diff --git a/CLAUDE.md b/CLAUDE.md
index 9adacdc..001cda1 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -12,12 +12,15 @@ Plyngent is an LLM chat and agent toolkit (Python 3.14+, PDM-managed). Single-us
 pdm install          # first-time dependency setup
 pdm sync             # sync after pulling changes
 
-pdm run basedpyright .   # type checking (basedpyright, "recommended" strictness)
-pdm run ruff check .     # linting
-pdm run ruff format .    # formatting
-pdm run pytest           # tests (pytest-asyncio auto mode)
+pdm run ruff check .           # linting
+pdm run ruff format .          # apply formatting
+pdm run ruff format --check .  # CI: fail if unformatted (do not skip)
+pdm run basedpyright .         # type checking (basedpyright, "recommended" strictness)
+pdm run pytest                 # tests (pytest-asyncio auto mode)
 ```
 
+GitHub Actions runs `ruff check`, `ruff format --check`, `basedpyright`, then `pytest`. Format locally with `pdm run ruff format .` so CI does not fail after publish.
+
 ## Architecture
 
 ### Data modeling: `msgspec.Struct`
diff --git a/README.md b/README.md
index aaa7663..0899fbf 100644
--- a/README.md
+++ b/README.md
@@ -62,15 +62,17 @@ pdm sync             # after pull
 pdm run plyngent --help
 ```
 
-Dev checks:
+Dev checks (same order as CI):
 
 ```bash
-pdm run basedpyright .
 pdm run ruff check .
-pdm run ruff format .
+pdm run ruff format --check .   # or: pdm run ruff format .  to apply
+pdm run basedpyright .
 pdm run pytest
 ```
 
+CI fails if sources are not Ruff-formatted (`ruff format --check`). Run `pdm run ruff format .` before push.
+
 ## Basic usage
 
 ```bash
diff --git a/doc/development-principles.md b/doc/development-principles.md
index 96fe01f..4843e51 100644
--- a/doc/development-principles.md
+++ b/doc/development-principles.md
@@ -45,7 +45,10 @@ Then for every projects, check the dev dependency group where you can find tools
 
 Type checking: `pdm run basedpyright .`
 Linting: `pdm run ruff check .`
-Formating: `pdm run ruff format .`
+Formatting (apply): `pdm run ruff format .`
+Formatting (CI check): `pdm run ruff format --check .`
+
+CI (`.github/workflows/ci.yml`) runs lint, **format check**, typecheck, then tests. Always run `pdm run ruff format .` before push so `ruff format --check` does not fail on `main` after a release tag has already published.
 
 <!-- Contents in comments are for projects with long-period developments, but this is a new project.
 
diff --git a/src/plyngent/cli/app.py b/src/plyngent/cli/app.py
index 27761c6..74ea553 100644
--- a/src/plyngent/cli/app.py
+++ b/src/plyngent/cli/app.py
@@ -257,7 +257,7 @@ async def _run_chat(  # noqa: C901, PLR0912, PLR0915 — chat orchestration
             try:
                 if client_supports_models(client):
                     remote_ids = await fetch_remote_model_ids(client)
-            except (RuntimeError, TypeError, OSError, ValueError):
+            except RuntimeError, TypeError, OSError, ValueError:
                 remote_ids = None
             choices = model_choices_for_provider(provider, remote_ids=remote_ids)
             model_id = select_model(