diff --git a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js
index 9885f7d3..b2909005 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js
+++ b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js
@@ -645,7 +645,7 @@ function flushDeferredDecodeMapSync() {
   if (!decodeMapSyncPending || decodeHistoryReplayActive || !window.trx?.map?.aprsMap) return;
   decodeMapSyncPending = false;
   scheduleUiFrameJob("decode-map-maintenance", () => {
-    window.trx.map?.pruneMapHistory();
+    window.trx.modules.map?.pruneMapHistory();
   });
 }
 
@@ -1279,7 +1279,7 @@ function applyRigList(activeRigId, rigIds, displayNames) {
     if (typeof bmPopulateScopePicker === "function") bmPopulateScopePicker();
     if (typeof bmFetch === "function") bmFetch(document.getElementById("bm-category-filter")?.value || "");
   }
-  window.trx.map?.updateMapRigFilter();
+  window.trx.modules.map?.updateMapRigFilter();
 }
 
 
@@ -1305,7 +1305,7 @@ async function refreshRigList() {
     serverRigs = rigs;
     serverActiveRigId = data.active_remote || null;
     applyRigList(data.active_remote, rigIds, displayNames);
-    window.trx.map?.syncAprsReceiverMarker();
+    window.trx.modules.map?.syncAprsReceiverMarker();
   } catch (e) {
     // Non-fatal: SSE/status path still drives main UI.
   }
@@ -3143,9 +3143,9 @@ function render(update) {
     const grid = latLonToMaidenhead(serverLat, serverLon);
     locationSubtitle.textContent = `Location: ${grid}`;
     locationSubtitle.style.display = "";
-    window.trx.map?.reverseGeocodeLocation(serverLat, serverLon, grid);
+    window.trx.modules.map?.reverseGeocodeLocation(serverLat, serverLon, grid);
   }
-  window.trx.map?.syncAprsReceiverMarker();
+  window.trx.modules.map?.syncAprsReceiverMarker();
   if (typeof update.initial_map_zoom === "number" && Number.isFinite(update.initial_map_zoom)) {
     initialMapZoom = Math.max(1, Math.round(update.initial_map_zoom));
   }
@@ -3894,7 +3894,7 @@ async function switchRigFromSelect(selectEl) {
   if (typeof setSchedulerRig === "function") setSchedulerRig(lastActiveRigId);
   if (typeof setBackgroundDecodeRig === "function") setBackgroundDecodeRig(lastActiveRigId);
   if (typeof bmFetch === "function") bmFetch(document.getElementById("bm-category-filter")?.value || "");
-  window.trx.map?.syncAprsReceiverMarker();
+  window.trx.modules.map?.syncAprsReceiverMarker();
   // Switch this session's rig and reconnect SSE to the new rig's
   // state channel.
   try {
@@ -4480,23 +4480,23 @@ function updateTabHistory(name, replaceHistory = false) {
 }
 
