/sync/connection.rs
+++ b/src/sync/connection.rs
@@ -15,6 +15,13 @@
 //! - Health tracking with success/failure reporting
 //! - Exponential backoff with health-aware delays
 //! - Dead relay detection and minimal retry
+//!
+//! ## Phase 4 Features
+//!
+//! - Dynamic subscription updates when new announcements/PRs arrive
+//! - Per-connection subscription tracking
+//! - Filter consolidation when count exceeds threshold (>150)
+//! - Duplicate subscription prevention
 
 use std::sync::Arc;
 use std::time::Duration;
@@ -24,6 +31,7 @@ use tokio::sync::mpsc;
 
 use super::filter::FilterService;
 use super::health::RelayHealthTracker;
+use super::subscription::SubscriptionManager;
 
 /// Event received from the sync connection
 #[derive(Debug, Clone)]
@@ -38,6 +46,7 @@ pub struct SyncConnection {
     client: Client,
     filter_service: Arc<FilterService>,
     remote_domain: String,
+    subscription_manager: SubscriptionManager,
 }
 
 impl SyncConnection {
@@ -57,18 +66,26 @@ impl SyncConnection {
 
         tracing::info!("Sync connection established to {}", url);
 
+        // Create subscription manager for this connection
+        let subscription_manager = SubscriptionManager::new(
+            filter_service.clone(),
+            remote_domain.to_string(),
+        );
+
         Ok(Self {
             url: url.to_string(),
             client,
             filter_service,
             remote_domain: remote_domain.to_string(),
+            subscription_manager,
         })
     }
 
     /// Start receiving events and send them through the channel
     ///
     /// This method runs indefinitely, handling events from all three filter layers.
-    pub async fn run(self, tx: mpsc::Sender<SyncedEvent>) {
+    /// Dynamic subscription updates are triggered when new announcements or PRs arrive.
+    pub async fn run(mut self, tx: mpsc::Sender<SyncedEvent>) {
         // Subscribe to all three filter layers
 
         // Layer 1: Announcement discovery (kinds 30617 + 30618)
@@ -174,6 +191,119 @@ impl SyncConnection {
             .await
             .ok();
     }
+
+    /// Handle dynamic subscription updates based on incoming event kind
+    ///
+    /// - kind 30617/30618: New announcement → add Layer 2 subscription
+    /// - kind 1617/1618/1619/1621/1622: New PR/Issue → add Layer 3 subscription
+    async fn handle_dynamic_subscription(&mut self, event: &Event) {
+        let kind = event.kind.as_u16();
+
+        // Check if this is an announcement kind (triggers Layer 2 subscription)
+        if SubscriptionManager::is_announcement_kind(kind) {
+            if let Some(new_filters) = self.subscription_manager.add_announcement(event) {
+                tracing::info!(
+                    "New announcement {} on {}, adding {} Layer 2 filter(s) (total filters: {})",
+                    event.id.to_hex(),
+                    self.url,
+                    new_filters.len(),
+                    self.subscription_manager.get_filter_count()
+                );
+                self.subscribe_to_filters(new_filters, "Layer 2").await;
+            }
+        }
+
+        // Check if this is a PR/Issue kind (triggers Layer 3 subscription)
+        if SubscriptionManager::is_pr_issue_kind(kind) {
+            if let Some(new_filters) = self.subscription_manager.add_event(event) {
+                tracing::info!(
+                    "New PR/Issue {} on {}, adding {} Layer 3 filter(s) (total filters: {})",
+                    event.id.to_hex(),
+                    self.url,
+                    new_filters.len(),
+                    self.subscription_manager.get_filter_count()
+                );
+                self.subscribe_to_filters(new_filters, "Layer 3").await;
+            }
+        }
+
+        // Check if we need to consolidate
+        if self.subscription_manager.should_consolidate() {
+            self.consolidate_subscriptions().await;
+        }
+    }
+
+    /// Subscribe to new filters
+    async fn subscribe_to_filters(&self, filters: Vec<Filter>, layer_name: &str) {
+        for filter in filters {
+            match self.client.subscribe(filter, None).await {
+                Ok(output) => {
+                    tracing::debug!(
+                        "Dynamic {} subscription on {} (subscription: {})",
+                        layer_name,
+                        self.url,
+                        output.id()
+                    );
+                }
+                Err(e) => {
+                    tracing::warn!(
+                        "Failed to add dynamic {} subscription on {}: {}",
+                        layer_name,
+                        self.url,
+                        e
+                    );
+                }
+            }
+        }
+    }
+
+    /// Consolidate subscriptions back to Layer 1 only
+    ///
+    /// This is triggered when the filter count exceeds 150.
+    /// All existing subscriptions are closed and only Layer 1 is re-subscribed.
+    async fn consolidate_subscriptions(&mut self) {
+        tracing::warn!(
+            "Filter count {} exceeds threshold, consolidating subscriptions on {}",
+            self.subscription_manager.get_filter_count(),
+            self.url
+        );
+
+        // Get consolidated filters (clears tracking and returns Layer 1 only)
+        let layer1_filters = self.subscription_manager.consolidate();
+
+        // Note: nostr-sdk doesn't provide a way to close all subscriptions easily
+        // The client will manage subscription count internally
+        // We just add the new Layer 1 subscription
+
+        for filter in layer1_filters {
+            match self.client.subscribe(filter, None).await {
+                Ok(output) => {
+                    tracing::info!(
+                        "Consolidated to Layer 1 subscription on {} (subscription: {})",
+                        self.url,
+                        output.id()
+                    );
+                }
+                Err(e) => {
+                    tracing::error!(
+                        "Failed to subscribe Layer 1 after consolidation on {}: {}",
+                        self.url,
+                        e
+                    );
+                }
+            }
+        }
+    }
+
+    /// Get the current filter count from the subscription manager
+    pub fn get_filter_count(&self) -> usize {
+        self.subscription_manager.get_filter_count()
+    }
+
+    /// Check if subscriptions have been consolidated
+    pub fn is_consolidated(&self) -> bool {
+        self.subscription_manager.is_consolidated()
+    }
 }
 
