Release v2.22.0

Waterfall overhaul, new modes (fingerprint, RF heatmap, SignalID, voice
alerts), PWA support, mode stop responsiveness improvements, ADS-B MSG2
surface tracking, WebSDR overhaul, and full documentation audit.

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

CHANGELOG.md

@@ -2,6 +2,47 @@
 
 All notable changes to iNTERCEPT will be documented in this file.
 
+## [2.22.0] - 2026-02-23
+
+### Added
+- **Waterfall Receiver Overhaul** - WebSocket-based I/Q streaming with server-side FFT, click-to-tune, zoom controls, and auto-scaling
+- **Voice Alerts** - Configurable text-to-speech event notifications across modes
+- **Signal Fingerprinting** - RF device identification and pattern analysis mode
+- **RF Heatmap** - Geographic signal density visualization with Leaflet heatmap overlay
+- **SignalID** - Automatic signal classification via SigIDWiki API integration
+- **PWA Support** - Installable web app with service worker caching and manifest
+- **Real-time Signal Scope** - Live signal visualization for pager, sensor, and SSTV modes
+- **ADS-B MSG2 Surface Parsing** - Ground vehicle movement tracking from MSG2 frames
+- **Cheat Sheets** - Quick reference overlays for keyboard shortcuts and mode controls
+- App icon (SVG) for PWA and browser tab
+
+### Changed
+- **WebSDR overhaul** - Improved receiver management, audio streaming, and UI
+- **Mode stop responsiveness** - Faster timeout handling and improved WiFi/Bluetooth scanner shutdown
+- **Mode transitions** - Smoother navigation with performance instrumentation
+- **BT Locate** - Refactored JS engine with improved trail management and signal smoothing
+- **Listening Post** - Refactored with cross-module frequency routing
+- **SSTV decoder** - State machine improvements and partial image streaming
+- Analytics mode removed; per-mode analytics panels integrated into existing dashboards
+
+### Fixed
+- ADS-B SSE multi-client fanout stability and update flush timing
+- WiFi scanner robustness and monitor mode teardown reliability
+- Agent client reliability improvements for remote sensor nodes
+- SSTV VIS detector state reporting in signal monitor diagnostics
+
+### Documentation
+- Complete documentation audit across README, FEATURES, USAGE, help modal, and GitHub Pages
+- Fixed license badge (MIT → Apache 2.0) to match actual LICENSE file
+- Fixed tool name `rtl_amr` → `rtlamr` throughout all docs
+- Fixed incorrect entry point examples (`python app.py` → `sudo -E venv/bin/python intercept.py`)
+- Removed duplicate AIS Vessel Tracking section from FEATURES.md
+- Updated SSTV requirements: pure Python decoder, no external `slowrx` needed
+- Added ACARS and VDL2 mode descriptions to in-app help modal
+- GitHub Pages site: corrected Docker command, license, and tool name references
+
+---
+
 ## [2.21.1] - 2026-02-20
 
 ### Fixed

Dockerfile

@@ -57,7 +57,6 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     soapysdr-module-airspy \
     airspy \
     limesuite \
-    hackrf \
     # Utilities
     curl \
     procps \
@@ -190,6 +189,17 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     fi \
     && cd /tmp \
     && rm -rf /tmp/SatDump \
+    # Build hackrf CLI tools from source — avoids libhackrf0 version conflict
+    # between the 'hackrf' apt package and soapysdr-module-hackrf's newer libhackrf0
+    && cd /tmp \
+    && git clone --depth 1 https://github.com/greatscottgadgets/hackrf.git \
+    && cd hackrf/host \
+    && mkdir build && cd build \
+    && cmake .. \
+    && make \
+    && make install \
+    && ldconfig \
+    && rm -rf /tmp/hackrf \
     # Build rtlamr (utility meter decoder - requires Go)
     && cd /tmp \
     && curl -fsSL "https://go.dev/dl/go1.22.5.linux-$(dpkg --print-architecture).tar.gz" | tar -C /usr/local -xz \

README.md

@@ -2,7 +2,7 @@
 
 <p align="center">
   <img src="https://img.shields.io/badge/python-3.9+-blue.svg" alt="Python 3.9+">
-  <img src="https://img.shields.io/badge/license-MIT-green.svg" alt="MIT License">
+  <img src="https://img.shields.io/badge/license-Apache--2.0-green.svg" alt="Apache 2.0 License">
   <img src="https://img.shields.io/badge/platform-macOS%20%7C%20Linux-lightgrey.svg" alt="Platform">
 </p>
 
