v0.0.8: Server-side message deduplication

Server:
- DedupTracker in AppState: bounded HashSet (10,000 IDs, FIFO eviction)
- send_message: extracts message ID from bincode, drops duplicates
- WS handler: dedup on both binary and JSON message frames
- extract_message_id() parses all WireMessage variants

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

warzone/crates/warzone-server/src/routes/ws.rs

@@ -17,9 +17,25 @@ use axum::{
     Router,
 };
 use futures_util::{SinkExt, StreamExt};
+use warzone_protocol::message::WireMessage;
 
 use crate::state::AppState;
 
+/// Try to extract the message ID from raw bincode-serialized WireMessage bytes.
+fn extract_message_id(data: &[u8]) -> Option<String> {
+    if let Ok(wire) = bincode::deserialize::<WireMessage>(data) {
+        match wire {
+            WireMessage::KeyExchange { id, .. } => Some(id),
+            WireMessage::Message { id, .. } => Some(id),
+            WireMessage::FileHeader { id, .. } => Some(id),
+            WireMessage::FileChunk { id, .. } => Some(id),
+            WireMessage::Receipt { message_id, .. } => Some(message_id),
+        }
+    } else {
+        None
+    }
+}
+
 pub fn routes() -> Router<AppState> {
     Router::new().route("/ws/:fingerprint", get(ws_handler))
 }
@@ -90,6 +106,14 @@ async fn handle_socket(socket: WebSocket, state: AppState, fingerprint: String)
                         let to_fp = normalize_fp(&header);
                         let message = &data[64..];
 
+                        // Dedup: skip if we already processed this message ID
+                        if let Some(msg_id) = extract_message_id(message) {
+                            if state_clone.dedup.check_and_insert(&msg_id) {
+                                tracing::debug!("WS dedup: dropping duplicate binary message {}", msg_id);
+                                continue;
+                            }
+                        }
+
                         // Try push to connected client first
                         if !state_clone.push_to_client(&to_fp, message).await {
                             // Queue in DB
@@ -110,6 +134,14 @@ async fn handle_socket(socket: WebSocket, state: AppState, fingerprint: String)
                                 .filter_map(|v| v.as_u64().map(|n| n as u8))
                                 .collect();
 
+                            // Dedup: skip if we already processed this message ID
+                            if let Some(msg_id) = extract_message_id(&message) {
+                                if state_clone.dedup.check_and_insert(&msg_id) {
+                                    tracing::debug!("WS dedup: dropping duplicate JSON message {}", msg_id);
+                                    continue;
+                                }
+                            }
+
                             if !state_clone.push_to_client(&to_fp, &message).await {
                                 let key = format!("queue:{}:{}", to_fp, uuid::Uuid::new_v4());
                                 let _ = state_clone.db.messages.insert(key.as_bytes(), message);