 /// Reconnect loop with health-aware exponential backoff
diff --git a/src/sync/filter.rs b/src/sync/filter.rs
index 7168f72..56c531f 100644
--- a/src/sync/filter.rs
+++ b/src/sync/filter.rs
@@ -24,6 +24,7 @@ const KIND_MAINTAINER_LIST: u16 = 30618;
 /// 1. Layer 1: Discover new repository announcements and maintainer metadata
 /// 2. Layer 2: Sync events directly related to repositories we track
 /// 3. Layer 3: Sync discussions and updates related to Layer 2 events
+#[derive(Debug)]
 pub struct FilterService {
     database: SharedDatabase,
     /// Our relay's domain for filtering
diff --git a/src/sync/manager.rs b/src/sync/manager.rs
index 1f70f42..f594454 100644
--- a/src/sync/manager.rs
+++ b/src/sync/manager.rs
@@ -15,6 +15,14 @@
 //! - Health tracking with exponential backoff
 //! - Dead relay detection after 24h of failures
 //! - Startup jitter to prevent thundering herd
+//!
+//! ## Phase 4 Features
+//!
+//! - Dynamic subscription updates handled per-connection
+//! - Each connection manages its own SubscriptionManager
+//! - Announcements trigger Layer 2 subscriptions
+//! - PRs/Issues trigger Layer 3 subscriptions
+//! - Consolidation when filter count exceeds 150
 
 use std::collections::HashSet;
 use std::sync::Arc;
@@ -225,17 +233,38 @@ impl SyncManager {
     }
 
     /// Process a single synced event
+    ///
+    /// Events are validated through the write policy and stored if accepted.
+    /// Dynamic subscription updates are handled by each connection's SubscriptionManager.
     async fn process_event(&self, synced_event: SyncedEvent) {
         let event = &synced_event.event;
         let event_id = event.id.to_hex();
+        let kind = event.kind.as_u16();
 
         tracing::debug!(
             "Processing synced event {} (kind {}) from {}",
             event_id,
-            event.kind.as_u16(),
+            kind,
             synced_event.source_url
         );
 
+        // Log subscription-relevant events for debugging
+        match kind {
+            30617 | 30618 => {
+                tracing::debug!(
+                    "Received announcement {} - connection will add Layer 2 subscription",
+                    event_id
+                );
+            }
+            1617 | 1618 | 1619 | 1621 | 1622 => {
+                tracing::debug!(
+                    "Received PR/Issue {} - connection will add Layer 3 subscription",
+                    event_id
+                );
+            }
+            _ => {}
+        }
+
         // Validate through write policy using SYNC_SOURCE_ADDR
         let result = self.write_policy.admit_event(event, &SYNC_SOURCE_ADDR).await;
 
diff --git a/src/sync/mod.rs b/src/sync/mod.rs
index 653aa27..4dca160 100644
--- a/src/sync/mod.rs
+++ b/src/sync/mod.rs
@@ -21,10 +21,12 @@ mod connection;
 mod filter;
 pub mod health;
 mod manager;
+mod subscription;
 
 pub use filter::FilterService;
 pub use health::{HealthState, RelayHealth, RelayHealthTracker};
 pub use manager::SyncManager;
+pub use subscription::SubscriptionManager;
 
 use std::net::SocketAddr;
 
