Add pyrefly type checker & lsp support (and fix defects)

Makefile

@@ -7,6 +7,7 @@ VICEROY ?= viceroy
 STUBS_DIR := stubs
 BUILD_DIR := build
 EXAMPLES_DIR := examples
+COMPUTE_WIT := wit/deps/fastly/compute.wit
 
 # Define all available examples (add new ones here)
 EXAMPLES := bottle-app flask-app game-of-life
@@ -29,15 +30,17 @@ WASILESS_WASM := $(WASILESS_ROOT)/wasiless.wasm
 # Default target builds all examples
 all: $(COMPOSED_WASMS)
 
+$(STUBS_DIR): $(COMPUTE_WIT)
+	rm -rf $(STUBS_DIR)
+	uv run componentize-py -d wit -w $(TARGET_WORLD) bindings $(STUBS_DIR)
+
 $(BUILD_DIR)/%.composed.wasm: $(BUILD_DIR)/%.wasm $(WASILESS_WASM)
 	@echo "Composing $* example"
 	wac compose --dep fastly:wasiless=$(WASILESS_WASM) --dep app:component=$< -o $@ wrap_app_in_wasiless.wac
 
 # Pattern rule for building any example
-$(BUILD_DIR)/%.wasm: $(EXAMPLES_DIR)/%.py wit/viceroy.wit wit/deps/fastly/compute.wit fastly_compute/wsgi.py | $(BUILD_DIR)
+$(BUILD_DIR)/%.wasm: $(EXAMPLES_DIR)/%.py wit/viceroy.wit wit/deps/fastly/compute.wit fastly_compute/wsgi.py | $(BUILD_DIR) $(STUBS_DIR)
 	@echo "Building $* example..."
-	rm -rf $(STUBS_DIR)
-	uv run componentize-py -d wit -w $(TARGET_WORLD) bindings $(STUBS_DIR)
 	uv run componentize-py -d wit -w $(TARGET_WORLD) componentize $* -p $(EXAMPLES_DIR) -p . -o $@
 
 $(WASILESS_WASM):
@@ -69,8 +72,9 @@ clean:
 	rm -rf $(BUILD_DIR) $(STUBS_DIR)
 
 # Development tools
-lint:
+lint: | $(STUBS_DIR)
 	uv run --extra dev ruff check .
+	uv run --extra dev --extra test pyrefly check .
 
 lint-fix:
 	uv run --extra dev ruff check --fix .

examples/bottle-app.py

@@ -1,4 +1,6 @@
-from bottle import Bottle
+import typing
+
+from bottle import Bottle, request
 from wit_world.imports import compute_runtime
 
 from fastly_compute.wsgi import WsgiHttpIncoming
@@ -15,19 +17,21 @@ def hello(name):
 @app.route("/info")
 def info():
     """Return JSON with request information we can test against"""
-    from bottle import request
-
     # Get some runtime info we can test
     vcpu_time = compute_runtime.get_vcpu_ms()
 
+    # type checker doesn't quite understand bottle's DictProperty
+    # so we need to give it a hint.
+    headers = typing.cast(typing.Mapping[str, str], request.headers)
+
     return {
         "service": "fastly-compute-python",
         "status": "ok",
         "message": "Hello from Fastly Compute!",
         "vcpu_time_ms": vcpu_time,
         "request_method": request.environ.get("REQUEST_METHOD"),
         "path_info": request.environ.get("PATH_INFO"),
-        "request_headers": dict(request.headers),
+        "request_headers": dict(headers),
     }
 
 

examples/game-of-life.py

@@ -264,4 +264,4 @@ def root():
 
 
 if running_under_compute:
-    HttpIncoming = WsgiHttpIncoming(app, reuse_sandboxes_for_ms=300)
+    HttpIncoming = WsgiHttpIncoming(app, reuse_sandboxes_for_ms=300)  # type: ignore

fastly_compute/testing.py

@@ -52,7 +52,12 @@ def test_my_endpoint(self):
 
     REQUEST_TIMEOUT = 10
     WASM_FILE = "build/bottle-app.composed.wasm"  # Default to the main example
-    server: ViceroyServer = None  # Will be set by the fixture
+    _server: ViceroyServer | None = None  # Will be set by the fixture
+
+    @property
+    def server(self) -> ViceroyServer:
+        assert self._server is not None
+        return self._server
 
     @staticmethod
     def _find_free_port() -> int:
@@ -64,7 +69,7 @@ def _find_free_port() -> int:
 
     @pytest.fixture(scope="class", autouse=True)
     @classmethod
-    def viceroy_server(cls) -> ViceroyServer:
+    def viceroy_server(cls):
         """Start viceroy server for the duration of the test class.
 
         Note: This assumes the WASM file already exists. Use your build system
@@ -85,7 +90,7 @@ def viceroy_server(cls) -> ViceroyServer:
         # Find an available port
         port = cls._find_free_port()
         base_url = f"http://127.0.0.1:{port}"
-        output_lines = []  # Capture all output for debugging
+        output_lines: list[str] = []  # Capture all output for debugging
         output_lock = threading.Lock()
         stop_capture = threading.Event()
 
@@ -107,6 +112,7 @@ def viceroy_server(cls) -> ViceroyServer:
         # Start background thread to continuously capture output
         def capture_output_thread():
             """Continuously capture viceroy output throughout test execution."""
+            assert process.stdout is not None, "stdout should be PIPE"
             while not stop_capture.is_set():
                 line = process.stdout.readline()
                 if not line:  # EOF
@@ -157,7 +163,7 @@ def capture_output_thread():
         )
 
         # Set the server as a class attribute so methods can access it
-        cls.server = server
+        cls._server = server
 
         yield server
 
@@ -181,11 +187,7 @@ def get(self, path: str, **kwargs) -> requests.Response:
         Returns:
             requests.Response: The HTTP response
         """
-        timeout = kwargs.pop("timeout", self.REQUEST_TIMEOUT)
-        response = requests.get(
-            f"{self.server.base_url}{path}", timeout=timeout, **kwargs
-        )
-        return response
+        return self.request("GET", path, **kwargs)
 
     def post(self, path: str, **kwargs) -> requests.Response:
         """Make a POST request to the viceroy server.
@@ -197,11 +199,7 @@ def post(self, path: str, **kwargs) -> requests.Response:
         Returns:
             requests.Response: The HTTP response
         """
-        timeout = kwargs.pop("timeout", self.REQUEST_TIMEOUT)
-        response = requests.post(
-            f"{self.server.base_url}{path}", timeout=timeout, **kwargs
-        )
-        return response
+        return self.request("POST", path, **kwargs)
 
     def request(self, method: str, path: str, **kwargs) -> requests.Response:
         """Make an HTTP request to the viceroy server.

fastly_compute/wsgi.py

@@ -152,7 +152,7 @@ def start_response(
         error_response.set_status(500)
         error_response.append_header("content-type", b"text/plain")
         error_message = f"Internal Server Error: {e}"
-        http_body.write(error_body, error_message.encode(), http_body.WriteEnd.BACK)
+        http_body.write(error_body, error_message.encode())
         send_downstream(error_response, error_body)
 
 

pyproject.toml

@@ -17,6 +17,7 @@ test = [
 ]
 dev = [
     "ruff (>=0.12.11,<0.13.0)",
+    "pyrefly (>=0.45.1,<0.46.0)",
 ]
 
 [tool.pytest.ini_options]
@@ -64,3 +65,7 @@ build-backend = "setuptools.build_meta"
 
 [tool.setuptools]
 py-modules = ["app"]
+
+[tool.pyrefly]
+python-version = "3.12"
+search-path = ["stubs"]