fix: propagate has_wifi from compiler to startBoard for reliable WiFi detection

Frontend WiFi detection via file-content scanning was unreliable because
fileGroups[board.activeFileGroupId] could be an empty array (not null),
bypassing the ?? fallback to editorState.files.

Fix: the ESP-IDF compiler now returns has_wifi:bool in its compile response.
The frontend stores this on the BoardInstance and uses it in startBoard()
instead of scanning file contents. The file-content scan is kept as a
fallback for boards that haven't been compiled in this session.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/routes/compile.py

@@ -29,6 +29,7 @@ class CompileResponse(BaseModel):
     hex_content: str | None = None
     binary_content: str | None = None  # base64-encoded .bin for RP2040
     binary_type: str | None = None     # 'bin' or 'uf2'
+    has_wifi: bool = False             # True when sketch uses WiFi (ESP32 only)
     stdout: str
     stderr: str
     error: str | None = None
@@ -63,6 +64,7 @@ async def compile_sketch(request: CompileRequest):
                 hex_content=result.get("hex_content"),
                 binary_content=result.get("binary_content"),
                 binary_type=result.get("binary_type"),
+                has_wifi=result.get("has_wifi", False),
                 stdout=result.get("stdout", ""),
                 stderr=result.get("stderr", ""),
                 error=result.get("error"),

backend/app/services/espidf_compiler.py

@@ -477,6 +477,8 @@ class ESPIDFCompiler:
             # QEMU's WiFi AP broadcasts "Velxio-GUEST" on channel 6.
             # We normalize ANY user SSID → "Velxio-GUEST", enforce channel 6,
             # and use open auth (empty password) so the connection always works.
+            # Detect WiFi BEFORE normalization so the flag reflects the original sketch.
+            has_wifi = self._detect_wifi_usage(main_content)
             main_content = self._normalize_wifi_for_qemu(main_content)
 
             if self.has_arduino:
@@ -622,13 +624,14 @@ class ESPIDFCompiler:
                 }
 
             binary_b64 = base64.b64encode(merged_path.read_bytes()).decode('ascii')
-            logger.info(f'[espidf] Compilation successful — {len(binary_b64) // 1024} KB (base64)')
+            logger.info(f'[espidf] Compilation successful — {len(binary_b64) // 1024} KB (base64), has_wifi={has_wifi}')
 
             return {
                 'success': True,
                 'hex_content': None,
                 'binary_content': binary_b64,
                 'binary_type': 'bin',
+                'has_wifi': has_wifi,
                 'stdout': all_stdout,
                 'stderr': all_stderr,
             }

frontend/src/components/editor/EditorToolbar.tsx

@@ -49,6 +49,7 @@ export const EditorToolbar = ({ consoleOpen, setConsoleOpen, compileLogs: _compi
     boards,
     activeBoardId,
     compileBoardProgram,
+    updateBoard,
     startBoard,
     stopBoard,
     resetBoard,
@@ -135,6 +136,9 @@ export const EditorToolbar = ({ consoleOpen, setConsoleOpen, compileLogs: _compi
         const program = result.hex_content ?? result.binary_content ?? null;
         if (program && activeBoardId) {
           compileBoardProgram(activeBoardId, program);
+          if (result.has_wifi !== undefined) {
+            updateBoard(activeBoardId, { hasWifi: result.has_wifi });
+          }
         }
         setMessage({ type: 'success', text: 'Compiled successfully' });
         markCompiled();
@@ -279,7 +283,12 @@ export const EditorToolbar = ({ consoleOpen, setConsoleOpen, compileLogs: _compi
 
         if (result.success) {
           const program = result.hex_content ?? result.binary_content ?? null;
-          if (program) compileBoardProgram(board.id, program);
+          if (program) {
+            compileBoardProgram(board.id, program);
+            if (result.has_wifi !== undefined) {
+              updateBoard(board.id, { hasWifi: result.has_wifi });
+            }
+          }
           updateStatus({ state: 'success' });
         } else {
           updateStatus({ state: 'error', error: result.stderr || result.error || 'Compilation failed' });

frontend/src/services/compilation.ts

@@ -12,6 +12,7 @@ export interface CompileResult {
   hex_content?: string;
   binary_content?: string;  // base64-encoded .bin for RP2040
   binary_type?: 'bin' | 'uf2';
+  has_wifi?: boolean;        // True when sketch uses WiFi (ESP32 only)
   stdout: string;
   stderr: string;
   error?: string;

frontend/src/store/useSimulatorStore.ts

@@ -659,17 +659,20 @@ export const useSimulatorStore = create<SimulatorState>((set, get) => {
           }
           esp32Bridge.setSensors(sensors);
 
-          // Auto-detect WiFi usage in this board's sketch files.
+          // Use WiFi flag set by the compiler (most reliable — avoids stale file group issues).
-          // Use the board's file group (not the legacy global files array).
+          // Fall back to scanning the active file group if the flag hasn't been set yet.
-          const editorState = useEditorStore.getState();
+          let hasWifi = board.hasWifi;
-          const boardFiles = editorState.fileGroups[board.activeFileGroupId]
+          if (hasWifi === undefined) {
-            ?? editorState.files;
+            const editorState = useEditorStore.getState();
-          const hasWifi = boardFiles.some(f =>
+            const rawFiles = editorState.fileGroups[board.activeFileGroupId];
-            f.content.includes('#include <WiFi.h>') ||
+            const boardFiles = (rawFiles && rawFiles.length > 0) ? rawFiles : editorState.files;
-            f.content.includes('#include <esp_wifi.h>') ||
+            hasWifi = boardFiles.some(f =>
-            f.content.includes('#include "WiFi.h"') ||
+              f.content.includes('#include <WiFi.h>') ||
-            f.content.includes('WiFi.begin(')
+              f.content.includes('#include <esp_wifi.h>') ||
-          );
+              f.content.includes('#include "WiFi.h"') ||
+              f.content.includes('WiFi.begin(')
+            );
+          }
           esp32Bridge.wifiEnabled = hasWifi;
 
           // Ensure firmware is loaded into the bridge (handles page-refresh case

frontend/src/types/board.ts

@@ -38,6 +38,7 @@ export interface BoardInstance {
   serialBaudRate: number;
   serialMonitorOpen: boolean;
   activeFileGroupId: string;
+  hasWifi?: boolean;         // set by compiler — true when sketch uses WiFi
   wifiStatus?: WifiStatus;
   bleStatus?: BleStatus;
 }