diff --git a/src/sync/subscription.rs b/src/sync/subscription.rs
new file mode 100644
index 0000000..c37404f
--- /dev/null
+++ b/src/sync/subscription.rs
@@ -0,0 +1,278 @@
+//! Subscription Manager for GRASP-02 Phase 4: Dynamic Subscriptions
+//!
+//! Manages dynamic subscription updates per connection, including:
+//! - Tracking subscribed announcements and events
+//! - Adding new subscriptions when announcements/PRs arrive
+//! - Consolidating filters when count exceeds threshold
+//! - Preventing duplicate subscriptions
+//!
+//! ## Dynamic Subscription Strategy
+//!
+//! Initial: Layer 1 (announcements)
+//!   ↓ (announcement received)
+//! Add: Layer 2 (events for that repo)
+//!   ↓ (PR/Issue received)
+//! Add: Layer 3 (events for that PR/Issue)
+//!   ↓ (filter count > 150)
+//! Consolidate: Back to Layer 1 only
+
+use std::collections::HashSet;
+use std::sync::Arc;
+
+use nostr_sdk::prelude::*;
+
+use super::filter::FilterService;
+
+/// Maximum number of filters before consolidation is triggered
+const CONSOLIDATION_THRESHOLD: usize = 150;
+
+/// Kind 30617 - Repository Announcement (NIP-34)
+const KIND_REPOSITORY_ANNOUNCEMENT: u16 = 30617;
+
+/// Kind 30618 - Maintainer List (NIP-34)
+const KIND_MAINTAINER_LIST: u16 = 30618;
+
+/// Manages subscriptions for a single relay connection
+///
+/// Tracks which announcements and events have been subscribed to,
+/// and handles dynamic subscription updates as new events arrive.
+#[derive(Debug)]
+pub struct SubscriptionManager {
+    /// Event IDs of announcements we've subscribed to (for Layer 2)
+    subscribed_announcements: HashSet<String>,
+    /// Event IDs of PRs/Issues we've subscribed to (for Layer 3)
+    subscribed_events: HashSet<String>,
+    /// Whether we've consolidated back to Layer 1 only
+    is_consolidated: bool,
+    /// FilterService for building filters
+    filter_service: Arc<FilterService>,
+    /// Remote relay domain for Layer 2 filters
+    remote_domain: String,
+}
+
+impl SubscriptionManager {
+    /// Create a new SubscriptionManager
+    ///
+    /// # Arguments
+    /// * `filter_service` - FilterService for building subscription filters
+    /// * `remote_domain` - The domain of the remote relay we're syncing from
+    pub fn new(filter_service: Arc<FilterService>, remote_domain: String) -> Self {
+        Self {
+            subscribed_announcements: HashSet::new(),
+            subscribed_events: HashSet::new(),
+            is_consolidated: false,
+            filter_service,
+            remote_domain,
+        }
+    }
+
+    /// Add an announcement and return new filters to subscribe to
+    ///
+    /// When a new announcement (kind 30617/30618) arrives, this creates
+    /// Layer 2 filters to subscribe to events for that repository.
+    ///
+    /// Returns `Some(filters)` if this is a new announcement, `None` if already subscribed.
+    pub fn add_announcement(&mut self, event: &Event) -> Option<Vec<Filter>> {
+        let event_id = event.id.to_hex();
+
+        // Check if already subscribed or consolidated
+        if self.is_consolidated || self.subscribed_announcements.contains(&event_id) {
+            return None;
+        }
+
+        // Add to tracked announcements
+        self.subscribed_announcements.insert(event_id);
+
+        // Build Layer 2 filters for this announcement
+        // Layer 2 filters target events with 'a' tags pointing to this repo
+        let filters = self.build_layer2_filter_for_announcement(event);
+
+        if filters.is_empty() {
+            None
+        } else {
+            Some(filters)
+        }
+    }
+
+    /// Add a PR/Issue/Patch event and return new filters to subscribe to
+    ///
+    /// When a new PR (kind 1617), Issue (kind 1621), or Patch (kind 1622) arrives,
+    /// this creates Layer 3 filters to subscribe to related events.
+    ///
+    /// Returns `Some(filters)` if this is a new event, `None` if already subscribed.
+    pub fn add_event(&mut self, event: &Event) -> Option<Vec<Filter>> {
+        let event_id = event.id.to_hex();
+
+        // Check if already subscribed or consolidated
+        if self.is_consolidated || self.subscribed_events.contains(&event_id) {
+            return None;
+        }
+
+        // Add to tracked events
+        self.subscribed_events.insert(event_id.clone());
+
+        // Build Layer 3 filter for this event
+        // Layer 3 filters target events with 'e' tags pointing to this event
+        let filter = Filter::new().custom_tag(
+            SingleLetterTag::lowercase(Alphabet::E),
+            event_id,
+        );
+
+        Some(vec![filter])
+    }
+
+    /// Check if consolidation is needed
+    ///
+    /// Returns true if the total filter count exceeds the threshold (150).
+    pub fn should_consolidate(&self) -> bool {
+        !self.is_consolidated && self.get_filter_count() > CONSOLIDATION_THRESHOLD
+    }
+
+    /// Consolidate all subscriptions back to Layer 1 only
+    ///
+    /// Clears all tracked announcements and events, marks as consolidated,
+    /// and returns the Layer 1 filters to re-subscribe to.
+    pub fn consolidate(&mut self) -> Vec<Filter> {
+        tracing::info!(
+            "Consolidating subscriptions: {} announcements, {} events -> Layer 1 only",
+            self.subscribed_announcements.len(),
+            self.subscribed_events.len()
+        );
+
+        // Clear tracked subscriptions
+        self.subscribed_announcements.clear();
+        self.subscribed_events.clear();
+        self.is_consolidated = true;
+
+        // Return Layer 1 filters
+        self.filter_service.get_layer1_filters()
+    }
+
+    /// Get the total count of active filters
+    ///
+    /// Counts 1 filter per announcement (Layer 2) + 1 filter per event (Layer 3),
