feat(dm): Auto-retry for undelivered DM messages

Implement automatic retry for DM messages when ACK is not received,
similar to the MeshCore mobile app's Auto Retry feature. The bridge
monitors for ACK after each send and retries up to 3 times, switching
to flood routing after 2 failed direct attempts via reset_path.

- Bridge: background retry engine with configurable max_attempts,
  flood_after; retry group tracking to prevent duplicate messages
- Bridge: enhanced ACK status checks retry groups so delivery is
  detected even if only a retry attempt's ACK arrives
- Backend: filter retry SENT_MSG duplicates from message list
- Frontend: extended ACK polling window, auto-retry toggle in DM bar

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/meshcore/cli.py

@@ -427,6 +427,64 @@ def check_dm_delivery(ack_codes: list) -> Tuple[bool, Dict, str]:
         return False, {}, str(e)
 
 
+# =============================================================================
+# Auto-retry helpers
+# =============================================================================
+
+def get_retry_ack_codes() -> set:
+    """Get set of expected_ack codes belonging to retry attempts (not first send)."""
+    try:
+        response = requests.get(
+            f"{config.MC_BRIDGE_URL.replace('/cli', '/retry_ack_codes')}",
+            timeout=DEFAULT_TIMEOUT
+        )
+        if response.status_code == 200:
+            data = response.json()
+            return set(data.get('retry_ack_codes', []))
+    except Exception as e:
+        logger.debug(f"Failed to fetch retry_ack_codes: {e}")
+    return set()
+
+
+def get_auto_retry_config() -> Tuple[bool, Dict]:
+    """Get current auto-retry configuration from bridge."""
+    try:
+        response = requests.get(
+            f"{config.MC_BRIDGE_URL.replace('/cli', '/auto_retry/config')}",
+            timeout=DEFAULT_TIMEOUT
+        )
+        if response.status_code == 200:
+            data = response.json()
+            return True, data
+    except Exception as e:
+        logger.debug(f"Failed to fetch auto_retry config: {e}")
+    return False, {}
+
+
+def set_auto_retry_config(enabled=None, max_attempts=None, flood_after=None) -> Tuple[bool, Dict]:
+    """Update auto-retry configuration on bridge."""
+    payload = {}
+    if enabled is not None:
+        payload['enabled'] = enabled
+    if max_attempts is not None:
+        payload['max_attempts'] = max_attempts
+    if flood_after is not None:
+        payload['flood_after'] = flood_after
+
+    try:
+        response = requests.post(
+            f"{config.MC_BRIDGE_URL.replace('/cli', '/auto_retry/config')}",
+            json=payload,
+            timeout=DEFAULT_TIMEOUT
+        )
+        if response.status_code == 200:
+            data = response.json()
+            return True, data
+    except Exception as e:
+        logger.debug(f"Failed to set auto_retry config: {e}")
+    return False, {}
+
+
 # =============================================================================
 # Contact Management (Existing & Pending Contacts)
 # =============================================================================

app/routes/api.py

@@ -1670,6 +1670,16 @@ def get_dm_messages():
             days=days
         )
 
+        # Filter out retry duplicate messages (keep only the first send)
+        try:
+            retry_codes = cli.get_retry_ack_codes()
+            if retry_codes:
+                messages = [msg for msg in messages
+                            if not (msg.get('direction') == 'outgoing'
+                                    and msg.get('expected_ack') in retry_codes)]
+        except Exception as e:
+            logger.debug(f"Retry dedup failed (non-critical): {e}")
+
         # Determine display name from conversation_id or messages
         display_name = 'Unknown'
         if conversation_id.startswith('pk_'):
@@ -1793,6 +1803,38 @@ def send_dm_message():
         }), 500
 
 
+@api_bp.route('/dm/auto_retry', methods=['GET'])
+def get_auto_retry_config():
+    """Get auto-retry configuration."""
+    try:
+        success, data = cli.get_auto_retry_config()
+        if success:
+            return jsonify(data), 200
+        return jsonify({'success': False, 'error': 'Failed to get config'}), 500
+    except Exception as e:
+        return jsonify({'success': False, 'error': str(e)}), 500
+
+
+@api_bp.route('/dm/auto_retry', methods=['POST'])
+def set_auto_retry_config():
+    """Update auto-retry configuration."""
+    try:
+        data = request.get_json()
+        if not data:
+            return jsonify({'success': False, 'error': 'Missing JSON body'}), 400
+
+        success, result = cli.set_auto_retry_config(
+            enabled=data.get('enabled'),
+            max_attempts=data.get('max_attempts'),
+            flood_after=data.get('flood_after')
+        )
+        if success:
+            return jsonify(result), 200
+        return jsonify({'success': False, 'error': 'Failed to update config'}), 500
+    except Exception as e:
+        return jsonify({'success': False, 'error': str(e)}), 500
+
+
 @api_bp.route('/dm/updates', methods=['GET'])
 def get_dm_updates():
     """

app/static/js/dm.js

@@ -58,6 +58,9 @@ document.addEventListener('DOMContentLoaded', async function() {
     // Initialize FAB toggle
     initializeDmFabToggle();
 