 // Initialise the Leaflet map, waiting for both Leaflet (L) and map-core.js
-// (window.trx.map) if they haven't loaded yet.
+// (window.trx.modules.map) if they haven't loaded yet.
 let _mapInitTimer = null;
 function _initMapWhenReady() {
   const loadingEl = document.getElementById("map-loading");
-  if (window.trx.map && typeof L !== "undefined") {
+  if (window.trx.modules.map && typeof L !== "undefined") {
     if (_mapInitTimer) { clearInterval(_mapInitTimer); _mapInitTimer = null; }
     if (loadingEl) loadingEl.classList.add("is-hidden");
-    window.trx.map.initAprsMap();
-    window.trx.map.sizeAprsMapToViewport();
+    window.trx.modules.map.initAprsMap();
+    window.trx.modules.map.sizeAprsMapToViewport();
     // The map panel was just made visible (display:none → ""); the browser
     // may not have laid it out yet, so getBoundingClientRect() can return
     // stale/zero dimensions.  Double-rAF ensures a full layout pass has
     // completed before we re-measure and tell Leaflet about its real size.
     requestAnimationFrame(() => {
       requestAnimationFrame(() => {
-        window.trx.map.sizeAprsMapToViewport();
-        if (window.trx.map.aprsMap) window.trx.map.aprsMap.invalidateSize();
+        window.trx.modules.map.sizeAprsMapToViewport();
+        if (window.trx.modules.map.aprsMap) window.trx.modules.map.aprsMap.invalidateSize();
       });
     });
     return;
@@ -4544,7 +4544,7 @@ function navigateToTab(name, options = {}) {
     _initMapWhenReady();
   }
   if (name === "statistics") {
-    window.trx.map?.scheduleStatsRender();
+    window.trx.modules.map?.scheduleStatsRender();
   }
   if (name === "recorder") {
     refreshRecorderStatus();
@@ -4721,10 +4721,11 @@ if (headerAuthBtn) {
 // ── Shared namespace for lazy-loaded modules ────────────────────────────────
 // Modules (map-core.js, screenshot.js) access core state and utilities via
 // window.trx.  Modules register their own APIs as sub-namespaces
-// (e.g. window.trx.map, window.trx.screenshot).
-window.trx = Object.create(null);
+// (e.g. window.trx.modules.map, window.trx.modules.screenshot).
+const trxState = Object.create(null);
+const trxModules = Object.create(null);
 // -- State getters (backed by core-scoped variables) --
-Object.defineProperties(window.trx, {
+Object.defineProperties(trxState, {
   serverLat:              { get() { return serverLat;              }, set(v) { serverLat = v; } },
   serverLon:              { get() { return serverLon;              }, set(v) { serverLon = v; } },
   lastFreqHz:             { get() { return lastFreqHz;             } },
@@ -4762,7 +4763,7 @@ Object.defineProperties(window.trx, {
   signalOverlayGl:        { get() { return signalOverlayGl;      } },
 });
 // -- Shared utility functions --
-Object.assign(window.trx, {
+const trxCore = Object.freeze({
   saveSetting, loadSetting, showHint, escapeMapHtml, formatFreq, formatFreqForHumans,
   formatWavelength, formatBwLabel, formatUptime, formatSigStrength, formatSignal,
   postPath, scheduleUiFrameJob, navigateToTab, rigBadgeColor,
@@ -4772,18 +4773,19 @@ Object.assign(window.trx, {
   currentTheme, canvasPalette, currentStyle,
   cssColorToRgba, rgbaWithAlpha, isBinsArray, estimateNoiseFloorDb,
   spectrumVisibleRange, drawSpectrum,
-  bandForHz: function(hz) { return window.trx.map?.bandForHz?.(hz); },
+  bandForHz: function(hz) { return trxModules.map?.bandForHz?.(hz); },
   markDecodeMapSyncPending,
   decodeHistoryMapRenderingDeferred,
   updateDocumentTitle,
   activeChannelRds,
 });
-Object.defineProperties(window.trx, {
+Object.defineProperties(trxState, {
   decodeHistoryReplayActive: { get() { return decodeHistoryReplayActive; } },
   decodeMapSyncPending:      { get() { return decodeMapSyncPending; } },
   _activeTab:                { get() { return _activeTab; } },
   locationSubtitle:          { get() { return locationSubtitle; } },
 });
+window.trx = Object.freeze({ state: trxState, core: trxCore, modules: trxModules });
 
 // Load plugin scripts now that window.trx is populated.  Dynamic scripts are
 // async so they must not be created before the namespace they depend on exists.
@@ -4797,7 +4799,7 @@ window.addEventListener("resize", resizeHeaderSignalCanvas);
 // ── Map module (extracted to map-core.js, lazy-loaded) ──────────────────────
 // The map, statistics, and geolocation code (~3,450 lines) has been moved to
 // map-core.js and is loaded on demand when the Map tab is first activated.
-// Core communicates with the map module via window.trx.map.* namespace.
+// Core communicates with the map module via window.trx.modules.map.* namespace.
 