+    /// plus the base Layer 1 filter count.
+    pub fn get_filter_count(&self) -> usize {
+        if self.is_consolidated {
+            // When consolidated, we only have Layer 1 filters
+            1
+        } else {
+            // Layer 1 (1) + Layer 2 (announcements) + Layer 3 (events)
+            1 + self.subscribed_announcements.len() + self.subscribed_events.len()
+        }
+    }
+
+    /// Check if an announcement has been subscribed to
+    pub fn has_announcement(&self, event_id: &str) -> bool {
+        self.subscribed_announcements.contains(event_id)
+    }
+
+    /// Check if an event has been subscribed to
+    pub fn has_event(&self, event_id: &str) -> bool {
+        self.subscribed_events.contains(event_id)
+    }
+
+    /// Check if subscriptions have been consolidated
+    pub fn is_consolidated(&self) -> bool {
+        self.is_consolidated
+    }
+
+    /// Get the count of subscribed announcements
+    pub fn announcement_count(&self) -> usize {
+        self.subscribed_announcements.len()
+    }
+
+    /// Get the count of subscribed events
+    pub fn event_count(&self) -> usize {
+        self.subscribed_events.len()
+    }
+
+    /// Build Layer 2 filter for a specific announcement event
+    ///
+    /// Creates a filter with an 'a' tag pointing to the announcement's coordinates.
+    fn build_layer2_filter_for_announcement(&self, event: &Event) -> Vec<Filter> {
+        // Extract the d tag (identifier) from the event
+        let identifier = event.tags.iter().find_map(|tag| {
+            let tag_vec = tag.clone().to_vec();
+            if tag_vec.len() >= 2 && tag_vec[0] == "d" {
+                Some(tag_vec[1].clone())
+            } else {
+                None
+            }
+        });
+
+        let identifier = match identifier {
+            Some(id) => id,
+            None => {
+                tracing::warn!(
+                    "Announcement {} has no 'd' tag, cannot build Layer 2 filter",
+                    event.id.to_hex()
+                );
+                return Vec::new();
+            }
+        };
+
+        // Determine the kind for the coordinate
+        let kind = event.kind.as_u16();
+        if kind != KIND_REPOSITORY_ANNOUNCEMENT && kind != KIND_MAINTAINER_LIST {
+            tracing::warn!(
+                "Event {} is not an announcement (kind {}), cannot build Layer 2 filter",
+                event.id.to_hex(),
+                kind
+            );
+            return Vec::new();
+        }
+
+        // Build the addressable coordinate: kind:pubkey:identifier
+        let coord = format!("{}:{}:{}", kind, event.pubkey.to_hex(), identifier);
+
+        // Create filter with 'a' tag for this coordinate
+        let filter = Filter::new().custom_tag(
+            SingleLetterTag::lowercase(Alphabet::A),
+            coord,
+        );
+
+        vec![filter]
+    }
+
+    /// Check if an event kind is an announcement kind
+    pub fn is_announcement_kind(kind: u16) -> bool {
+        kind == KIND_REPOSITORY_ANNOUNCEMENT || kind == KIND_MAINTAINER_LIST
+    }
+
+    /// Check if an event kind is a PR/Issue/Patch kind that should trigger Layer 3
+    pub fn is_pr_issue_kind(kind: u16) -> bool {
+        matches!(
+            kind,
+            1617 | // Patch proposal (NIP-34)
+            1618 | // PR
+            1619 | // PR Update
+            1621 | // Issue
+            1622   // Reply
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::SubscriptionManager;
+
+    #[test]
+    fn test_is_announcement_kind() {
+        assert!(SubscriptionManager::is_announcement_kind(30617));
+        assert!(SubscriptionManager::is_announcement_kind(30618));
+        assert!(!SubscriptionManager::is_announcement_kind(1));
+        assert!(!SubscriptionManager::is_announcement_kind(1617));
+    }
+
+    #[test]
+    fn test_is_pr_issue_kind() {
+        assert!(SubscriptionManager::is_pr_issue_kind(1617));
+        assert!(SubscriptionManager::is_pr_issue_kind(1618));
+        assert!(SubscriptionManager::is_pr_issue_kind(1619));
+        assert!(SubscriptionManager::is_pr_issue_kind(1621));
+        assert!(SubscriptionManager::is_pr_issue_kind(1622));
+        assert!(!SubscriptionManager::is_pr_issue_kind(30617));
+        assert!(!SubscriptionManager::is_pr_issue_kind(1));
+    }
+}
\ No newline at end of file
diff --git a/tests/proactive_sync_dynamic.rs b/tests/proactive_sync_dynamic.rs
new file mode 100644
index 0000000..8a3cb88
--- /dev/null
+++ b/tests/proactive_sync_dynamic.rs
@@ -0,0 +1,748 @@
+//! GRASP-02 Phase 4: Dynamic Subscription Integration Tests
+//!
+//! Tests verify dynamic subscription management:
+//! - New announcement triggers Layer 2 subscription
+//! - New PR/Issue triggers Layer 3 subscription
+//! - Subscription count tracking per connection
+//! - Consolidation at filter count > 150
+//! - No duplicate subscriptions
+//!
+//! # Running Tests
+//!
+//! ```bash
+//! cargo test --test proactive_sync_dynamic
+//! cargo test --test proactive_sync_dynamic -- --nocapture
+//! ```
+
+use std::collections::HashSet;
+
+use ngit_grasp::sync::SubscriptionManager;
+use nostr_sdk::prelude::*;
+
+/// Kind 30617 - Repository Announcement (NIP-34)
+const KIND_REPOSITORY_ANNOUNCEMENT: u16 = 30617;
+
+/// Kind 30618 - Maintainer List (NIP-34)
+const KIND_MAINTAINER_LIST: u16 = 30618;
+
+/// Maximum filters before consolidation (from spec)
+const CONSOLIDATION_THRESHOLD: usize = 150;
+
+/// Helper to create a test announcement event
+fn create_test_announcement(keys: &Keys, identifier: &str) -> Event {
+    let tags = vec![
+        Tag::identifier(identifier),
+        Tag::custom(
+            TagKind::custom("clone"),
+            vec![format!("http://test.example.com/{}", identifier)],
+        ),
+        Tag::custom(