+    // Load auto-retry config
+    loadAutoRetryConfig();
+
     // Setup auto-refresh
     setupAutoRefresh();
 });
@@ -518,8 +521,8 @@ async function sendMessage() {
             showNotification('Message sent', 'success');
 
             // Reload messages to show sent message + ACK delivery status
-            // Stop early once the last own message gets a delivery checkmark
-            const ackRefreshDelays = [1000, 6000, 15000];
+            // Extended delays to cover auto-retry window (retries happen in background)
+            const ackRefreshDelays = [2000, 8000, 20000, 40000, 60000];
             let ackRefreshIdx = 0;
             const scheduleAckRefresh = () => {
                 if (ackRefreshIdx >= ackRefreshDelays.length) return;
@@ -1169,3 +1172,47 @@ function clearDmFilterState() {
         }, 50);
     }
 }
+
+// =============================================================================
+// Auto-retry configuration
+// =============================================================================
+
+/**
+ * Load auto-retry config from bridge and sync toggle state
+ */
+async function loadAutoRetryConfig() {
+    const toggle = document.getElementById('dmAutoRetryToggle');
+    if (!toggle) return;
+
+    try {
+        const response = await fetch('/api/dm/auto_retry');
+        const data = await response.json();
+        if (data.success) {
+            toggle.checked = data.enabled;
+        }
+    } catch (e) {
+        console.debug('Failed to load auto-retry config:', e);
+    }
+
+    // Setup change handler
+    toggle.addEventListener('change', async function() {
+        try {
+            const response = await fetch('/api/dm/auto_retry', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify({ enabled: this.checked })
+            });
+            const data = await response.json();
+            if (data.success) {
+                showNotification(
+                    data.enabled ? 'Auto Retry enabled' : 'Auto Retry disabled',
+                    'info'
+                );
+            }
+        } catch (e) {
+            console.error('Failed to update auto-retry config:', e);
+            // Revert toggle on error
+            this.checked = !this.checked;
+        }
+    });
+}

app/templates/dm.html

@@ -66,10 +66,16 @@
             <!-- Conversation Selector Bar -->
             <div class="row border-bottom bg-light">
                 <div class="col-12 p-2">
-                    <select id="dmConversationSelector" class="form-select" title="Select conversation">
-                        <option value="">Select chat...</option>
-                        <!-- Conversations loaded dynamically via JavaScript -->
-                    </select>
+                    <div class="d-flex align-items-center gap-2">
+                        <select id="dmConversationSelector" class="form-select" title="Select conversation">
+                            <option value="">Select chat...</option>
+                            <!-- Conversations loaded dynamically via JavaScript -->
+                        </select>
+                        <div class="form-check form-switch flex-shrink-0" title="Auto Retry: resend DM if no ACK received">
+                            <input class="form-check-input" type="checkbox" id="dmAutoRetryToggle" checked>
+                            <label class="form-check-label small text-nowrap" for="dmAutoRetryToggle">Retry</label>
+                        </div>
+                    </div>
                 </div>
             </div>
             <!-- Messages Container -->

meshcore-bridge/bridge.py

@@ -157,6 +157,15 @@ class MeshCLISession:
         self.acks = {}  # ack_code -> {snr, rssi, route, path, ts}
         self.acks_file = self.config_dir / f"{device_name}.acks.jsonl"
 
+        # Auto-retry for DM messages
+        self.auto_retry_enabled = True
+        self.auto_retry_max_attempts = 3      # total attempts including first send
+        self.auto_retry_flood_after = 2       # switch to flood after N failed direct attempts
+        self.retry_ack_codes = set()          # expected_ack codes of retry attempts (not first)
+        self.retry_groups = {}                # original_ack -> [retry_ack_1, retry_ack_2, ...]
+        self.retry_lock = threading.Lock()
+        self.active_retries = {}              # original_ack -> threading.Event (cancel signal)
+
         # Load persisted data from disk
         self._load_echoes()
         self._load_acks()
@@ -805,6 +814,148 @@ class MeshCLISession:
         except Exception as e:
             logger.error(f"Failed to load ACKs: {e}")
 
