chore: replace flake8 and black with ruff

Swap the two separate dev tools -- flake8 (lint) and black (format) -- for
a single ruff binary that does both.

- pyproject.toml: add [tool.ruff] (line-length = 125) and [tool.ruff.lint]
  with select = ["E", "W", "F"] plus the ignore set carried over from
  .flake8 (F841, F821, E402); drop [tool.black].
- requirements/dev_tools.txt: replace flake8 and black with ruff.
- delete .flake8 (settings now live in pyproject.toml).
- scripts/format.sh: ruff check --fix + ruff format.
- scripts/lint.sh: ruff check.
- rename the file-level `# flake8: noqa` directives to `# ruff: noqa`.
- freeze three middleware/handler dispatch calls with `# fmt: skip` so
  ruff format cannot detach their `# type: ignore` comments (which would
  break mypy under warn_unused_ignores).
- record the reformat commit in .git-blame-ignore-revs.

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>

Author: WilliamBergamin

.flake8

@@ -1,2 +1,5 @@
 # change black settings
 0e4cd56b69e8f83166cd262f762802b7f18c3d21
+
+# apply ruff format across the codebase
+07e8ac9d98c535ade20040883a04734b4c9d04b8

.git-blame-ignore-revs

@@ -16,7 +16,7 @@ Slack Bolt for Python -- a framework for building Slack apps in Python.
 
 ## Environment Setup
 
-You can verify the venv is active by checking `echo $VIRTUAL_ENV`. If tools like `black`, `flake8`, `mypy` or `pytest` are not found, ask the user to activate the venv.
+You can verify the venv is active by checking `echo $VIRTUAL_ENV`. If tools like `ruff`, `mypy` or `pytest` are not found, ask the user to activate the venv.
 
 A python virtual environment (`venv`) should be activated before running any commands.
 
@@ -65,10 +65,10 @@ Always use the project scripts instead of calling `pytest` directly:
 ### Formatting, Linting, Type Checking
 
 ```bash
-# Format -- Black, configured in pyproject.toml
+# Format -- Ruff formatter (+ lint autofix), configured in pyproject.toml
 ./scripts/format.sh --no-install
 
-# Lint -- Flake8, configured in .flake8
+# Lint -- Ruff linter, configured in pyproject.toml
 ./scripts/lint.sh --no-install
 
 # Type check -- mypy, configured in pyproject.toml
@@ -210,7 +210,7 @@ The core package has a **single required runtime dependency**: `slack_sdk` (defi
 - `test_async.txt` -- test runner deps (`pytest`, `pytest-asyncio`, includes `async_dev.txt`)
 - `test.txt` -- test deps without async (`pytest`, `pytest-cov`)
 - `test_adapter.txt` -- adapter-specific test deps (`moto`, `boddle`, `sanic-testing`)
-- `dev_tools.txt` -- dev tools (`mypy`, `flake8`, `black`)
+- `dev_tools.txt` -- dev tools (`mypy`, `ruff`)
 
 When adding a new dependency: add it to the appropriate `requirements/*.txt` file with version constraints, never to `pyproject.toml` `dependencies` (unless it's a core runtime dep, which is very rare).
 

AGENTS.md

@@ -1,4 +1,4 @@
-# flake8: noqa F811
+# ruff: noqa: F811
 import asyncio
 import logging
 import os

examples/assistants/async_interaction_app.py

@@ -38,9 +38,13 @@ readme = { file = ["README.md"], content-type = "text/markdown" }
 [tool.distutils.bdist_wheel]
 universal = true
 
-[tool.black]
+[tool.ruff]
 line-length = 125
 
+[tool.ruff.lint]
+select = ["E", "W", "F"]
+ignore = ["F841", "F821", "E402"]
+
 [tool.pytest.ini_options]
 testpaths = ["tests"]
 log_file = "logs/pytest.log"

pyproject.toml

@@ -3,8 +3,6 @@
 # mypy
 mypy==2.3.0
 
-# flake8
-flake8==7.3.0
-
-# black
-black==26.3.1
+# ruff
+# Note: replaces flake8 (lint) and black (format)
+ruff==0.16.4

requirements/dev_tools.txt

@@ -10,4 +10,5 @@ if [[ "$1" != "--no-install" ]]; then
     pip install -U -r requirements/dev_tools.txt
 fi
 
-black slack_bolt/ tests/
+ruff check --fix slack_bolt/ examples/
+ruff format slack_bolt/ tests/

scripts/format.sh

@@ -9,4 +9,4 @@ if [[ "$1" != "--no-install" ]]; then
     pip install -U -r requirements/dev_tools.txt
 fi
 
-flake8 slack_bolt/ && flake8 examples/
+ruff check slack_bolt/ examples/

scripts/lint.sh

@@ -59,7 +59,7 @@ async def __call__(self, scope: scope_type, receive: Callable, send: Callable) -
         if scope["type"] == "http":
             response: AsgiHttpResponse = await self._get_http_response(
                 method=scope["method"], path=scope["path"], request=AsgiHttpRequest(scope, receive)  # type: ignore[arg-type]
-            )
+            )  # fmt: skip
             await send(response.get_response_start())
             await send(response.get_response_body())
             return

slack_bolt/adapter/asgi/base_handler.py

@@ -1,4 +1,4 @@
-# flake8: noqa
+# ruff: noqa
 """Application interface in Bolt.
 
 For most use cases, we recommend using `slack_bolt.app.app`.