refactor: reuse built-ins and shared helpers

crates/chanora_diagnostics/src/lib.rs

@@ -36,7 +36,7 @@
 #![forbid(unsafe_code)]
 #![warn(missing_docs)]
 
-use std::collections::HashSet;
+use std::collections::{HashSet, VecDeque};
 use std::sync::{Arc, Mutex};
 
 use thiserror::Error;
@@ -712,7 +712,7 @@ impl DiagnosticExport {
 /// diagnostic export and state-sync replay verification.
 #[derive(Debug, Clone)]
 pub struct ProtocolEventRecorder {
-    events: Vec<String>,
+    events: VecDeque<String>,
     capacity: usize,
 }
 
@@ -720,17 +720,20 @@ impl ProtocolEventRecorder {
     /// Create a recorder with the given ring-buffer capacity.
     pub fn new(capacity: usize) -> Self {
         Self {
-            events: Vec::with_capacity(capacity),
+            events: VecDeque::with_capacity(capacity),
             capacity,
         }
     }
 
     fn push(&mut self, ts: &str, kind: &str, detail: &str) {
+        if self.capacity == 0 {
+            return;
+        }
         let s = format!("[{ts}] {kind}: {detail}");
         if self.events.len() >= self.capacity {
-            self.events.remove(0);
+            self.events.pop_front();
         }
-        self.events.push(s);
+        self.events.push_back(s);
     }
 
     /// Record a successful connection.
@@ -777,12 +780,12 @@ impl ProtocolEventRecorder {
 
     /// Drain all recorded events and reset the buffer.
     pub fn drain(&mut self) -> Vec<String> {
-        std::mem::take(&mut self.events)
+        self.events.drain(..).collect()
     }
 
     /// Snapshot all recorded events without clearing the buffer.
     pub fn snapshot(&self) -> Vec<String> {
-        self.events.clone()
+        self.events.iter().cloned().collect()
     }
 }
 
@@ -1103,4 +1106,13 @@ mod tests {
         assert_eq!(first, second);
         assert_eq!(drained, first);
     }
+
+    #[test]
+    fn protocol_event_zero_capacity_drops_events() {
+        let mut recorder = ProtocolEventRecorder::new(0);
+        recorder.record_connected("Server");
+
+        assert!(recorder.snapshot().is_empty());
+        assert!(recorder.drain().is_empty());
+    }
 }