Fix ESP32-S2 firmware build errors

lib/libcanard/canard_pio.c

@@ -0,0 +1,17 @@
+// canard_pio.c - PlatformIO/ESP-IDF wrapper for canard.c
+//
+// Problem: ESP-IDF's platform_include/assert.h (included by canard.c via
+//          <assert.h>) unconditionally includes <stdlib.h>, which in
+//          Espressif's picolibc declares `long int random(void)`.
+//          This conflicts with libcanard's internal `static uint64_t random(...)`.
+//
+// Fix: include <stdlib.h> here first, with _GNU_SOURCE and _BSD_SOURCE
+//      temporarily undefined so that random() is NOT declared.  The stdlib.h
+//      header guard then prevents the double-inclusion that would re-declare
+//      random() when assert.h later pulls it in.
+
+#undef _GNU_SOURCE
+#undef _BSD_SOURCE
+#include <stdlib.h>
+
+#include "canard.c"

lib/libcanard/library.json

@@ -0,0 +1,9 @@
+{
+  "name": "libcanard",
+  "version": "4.0.0",
+  "build": {
+    "srcFilter": "+<canard_pio.c>",
+    "flags": ["-std=c11", "-Wno-error"],
+    "unflags": ["-std=gnu23", "-std=gnu17"]
+  }
+}

lib/o1heap/library.json

@@ -0,0 +1,8 @@
+{
+  "name": "o1heap",
+  "version": "2.0.0",
+  "build": {
+    "flags": ["-std=c11", "-Wno-error"],
+    "unflags": ["-std=gnu23", "-std=gnu17"]
+  }
+}

src/main.cpp

@@ -10,6 +10,7 @@
 #include "cyphal/timesync.hpp"
 #include "cyphal/variable_fetcher.hpp"
 #include "esp_efuse.h"
+#include "esp_efuse_table.h"
 #include "esp_timer.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
@@ -73,7 +74,7 @@ extern "C" void app_main() {
 
   // Wire CAN → Cyphal
   transport.SetSendFn([&](const cymon::CanFrame& f) { return can_driver.Transmit(f); });
-  can_driver.SetRxCallback([&transport](const cymon::CanFrame& frame) { transport.IngestFrame(frame); });
+  can_driver.SetRxCallback([](const cymon::CanFrame& frame) { transport.IngestFrame(frame); });
 
   // Cyphal node
   cymon::CyphalNode::NodeInfo node_info{};

src/web/web_server.cpp

@@ -48,19 +48,62 @@ bool WebServer::Start() {
 
   // Register REST endpoints
   static const httpd_uri_t uris[] = {
-      {"/api/nodes", HTTP_GET, HandleGetNodes, nullptr},
-      {"/api/session", HTTP_POST, HandlePostSession, nullptr},
-      {"/api/session/*", HTTP_DELETE, HandleDeleteSession, nullptr},
-      {"/api/wifi", HTTP_POST, HandlePostWifi, nullptr},
-      {"/api/can", HTTP_POST, HandlePostCan, nullptr},
-      {"/api/settings", HTTP_GET, HandleGetSettings, nullptr},
+      {.uri = "/api/nodes",
+       .method = HTTP_GET,
+       .handler = HandleGetNodes,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},
+      {.uri = "/api/session",
+       .method = HTTP_POST,
+       .handler = HandlePostSession,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},
+      {.uri = "/api/session/*",
+       .method = HTTP_DELETE,
+       .handler = HandleDeleteSession,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},
+      {.uri = "/api/wifi",
+       .method = HTTP_POST,
+       .handler = HandlePostWifi,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},
+      {.uri = "/api/can",
+       .method = HTTP_POST,
+       .handler = HandlePostCan,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},
+      {.uri = "/api/settings",
+       .method = HTTP_GET,
+       .handler = HandleGetSettings,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},
       {.uri = "/ws",
        .method = HTTP_GET,
        .handler = HandleWebSocket,
        .user_ctx = nullptr,
        .is_websocket = true,
-       .handle_ws_control_frames = true},
-      {"/*", HTTP_GET, HandleStaticFile, nullptr},  // catch-all for SPIFFS
+       .handle_ws_control_frames = true,
+       .supported_subprotocol = nullptr},
+      {.uri = "/*",
+       .method = HTTP_GET,
+       .handler = HandleStaticFile,
+       .user_ctx = nullptr,
+       .is_websocket = false,
+       .handle_ws_control_frames = false,
+       .supported_subprotocol = nullptr},  // catch-all for SPIFFS
   };
 
   for (const auto& uri : uris) {