+    # =========================================================================
+    # Auto-retry for DM messages
+    # =========================================================================
+
+    def _start_retry(self, recipient, text, original_ack, suggested_timeout):
+        """Start background retry thread for a DM message."""
+        cancel_event = threading.Event()
+        with self.retry_lock:
+            self.active_retries[original_ack] = cancel_event
+            self.retry_groups[original_ack] = []
+
+        thread = threading.Thread(
+            target=self._retry_send,
+            args=(recipient, text, original_ack, suggested_timeout, cancel_event),
+            daemon=True,
+            name=f"retry-{original_ack[:8]}"
+        )
+        thread.start()
+        logger.info(f"Auto-retry started for ack={original_ack}, "
+                     f"max_attempts={self.auto_retry_max_attempts}, "
+                     f"timeout={suggested_timeout}ms")
+
+    def _retry_send(self, recipient, text, original_ack, suggested_timeout, cancel_event):
+        """Background retry loop for a DM message.
+
+        Waits for ACK after initial send, retries up to max_attempts total.
+        After flood_after failed direct attempts, resets path to force flood routing.
+        """
+        # Wait timeout in seconds (use suggested_timeout from device, with 1.2x margin)
+        wait_timeout = max(suggested_timeout / 1000 * 1.2, 5.0)
+
+        # Attempt 1 was already sent by the caller. Start from attempt 2.
+        attempt = 1  # 0-indexed, so attempt=1 is the second try
+        flood_sent = False
+
+        while attempt < self.auto_retry_max_attempts:
+            if cancel_event.is_set():
+                logger.info(f"Retry cancelled for ack={original_ack}")
+                break
+
+            # Wait for ACK of the most recent expected_ack
+            with self.retry_lock:
+                all_acks = [original_ack] + self.retry_groups.get(original_ack, [])
+            latest_ack = all_acks[-1]
+
+            # Poll for ACK (check all ack codes in the group — any ACK means delivered)
+            ack_received = self._wait_for_any_ack(all_acks, wait_timeout, cancel_event)
+            if ack_received:
+                logger.info(f"ACK received for ack={latest_ack} (attempt {attempt}), "
+                             f"retry done for original={original_ack}")
+                break
+
+            if cancel_event.is_set():
+                break
+
+            # No ACK received - retry
+            attempt += 1
+
+            # Reset path to flood before the configured attempt
+            if attempt >= self.auto_retry_flood_after and not flood_sent:
+                logger.info(f"Retry: resetting path for {recipient} (switching to flood)")
+                try:
+                    self.execute_command(['reset_path', recipient], timeout=5)
+                    flood_sent = True
+                except Exception as e:
+                    logger.error(f"Retry: reset_path failed: {e}")
+
+            logger.info(f"Retry attempt {attempt + 1}/{self.auto_retry_max_attempts} "
+                         f"for '{text[:20]}...' → {recipient}")
+
+            try:
+                result = self.execute_command(['msg', recipient, text], timeout=DEFAULT_TIMEOUT)
+                if result.get('success'):
+                    # Parse the response to get new expected_ack
+                    new_ack = self._extract_ack_from_response(result.get('stdout', ''))
+                    new_timeout = self._extract_timeout_from_response(result.get('stdout', ''))
+                    if new_ack:
+                        with self.retry_lock:
+                            self.retry_ack_codes.add(new_ack)
+                            self.retry_groups.setdefault(original_ack, []).append(new_ack)
+                        if new_timeout:
+                            wait_timeout = max(new_timeout / 1000 * 1.2, 5.0)
+                        logger.info(f"Retry sent, new ack={new_ack}")
+                    else:
+                        logger.warning(f"Retry: could not parse expected_ack from response")
+                        break
+                else:
+                    logger.error(f"Retry: msg command failed: {result.get('stderr', '')}")
+                    break
+            except Exception as e:
+                logger.error(f"Retry: send failed: {e}")
+                break
+
+        # Cleanup active retry tracking
+        with self.retry_lock:
+            self.active_retries.pop(original_ack, None)
+
+        if attempt >= self.auto_retry_max_attempts:
+            logger.warning(f"Auto-retry exhausted ({self.auto_retry_max_attempts} attempts) "
+                            f"for '{text[:20]}...' → {recipient}")
+
+    def _wait_for_any_ack(self, ack_codes, timeout_seconds, cancel_event):
+        """Poll self.acks dict for any of the given ack_codes with timeout."""
+        start = time.time()
+        poll_interval = 0.5  # Check every 500ms
+        while time.time() - start < timeout_seconds:
+            for code in ack_codes:
+                if code in self.acks:
+                    return True
+            if cancel_event.is_set():
+                return False
+            cancel_event.wait(poll_interval)
+        return any(code in self.acks for code in ack_codes)
+
+    def _extract_ack_from_response(self, stdout):
+        """Extract expected_ack from msg command JSON response."""
+        try:
+            for line in stdout.strip().split('\n'):
+                line = line.strip()
+                if not line:
+                    continue
+                data = json.loads(line)
+                if isinstance(data, dict) and 'expected_ack' in data:
+                    return data['expected_ack']
+        except (json.JSONDecodeError, ValueError):
+            pass
+        return None
+
+    def _extract_timeout_from_response(self, stdout):
+        """Extract suggested_timeout from msg command JSON response."""
+        try:
+            for line in stdout.strip().split('\n'):
+                line = line.strip()
+                if not line:
+                    continue
+                data = json.loads(line)
+                if isinstance(data, dict) and 'suggested_timeout' in data:
+                    return data['suggested_timeout']
+        except (json.JSONDecodeError, ValueError):
+            pass
+        return None
+
     def _log_advert(self, json_line):
         """Log advert JSON to .jsonl file with timestamp"""
         try:
@@ -1086,6 +1237,20 @@ def execute_cli():
         # Execute via persistent session
         result = meshcli_session.execute_command(args, timeout)
 