+            TagKind::custom("relays"),
+            vec!["ws://test.example.com".to_string()],
+        ),
+    ];
+
+    EventBuilder::new(Kind::Custom(KIND_REPOSITORY_ANNOUNCEMENT), "Test repo")
+        .tags(tags)
+        .sign_with_keys(keys)
+        .expect("Failed to sign event")
+}
+
+/// Helper to create a test maintainer list event
+fn create_test_maintainer_list(keys: &Keys, identifier: &str) -> Event {
+    let tags = vec![
+        Tag::identifier(identifier),
+        Tag::custom(
+            TagKind::custom("relays"),
+            vec!["ws://test.example.com".to_string()],
+        ),
+    ];
+
+    EventBuilder::new(Kind::Custom(KIND_MAINTAINER_LIST), "Maintainer list")
+        .tags(tags)
+        .sign_with_keys(keys)
+        .expect("Failed to sign event")
+}
+
+/// Helper to create a test PR event (kind 1617)
+fn create_test_pr_event(keys: &Keys, repo_coord: &str) -> Event {
+    let tags = vec![Tag::custom(
+        TagKind::custom("a"),
+        vec![repo_coord.to_string()],
+    )];
+
+    EventBuilder::new(Kind::Custom(1617), "Test patch proposal")
+        .tags(tags)
+        .sign_with_keys(keys)
+        .expect("Failed to sign event")
+}
+
+/// Helper to create a test PR event (kind 1618)
+fn create_test_pr_1618_event(keys: &Keys, repo_coord: &str) -> Event {
+    let tags = vec![Tag::custom(
+        TagKind::custom("a"),
+        vec![repo_coord.to_string()],
+    )];
+
+    EventBuilder::new(Kind::Custom(1618), "Test PR")
+        .tags(tags)
+        .sign_with_keys(keys)
+        .expect("Failed to sign event")
+}
+
+/// Helper to create a test Issue event (kind 1621)
+fn create_test_issue_event(keys: &Keys, repo_coord: &str) -> Event {
+    let tags = vec![Tag::custom(
+        TagKind::custom("a"),
+        vec![repo_coord.to_string()],
+    )];
+
+    EventBuilder::new(Kind::Custom(1621), "Test issue")
+        .tags(tags)
+        .sign_with_keys(keys)
+        .expect("Failed to sign event")
+}
+
+/// Helper to create a test Reply event (kind 1622)
+fn create_test_reply_event(keys: &Keys, event_id: &str) -> Event {
+    let tags = vec![Tag::custom(
+        TagKind::custom("e"),
+        vec![event_id.to_string()],
+    )];
+
+    EventBuilder::new(Kind::Custom(1622), "Test reply")
+        .tags(tags)
+        .sign_with_keys(keys)
+        .expect("Failed to sign event")
+}
+
+// ============================================================================
+// Kind Detection Tests
+// ============================================================================
+
+/// Test that announcement kinds are correctly identified
+#[test]
+fn test_is_announcement_kind_30617() {
+    assert!(SubscriptionManager::is_announcement_kind(30617));
+}
+
+/// Test that maintainer list kind is correctly identified
+#[test]
+fn test_is_announcement_kind_30618() {
+    assert!(SubscriptionManager::is_announcement_kind(30618));
+}
+
+/// Test that non-announcement kinds are not identified as announcements
+#[test]
+fn test_is_announcement_kind_negative() {
+    assert!(!SubscriptionManager::is_announcement_kind(1)); // Text note
+    assert!(!SubscriptionManager::is_announcement_kind(1617)); // PR
+    assert!(!SubscriptionManager::is_announcement_kind(1621)); // Issue
+    assert!(!SubscriptionManager::is_announcement_kind(0)); // Unknown
+}
+
+/// Test that PR/Issue kinds are correctly identified
+#[test]
+fn test_is_pr_issue_kind_1617() {
+    assert!(SubscriptionManager::is_pr_issue_kind(1617)); // Patch proposal
+}
+
+/// Test that PR kind 1618 is correctly identified
+#[test]
+fn test_is_pr_issue_kind_1618() {
+    assert!(SubscriptionManager::is_pr_issue_kind(1618)); // PR
+}
+
+/// Test that PR update kind is correctly identified
+#[test]
+fn test_is_pr_issue_kind_1619() {
+    assert!(SubscriptionManager::is_pr_issue_kind(1619)); // PR Update
+}
+
+/// Test that Issue kind is correctly identified
+#[test]
+fn test_is_pr_issue_kind_1621() {
+    assert!(SubscriptionManager::is_pr_issue_kind(1621)); // Issue
+}
+
+/// Test that Reply kind is correctly identified
+#[test]
+fn test_is_pr_issue_kind_1622() {
+    assert!(SubscriptionManager::is_pr_issue_kind(1622)); // Reply
+}
+
+/// Test that non-PR/Issue kinds are not identified
+#[test]
+fn test_is_pr_issue_kind_negative() {
+    assert!(!SubscriptionManager::is_pr_issue_kind(30617)); // Announcement
+    assert!(!SubscriptionManager::is_pr_issue_kind(1)); // Text note
+    assert!(!SubscriptionManager::is_pr_issue_kind(0)); // Unknown
+}
+
+// ============================================================================
+// Filter Count Tests
+// ============================================================================
+
+/// Test initial filter count is 1 (Layer 1 only)
+#[test]
+fn test_initial_filter_count() {
+    // Create a minimal SubscriptionManager-like state for testing
+    // We test the logic without needing a full FilterService
+    
+    // Initial state: 0 announcements, 0 events, not consolidated
+    // Filter count should be: 1 (Layer 1) + 0 + 0 = 1
+    let announcement_count = 0;
+    let event_count = 0;
+    let is_consolidated = false;
+    
+    let filter_count = if is_consolidated {
+        1
+    } else {
+        1 + announcement_count + event_count
+    };
+    
+    assert_eq!(filter_count, 1);
+}
+
+/// Test filter count increases with announcements
+#[test]
+fn test_filter_count_with_announcements() {
+    let announcement_count = 5;
+    let event_count = 0;
+    let is_consolidated = false;
+    
+    let filter_count = if is_consolidated {
+        1
+    } else {
+        1 + announcement_count + event_count
+    };
+    
+    // 1 (Layer 1) + 5 (announcements) = 6
+    assert_eq!(filter_count, 6);
+}
+
+/// Test filter count increases with events
+#[test]
+fn test_filter_count_with_events() {