 // ── Geo utilities (shared with map-core.js via window.trx) ─────────────────
 function haversineKm(lat1, lon1, lat2, lon2) {
@@ -4932,7 +4934,7 @@ document.querySelectorAll(".sub-tab-bar").forEach(_wireSubTabBar);
 window.addEventListener("resize", () => {
   const mapTab = document.getElementById("tab-map");
   if (!mapTab || mapTab.style.display === "none") return;
-  window.trx.map?.sizeAprsMapToViewport();
+  window.trx.modules.map?.sizeAprsMapToViewport();
 });
 
 // --- Signal measurement ---
@@ -6102,8 +6104,8 @@ function dispatchDecodeMessage(msg, skipStats) {
   if (msg.type === "wefax" && window.onServerWefax) window.onServerWefax(msg);
   if (msg.type === "wefax_progress" && window.onServerWefaxProgress) window.onServerWefaxProgress(msg);
   if (!skipStats && msg.type && msg.type !== "lrpt_image" && msg.type !== "lrpt_progress" && msg.type !== "wefax" && msg.type !== "wefax_progress") {
-    window.trx.map?.statsRecordDecode(msg.type, msg.rig_id || msg.remote || null);
-    window.trx.map?.scheduleStatsRender();
+    window.trx.modules.map?.statsRecordDecode(msg.type, msg.rig_id || msg.remote || null);
+    window.trx.modules.map?.scheduleStatsRender();
   }
 }
 
@@ -6112,10 +6114,10 @@ function dispatchDecodeBatch(batch) {
   // Record statistics for every message in the batch regardless of dispatch path.
   for (const msg of batch) {
     if (msg.type && msg.type !== "lrpt_image" && msg.type !== "lrpt_progress" && msg.type !== "wefax" && msg.type !== "wefax_progress") {
-      window.trx.map?.statsRecordDecode(msg.type, msg.rig_id || msg.remote || null);
+      window.trx.modules.map?.statsRecordDecode(msg.type, msg.rig_id || msg.remote || null);
     }
   }
-  window.trx.map?.scheduleStatsRender();
+  window.trx.modules.map?.scheduleStatsRender();
   const type = String(batch[0]?.type || "");
   const uniformType = batch.every((msg) => String(msg?.type || "") === type);
   if (uniformType) {
@@ -6200,9 +6202,9 @@ function restoreDecodeHistoryGroup(kind, messages) {
   // Record statistics for restored history messages.
   if (kind !== "lrpt_image" && kind !== "lrpt_progress" && kind !== "wefax" && kind !== "wefax_progress") {
     for (const msg of messages) {
-      window.trx.map?.statsRecordDecode(kind, msg.rig_id || msg.remote || null, msg.ts_ms || undefined);
+      window.trx.modules.map?.statsRecordDecode(kind, msg.rig_id || msg.remote || null, msg.ts_ms || undefined);
     }
-    window.trx.map?.scheduleStatsRender();
+    window.trx.modules.map?.scheduleStatsRender();
   }
   if (kind === "ais") {
     if (window.restoreAisHistory) { window.restoreAisHistory(messages); }
@@ -8000,12 +8002,12 @@ window.addEventListener("keydown", (event) => {
   // S — spectrum screenshot (lazy-loads screenshot.js on first use)
   if (key === "s") {
     event.preventDefault();
-    if (window.trx.screenshot) {
-      void window.trx.screenshot.captureSpectrumScreenshot();
+    if (window.trx.modules.screenshot) {
+      void window.trx.modules.screenshot.captureSpectrumScreenshot();
     } else {
       const s = document.createElement("script");
       s.src = "/screenshot.js";
-      s.onload = () => { void window.trx.screenshot?.captureSpectrumScreenshot(); };
+      s.onload = () => { void window.trx.modules.screenshot?.captureSpectrumScreenshot(); };
       document.body.appendChild(s);
     }
     return;
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/map-core.js b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/map-core.js
index da82dc7d..2e69dd8b 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/map-core.js
+++ b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/map-core.js
@@ -3,10 +3,10 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 // Map, statistics, and geolocation module (lazy-loaded on map tab activation).
-// Communicates with app.js core via window.trx namespace.
+// Communicates with app.js through explicit state/core/module services.
 (function () {
   "use strict";
-  const T = window.trx;
+  const { state: T, core: C, modules } = window.trx;
 
