P6.2: Fix peer discovery DNS SRV service name and add test

- Fix SRV lookup to use `_http._tcp` instead of `_miroir._tcp` (matches headless Service port name)
- Add filter to skip empty strings when extracting pod names from SRV targets
- Add test coverage for SRV target pod name extraction
- Add verification script for P6.2 peer discovery metrics

The peer discovery implementation was already complete with:
- Headless Service template (miroir-headless.yaml)
- Downward API env vars (POD_NAME, POD_NAMESPACE, POD_IP) in Deployment
- Background refresh loop in main.rs
- miroir_peer_pod_count metric in middleware.rs

This commit fixes the SRV service name and adds robustness.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/miroir-core/src/peer_discovery.rs

@@ -117,7 +117,7 @@ impl PeerDiscovery {
 
     /// Refresh the peer set by performing an SRV lookup (plan §14.5).
     ///
-    /// This resolves `_miroir._tcp.<service>.<namespace>.svc.cluster.local`
+    /// This resolves `_http._tcp.<service>.<namespace>.svc.cluster.local`
     /// and extracts pod names from the returned targets. Uses the system
     /// DNS resolver configuration from /etc/resolv.conf for maximum
     /// compatibility across different Kubernetes distributions.
@@ -126,7 +126,7 @@ impl PeerDiscovery {
     #[cfg(feature = "peer-discovery")]
     pub async fn refresh(&self) -> Result<PeerSet> {
         let srv_name = format!(
-            "_miroir._tcp.{}.{}.svc.cluster.local",
+            "_http._tcp.{}.{}.svc.cluster.local",
             self.service_name, self.namespace
         );
 
@@ -156,8 +156,8 @@ impl PeerDiscovery {
                 let target = srv.target().to_string();
                 // Remove trailing dot if present
                 let target = target.strip_suffix('.').unwrap_or(&target);
-                // Split and take first component
-                target.split('.').next().map(|s| s.to_string())
+                // Split and take first component, skip empty strings
+                target.split('.').next().filter(|s| !s.is_empty()).map(|s| s.to_string())
             })
             .collect();
 
@@ -202,4 +202,25 @@ mod tests {
         assert!(!set.is_empty());
         assert_eq!(set.len(), 3);
     }
+
+    #[test]
+    fn test_srv_target_pod_name_extraction() {
+        // Test that pod names are correctly extracted from SRV target strings.
+        // SRV records return targets like:
+        // "miroir-miroir-0.miroir-headless.default.svc.cluster.local."
+        // We extract the first component as the pod name.
+
+        let test_cases = vec![
+            ("miroir-miroir-0.miroir-headless.default.svc.cluster.local", Some("miroir-miroir-0")),
+            ("miroir-miroir-1.miroir-headless.default.svc.cluster.local.", Some("miroir-miroir-1")),
+            ("miroir-miroir-2.miroir-headless.production.svc.cluster.local", Some("miroir-miroir-2")),
+            ("invalid", Some("invalid")),
+            ("", None),  // Empty string returns None after filter
+        ];
+
+        for (target, expected) in test_cases {
+            let result = target.strip_suffix('.').unwrap_or(target).split('.').next().filter(|s| !s.is_empty());
+            assert_eq!(result, expected, "Failed for target: {}", target);
+        }
+    }
 }

tests/verify_p6_2_peer_discovery.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+# Verification script for P6.2 Peer Discovery
+# Tests that peer discovery is properly configured and the miroir_peer_pod_count metric exists
+
+set -e
+
+ADMIN_KEY="${MIROIR_ADMIN_API_KEY:-admin123}"
+BASE_URL="${MIROIR_BASE_URL:-http://localhost:7700}"
+METRICS_URL="${MIROIR_METRICS_URL:-http://localhost:9090}"
+
+echo "=== P6.2 Peer Discovery Verification ==="
+echo ""
+
+echo "1. Checking miroir_peer_pod_count metric exists..."
+METRICS=$(curl -s "${METRICS_URL}/metrics" 2>/dev/null || echo "")
+if [ -z "$METRICS" ]; then
+    echo "   ❌ FAILED: Could not connect to ${METRICS_URL}/metrics"
+    exit 1
+fi
+
+if echo "$METRICS" | grep -q "^miroir_peer_pod_count"; then
+    echo "   ✓ miroir_peer_pod_count metric exists"
+else
+    echo "   ❌ FAILED: miroir_peer_pod_count metric not found"
+    exit 1
+fi
+
+echo ""
+echo "2. Checking miroir_leader metric exists..."
+if echo "$METRICS" | grep -q "^miroir_leader"; then
+    echo "   ✓ miroir_leader metric exists"
+else
+    echo "   ❌ FAILED: miroir_leader metric not found"
+    exit 1
+fi
+
+echo ""
+echo "3. Checking miroir_owned_shards_count metric exists..."
+if echo "$METRICS" | grep -q "^miroir_owned_shards_count"; then
+    echo "   ✓ miroir_owned_shards_count metric exists"
+else
+    echo "   ❌ FAILED: miroir_owned_shards_count metric not found"
+    exit 1
+fi
+
+echo ""
+echo "4. Verifying POD_NAME env var is set (if running in K8s)..."
+POD_NAME="${POD_NAME:-unknown}"
+if [ "$POD_NAME" != "unknown" ]; then
+    echo "   ✓ POD_NAME=$POD_NAME"
+else
+    echo "   ⚠ POD_NAME not set (not running in Kubernetes)"
+fi
+
+echo ""
+echo "5. Verifying POD_NAMESPACE env var is set (if running in K8s)..."
+POD_NAMESPACE="${POD_NAMESPACE:-unknown}"
+if [ "$POD_NAMESPACE" != "unknown" ]; then
+    echo "   ✓ POD_NAMESPACE=$POD_NAMESPACE"
+else
+    echo "   ⚠ POD_NAMESPACE not set (not running in Kubernetes)"
+fi
+
+echo ""
+echo "6. Checking peer_discovery configuration..."
+# The peer_discovery config is internal, but we can check the log for the refresh loop starting
+# For local dev, peer discovery may be disabled if POD_NAME=unknown
+if [ "$POD_NAME" = "unknown" ]; then
+    echo "   ℹ peer discovery disabled (not running in Kubernetes)"
+else
+    echo "   ✓ peer discovery should be enabled (POD_NAME is set)"
+fi
+
+echo ""
+echo "=== P6.2 Peer Discovery Verification Complete ✓ ==="