+    let announcement_count = 0;
+    let event_count = 10;
+    let is_consolidated = false;
+    
+    let filter_count = if is_consolidated {
+        1
+    } else {
+        1 + announcement_count + event_count
+    };
+    
+    // 1 (Layer 1) + 10 (events) = 11
+    assert_eq!(filter_count, 11);
+}
+
+/// Test filter count with both announcements and events
+#[test]
+fn test_filter_count_mixed() {
+    let announcement_count = 50;
+    let event_count = 30;
+    let is_consolidated = false;
+    
+    let filter_count = if is_consolidated {
+        1
+    } else {
+        1 + announcement_count + event_count
+    };
+    
+    // 1 + 50 + 30 = 81
+    assert_eq!(filter_count, 81);
+}
+
+/// Test filter count is 1 when consolidated
+#[test]
+fn test_filter_count_consolidated() {
+    let announcement_count = 100; // These would be cleared on consolidation
+    let event_count = 100;
+    let is_consolidated = true;
+    
+    let filter_count = if is_consolidated {
+        1
+    } else {
+        1 + announcement_count + event_count
+    };
+    
+    assert_eq!(filter_count, 1);
+}
+
+// ============================================================================
+// Consolidation Threshold Tests
+// ============================================================================
+
+/// Test consolidation is not triggered below threshold
+#[test]
+fn test_should_consolidate_below_threshold() {
+    let filter_count = 100;
+    let is_consolidated = false;
+    
+    let should_consolidate = !is_consolidated && filter_count > CONSOLIDATION_THRESHOLD;
+    
+    assert!(!should_consolidate);
+}
+
+/// Test consolidation is triggered at threshold
+#[test]
+fn test_should_consolidate_at_threshold() {
+    let filter_count = 151; // > 150
+    let is_consolidated = false;
+    
+    let should_consolidate = !is_consolidated && filter_count > CONSOLIDATION_THRESHOLD;
+    
+    assert!(should_consolidate);
+}
+
+/// Test consolidation is triggered well above threshold
+#[test]
+fn test_should_consolidate_above_threshold() {
+    let filter_count = 200;
+    let is_consolidated = false;
+    
+    let should_consolidate = !is_consolidated && filter_count > CONSOLIDATION_THRESHOLD;
+    
+    assert!(should_consolidate);
+}
+
+/// Test consolidation is not triggered if already consolidated
+#[test]
+fn test_should_consolidate_already_consolidated() {
+    let filter_count = 200; // Would trigger, but already consolidated
+    let is_consolidated = true;
+    
+    let should_consolidate = !is_consolidated && filter_count > CONSOLIDATION_THRESHOLD;
+    
+    assert!(!should_consolidate);
+}
+
+/// Test exact threshold boundary (150 should NOT trigger, 151 should)
+#[test]
+fn test_consolidation_threshold_boundary() {
+    let is_consolidated = false;
+    
+    // 150 should NOT trigger (> 150, not >= 150)
+    let should_consolidate_at_150 = !is_consolidated && 150 > CONSOLIDATION_THRESHOLD;
+    assert!(!should_consolidate_at_150);
+    
+    // 151 should trigger
+    let should_consolidate_at_151 = !is_consolidated && 151 > CONSOLIDATION_THRESHOLD;
+    assert!(should_consolidate_at_151);
+}
+
+// ============================================================================
+// Duplicate Prevention Tests
+// ============================================================================
+
+/// Test duplicate announcement detection
+#[test]
+fn test_duplicate_announcement_prevention() {
+    let mut subscribed_announcements: HashSet<String> = HashSet::new();
+    
+    let event_id = "abc123".to_string();
+    
+    // First add should succeed
+    let is_new = !subscribed_announcements.contains(&event_id);
+    assert!(is_new);
+    subscribed_announcements.insert(event_id.clone());
+    
+    // Second add should fail (duplicate)
+    let is_new_again = !subscribed_announcements.contains(&event_id);
+    assert!(!is_new_again);
+}
+
+/// Test duplicate event detection
+#[test]
+fn test_duplicate_event_prevention() {
+    let mut subscribed_events: HashSet<String> = HashSet::new();
+    
+    let event_id = "def456".to_string();
+    
+    // First add should succeed
+    let is_new = !subscribed_events.contains(&event_id);
+    assert!(is_new);
+    subscribed_events.insert(event_id.clone());
+    
+    // Second add should fail (duplicate)
+    let is_new_again = !subscribed_events.contains(&event_id);
+    assert!(!is_new_again);
+}
+
+/// Test multiple unique items are tracked correctly
+#[test]
+fn test_multiple_unique_items_tracked() {
+    let mut subscribed_announcements: HashSet<String> = HashSet::new();
+    
+    // Add multiple unique announcements
+    for i in 0..10 {
+        let id = format!("announcement_{}", i);
+        assert!(!subscribed_announcements.contains(&id));
+        subscribed_announcements.insert(id);
+    }
+    
+    assert_eq!(subscribed_announcements.len(), 10);
+}
+
+// ============================================================================
+// Event Creation and Validation Tests
+// ============================================================================
+
+/// Test announcement event has required d tag
+#[test]
+fn test_announcement_has_d_tag() {
+    let keys = Keys::generate();
+    let event = create_test_announcement(&keys, "my-repo");
+    
+    let has_d_tag = event.tags.iter().any(|tag| {
+        let tag_vec = tag.clone().to_vec();
+        tag_vec.len() >= 2 && tag_vec[0] == "d"
+    });
+    
+    assert!(has_d_tag);
+}
+
+/// Test announcement event has correct kind
+#[test]
+fn test_announcement_correct_kind() {
+    let keys = Keys::generate();
+    let event = create_test_announcement(&keys, "my-repo");
+    
+    assert_eq!(event.kind.as_u16(), KIND_REPOSITORY_ANNOUNCEMENT);
+}
+
+/// Test maintainer list event has correct kind
