update brand ESPE

include/lidarlib/lidar.hpp

@@ -47,6 +47,10 @@ struct ExtraInfo {
 
     // SICK nanoScan3 only — General System State byte 0 (see kNanoState* bits).
     std::optional<uint8_t> nano_general_state;
+
+    // ESPE LGA60 only — fault word from the newest "WSimu" area frame; the
+    // device only sends those when area data is polled, so usually nullopt.
+    std::optional<uint16_t> espe_error_status;
 };
 
 struct ScanResult {
@@ -101,7 +105,11 @@ public:
     // timeout_ms = 0 → block indefinitely. No default on purpose: drivers
     // differ (OLEI 1000, SICK 2000).
     virtual bool recv_scan(ScanResult& out, int timeout_ms) = 0;
+    // The callback fires only from spin_once() — recv_scan() never invokes
+    // it. Pick one pump style: recv_scan() to poll, or callback + spin_once().
     virtual void set_scan_callback(ScanCallback cb) = 0;
+    // Process one unit of input (may block on the socket while the device is
+    // silent); fires the scan callback when a scan completed. False on error.
     virtual bool spin_once() = 0;
     virtual const char* detected_model() const = 0;
 
@@ -151,6 +159,7 @@ public:
     Diagnostics get_diagnostics() const override { return latest_diag_; }
 
 private:
+    bool poll_packet();  // one recvfrom() + dispatch to the family parser
     bool parse_family_a(const uint8_t* buf, int len);  // ID=0xFAF0
     bool parse_family_b(const uint8_t* buf, int len);  // ID=0xFEF0
     bool parse_family_c(const uint8_t* buf, int len);  // Magic=0xFEAC (GS1-5)