exp: proof of concept for VSCode debug server

examples/launch.json

@@ -0,0 +1,20 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Python Debugger: Remote Attach",
+            "type": "debugpy",
+            "request": "attach",
+            "connect": {
+                "host": "localhost",
+                "port": 5678
+            },
+            "pathMappings": [
+                {
+                    "localRoot": "${workspaceFolder}",
+                    "remoteRoot": "."
+                }
+            ]
+        }
+    ]
+}

launch.json

@@ -0,0 +1,20 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Python Debugger: Remote Attach",
+            "type": "debugpy",
+            "request": "attach",
+            "connect": {
+                "host": "localhost",
+                "port": 5678
+            },
+            "pathMappings": [
+                {
+                    "localRoot": "${workspaceFolder}",
+                    "remoteRoot": "."
+                }
+            ]
+        }
+    ]
+}

marimo/_ast/compiler.py

@@ -35,6 +35,9 @@
 else:
     from typing import TypeAlias
 
+# TODO: Hack for POC
+lookup = {}
+
 LOGGER = _loggers.marimo_logger()
 Cls: TypeAlias = type
 
@@ -213,12 +216,19 @@ def compile_cell(
     expr.end_col_offset = final_expr.end_col_offset  # type: ignore[attr-defined]
 
     filename: str
+    print(source_position)
     if source_position:
+        print("source_position details")
         # Modify the "source" position for meaningful stacktraces
         fix_source_position(module, source_position)
         fix_source_position(expr, source_position)
         filename = source_position.filename
+        lookup[cell_id] = source_position
     else:
+        print("caching cell code")
+        raise NotImplementedError(
+            "Source position is required for non-anonymous files."
+        )
         # store the cell's code in Python's linecache so debuggers can find it
         filename = get_filename(cell_id)
         # cache the entire cell's code, doesn't need to be done in source case
@@ -296,24 +306,24 @@ def get_source_position(
     f: Cls | Callable[..., Any], lineno: int, col_offset: int
 ) -> Optional[SourcePosition]:
     # Fallback won't capture embedded scripts
-    if inspect.isclass(f):
-        is_script = f.__module__ == "__main__"
-    # Could be something wrapped in a decorator, like
-    # functools._lru_cache_wrapper.
-    elif hasattr(f, "__wrapped__"):
-        return get_source_position(f.__wrapped__, lineno, col_offset)
-    # Larger catch all than if inspect.isfunction(f):
-    elif hasattr(f, "__globals__") and hasattr(f, "__name__"):
-        is_script = f.__globals__["__name__"] == "__main__"  # type: ignore
-    else:
-        return None
-    # TODO: spec is None for markdown notebooks, which is fine for now
-    if module := inspect.getmodule(f):
-        spec = module.__spec__
-        is_script = spec is None or spec.name != "marimo_app"
-
-    if not is_script:
-        return None
+    # if inspect.isclass(f):
+    #     is_script = f.__module__ == "__main__"
+    # # Could be something wrapped in a decorator, like
+    # # functools._lru_cache_wrapper.
+    # elif hasattr(f, "__wrapped__"):
+    #     return get_source_position(f.__wrapped__, lineno, col_offset)
+    # # Larger catch all than if inspect.isfunction(f):
+    # elif hasattr(f, "__globals__") and hasattr(f, "__name__"):
+    #     is_script = f.__globals__["__name__"] == "__main__"  # type: ignore
+    # else:
+    #     return None
+    # # TODO: spec is None for markdown notebooks, which is fine for now
+    # if module := inspect.getmodule(f):
+    #     spec = module.__spec__
+    #     is_script = spec is None or spec.name != "marimo_app"
+
+    # if not is_script:
+    #     return None
 
     return SourcePosition(
         filename=inspect.getfile(f),
@@ -461,10 +471,11 @@ def cell_factory(
 