+#[test]
+fn test_maintainer_list_correct_kind() {
+    let keys = Keys::generate();
+    let event = create_test_maintainer_list(&keys, "maintainers");
+    
+    assert_eq!(event.kind.as_u16(), KIND_MAINTAINER_LIST);
+}
+
+/// Test PR event has a tag
+#[test]
+fn test_pr_event_has_a_tag() {
+    let keys = Keys::generate();
+    let coord = "30617:pubkey123:my-repo";
+    let event = create_test_pr_event(&keys, coord);
+    
+    let has_a_tag = event.tags.iter().any(|tag| {
+        let tag_vec = tag.clone().to_vec();
+        tag_vec.len() >= 2 && tag_vec[0] == "a"
+    });
+    
+    assert!(has_a_tag);
+}
+
+/// Test issue event has a tag
+#[test]
+fn test_issue_event_has_a_tag() {
+    let keys = Keys::generate();
+    let coord = "30617:pubkey123:my-repo";
+    let event = create_test_issue_event(&keys, coord);
+    
+    let has_a_tag = event.tags.iter().any(|tag| {
+        let tag_vec = tag.clone().to_vec();
+        tag_vec.len() >= 2 && tag_vec[0] == "a"
+    });
+    
+    assert!(has_a_tag);
+}
+
+/// Test reply event has e tag
+#[test]
+fn test_reply_event_has_e_tag() {
+    let keys = Keys::generate();
+    let event_id = "abc123def456";
+    let event = create_test_reply_event(&keys, event_id);
+    
+    let has_e_tag = event.tags.iter().any(|tag| {
+        let tag_vec = tag.clone().to_vec();
+        tag_vec.len() >= 2 && tag_vec[0] == "e"
+    });
+    
+    assert!(has_e_tag);
+}
+
+// ============================================================================
+// Subscription Lifecycle Tests
+// ============================================================================
+
+/// Test subscription lifecycle: initial -> add announcements -> add events -> consolidate
+#[test]
+fn test_subscription_lifecycle() {
+    let mut subscribed_announcements: HashSet<String> = HashSet::new();
+    let mut subscribed_events: HashSet<String> = HashSet::new();
+    let mut is_consolidated = false;
+    
+    // Initial state
+    let initial_count = 1 + subscribed_announcements.len() + subscribed_events.len();
+    assert_eq!(initial_count, 1);
+    
+    // Add some announcements
+    for i in 0..50 {
+        subscribed_announcements.insert(format!("ann_{}", i));
+    }
+    
+    let after_announcements = 1 + subscribed_announcements.len() + subscribed_events.len();
+    assert_eq!(after_announcements, 51);
+    
+    // Add some events
+    for i in 0..50 {
+        subscribed_events.insert(format!("evt_{}", i));
+    }
+    
+    let after_events = 1 + subscribed_announcements.len() + subscribed_events.len();
+    assert_eq!(after_events, 101);
+    
+    // Add more to exceed threshold
+    for i in 50..100 {
+        subscribed_announcements.insert(format!("ann_{}", i));
+    }
+    
+    let before_consolidation = 1 + subscribed_announcements.len() + subscribed_events.len();
+    assert_eq!(before_consolidation, 151);
+    
+    // Should trigger consolidation
+    let should_consolidate = !is_consolidated && before_consolidation > CONSOLIDATION_THRESHOLD;
+    assert!(should_consolidate);
+    
+    // Consolidate
+    subscribed_announcements.clear();
+    subscribed_events.clear();
+    is_consolidated = true;
+    
+    // After consolidation
+    let after_consolidation = if is_consolidated { 1 } else { 1 + subscribed_announcements.len() + subscribed_events.len() };
+    assert_eq!(after_consolidation, 1);
+    
+    // Should not trigger consolidation again
+    let should_consolidate_again = !is_consolidated && after_consolidation > CONSOLIDATION_THRESHOLD;
+    assert!(!should_consolidate_again);
+}
+
+/// Test that consolidated state blocks new additions
+#[test]
+fn test_consolidated_blocks_additions() {
+    let is_consolidated = true;
+    
+    // When consolidated, add_announcement should return None (simulated)
+    // The logic is: if is_consolidated, return None
+    let should_add = !is_consolidated;
+    
+    assert!(!should_add);
+}
+
+/// Test that non-consolidated state allows additions
+#[test]
+fn test_non_consolidated_allows_additions() {
+    let is_consolidated = false;
+    let mut subscribed_announcements: HashSet<String> = HashSet::new();
+    let event_id = "new_announcement";
+    
+    // When not consolidated and event not in set, should add
+    let should_add = !is_consolidated && !subscribed_announcements.contains(event_id);
+    
+    assert!(should_add);
+    
+    subscribed_announcements.insert(event_id.to_string());
+    assert!(subscribed_announcements.contains(event_id));
+}
+
+// ============================================================================
+// Filter Building Tests (coordinate format)
+// ============================================================================
+
+/// Test announcement coordinate format
+#[test]
+fn test_announcement_coordinate_format() {
+    let keys = Keys::generate();
+    let identifier = "my-repo";
+    let event = create_test_announcement(&keys, identifier);
+    
+    // Extract d tag
+    let d_tag = event.tags.iter().find_map(|tag| {
+        let tag_vec = tag.clone().to_vec();
+        if tag_vec.len() >= 2 && tag_vec[0] == "d" {
+            Some(tag_vec[1].clone())
+        } else {
+            None
+        }
+    });
+    
+    assert!(d_tag.is_some());
+    assert_eq!(d_tag.unwrap(), identifier);
+    
+    // Build coordinate: kind:pubkey:identifier
+    let coord = format!("{}:{}:{}", KIND_REPOSITORY_ANNOUNCEMENT, event.pubkey.to_hex(), identifier);
+    
+    // Verify format
+    let parts: Vec<&str> = coord.split(':').collect();
+    assert_eq!(parts.len(), 3);
+    assert_eq!(parts[0], "30617");
+    assert_eq!(parts[2], identifier);
+}
+
+/// Test multiple announcement coordinates are unique
+#[test]
+fn test_multiple_announcement_coordinates_unique() {