@@ -40,7 +40,7 @@ Support the developer of this open-source project
 - **HF SSTV** - Terrestrial SSTV on shortwave frequencies (80m-10m, VHF, UHF)
 - **APRS** - Amateur packet radio position reports and telemetry via direwolf
 - **Satellite Tracking** - Pass prediction with polar plot and ground track map
-- **Utility Meters** - Electric, gas, and water meter reading via rtl_amr
+- **Utility Meters** - Electric, gas, and water meter reading via rtlamr
 - **ADS-B History** - Persistent aircraft history with reporting dashboard (Postgres optional)
 - **WiFi Scanning** - Monitor mode reconnaissance via aircrack-ng
 - **Bluetooth Scanning** - Device discovery and tracker detection (with Ubertooth support)
@@ -57,8 +57,6 @@ Support the developer of this open-source project
 
 ## Installation / Debian / Ubuntu / MacOS
 
-```
-
 **1. Clone and run:**
 ```bash
 git clone https://github.com/smittix/intercept.git
@@ -150,7 +148,7 @@ Set these as environment variables for either local installs or Docker:
 ```bash
 INTERCEPT_ADSB_AUTO_START=true \
 INTERCEPT_SHARED_OBSERVER_LOCATION=false \
-python app.py
+sudo -E venv/bin/python intercept.py
 ```
 
 **Docker example (.env)**
@@ -172,7 +170,7 @@ Then open **/adsb/history** for the reporting dashboard.
 
 After starting, open **http://localhost:5050** in your browser. The username and password is <b>admin</b>:<b>admin</b> 
 
-The credentials can be change in the ADMIN_USERNAME & ADMIN_PASSWORD variables in config.py
+The credentials can be changed in the ADMIN_USERNAME & ADMIN_PASSWORD variables in config.py
 
 ---
 
@@ -245,7 +243,7 @@ Created by **smittix** - [GitHub](https://github.com/smittix)
 [AIS-catcher](https://github.com/jvde-github/AIS-catcher) |
 [acarsdec](https://github.com/TLeconte/acarsdec) |
 [direwolf](https://github.com/wb2osz/direwolf) |
-[rtl_amr](https://github.com/bemasher/rtlamr) |
+[rtlamr](https://github.com/bemasher/rtlamr) |
 [dumpvdl2](https://github.com/szpajder/dumpvdl2) |
 [aircrack-ng](https://www.aircrack-ng.org/) |
 [Leaflet.js](https://leafletjs.com/) |

config.py

@@ -7,10 +7,29 @@ import os
 import sys
 
 # Application version
-VERSION = "2.21.1"
+VERSION = "2.22.0"
 
 # Changelog - latest release notes (shown on welcome screen)
 CHANGELOG = [
+    {
+        "version": "2.22.0",
+        "date": "February 2026",
+        "highlights": [
+            "Waterfall receiver overhaul: WebSocket I/Q streaming with server-side FFT, click-to-tune, and zoom controls",
+            "Voice alerts for configurable event notifications across modes",
+            "Signal fingerprinting mode for RF device identification and pattern analysis",
+            "RF Heatmap for geographic signal density visualization",
+            "SignalID integration via SigIDWiki API for automatic signal classification",
+            "PWA support: installable web app with service worker and manifest",
+            "Mode stop responsiveness improvements with faster timeout handling",
+            "Navigation performance instrumentation and smoother mode transitions",
+            "Pager, sensor, and SSTV real-time signal scope visualization",
+            "ADS-B MSG2 surface movement parsing for ground vehicle tracking",
+            "WebSDR major overhaul with improved receiver management and audio streaming",
+            "Documentation audit: fixed license, tool names, entry points, and SSTV decoder references",
+            "Help modal updated with ACARS and VDL2 mode descriptions",
+        ]
+    },
     {
         "version": "2.21.1",
         "date": "February 2026",

docs/FEATURES.md

@@ -24,17 +24,6 @@ Complete feature list for all modules.
 - **Wideband spectrum analysis** with real-time visualization
 - **I/Q capture** - record raw samples for offline analysis
 
-## AIS Vessel Tracking
-
-- **Real-time vessel tracking** via AIS-catcher on 161.975/162.025 MHz
-- **Full-screen dashboard** - dedicated popout with interactive map
-- **Interactive Leaflet map** with OpenStreetMap tiles (dark-themed)
-- **Vessel details popup** - name, MMSI, callsign, destination, ETA
-- **Navigation data** - speed, course, heading, rate of turn
-- **Ship type classification** - cargo, tanker, passenger, fishing, etc.
