From a05c0833e1792c81afb86bb615944932e0ad1944 Mon Sep 17 00:00:00 2001
From: Alexandre Edmond <145270396+AlexandreEDMOND@users.noreply.github.com>
Date: Tue, 28 Jul 2026 16:25:45 +0200
Subject: [PATCH] chore(mypy): cover annotations and transforms (#3860)

Co-authored-by: Steven Palma <imstevenpmwork@ieee.org>
---
 pyproject.toml                       | 13 +++++++++++++
 src/lerobot/envs/robotwin.py         |  4 +++-
 src/lerobot/envs/vlabench.py         |  2 +-
 src/lerobot/transforms/transforms.py | 14 +++++++-------
 4 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index 9e88e8eca..38b1b5825 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -494,6 +494,19 @@ ignore_errors = true
 module = "lerobot.envs.*"
 ignore_errors = false
 
+[[tool.mypy.overrides]]
+module = "lerobot.annotations.*"
+ignore_errors = false
+disallow_untyped_defs = true
+disallow_incomplete_defs = true
+check_untyped_defs = true
+
+[[tool.mypy.overrides]]
+module = "lerobot.transforms.*"
+ignore_errors = false
+disallow_untyped_defs = true
+disallow_incomplete_defs = true
+check_untyped_defs = true
 
 # [[tool.mypy.overrides]]
 # module = "lerobot.utils.*"
diff --git a/src/lerobot/envs/robotwin.py b/src/lerobot/envs/robotwin.py
index 5b03f337b..cd0cef28f 100644
--- a/src/lerobot/envs/robotwin.py
+++ b/src/lerobot/envs/robotwin.py
@@ -384,7 +384,9 @@ class RoboTwinEnv(gym.Env):
 
         self._env: Any | None = None  # deferred — created on first reset() inside worker
         self._step_count: int = 0
-        self._black_frame = np.zeros((self.observation_height, self.observation_width, 3), dtype=np.uint8)
+        self._black_frame: np.ndarray = np.zeros(
+            (self.observation_height, self.observation_width, 3), dtype=np.uint8
+        )
 
         image_spaces = {
             cam: spaces.Box(
diff --git a/src/lerobot/envs/vlabench.py b/src/lerobot/envs/vlabench.py
index 922973a16..02d6bdcc5 100644
--- a/src/lerobot/envs/vlabench.py
+++ b/src/lerobot/envs/vlabench.py
@@ -373,7 +373,7 @@ class VLABenchEnv(gym.Env):
 
         if action.shape[0] != 7:
             # Unknown layout — fall back to zero-pad so the sim doesn't crash.
-            padded = np.zeros(ctrl_dim, dtype=np.float64)
+            padded: np.ndarray = np.zeros(ctrl_dim, dtype=np.float64)
             padded[: min(action.shape[0], ctrl_dim)] = action[:ctrl_dim]
             return padded
 
diff --git a/src/lerobot/transforms/transforms.py b/src/lerobot/transforms/transforms.py
index 5240619cb..d8c0a1dfa 100644
--- a/src/lerobot/transforms/transforms.py
+++ b/src/lerobot/transforms/transforms.py
@@ -41,7 +41,7 @@ class RandomSubsetApply(Transform):
 
     def __init__(
         self,
-        transforms: Sequence[Callable],
+        transforms: Sequence[Callable[..., Any]],
         p: list[float] | None = None,
         n_subset: int | None = None,
         random_order: bool = False,
@@ -50,7 +50,7 @@ class RandomSubsetApply(Transform):
         if not isinstance(transforms, Sequence):
             raise TypeError("Argument transforms should be a sequence of callables")
         if p is None:
-            p = [1] * len(transforms)
+            p = [1.0] * len(transforms)
         elif len(p) != len(transforms):
             raise ValueError(
                 f"Length of p doesn't match the number of transforms: {len(p)} != {len(transforms)}"
@@ -69,7 +69,7 @@ class RandomSubsetApply(Transform):
         self.n_subset = n_subset
         self.random_order = random_order
 
-        self.selected_transforms = None
+        self.selected_transforms: list[Callable[..., Any]] = []
 
     def forward(self, *inputs: Any) -> Any:
         needs_unpacking = len(inputs) > 1
@@ -119,7 +119,7 @@ class SharpnessJitter(Transform):
         super().__init__()
         self.sharpness = self._check_input(sharpness)
 
-    def _check_input(self, sharpness):
+    def _check_input(self, sharpness: float | Sequence[float]) -> tuple[float, float]:
         if isinstance(sharpness, (int | float)):
             if sharpness < 0:
                 raise ValueError("If sharpness is a single number, it must be non negative.")
@@ -215,7 +215,7 @@ class ImageTransformsConfig:
     )
 
 
-def make_transform_from_config(cfg: ImageTransformConfig):
+def make_transform_from_config(cfg: ImageTransformConfig) -> Transform:
     if cfg.type == "SharpnessJitter":
         return SharpnessJitter(**cfg.kwargs)
 
@@ -236,8 +236,8 @@ class ImageTransforms(Transform):
         super().__init__()
         self._cfg = cfg
 
-        self.weights = []
-        self.transforms = {}
+        self.weights: list[float] = []
+        self.transforms: dict[str, Transform] = {}
         for tf_name, tf_cfg in cfg.tfs.items():
             if tf_cfg.weight <= 0.0:
                 continue