   // Destructure shared utility functions for convenience
   const { saveSetting, loadSetting, showHint, escapeMapHtml, formatFreq, formatFreqForHumans,
@@ -14,7 +14,7 @@
           formatUptime, latLonToMaidenhead, locatorToLatLon, haversineKm,
           formatDistanceKm, formatTimeAgo, currentDecodeHistoryRetentionMs,
           formatWavelength, bookmarkDistanceText, buildBookmarkTooltipText,
-          nearestBookmarkForHz } = T;
+          nearestBookmarkForHz } = C;
 
   function updateMapRigFilter() {
     const el = document.getElementById("map-rig-filter");
@@ -261,7 +261,7 @@
     if (canRenderMap) {
       refreshAprsTrack(call, entry);
     } else {
-      T.markDecodeMapSyncPending();
+      C.markDecodeMapSyncPending();
     }
     if (!visible) {
       if (canRenderMap && selectedAprsTrackCall && String(selectedAprsTrackCall) === String(call)) {
@@ -294,7 +294,7 @@
     if (canRenderMap) {
       refreshAisTrack(key, entry);
     } else {
-      T.markDecodeMapSyncPending();
+      C.markDecodeMapSyncPending();
     }
     if (!visible) {
       if (canRenderMap && selectedAisTrackMmsi && String(selectedAisTrackMmsi) === String(key)) {
@@ -337,7 +337,7 @@
       entry.stations = new Set();
       entry.bandMeta = new Map();
       if (canRenderMap) setRetainedMapMarkerVisible(entry.marker, false);
-      else T.markDecodeMapSyncPending();
+      else C.markDecodeMapSyncPending();
       return false;
     }
     const nextStations = new Set();
@@ -352,7 +352,7 @@
     );
     const count = Math.max(nextDetails.size, nextStations.size || 0, 1);
     if (!canRenderMap) {
-      T.markDecodeMapSyncPending();
+      C.markDecodeMapSyncPending();
       return true;
     }
     ensureDecodeLocatorMarker(entry);
@@ -392,7 +392,7 @@
       pruneLocatorEntry(key, entry, cutoffMs);
     }
     if (!aprsMap || T.decodeHistoryReplayActive) {
-      T.markDecodeMapSyncPending();
+      C.markDecodeMapSyncPending();
       return;
     }
     rebuildDecodeContactPaths();
@@ -415,7 +415,7 @@
 
   function locatorFilterColor(type) {
     const hues = locatorThemeHues();
-    const lightTheme = T.currentTheme() === "light";
+    const lightTheme = C.currentTheme() === "light";
     const sat = lightTheme ? 66 : 76;
     const light = lightTheme ? 42 : 56;
     const hue = type === "bookmark"
@@ -539,7 +539,7 @@
   }
 
   function locatorThemeHues() {
-    const pal = T.canvasPalette();
+    const pal = C.canvasPalette();
     const baseHue = paletteHue(pal?.spectrumLine, 145);
     const waveHue = paletteHue(pal?.waveformLine, baseHue + 34);
     const peakHue = paletteHue(pal?.waveformPeak, baseHue - 42);
@@ -560,7 +560,7 @@
 