     # anonymous file is required for deterministic testing.
     source_position = None
-    if not anonymous_file:
-        source_position = get_source_position(
-            f, lnum + cell_def.lineno - 1, cell_def.col_offset
-        )
+    print("anonymous_file", anonymous_file)
+    # if not anonymous_file:
+    source_position = get_source_position(
+        f, lnum + cell_def.lineno - 1, cell_def.col_offset
+    )
 
     cell = compile_cell(
         cell_def.code,

marimo/_ast/load.py

@@ -165,16 +165,16 @@ def load_app(filename: Optional[str]) -> Optional[App]:
     elif not path.suffix == ".py":
         raise MarimoFileError("File must end with .py or .md")
 
-    try:
-        return _static_load(path)
-    except MarimoFileError:
-        # Security advantages of static load are lost here, but reasonable
-        # fallback for now.
-        _app = _dynamic_load(filename)
-        LOGGER.warning(
-            "Static loading of notebook failed; "
-            "falling back to dynamic loading. "
-            "If you can, please report this issue to the marimo team — "
-            "https://github.com/marimo-team/marimo/issues/new?template=bug_report.yaml"
-        )
-        return _app
+    # try:
+    # return _static_load(path)
+    # except MarimoFileError:
+    # Security advantages of static load are lost here, but reasonable
+    # fallback for now.
+    _app = _dynamic_load(filename)
+    LOGGER.warning(
+        "Static loading of notebook failed; "
+        "falling back to dynamic loading. "
+        "If you can, please report this issue to the marimo team — "
+        "https://github.com/marimo-team/marimo/issues/new?template=bug_report.yaml"
+    )
+    return _app

marimo/_runtime/runtime.py

@@ -840,8 +840,13 @@ def _try_compiling_cell(
     ) -> tuple[Optional[CellImpl], Optional[Error]]:
         error: Optional[Error] = None
         try:
+            from marimo._ast.compiler import lookup
+
             cell = compile_cell(
-                code, cell_id=cell_id, carried_imports=carried_imports
+                code,
+                cell_id=cell_id,
+                carried_imports=carried_imports,
+                source_position=lookup.get(cell_id, None),
             )
         except Exception as e:
             cell = None

marimo/_server/api/lifespans.py

@@ -93,6 +93,48 @@ async def mcp(app: Starlette) -> AsyncIterator[None]:
             LOGGER.error(f"Error during MCP cleanup: {e}")
 
 
+@contextlib.asynccontextmanager
+async def debug_server(app: Starlette) -> AsyncIterator[None]:
+    state = AppState.from_app(app)
+    session_mgr = state.session_manager
+
+    dap_server = None  # Track DAP server for cleanup
+
+    # Only start the debug server in Edit mode
+    if session_mgr.mode == SessionMode.EDIT:
+        try:
+            from marimo._server.debug.dap_server import get_dap_server
+            from marimo._server.utils import find_free_port
+
+            dap_server = get_dap_server(session_mgr)
+            LOGGER.info("Starting DAP debug server")
+
+            # Find a free port for debug server
+            debug_port = find_free_port(5678, addr="localhost")
+
+            actual_port = await dap_server.start(
+                host="localhost", port=debug_port
+            )
+            LOGGER.info(f"DAP debug server started on localhost:{actual_port}")
+
+            # Store the port in app state for middleware
+            app.state.debug_port = actual_port
+
+        except Exception as e:
+            LOGGER.warning(f"Failed to start DAP debug server: {e}")
+
+    yield
+
+    # Clean up DAP server on shutdown
+    if dap_server:
+        try:
+            LOGGER.info("Stopping DAP debug server")
+            await dap_server.stop()
+            LOGGER.info("DAP debug server stopped")
+        except Exception as e:
+            LOGGER.error(f"Error during DAP server cleanup: {e}")
+
+
 @contextlib.asynccontextmanager
 async def open_browser(app: Starlette) -> AsyncIterator[None]:
     state = AppState.from_app(app)