fix: correct ilspycmd output parsing and heap access

- Fix _TYPE_LINE_PATTERN regex to match ilspycmd format (no colon)
- Fix UserStringHeap data access using getattr instead of name mangling
- Add _decompile_to_stdout method for simple decompilation
- Fix decompile to not always use -o flag when stdout is desired
- Update test data to match actual ilspycmd output format

src/mcilspy/ilspy_wrapper.py

@@ -194,15 +194,18 @@ class ILSpyWrapper:
                 assembly_name=os.path.basename(request.assembly_path),
             )
 
-        # Use TemporaryDirectory context manager for guaranteed cleanup (no race condition)
+        # When user specifies output_dir OR uses project mode, we need files
-        # when user doesn't specify an output directory
+        # Otherwise, we can get output directly from stdout
         if request.output_dir:
             # User specified output directory - use it directly
             return await self._decompile_to_dir(request, request.output_dir)
-        else:
+        elif request.create_project:
-            # Create a temporary directory with guaranteed cleanup
+            # Project mode needs temp directory for multiple files
             with tempfile.TemporaryDirectory() as temp_dir:
                 return await self._decompile_to_dir(request, temp_dir)
+        else:
+            # Simple decompilation - get output from stdout (no -o flag)
+            return await self._decompile_to_stdout(request)
 
     async def _decompile_to_dir(
         self, request: DecompileRequest, output_dir: str
@@ -312,6 +315,79 @@ class ILSpyWrapper:
                 type_name=request.type_name,
             )
 
+    async def _decompile_to_stdout(self, request: DecompileRequest) -> DecompileResponse:
+        """Decompile to stdout (no -o flag) for simple single-file decompilation.
+
+        Args:
+            request: Decompilation request (output_dir must be None)
+
+        Returns:
+            Decompilation response with source_code from stdout
+        """
+        args = [request.assembly_path]
+
+        # Add language version
+        args.extend(["-lv", request.language_version.value])
+
+        # Add type filter if specified
+        if request.type_name:
+            args.extend(["-t", request.type_name])
+
+        # No -o flag - output goes to stdout
+
+        # Add IL code flag
+        if request.show_il_code:
+            args.append("-il")
+
+        # Add reference paths
+        for ref_path in request.reference_paths:
+            args.extend(["-r", ref_path])
+
+        # Add optimization flags
+        if request.remove_dead_code:
+            args.append("--no-dead-code")
+
+        if request.remove_dead_stores:
+            args.append("--no-dead-stores")
+
+        # Add IL sequence points flag
+        if request.show_il_sequence_points:
+            args.append("--il-sequence-points")
+
+        # Disable update check for automation
+        args.append("--disable-updatecheck")
+
+        assembly_name = os.path.splitext(os.path.basename(request.assembly_path))[0]
+
+        try:
+            return_code, stdout, stderr = await self._run_command(args)
+
+            if return_code == 0:
+                return DecompileResponse(
+                    success=True,
+                    source_code=stdout,
+                    output_path=None,
+                    assembly_name=assembly_name,
+                    type_name=request.type_name,
+                )
+            else:
+                error_msg = stderr or stdout or "Unknown error occurred"
+                return DecompileResponse(
+                    success=False,
+                    error_message=error_msg,
+                    assembly_name=assembly_name,
+                    type_name=request.type_name,
+                )
+
+        except OSError as e:
+            logger.exception(f"Error during decompilation: {e}")
+            return DecompileResponse(
+                success=False,
+                error_message=str(e),
+                assembly_name=assembly_name,
+                type_name=request.type_name,
+            )
+
     async def list_types(self, request: ListTypesRequest) -> ListTypesResponse:
         """List types in a .NET assembly.
 
@@ -359,8 +435,9 @@ class ILSpyWrapper:
             return ListTypesResponse(success=False, error_message=str(e))
 
     # Compiled regex for parsing ilspycmd list output
-    # Format: "TypeKind: FullTypeName" (e.g., "Class: MyNamespace.MyClass")
+    # Format: "TypeKind FullTypeName" (e.g., "Class MyNamespace.MyClass")
-    _TYPE_LINE_PATTERN = re.compile(r"^(\w+):\s*(.+)$")
+    # Only matches valid type kinds: Class, Interface, Struct, Enum, Delegate
+    _TYPE_LINE_PATTERN = re.compile(r"^(Class|Interface|Struct|Enum|Delegate)\s+(.+)$")
 
     def _parse_types_output(self, output: str) -> list[TypeInfo]:
         """Parse the output from list types command.

src/mcilspy/metadata_reader.py

@@ -570,7 +570,8 @@ class MetadataReader:
             return
 
         heap = pe.net.user_strings
-        data = heap._ClrStream__data__  # Access the raw bytes
+        # Access raw bytes using getattr to avoid Python name mangling issues
+        data = getattr(heap, "__data__", None)  # Raw heap bytes
 
         if not data:
             return

tests/test_ilspy_wrapper.py

@@ -41,7 +41,7 @@ class TestILSpyWrapperTypeParsing:
         except RuntimeError:
             pytest.skip("ilspycmd not installed")
 
-        output = "Class: MyNamespace.MyClass"
+        output = "Class MyNamespace.MyClass"
         types = wrapper._parse_types_output(output)
 
         assert len(types) == 1
@@ -57,11 +57,11 @@ class TestILSpyWrapperTypeParsing:
         except RuntimeError:
             pytest.skip("ilspycmd not installed")
 
-        output = """Class: NS.ClassA
+        output = """Class NS.ClassA
-Interface: NS.IService
+Interface NS.IService
-Struct: NS.MyStruct
+Struct NS.MyStruct
-Enum: NS.MyEnum
+Enum NS.MyEnum
-Delegate: NS.MyDelegate"""
+Delegate NS.MyDelegate"""
 
         types = wrapper._parse_types_output(output)
         assert len(types) == 5
@@ -81,7 +81,7 @@ Delegate: NS.MyDelegate"""
         except RuntimeError:
             pytest.skip("ilspycmd not installed")
 
-        output = "Class: MyNamespace.Outer+Nested"
+        output = "Class MyNamespace.Outer+Nested"
         types = wrapper._parse_types_output(output)
 
         assert len(types) == 1
@@ -95,7 +95,7 @@ Delegate: NS.MyDelegate"""
         except RuntimeError:
             pytest.skip("ilspycmd not installed")
 
-        output = "Class: MyClass"
+        output = "Class MyClass"
         types = wrapper._parse_types_output(output)
 
         assert len(types) == 1
@@ -109,10 +109,10 @@ Delegate: NS.MyDelegate"""
         except RuntimeError:
             pytest.skip("ilspycmd not installed")
 
-        output = """Class: NS.Valid
+        output = """Class NS.Valid
 This is not a valid line
 Another invalid line
-Interface: NS.AlsoValid"""
+Interface NS.AlsoValid"""
 
         types = wrapper._parse_types_output(output)
         assert len(types) == 2