-- **Vessel dimensions** - length, width, draught
-- **Multi-SDR support** - RTL-SDR, HackRF, LimeSDR, Airspy, SDRplay
-
 ## Spy Stations (Number Stations)
 
 - **Comprehensive database** of active number stations and diplomatic networks

docs/USAGE.md

@@ -172,7 +172,7 @@ Set the following environment variables (Docker recommended):
 ```bash
 INTERCEPT_ADSB_AUTO_START=true \
 INTERCEPT_SHARED_OBSERVER_LOCATION=false \
-python app.py
+sudo -E venv/bin/python intercept.py
 ```
 
 **Docker example (.env)**

docs/index.html

@@ -110,7 +110,7 @@
                     <div class="feature-card" data-category="signals">
                         <div class="feature-icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path d="M13 2L3 14h9l-1 8 10-12h-9l1-8z"/></svg></div>
                         <h3>Utility Meters</h3>
-                        <p>Smart meter monitoring via rtl_amr. Receive electric, gas, and water meter broadcasts in real time.</p>
+                        <p>Smart meter monitoring via rtlamr. Receive electric, gas, and water meter broadcasts in real time.</p>
                     </div>
                     <div class="feature-card" data-category="tracking">
                         <div class="feature-icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"><path d="M17.8 19.2L16 11l3.5-3.5C21 6 21.5 4 21 3c-1-.5-3 0-4.5 1.5L13 8 4.8 6.2c-.5-.1-.9.1-1.1.5l-.3.5c-.2.5-.1 1 .3 1.3L9 12l-2 3H4l-1 1 3 2 2 3 1-1v-3l3-2 3.5 5.3c.3.4.8.5 1.3.3l.5-.2c.4-.3.6-.7.5-1.2z"/></svg></div>
@@ -321,7 +321,7 @@ sudo -E venv/bin/python intercept.py</code></pre>
                     <div class="code-block">
                         <pre><code>git clone https://github.com/smittix/intercept.git
 cd intercept
-docker compose up -d</code></pre>
+docker compose --profile basic up -d --build</code></pre>
                     </div>
                     <p class="install-note">Requires privileged mode for USB SDR access</p>
                 </div>
@@ -422,7 +422,7 @@ docker compose up -d</code></pre>
                 </div>
             </div>
             <div class="footer-bottom">
-                <p>Created by <a href="https://github.com/smittix" target="_blank">smittix</a> · MIT License</p>
+                <p>Created by <a href="https://github.com/smittix" target="_blank">smittix</a> · Apache 2.0 License</p>
                 <p class="disclaimer">For educational and authorized testing purposes only.</p>
             </div>
         </div>

static/css/modes/bt_locate.css

@@ -560,3 +560,69 @@
         font-size: 9px;
     }
 }
+
+/* ── Crosshair sweep animation ───────────────────────────────────── */
+.btl-crosshair-overlay {
+    position: absolute;
+    inset: 0;
+    pointer-events: none;
+    overflow: hidden;
+    z-index: 1200;
+    --btl-crosshair-x-start: 100%;
+    --btl-crosshair-y-start: 100%;
+    --btl-crosshair-x-end: 50%;
+    --btl-crosshair-y-end: 50%;
+    --btl-crosshair-duration: 1500ms;
+}
+
+.btl-crosshair-line {
+    position: absolute;
+    opacity: 0;
+    background: var(--accent-cyan);
+    will-change: transform, opacity;
+}
+
+.btl-crosshair-vertical {
+    top: 0;
+    bottom: 0;
+    width: 1px;
+    left: 0;
+    transform: translateX(var(--btl-crosshair-x-start));
+}
+
+.btl-crosshair-horizontal {
+    left: 0;
+    right: 0;
+    height: 1px;
+    top: 0;
+    transform: translateY(var(--btl-crosshair-y-start));
+}
+
+.btl-crosshair-overlay.active .btl-crosshair-vertical {
+    animation: btlCrosshairSweepX var(--btl-crosshair-duration) cubic-bezier(0.2, 0.85, 0.28, 1) forwards;
+}
+
+.btl-crosshair-overlay.active .btl-crosshair-horizontal {
+    animation: btlCrosshairSweepY var(--btl-crosshair-duration) cubic-bezier(0.2, 0.85, 0.28, 1) forwards;
+}
+
+@keyframes btlCrosshairSweepX {
+    0%   { transform: translateX(var(--btl-crosshair-x-start)); opacity: 0; }
+    12%  { opacity: 1; }
+    85%  { opacity: 1; }
+    100% { transform: translateX(var(--btl-crosshair-x-end));   opacity: 0; }
+}
+
+@keyframes btlCrosshairSweepY {
+    0%   { transform: translateY(var(--btl-crosshair-y-start)); opacity: 0; }
+    12%  { opacity: 1; }
+    85%  { opacity: 1; }
