M3 step 4: the LoRa Scanner App, Sniffer and Captures

The Sniffer lists packets newest first (time, RSSI, SNR, and for
Meshtastic the sender, receiver and hops), with the clear header and a
hex dump on Enter (Q96); `p` picks an EU868 preset, kept in Settings
(Q95). `c` starts a Capture: pcap with LoRaTap in /captures/lora, its own
Clean-up category, recorded by a small Service so it carries on with the
App closed (Q97, Q100). The Status Bar shows L while listening, bright on
each packet, and CAP while capturing (Q101). StorageService gains raw
appends for binary files. Debug Builds get `lora inject` to test all of
this with no transmitter in range: a Capture made on the device reads
back in TShark field for field.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/services/radio_service.h

@@ -68,7 +68,9 @@ class RadioService : public Service {
     void setConfig(const Config& config);  // custom settings (Q95), named "Custom"
 
     uint32_t received() const { return seq_; }  // seq of the newest packet
+    uint32_t lastPacketMs() const { return lastPacketMs_; }  // millis(), 0 before the first
     bool packet(uint32_t seq, RadioPacket& out) const;  // false once it has left the ring
+    uint32_t available() const;  // packets in the ring: seqs received()-available()+1 to received()
     float noiseFloor() const { return noise_; }
     Counters counters() const {
         return {packets_, crcErrors_, radioErrors_, restarts_, preambles_, headers_, headerErrors_};
@@ -78,6 +80,11 @@ class RadioService : public Service {
     void printStatus(Print& out) const;
     void setEcho(bool echo);
     void probe(Print& out);  // `lora probe`: runs on the radio task
+#ifdef RORO_DEBUG
+    // `lora inject`: a packet into the ring as if received, to test the App and Captures with no
+    // transmitter in range. Nothing goes on air.
+    void inject(const uint8_t* data, size_t len, float rssi, float snr);
+#endif
 
    private:
     enum Notify : uint32_t { kIrq = 1, kRequest = 2 };
@@ -90,6 +97,7 @@ class RadioService : public Service {
     void stopListening();
     int16_t receive();
     void readPacket();
+    void store(RadioPacket& p);
     void sampleNoise();
     void runProbe();
     void wake(Notify why);
@@ -107,6 +115,8 @@ class RadioService : public Service {
     std::atomic<bool> listening_{false}, configChanged_{false}, probeWanted_{false}, echo_{false};
     std::atomic<uint32_t> seq_{0}, packets_{0}, crcErrors_{0}, radioErrors_{0}, restarts_{0};
     std::atomic<uint32_t> preambles_{0}, headers_{0}, headerErrors_{0};
+    std::atomic<uint32_t> lastPacketMs_{0};
+    std::atomic<uint32_t> ringFirst_{1};  // the first seq the current ring can hold
     std::atomic<float> noise_{0};
     uint32_t lastNoiseMs_ = 0, echoed_ = 0;
     Print* probeOut_ = nullptr;