Fetch-and-delete: server deletes messages after poll delivery

poll_messages now collects all queued messages, returns them,
then deletes them from sled. No more duplicate delivery.

This is correct for store-and-forward: once the client receives
the messages, the server's job is done. If the client crashes
before processing, the messages are lost — acceptable for Phase 1.
Phase 2 can add explicit ack-based delivery if needed.

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

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

@@ -22,37 +22,59 @@ struct SendRequest {
 }
 
 fn normalize_fp(fp: &str) -> String {
-    fp.chars().filter(|c| c.is_ascii_hexdigit()).collect::<String>().to_lowercase()
+    fp.chars()
+        .filter(|c| c.is_ascii_hexdigit())
+        .collect::<String>()
+        .to_lowercase()
 }
 
 async fn send_message(
     State(state): State<AppState>,
     Json(req): Json<SendRequest>,
 ) -> AppResult<Json<serde_json::Value>> {
-    let key = format!("queue:{}", normalize_fp(&req.to));
-    state.db.messages.insert(
-        format!("{}:{}", key, uuid::Uuid::new_v4()).as_bytes(),
-        req.message,
-    )?;
+    let to = normalize_fp(&req.to);
+    let key = format!("queue:{}:{}", to, uuid::Uuid::new_v4());
+    tracing::info!("Queuing message for {} ({} bytes)", to, req.message.len());
+    state.db.messages.insert(key.as_bytes(), req.message)?;
     Ok(Json(serde_json::json!({ "ok": true })))
 }
 
+/// Poll fetches all queued messages and deletes them from the server.
+/// This is store-and-forward: once delivered, the server drops them.
 async fn poll_messages(
     State(state): State<AppState>,
     Path(fingerprint): Path<String>,
 ) -> AppResult<Json<Vec<String>>> {
     let prefix = format!("queue:{}", normalize_fp(&fingerprint));
     let mut messages = Vec::new();
+    let mut keys_to_delete = Vec::new();
+
     for item in state.db.messages.scan_prefix(prefix.as_bytes()) {
-        let (_, value) = item?;
+        let (key, value) = item?;
         messages.push(base64::Engine::encode(
             &base64::engine::general_purpose::STANDARD,
             &value,
         ));
+        keys_to_delete.push(key);
     }
+
+    // Delete after collecting (fetch-and-delete)
+    for key in &keys_to_delete {
+        state.db.messages.remove(key)?;
+    }
+
+    if !messages.is_empty() {
+        tracing::info!(
+            "Delivered {} message(s) to {}, deleted from queue",
+            messages.len(),
+            normalize_fp(&fingerprint)
+        );
+    }
+
     Ok(Json(messages))
 }
 
+/// Explicit ack endpoint (for future use with selective delivery).
 async fn ack_message(
     State(state): State<AppState>,
     Path(id): Path<String>,