+    100% { transform: translateY(var(--btl-crosshair-y-end));   opacity: 0; }
+}
+
+@media (prefers-reduced-motion: reduce) {
+    .btl-crosshair-overlay.active .btl-crosshair-vertical,
+    .btl-crosshair-overlay.active .btl-crosshair-horizontal {
+        animation-duration: 220ms;
+    }
+}

static/js/core/keyboard-shortcuts.js

@@ -9,16 +9,16 @@ const KeyboardShortcuts = (function () {
         if (e.target.matches(GUARD_SELECTOR)) return;
 
         if (e.altKey) {
-            switch (e.key.toLowerCase()) {
+            switch (e.code) {
-                case 'w': e.preventDefault(); window.switchMode && switchMode('waterfall');    break;
+                case 'KeyW': e.preventDefault(); window.switchMode && switchMode('waterfall');    break;
-                case 'm': e.preventDefault(); window.VoiceAlerts && VoiceAlerts.toggleMute(); break;
+                case 'KeyM': e.preventDefault(); window.VoiceAlerts && VoiceAlerts.toggleMute(); break;
-                case 's': e.preventDefault(); _toggleSidebar();                                break;
+                case 'KeyS': e.preventDefault(); _toggleSidebar();                                break;
-                case 'k': e.preventDefault(); showHelp();                                      break;
+                case 'KeyK': e.preventDefault(); showHelp();                                      break;
-                case 'c': e.preventDefault(); window.CheatSheets && CheatSheets.showForCurrentMode(); break;
+                case 'KeyC': e.preventDefault(); window.CheatSheets && CheatSheets.showForCurrentMode(); break;
                 default:
-                    if (e.key >= '1' && e.key <= '9') {
+                    if (e.code >= 'Digit1' && e.code <= 'Digit9') {
                         e.preventDefault();
-                        _switchToNthMode(parseInt(e.key) - 1);
+                        _switchToNthMode(parseInt(e.code.replace('Digit', '')) - 1);
                     }
             }
         } else if (!e.ctrlKey && !e.metaKey) {

static/js/modes/bt_locate.js

@@ -44,6 +44,7 @@ const BtLocate = (function() {
     let queuedDetectionTimer = null;
     let lastDetectionRenderAt = 0;
     let startRequestInFlight = false;
+    let crosshairResetTimer = null;
 
     const MAX_HEAT_POINTS = 1200;
     const MAX_TRAIL_POINTS = 1200;
@@ -349,19 +350,18 @@ const BtLocate = (function() {
     }
 
     function stop() {
+        // Update UI immediately — don't wait for the backend response.
+        if (queuedDetectionTimer) {
+            clearTimeout(queuedDetectionTimer);
+            queuedDetectionTimer = null;
+        }
+        queuedDetection = null;
+        queuedDetectionOptions = null;
+        showIdleUI();
+        disconnectSSE();
+        stopAudio();
+        // Notify backend asynchronously.
         fetch('/bt_locate/stop', { method: 'POST' })
-            .then(r => r.json())
-            .then(() => {
-                if (queuedDetectionTimer) {
-                    clearTimeout(queuedDetectionTimer);
-                    queuedDetectionTimer = null;
-                }
-                queuedDetection = null;
-                queuedDetectionOptions = null;
-                showIdleUI();
-                disconnectSSE();
-                stopAudio();
-            })
             .catch(err => console.error('[BtLocate] Stop error:', err));
     }
 
@@ -703,6 +703,32 @@ const BtLocate = (function() {
         if (gpsCountEl) gpsCountEl.textContent = gpsPoints || 0;
     }
 
+    function triggerCrosshairAnimation(lat, lon) {
+        if (!map) return;
+        const overlay = document.getElementById('btLocateCrosshairOverlay');
+        if (!overlay) return;
+        const size = map.getSize();
+        const point = map.latLngToContainerPoint([lat, lon]);
+        const targetX = Math.max(0, Math.min(size.x, point.x));
+        const targetY = Math.max(0, Math.min(size.y, point.y));
+        const startX = size.x + 8;
+        const startY = size.y + 8;
+        const duration = 1500;
+        overlay.style.setProperty('--btl-crosshair-x-start', `${startX}px`);
+        overlay.style.setProperty('--btl-crosshair-y-start', `${startY}px`);