+        # Auto-retry: after successful msg command, start background retry
+        if (result.get('success') and args and args[0] in ('msg', 'm')
+                and len(args) >= 3 and meshcli_session.auto_retry_enabled
+                and meshcli_session.auto_retry_max_attempts > 1):
+            stdout = result.get('stdout', '')
+            expected_ack = meshcli_session._extract_ack_from_response(stdout)
+            suggested_timeout = meshcli_session._extract_timeout_from_response(stdout)
+            if expected_ack and suggested_timeout:
+                recipient = args[1]
+                text = args[2]
+                meshcli_session._start_retry(
+                    recipient, text, expected_ack, suggested_timeout
+                )
+
         return jsonify(result), 200
 
     except Exception as e:
@@ -1468,11 +1633,82 @@ def get_ack_status():
 
     result = {}
     for code in codes:
-        result[code] = meshcli_session.acks.get(code)
+        ack_info = meshcli_session.acks.get(code)
+        # If no ACK for this code, check retry group (maybe a retry attempt got the ACK)
+        if ack_info is None:
+            with meshcli_session.retry_lock:
+                retry_codes = meshcli_session.retry_groups.get(code, [])
+            for retry_code in retry_codes:
+                ack_info = meshcli_session.acks.get(retry_code)
+                if ack_info is not None:
+                    break
+        result[code] = ack_info
 
     return jsonify({'success': True, 'acks': result}), 200
 
 
+# =============================================================================
+# Auto-retry endpoints
+# =============================================================================
+
+@app.route('/retry_ack_codes', methods=['GET'])
+def get_retry_ack_codes():
+    """Return set of expected_ack codes that belong to retry attempts (not first send)."""
+    if not meshcli_session:
+        return jsonify({'success': False, 'error': 'Not initialized'}), 503
+
+    with meshcli_session.retry_lock:
+        codes = list(meshcli_session.retry_ack_codes)
+
+    return jsonify({'success': True, 'retry_ack_codes': codes}), 200
+
+
+@app.route('/auto_retry/config', methods=['GET'])
+def get_auto_retry_config():
+    """Get current auto-retry configuration."""
+    if not meshcli_session:
+        return jsonify({'success': False, 'error': 'Not initialized'}), 503
+
+    return jsonify({
+        'success': True,
+        'enabled': meshcli_session.auto_retry_enabled,
+        'max_attempts': meshcli_session.auto_retry_max_attempts,
+        'flood_after': meshcli_session.auto_retry_flood_after,
+        'active_retries': len(meshcli_session.active_retries),
+    }), 200
+
+
+@app.route('/auto_retry/config', methods=['POST'])
+def set_auto_retry_config():
+    """Update auto-retry configuration."""
+    if not meshcli_session:
+        return jsonify({'success': False, 'error': 'Not initialized'}), 503
+
+    data = request.get_json()
+    if not data:
+        return jsonify({'success': False, 'error': 'Missing JSON body'}), 400
+
+    if 'enabled' in data:
+        meshcli_session.auto_retry_enabled = bool(data['enabled'])
+    if 'max_attempts' in data:
+        val = int(data['max_attempts'])
+        meshcli_session.auto_retry_max_attempts = max(1, min(val, 10))
+    if 'flood_after' in data:
+        val = int(data['flood_after'])
+        meshcli_session.auto_retry_flood_after = max(1, min(val, 10))
+
+    logger.info(f"Auto-retry config updated: enabled={meshcli_session.auto_retry_enabled}, "
+                f"max_attempts={meshcli_session.auto_retry_max_attempts}, "
+                f"flood_after={meshcli_session.auto_retry_flood_after}")
+
+    return jsonify({
+        'success': True,
+        'enabled': meshcli_session.auto_retry_enabled,
+        'max_attempts': meshcli_session.auto_retry_max_attempts,
+        'flood_after': meshcli_session.auto_retry_flood_after,
+    }), 200
+
+
 # =============================================================================
 # WebSocket handlers for console
 # =============================================================================