fix(#836): one discovery auto-retry over LoRa

D1: first Discover attempt sometimes drops (normal LoRa packet loss); the retry gets through. Per owner (Option A), discoverRegions now makes up to 2 attempts (_discoverRegionsOnce), each using the firmware est_timeout; an unreachable repeater still ends in a timeout after both. Test: first attempt times out, second succeeds, two sends.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/connector/meshcore_connector.dart

@@ -5839,6 +5839,20 @@ class MeshCoreConnector extends ChangeNotifier {
     Duration timeout = const Duration(seconds: 10),
   }) async {
     _guardRegionScope();
+    // One auto-retry: a single anon-request round-trip can drop over LoRa and a
+    // retry usually gets through; a genuinely unreachable repeater still ends in
+    // a timeout after both attempts (#836, D1 Option A).
+    for (var attempt = 0; attempt < 2; attempt++) {
+      final reply = await _discoverRegionsOnce(repeaterPubKey, timeout);
+      if (reply != null) return reply;
+    }
+    return null;
+  }
+
+  Future<RegionsReply?> _discoverRegionsOnce(
+    Uint8List repeaterPubKey,
+    Duration timeout,
+  ) async {
     // Reply travels back along the repeater's own stored path (firmware routes
     // it as-is), so a multi-hop repeater can answer. Empty => zero-hop.
     final (replyPathLenByte, replyPath) = _regionReplyPathFor(repeaterPubKey);

test/connector/region_connector_test.dart

@@ -146,6 +146,30 @@ void main() {
       expect(sent![34], 2); // packed path-len byte: 2 hops, 1-byte hashes
       expect(sent!.sublist(35), [0xAA, 0xBB]);
     });
+
+    test(
+      'auto-retries once: first attempt times out, second succeeds',
+      () async {
+        var sends = 0;
+        connector.sendFrameOverrideForTest = (_) {
+          sends++;
+          // First send injects nothing (that attempt times out); second answers.
+          if (sends >= 2) {
+            connector.handleFrameForTest(_respSent(0x77));
+            connector.handleFrameForTest(
+              _regionsReply(0x77, clock: 1, csv: 'oki'),
+            );
+          }
+        };
+        final reply = await connector.discoverRegions(
+          repeaterPubKey: pub,
+          timeout: const Duration(milliseconds: 60),
+        );
+        expect(reply, isNotNull);
+        expect(reply!.regionNames, ['oki']);
+        expect(sends, 2);
+      },
+    );
   });
 
   group('send-scope setters', () {