   function locatorBandChipColor(label) {
     const hues = locatorThemeHues();
-    const lightTheme = T.currentTheme() === "light";
+    const lightTheme = C.currentTheme() === "light";
     const hue = wrapHue(hues.bandBase + locatorBandIndex(label) * 137.508);
     const sat = lightTheme ? 68 : 78;
     const light = lightTheme ? 44 : 58;
@@ -606,7 +606,7 @@
     const safeCount = Math.max(1, Number.isFinite(count) ? count : 1);
     const intensity = Math.min(1, Math.log2(safeCount + 1) / 5);
     const hue = locatorHueForEntry(entry);
-    const lightTheme = T.currentTheme() === "light";
+    const lightTheme = C.currentTheme() === "light";
     const strokeSat = lightTheme ? 62 : 74;
     const fillSat = lightTheme ? 68 : 78;
     const strokeLight = lightTheme ? 40 : 56;
@@ -1573,7 +1573,7 @@
       stageResizeObserver = new ResizeObserver(() => sizeAprsMapToViewport());
       stageResizeObserver.observe(stage);
     }
-    updateMapBaseLayerForTheme(T.currentTheme());
+    updateMapBaseLayerForTheme(C.currentTheme());
     syncAprsReceiverMarker();
 
     // Rebuild popup content on open (keeps age/distance/rig list fresh)
@@ -2307,18 +2307,18 @@
         existing.rigIds.add(msgRigId);
       }
       if (!visible) {
-        if (!T.decodeHistoryMapRenderingDeferred()) {
+        if (!C.decodeHistoryMapRenderingDeferred()) {
           setRetainedMapMarkerVisible(existing.marker, false);
         } else {
-          T.markDecodeMapSyncPending();
+          C.markDecodeMapSyncPending();
         }
         return;
       }
-      if (!T.decodeHistoryMapRenderingDeferred()) {
+      if (!C.decodeHistoryMapRenderingDeferred()) {
         ensureVdesMarker(key, existing);
         setRetainedMapMarkerVisible(existing.marker, true);
       } else {
-        T.markDecodeMapSyncPending();
+        C.markDecodeMapSyncPending();
       }
       if (aprsMap && existing.marker && !T.decodeHistoryReplayActive) {
         existing.marker.setLatLng([msg.lat, msg.lon]);
@@ -2334,11 +2334,11 @@
     };
     vdesMarkers.set(key, entry);
     if (!visible) return;
-    if (!T.decodeHistoryMapRenderingDeferred()) {
+    if (!C.decodeHistoryMapRenderingDeferred()) {
       ensureVdesMarker(key, entry);
       setRetainedMapMarkerVisible(entry.marker, true);
     } else {
-      T.markDecodeMapSyncPending();
+      C.markDecodeMapSyncPending();
     }
     if (aprsMap && entry.marker && !T.decodeHistoryReplayActive) {
       entry.marker.setPopupContent(popupHtml);
@@ -2365,7 +2365,7 @@
         if (T.locationSubtitle) {
           T.locationSubtitle.textContent = `Location: ${grid} · ${label}`;
         }
-        T.updateDocumentTitle(T.activeChannelRds());
+        C.updateDocumentTitle(C.activeChannelRds());
       })
       .catch(() => {});
   }
@@ -2443,8 +2443,8 @@
   }
 
   function scheduleDecodeMapMaintenance() {
-    if (T.decodeHistoryMapRenderingDeferred()) {
-      T.markDecodeMapSyncPending();
+    if (C.decodeHistoryMapRenderingDeferred()) {
+      C.markDecodeMapSyncPending();
       return;
     }
     scheduleUiFrameJob("decode-map-maintenance", () => {
@@ -3461,7 +3461,7 @@
   }
 
   // Register module API for core to call
-  window.trx.map = {
+  modules.map = {
     initAprsMap,
     sizeAprsMapToViewport,
     syncAprsReceiverMarker,
diff --git a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/screenshot.js b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/screenshot.js
index f861d18d..7f57cc5a 100644
--- a/src/trx-client/trx-frontend/trx-frontend-http/assets/web/screenshot.js
+++ b/src/trx-client/trx-frontend/trx-frontend-http/assets/web/screenshot.js
@@ -257,7 +257,7 @@
   }
 
   // Register module API
-  window.trx.screenshot = {
+  window.trx.modules.screenshot = {
     captureSpectrumScreenshot,
     buildSpectrumSnapshotCanvas,
     saveCanvasAsPng,