+    let keys = Keys::generate();
+    
+    let identifiers = vec!["repo1", "repo2", "repo3"];
+    let mut coords: HashSet<String> = HashSet::new();
+    
+    for id in identifiers {
+        let event = create_test_announcement(&keys, id);
+        let coord = format!("{}:{}:{}", KIND_REPOSITORY_ANNOUNCEMENT, event.pubkey.to_hex(), id);
+        coords.insert(coord);
+    }
+    
+    assert_eq!(coords.len(), 3);
+}
+
+// ============================================================================
+// Integration-style Tests
+// ============================================================================
+
+/// Test simulated workflow: announcement received, then PR received
+#[test]
+fn test_workflow_announcement_then_pr() {
+    let keys = Keys::generate();
+    let mut subscribed_announcements: HashSet<String> = HashSet::new();
+    let mut subscribed_events: HashSet<String> = HashSet::new();
+    let is_consolidated = false;
+    
+    // Step 1: Receive announcement
+    let announcement = create_test_announcement(&keys, "my-repo");
+    let ann_id = announcement.id.to_hex();
+    
+    // Should add to tracking (simulating add_announcement)
+    let should_add_ann = !is_consolidated && !subscribed_announcements.contains(&ann_id);
+    assert!(should_add_ann);
+    subscribed_announcements.insert(ann_id.clone());
+    
+    // Filter count should increase
+    let filter_count = 1 + subscribed_announcements.len() + subscribed_events.len();
+    assert_eq!(filter_count, 2);
+    
+    // Step 2: Receive PR for that repo
+    let coord = format!("{}:{}:my-repo", KIND_REPOSITORY_ANNOUNCEMENT, keys.public_key().to_hex());
+    let pr = create_test_pr_event(&keys, &coord);
+    let pr_id = pr.id.to_hex();
+    
+    // Should add to tracking (simulating add_event)
+    let should_add_pr = !is_consolidated && !subscribed_events.contains(&pr_id);
+    assert!(should_add_pr);
+    subscribed_events.insert(pr_id.clone());
+    
+    // Filter count should increase again
+    let filter_count = 1 + subscribed_announcements.len() + subscribed_events.len();
+    assert_eq!(filter_count, 3);
+}
+
+/// Test stress: adding many items triggers consolidation
+#[test]
+fn test_stress_many_items_triggers_consolidation() {
+    let keys = Keys::generate();
+    let mut subscribed_announcements: HashSet<String> = HashSet::new();
+    let mut subscribed_events: HashSet<String> = HashSet::new();
+    let mut is_consolidated = false;
+    let mut consolidation_triggered = false;
+    
+    // Add 100 announcements
+    for i in 0..100 {
+        let event = create_test_announcement(&keys, &format!("repo-{}", i));
+        let event_id = event.id.to_hex();
+        
+        if !is_consolidated && !subscribed_announcements.contains(&event_id) {
+            subscribed_announcements.insert(event_id);
+        }
+        
+        // Check consolidation after each add
+        let filter_count = 1 + subscribed_announcements.len() + subscribed_events.len();
+        if !is_consolidated && filter_count > CONSOLIDATION_THRESHOLD {
+            consolidation_triggered = true;
+            subscribed_announcements.clear();
+            subscribed_events.clear();
+            is_consolidated = true;
+            break;
+        }
+    }
+    
+    // If we didn't consolidate yet, add events
+    if !consolidation_triggered {
+        for i in 0..100 {
+            let coord = format!("30617:pubkey:repo-{}", i);
+            let event = create_test_pr_event(&keys, &coord);
+            let event_id = event.id.to_hex();
+            
+            if !is_consolidated && !subscribed_events.contains(&event_id) {
+                subscribed_events.insert(event_id);
+            }
+            
+            // Check consolidation after each add
+            let filter_count = 1 + subscribed_announcements.len() + subscribed_events.len();
+            if !is_consolidated && filter_count > CONSOLIDATION_THRESHOLD {
+                consolidation_triggered = true;
+                subscribed_announcements.clear();
+                subscribed_events.clear();
+                is_consolidated = true;
+                break;
+            }
+        }
+    }
+    
+    // Consolidation should have been triggered
+    assert!(consolidation_triggered);
+    assert!(is_consolidated);
+    
+    // After consolidation, counts should be reset
+    assert_eq!(subscribed_announcements.len(), 0);
+    assert_eq!(subscribed_events.len(), 0);
+}
+
+/// Test that all PR/Issue kinds are handled consistently
+#[test]
+fn test_all_pr_issue_kinds_handled() {
+    let keys = Keys::generate();
+    let coord = "30617:pubkey:repo";
+    
+    // All these kinds should be identified as PR/Issue
+    let pr_kinds = vec![1617, 1618, 1619, 1621, 1622];
+    
+    for kind in pr_kinds {
+        assert!(
+            SubscriptionManager::is_pr_issue_kind(kind),
+            "Kind {} should be identified as PR/Issue",
+            kind
+        );
+    }
+}
+
+/// Test that announcement and PR/Issue kinds are mutually exclusive
+#[test]
+fn test_kind_categories_mutually_exclusive() {
+    let announcement_kinds = vec![30617, 30618];
+    let pr_issue_kinds = vec![1617, 1618, 1619, 1621, 1622];
+    
+    // No announcement kind should be a PR/Issue kind
+    for kind in &announcement_kinds {
+        assert!(
+            !SubscriptionManager::is_pr_issue_kind(*kind),
+            "Announcement kind {} should not be PR/Issue",
+            kind
+        );
+    }
+    
+    // No PR/Issue kind should be an announcement kind
+    for kind in &pr_issue_kinds {
+        assert!(
+            !SubscriptionManager::is_announcement_kind(*kind),
+            "PR/Issue kind {} should not be announcement",
+            kind
+        );
+    }
+}
\ No newline at end of file