Run the launch script snapshot tests by hand instead of in CI

tests/snapshots/README.md

@@ -5,13 +5,23 @@ generated: never edit a file by hand, regenerate it and review the diff.
 
 | Directory | Produced by | Contains |
 | --- | --- | --- |
-| `launch_scripts/sh/` | `tests/fast/launch_scripts/test_sh_launch_scripts.py` | every external command each `scripts/**.sh` and `examples/**.sh` launcher issues, including the full `ray job submit` argv |
-| `launch_scripts/py/` | `tests/fast/launch_scripts/test_py_launch_scripts.py` | every shell command each `scripts/run_*.py` entrypoint builds |
+| `launch_scripts/sh/` | `tests/manual/launch_scripts/test_sh_launch_scripts.py` | every external command each `scripts/**.sh` and `examples/**.sh` launcher issues, including the full `ray job submit` argv |
+| `launch_scripts/py/` | `tests/manual/launch_scripts/test_py_launch_scripts.py` | every shell command each `scripts/run_*.py` entrypoint builds |
+| `launch_scripts/self_executing/` | `tests/manual/launch_scripts/test_self_executing_launchers.py` | the `ray job submit` argv of the launchers that build their own command line |
+| `model_args/` | `tests/manual/launch_scripts/test_model_args.py` | the expanded argv of every `scripts/models/*.py` model definition |
+
+These tests live under `tests/manual/`, which the CI runner does not discover
+(see `_DISCOVERY_ROOTS` in `tests/ci/ci_register.py`), so they run only when
+invoked by hand. Run them after touching a launcher or a model definition:
+
+```bash
+pytest tests/manual/launch_scripts
+```
 
 Regenerate after an intentional change:
 
 ```bash
-MILES_UPDATE_LAUNCH_SCRIPT_SNAPSHOTS=1 pytest tests/fast/launch_scripts
+MILES_UPDATE_LAUNCH_SCRIPT_SNAPSHOTS=1 pytest tests/manual/launch_scripts
 ```
 
 The recordings are reproducible on any machine: the launchers run under a