Pepijn 8194897994 fix(deps): cap placo below 0.9.16 and harden kinematics import (#3647) ...

* fix(deps): cap placo below 0.9.16 and harden kinematics import

placo 0.9.16 links against liburdfdom_sensor.so.4, which is unavailable
on Ubuntu 24.04 (noble ships urdfdom 3.x). Importing placo on that base
crashes with:

  ImportError: liburdfdom_sensor.so.4.0: cannot open shared object file

This broke nightly Latest Deps tests (CPU and GPU) when the lockfile
upgrade picked placo 0.9.16, since lerobot.model.kinematics
unconditionally imports placo when _placo_available is true, and that
check (importlib.util.find_spec) cannot detect dlopen failures of
transitive shared libraries — so unrelated subsystems (RL actor,
gym_manipulator) became unimportable.

Two changes:

1. Pin placo to <0.9.16 in pyproject.toml + regenerate uv.lock
   (0.9.16 → 0.9.15). Short-term unblock for nightly CI until system
   urdfdom 4.x is broadly available.

2. Harden the import guard in src/lerobot/model/kinematics.py:
   wrap 'import placo' in try/except ImportError so a missing
   transitive .so no longer crashes module import. RobotKinematics
   instantiation now raises an informative ImportError citing the
   underlying dlopen failure via _raise_if_placo_unusable().

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix(kinematics): hoist _placo_runtime_error to module scope for mypy

Mypy walks the TYPE_CHECKING branch in which the runtime else-block is
not executed, so _placo_runtime_error was only defined at runtime and
mypy reported 'Name "_placo_runtime_error" is not defined' on the
three references inside _raise_if_placo_unusable. Declare the symbol
unconditionally at module scope with a default of None; the runtime
import-failure branch still assigns to it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* style(kinematics): drop verbose comments around placo import guard

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-22 12:03:07 +02:00

..

lerobot

fix(deps): cap placo below 0.9.16 and harden kinematics import (#3647)

2026-05-22 12:03:07 +02:00