fix(hl2): remember TUNE power, FFT AVG, the receiver set and every receiver's setpoints. Principle III.

docs/HERMES.md

@@ -2195,8 +2195,8 @@ The Display panel's FPS slider, Clone to all Pans and Reset to Defaults save;
 `MainWindow::wirePanDisplayStatus` restores into the widget before it seeds the
 shaper. FFT AVG and Wt Avg have a table of their own in that document
 (`fftAverages`), kept only for a backend that declares
-`BackendPanAveraging::clientPersistsAveraging`. The HL2 declares it false, so on
-this radio those two are not remembered.
+`BackendPanAveraging::clientPersistsAveraging`. The HL2 declares it, so the
+Display panel's FFT AVG slider and Wt Avg toggle are remembered per pan slot too.
 
 The dBm range is the odd one: the pan model, not the widget, is what every
 re-seed reads, so a scale the operator moves is put into the model
@@ -3696,7 +3696,10 @@ behavior is unchanged.
 
 The count was fixed at connect, from a persisted setting. It is now the
 operator's, at runtime: "Add Panadapter" and the pane close button. Connect
-always comes up with ONE receiver.
+always comes up with ONE receiver; the ones the operator had open come back
+after link-up through that same add (`Hl2Backend::replayRestoredSession`, from
+the `receivers` list of the `OperatingState` document), so the receiver
+ceiling at the current span still decides how many return (#5777).
 
 Retiring the persisted count mattered for a reason beyond tidiness: it made
 connect the only place the count could change, and a saved 4 was re-imposed on

src/core/RadioStateMemory.cpp

@@ -5,6 +5,7 @@
 #include <QJsonDocument>
 
 #include <cmath>
+#include <utility>
 
 namespace AetherSDR {
 namespace RadioStateMemory {
@@ -33,6 +34,27 @@ bool ownsAgcOffLevel(const RadioCapabilities& caps)
 // feature documents (one domain, one document — PR 6).
 constexpr const char* kExtRfGainKey = "rfGain";
 constexpr const char* kExtTxSetpointsKey = "txSetpoints";
+constexpr const char* kExtReceiversKey = "receivers";
+constexpr const char* kExtNotchesKey = "notches";
+
+// The declared domains' sub-objects of `ext`; load() and store() share it so
+// the two gates cannot drift apart.
+QJsonObject gateExtension(const RadioCapabilities& caps, const QJsonObject& ext)
+{
+    const std::pair<Domain, const char*> domains[] = {
+        {Domain::RfGain, kExtRfGainKey},
+        {Domain::TxSetpoints, kExtTxSetpointsKey},
+        {Domain::Receivers, kExtReceiversKey},
+        {Domain::Notches, kExtNotchesKey},
+    };
+    QJsonObject gated;
+    for (const auto& [domain, key] : domains) {
+        if (has(caps, domain) && ext.contains(QLatin1String(key))) {
+            gated.insert(QLatin1String(key), ext.value(QLatin1String(key)));
+        }
+    }
+    return gated;
+}
 
 } // namespace
 
@@ -115,18 +137,8 @@ RestoredRadioState load(const RadioSettingsScope& scope,
     // sub-object is handed over, so a narrowed declaration cannot smuggle
     // another domain's data to the backend (PR #4614 review — previously the
     // whole blob rode on any one of the ext domains).
-    const QJsonObject storedExt = doc.value(QStringLiteral("ext")).toObject();
-    QJsonObject gatedExt;
-    if (has(caps, Domain::RfGain)
-        && storedExt.contains(QLatin1String(kExtRfGainKey))) {
-        gatedExt.insert(QLatin1String(kExtRfGainKey),
-                        storedExt.value(QLatin1String(kExtRfGainKey)));
-    }
-    if (has(caps, Domain::TxSetpoints)
-        && storedExt.contains(QLatin1String(kExtTxSetpointsKey))) {
-        gatedExt.insert(QLatin1String(kExtTxSetpointsKey),
-                        storedExt.value(QLatin1String(kExtTxSetpointsKey)));
-    }
+    const QJsonObject gatedExt =
+        gateExtension(caps, doc.value(QStringLiteral("ext")).toObject());
     if (!gatedExt.isEmpty()) {
         state.extension = gatedExt;
         state.extensionSchemaVersion =
@@ -245,17 +257,7 @@ bool store(const RadioSettingsScope& scope, const RadioCapabilities& caps,
     }
 
     // Extension: same per-domain sub-object gate as load().
-    QJsonObject gatedExt;
-    if (has(caps, Domain::RfGain)
-        && state.extension.contains(QLatin1String(kExtRfGainKey))) {
-        gatedExt.insert(QLatin1String(kExtRfGainKey),
-                        state.extension.value(QLatin1String(kExtRfGainKey)));
-    }
-    if (has(caps, Domain::TxSetpoints)
-        && state.extension.contains(QLatin1String(kExtTxSetpointsKey))) {
-        gatedExt.insert(QLatin1String(kExtTxSetpointsKey),
-                        state.extension.value(QLatin1String(kExtTxSetpointsKey)));
-    }
+    const QJsonObject gatedExt = gateExtension(caps, state.extension);
     if (!gatedExt.isEmpty()) {
         doc.insert(QStringLiteral("ext"), gatedExt);
         doc.insert(QStringLiteral("extVersion"), state.extensionSchemaVersion);

src/core/backends/IRadioBackend.h

@@ -590,9 +590,10 @@ class IRadioBackend : public QObject {
     // rfpower drop notice.
     virtual void setTxPower(int percent) { Q_UNUSED(percent); }
 
-    // TUNE power (0..100) changed while the TUNE carrier may be up. NEVER keys:
-    // a backend generating its own carrier re-applies drive to one in progress
-    // and otherwise does nothing, since the next setTune() carries the value.
+    // TUNE power (0..100) changed: unkeyed, or on a carrier this client keyed.
+    // NEVER keys: a backend generating its own carrier re-applies drive to one in
+    // progress; otherwise it may only record the value (HL2 keeps it per band),
+    // since the next setTune() carries it.
     // Owner thread, like setTxPower(). Declaring
     // TransmitDriveControl::tunePowerAppliesLive promises it is implemented.
     virtual void setTunePower(int percent) { Q_UNUSED(percent); }

src/core/backends/RadioCapabilities.h

@@ -485,6 +485,10 @@ struct RadioCapabilities {
         // The radio's own receive output level. Not the PC sink's, which is
         // app-global and stays the flat MasterVolume key.
         ReceiveOutputLevel = 1u << 9,
+        // Each receiver's own setpoints (blanker, APF, squelch, RIT/XIT, audio,
+        // pan centre) and how many receivers run; the backend replays the set.
+        Receivers   = 1u << 10,
+        Notches     = 1u << 11,  // host-side manual notches (centre, width, active)
     };
     Q_DECLARE_FLAGS(ClientSettingsDomains, ClientSettingsDomain)
     ClientSettingsDomains clientSettingsDomains;   // default: empty — restore nothing