+        overlay.style.setProperty('--btl-crosshair-x-end', `${targetX}px`);
+        overlay.style.setProperty('--btl-crosshair-y-end', `${targetY}px`);
+        overlay.style.setProperty('--btl-crosshair-duration', `${duration}ms`);
+        overlay.classList.remove('active');
+        void overlay.offsetWidth;
+        overlay.classList.add('active');
+        if (crosshairResetTimer) clearTimeout(crosshairResetTimer);
+        crosshairResetTimer = setTimeout(() => {
+            overlay.classList.remove('active');
+            crosshairResetTimer = null;
+        }, duration + 100);
+    }
+
     function addMapMarker(point, options = {}) {
         if (!map || point.lat == null || point.lon == null) return false;
         const lat = Number(point.lat);
@@ -737,6 +763,7 @@ const BtLocate = (function() {
             'Time: ' + formatPointTimestamp(trailPoint.timestamp) +
             '</div>'
         );
+        marker.on('click', () => triggerCrosshairAnimation(lat, lon));
 
         trailPoints.push(trailPoint);
         mapMarkers.push(marker);

templates/index.html

@@ -1831,6 +1831,10 @@
                     </div>
                     <div class="btl-map-container" style="flex: 1; min-height: 250px; position: relative; overflow: hidden;">
                         <div id="btLocateMap" style="position: absolute; inset: 0;"></div>
+                        <div id="btLocateCrosshairOverlay" class="btl-crosshair-overlay" aria-hidden="true">
+                            <div class="btl-crosshair-line btl-crosshair-vertical"></div>
+                            <div class="btl-crosshair-line btl-crosshair-horizontal"></div>
+                        </div>
                         <div class="btl-map-overlay-controls">
                             <label class="btl-map-overlay-toggle">
                                 <input type="checkbox" id="btLocateHeatmapEnable" onchange="BtLocate.toggleHeatmap()">

templates/partials/help-modal.html

@@ -166,11 +166,27 @@
                 <li>View next pass predictions with elevation and duration</li>
             </ul>
 
+            <h3>ACARS Mode</h3>
+            <ul class="tip-list">
+                <li>Decodes Aircraft Communications Addressing and Reporting System messages via acarsdec</li>
+                <li>Receives operational, weather, and position reports on 129-136 MHz</li>
+                <li>Supports North America, Europe, and Asia-Pacific regional frequency presets</li>
+                <li>Filter by message type, flight ID, or aircraft registration</li>
+            </ul>
+
+            <h3>VDL2 Mode</h3>
+            <ul class="tip-list">
+                <li>Decodes VHF Data Link Mode 2 aircraft datalink messages via dumpvdl2</li>
+                <li>Captures ACARS-over-AVLC frames with full signal analysis (SNR, burst length)</li>
+                <li>Monitor multiple VDL2 frequencies simultaneously (136.725, 136.775, 136.975 MHz)</li>
+                <li>Export captured messages to CSV or JSON for offline analysis</li>
+            </ul>
+
             <h3>ISS SSTV Mode</h3>
             <ul class="tip-list">
                 <li>Decodes Slow Scan Television (SSTV) images from the International Space Station</li>
                 <li>Automated ISS pass tracking with Doppler correction on 145.800 MHz</li>
-                <li>Images decoded in real-time using slowrx</li>
+                <li>Images decoded in real-time using the built-in pure Python decoder</li>
                 <li>Gallery view with timestamped decoded images</li>
             </ul>
 
@@ -336,9 +352,11 @@
                 <li><strong>WebSDR:</strong> Internet connection (remote receivers)</li>
                 <li><strong>SubGHz:</strong> RTL-SDR or compatible SDR hardware</li>
                 <li><strong>Satellite:</strong> Internet for Celestrak (optional), skyfield</li>
-                <li><strong>ISS SSTV:</strong> RTL-SDR, slowrx</li>
+                <li><strong>ACARS:</strong> RTL-SDR, acarsdec</li>
+                <li><strong>VDL2:</strong> RTL-SDR, dumpvdl2</li>
+                <li><strong>ISS SSTV:</strong> RTL-SDR (pure Python decoder — no external tools needed)</li>
