Add detailed logging to Python isolate runner

Introduced a _pyLog helper for consistent timestamped debug output and replaced debugPrint calls with _pyLog in runPythonProgramInIsolate. Added more granular logging for interpreter initialization, script execution, module import, and thread state management to aid debugging and traceability.

Author: FeodorFitsner

src/serious_python_android/lib/src/cpython.dart

@@ -16,6 +16,10 @@ CPython? _cpython;
 bool _pythonInitialized = false;
 Pointer<PyThreadState>? _mainThreadState;
 
+void _pyLog(String msg) {
+  debugPrint("[PY] ${DateTime.now().toIso8601String()} $msg");
+}
+
 CPython getCPython(String dynamicLibPath) {
   return _cpython ??= _cpython = CPython(DynamicLibrary.open(dynamicLibPath));
 }
@@ -50,19 +54,22 @@ Future<String> runPythonProgramInIsolate(List<Object> arguments) async {
   var programDirPath = p.dirname(pythonProgramPath);
   var programModuleName = p.basenameWithoutExtension(pythonProgramPath);
 
-  debugPrint("dynamicLibPath: $dynamicLibPath");
-  debugPrint("programDirPath: $programDirPath");
-  debugPrint("programModuleName: $programModuleName");
+  _pyLog("dynamicLibPath: $dynamicLibPath");
+  _pyLog("programDirPath: $programDirPath");
+  _pyLog("programModuleName: $programModuleName");
+  _pyLog("script provided: ${script.isNotEmpty} length=${script.length}");
 
   final cpython = getCPython(dynamicLibPath);
   if (!_pythonInitialized) {
+    _pyLog("calling Py_Initialize()");
     cpython.Py_Initialize();
     // Release the GIL from the init thread so other threads can reacquire it.
     _mainThreadState = cpython.PyEval_SaveThread();
     _pythonInitialized = true;
-    debugPrint("after Py_Initialize()");
+    _pyLog(
+        "after Py_Initialize(), saved thread state: ${_mainThreadState?.address.toRadixString(16)}");
   } else {
-    debugPrint("Python already initialized; reusing interpreter");
+    _pyLog("Python already initialized; reusing interpreter");
   }
 
   var result = "";
@@ -73,31 +80,38 @@ Future<String> runPythonProgramInIsolate(List<Object> arguments) async {
     throw StateError("Python main thread state is null after initialization");
   }
 
+  _pyLog("restoring thread state ${mainState.address.toRadixString(16)}");
   cpython.PyEval_RestoreThread(mainState);
 
   try {
     if (script != "") {
       // run script
       final scriptPtr = script.toNativeUtf8();
+      _pyLog("calling PyRun_SimpleString");
       int sr = cpython.PyRun_SimpleString(scriptPtr.cast<Char>());
-      debugPrint("PyRun_SimpleString for script result: $sr");
+      _pyLog("PyRun_SimpleString result: $sr");
       malloc.free(scriptPtr);
       if (sr != 0) {
         result = getPythonError(cpython);
       }
     } else {
       // run program
       final moduleNamePtr = programModuleName.toNativeUtf8();
+      _pyLog("calling PyImport_ImportModule for $programModuleName");
       var modulePtr =
           cpython.PyImport_ImportModule(moduleNamePtr.cast<Char>());
       if (modulePtr == nullptr) {
         result = getPythonError(cpython);
+      } else {
+        _pyLog("PyImport_ImportModule returned ${modulePtr.address.toRadixString(16)}");
       }
       malloc.free(moduleNamePtr);
     }
   } finally {
     // Drop the GIL again so subsequent runs/threads can re-acquire it cleanly.
     _mainThreadState = cpython.PyEval_SaveThread();
+    _pyLog(
+        "saved thread state after run: ${_mainThreadState?.address.toRadixString(16)}");
   }
 
   // cpython.Py_Finalize();