                 <li><strong>Weather Sat:</strong> RTL-SDR, SatDump</li>
-                <li><strong>HF SSTV:</strong> RTL-SDR or SoapySDR-compatible hardware, slowrx</li>
+                <li><strong>HF SSTV:</strong> RTL-SDR or SoapySDR-compatible hardware (pure Python decoder)</li>
                 <li><strong>GPS:</strong> RTL-SDR or GPS-capable SDR</li>
                 <li><strong>Space Weather:</strong> Internet connection (public APIs)</li>
                 <li><strong>WiFi:</strong> Monitor-mode adapter, aircrack-ng suite</li>

templates/partials/nav.html

@@ -179,6 +179,9 @@
             <button type="button" class="nav-tool-btn" id="voiceMuteBtn" onclick="window.VoiceAlerts && VoiceAlerts.toggleMute()" title="Toggle voice alerts" aria-label="Toggle voice alerts">
                 <span class="icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><polygon points="11 5 6 9 2 9 2 15 6 15 11 19 11 5"/><path d="M19.07 4.93a10 10 0 0 1 0 14.14"/><path d="M15.54 8.46a5 5 0 0 1 0 7.07"/></svg></span>
             </button>
+            <button type="button" class="nav-tool-btn" onclick="window.CheatSheets && CheatSheets.showForCurrentMode()" title="Mode cheat sheet (Alt+C)" aria-label="Mode cheat sheet">
+                <span class="icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"/><polyline points="14 2 14 8 20 8"/><line x1="16" y1="13" x2="8" y2="13"/><line x1="16" y1="17" x2="8" y2="17"/><polyline points="10 9 9 9 8 9"/></svg></span>
+            </button>
             <button type="button" class="nav-tool-btn" onclick="window.KeyboardShortcuts && KeyboardShortcuts.showHelp()" title="Keyboard shortcuts (Alt+K)" aria-label="Keyboard shortcuts">
                 <span class="icon"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><rect x="2" y="4" width="20" height="16" rx="2"/><path d="M6 8h.01M10 8h.01M14 8h.01M18 8h.01M8 12h.01M12 12h.01M16 12h.01M7 16h10"/></svg></span>
             </button>

utils/aircraft_db.py

@@ -55,6 +55,12 @@ def _load_meta() -> dict[str, Any] | None:
         if os.path.exists(DB_META_FILE):
             with open(DB_META_FILE, 'r') as f:
                 return json.load(f)
+    except json.JSONDecodeError as e:
+        logger.warning(f"Corrupt aircraft db meta file, removing: {e}")
+        try:
+            os.remove(DB_META_FILE)
+        except OSError:
+            pass
     except Exception as e:
         logger.warning(f"Error loading aircraft db meta: {e}")
     return None

utils/bt_locate.py

@@ -637,27 +637,45 @@ def start_locate_session(
     """Start a new locate session, stopping any existing one."""
     global _session
 
+    # Grab and evict any existing session without holding the lock during stop()
+    # (stop() joins a thread which can block for up to 3 s).
+    old_session = None
     with _session_lock:
         if _session and _session.active:
-            _session.stop()
+            old_session = _session
-
-        _session = LocateSession(
-            target, environment, custom_exponent, fallback_lat, fallback_lon
-        )
-        if not _session.start():
             _session = None
-            raise RuntimeError("Bluetooth scanner failed to start")
+
-        return _session
+    if old_session:
+        old_session.stop()
+
+    new_session = LocateSession(
+        target, environment, custom_exponent, fallback_lat, fallback_lon
+    )
+    with _session_lock:
+        _session = new_session
+
+    if not new_session.start():
+        with _session_lock:
+            if _session is new_session:
+                _session = None
+        raise RuntimeError("Bluetooth scanner failed to start")
+
+    return new_session
 
 
 def stop_locate_session() -> None:
     """Stop the active locate session."""
     global _session
 
+    # Release the lock before stop() so concurrent status/SSE requests
+    # aren't blocked for up to 3 s while the poll thread is joined.
+    session_to_stop = None
     with _session_lock:
-        if _session:
+        session_to_stop = _session
-            _session.stop()
+        _session = None
-            _session = None
+
+    if session_to_stop:
+        session_to_stop.stop()
 
 
 def get_locate_session() -> LocateSession | None: