build(deps): bump the mujoco group with 2 updates

[dependabot]

Bumps the mujoco group with 2 updates: mujoco and mujoco-mjx.

Updates mujoco from 3.11.0 to 3.13.0

Release notes

Sourced from mujoco's releases.

3.13.0

Version 3.13.0 (September 8, 2026)

General

1. eb18d77ca The .mjz encoder now writes the root file as model.xml in the archive as this is less susceptible to breakage due to file renaming.

2. 4affbb64a Site geometries can now also be associated with meshes (type="mesh" with mesh="name"), supporting visualization, the insidesite sensor, and the new mj_insideSite function.

3. b59b07fae Added support for Python 3.15 (GIL and Free-Threading).

Engine

4. 5660353ec Added a new integrator discrete: the constraint solve and the implicit velocity update merge into one operation, performed in the effective metric $\widehat{M} = M + hD + h^2K$, which incorporates both implicit damping $hD$ and implicit position stiffness $h^2 K$. Under this integrator mjData.qacc is the discrete step map $(v^+ - v)/h$, and joint, tendon and actuator stiffness and damping join the solver's metric, making passive springs and actuator position gains stable at timesteps far beyond the explicit stability limit. Constraint rows are treated implicitly as well: solref spring--dampers are evaluated at the end of the step, so constraints are stable at any timeconst; under this integrator the refsafe flag replaces contact and limit rows stiffer than the timestep can resolve by the stiffest zero-restitution row instead of clamping timeconst. The actuator-gain treatment resolves the stiff-servo timestep limitation of #3443 (analysis contributed by @​qiayuanl). See the integrator documentation for semantics and current limitations.

[!WARNING] Breaking API changes

Removed the implicit flex effective-metric special case under implicit/implicitfast with the CG solver, introduced in 3.11.0. This behavior now requires integrator="discrete" (with a primal solver: CG or Newton), which additionally treats joint damping and stiffness implicitly inside the solve. Models relying on the old behavior should set integrator to discrete; models with flex elasticity or passive flex contact under implicit/implicitfast now raise a runtime error carrying this migration note.

5. 0b4e17747 Restored clamping of non-positive pivots in the sparse inertia factorization, along with the associated mjWARN_INERTIA warning. The guard was inadvertently dropped in the 3.3.0 conversion of qLD to CSR format; since then, models with singular mass matrices silently produced non-finite accelerations, typically surfacing as divergence warnings and automatic resets.

6. c9d997610 Added single-shot multicontact for collisions with cylinder geoms.

7. 10eeb8289 The Newton solver with elliptic cones now rebuilds the cone-augmented Hessian factor with a single refactorization instead of per-contact rank-1 updates when a flop-count model predicts this is faster. Scenes with many simultaneously sliding contacts speed up by 1.4-2x on average and 3-4x on the slowest steps. Contribution by @​kevinzakka.

... (truncated)

Changelog

Sourced from mujoco's changelog.

Version 3.13.0 (September 8, 2026)

General ^^^^^^^

1. :commit:eb18d77ca The :ref:.mjz <MJZArchives> encoder now writes the root file as model.xml in the archive as this is less susceptible to breakage due to file renaming.
2. :commit:4affbb64a Site geometries can now also be associated with meshes (:ref:type="mesh"<body-site-type> with :ref:mesh="name"<body-site-mesh>), supporting visualization, the :ref:insidesite<sensor-insidesite> sensor, and the new :ref:mj_insideSite function.
3. :commit:b59b07fae Added support for Python 3.15 (GIL and Free-Threading).

Engine ^^^^^^ 4. :commit:5660353ec Added a new integrator discrete: the constraint solve and the implicit velocity update merge into one operation, performed in the effective metric :math:\widehat{M} = M + hD + h^2K, which incorporates both implicit damping :math:hD and implicit position stiffness :math:h^2 K. Under this integrator mjData.qacc is the discrete step map :math:(v^+ - v)/h, and joint, tendon and actuator stiffness and damping join the solver's metric, making passive springs and actuator position gains stable at timesteps far beyond the explicit stability limit. Constraint rows are treated implicitly as well: :at:solref spring--dampers are evaluated at the end of the step, so constraints are stable at any timeconst; under this integrator the :ref:refsafe<option-flag-refsafe> flag replaces contact and limit rows stiffer than the timestep can resolve by the stiffest zero-restitution row instead of clamping timeconst. The actuator-gain treatment resolves the stiff-servo timestep limitation of :issue:3443 (analysis contributed by :github:user:qiayuanl). See the :ref:integrator documentation<geIntegrators> for semantics and current limitations.

.. admonition:: Breaking API changes :class: attention

  Removed the implicit flex effective-metric special case under ``implicit``/``implicitfast`` with the ``CG``
  solver, introduced in 3.11.0. This behavior now requires ``integrator="discrete"`` (with a primal solver:
  ``CG`` or ``Newton``), which additionally treats joint damping and stiffness implicitly inside the solve. Models
  relying on the old behavior should set :ref:`integrator<option-integrator>` to ``discrete``; models with flex
  elasticity or passive flex contact under ``implicit``/``implicitfast`` now raise a runtime error carrying this
  migration note.

5. :commit:0b4e17747 Restored clamping of non-positive pivots in the sparse inertia factorization, along with the associated mjWARN_INERTIA warning. The guard was inadvertently dropped in the 3.3.0 conversion of qLD to CSR format; since then, models with singular mass matrices silently produced non-finite accelerations, typically surfacing as divergence warnings and automatic resets.
6. :commit:c9d997610 Added single-shot :ref:multicontact<coMultiCCD> for collisions with cylinder geoms.
7. :commit:10eeb8289 The Newton solver with :ref:elliptic cones<option-cone> now rebuilds the cone-augmented Hessian factor with a single refactorization instead of per-contact rank-1 updates when a flop-count model predicts this is faster. Scenes with many simultaneously sliding contacts speed up by 1.4-2x on average and 3-4x on the slowest steps. Contribution by :github:user:kevinzakka.

Compiler ^^^^^^^^ 8. :commit:2a3957558 Custom text fields (:ref:custom/text<custom-text>) in MJCF now accept their values inside a <![CDATA[ ... ]]> block in addition to the data attribute. When saving a model via :ref:mj_saveXML, custom

... (truncated)

Commits

• 123347c Update changelog for the 3.13.0 release.
• 5cc54f3 Add Googler @​mention to failure alerts.
• 297f5fc Merge pull request #3267 from njfletcher215:order-siblings-deterministically
• 9f42b35 Keep the authored damping ratio in the discrete refsafe row.
• 6b5c05d Remove trailing underscore from local variable.
• a6cb503 Import NVIDIA Warp 1.17.0
• 4990fa5 Merge pull request #3541 from proudhare:fix/ph-issue-3540
• a90ca41 Enable MultiCCD by default in MuJoCo global settings.
• d1da09a Enable island rendering draw mode.
• 2944f5e Introduce internal mjPacked32 struct in engine_collision_driver.c to handle p...
• Additional commits viewable in compare view

Updates mujoco-mjx from 3.11.0 to 3.13.0

Release notes

Sourced from mujoco-mjx's releases.

3.13.0

Version 3.13.0 (September 8, 2026)

General

1. eb18d77ca The .mjz encoder now writes the root file as model.xml in the archive as this is less susceptible to breakage due to file renaming.

2. 4affbb64a Site geometries can now also be associated with meshes (type="mesh" with mesh="name"), supporting visualization, the insidesite sensor, and the new mj_insideSite function.

3. b59b07fae Added support for Python 3.15 (GIL and Free-Threading).

Engine

4. 5660353ec Added a new integrator discrete: the constraint solve and the implicit velocity update merge into one operation, performed in the effective metric $\widehat{M} = M + hD + h^2K$, which incorporates both implicit damping $hD$ and implicit position stiffness $h^2 K$. Under this integrator mjData.qacc is the discrete step map $(v^+ - v)/h$, and joint, tendon and actuator stiffness and damping join the solver's metric, making passive springs and actuator position gains stable at timesteps far beyond the explicit stability limit. Constraint rows are treated implicitly as well: solref spring--dampers are evaluated at the end of the step, so constraints are stable at any timeconst; under this integrator the refsafe flag replaces contact and limit rows stiffer than the timestep can resolve by the stiffest zero-restitution row instead of clamping timeconst. The actuator-gain treatment resolves the stiff-servo timestep limitation of #3443 (analysis contributed by @​qiayuanl). See the integrator documentation for semantics and current limitations.

[!WARNING] Breaking API changes

Removed the implicit flex effective-metric special case under implicit/implicitfast with the CG solver, introduced in 3.11.0. This behavior now requires integrator="discrete" (with a primal solver: CG or Newton), which additionally treats joint damping and stiffness implicitly inside the solve. Models relying on the old behavior should set integrator to discrete; models with flex elasticity or passive flex contact under implicit/implicitfast now raise a runtime error carrying this migration note.

5. 0b4e17747 Restored clamping of non-positive pivots in the sparse inertia factorization, along with the associated mjWARN_INERTIA warning. The guard was inadvertently dropped in the 3.3.0 conversion of qLD to CSR format; since then, models with singular mass matrices silently produced non-finite accelerations, typically surfacing as divergence warnings and automatic resets.

6. c9d997610 Added single-shot multicontact for collisions with cylinder geoms.

7. 10eeb8289 The Newton solver with elliptic cones now rebuilds the cone-augmented Hessian factor with a single refactorization instead of per-contact rank-1 updates when a flop-count model predicts this is faster. Scenes with many simultaneously sliding contacts speed up by 1.4-2x on average and 3-4x on the slowest steps. Contribution by @​kevinzakka.

... (truncated)

Changelog

Sourced from mujoco-mjx's changelog.

Version 3.13.0 (September 8, 2026)

General ^^^^^^^

1. :commit:eb18d77ca The :ref:.mjz <MJZArchives> encoder now writes the root file as model.xml in the archive as this is less susceptible to breakage due to file renaming.
2. :commit:4affbb64a Site geometries can now also be associated with meshes (:ref:type="mesh"<body-site-type> with :ref:mesh="name"<body-site-mesh>), supporting visualization, the :ref:insidesite<sensor-insidesite> sensor, and the new :ref:mj_insideSite function.
3. :commit:b59b07fae Added support for Python 3.15 (GIL and Free-Threading).

Engine ^^^^^^ 4. :commit:5660353ec Added a new integrator discrete: the constraint solve and the implicit velocity update merge into one operation, performed in the effective metric :math:\widehat{M} = M + hD + h^2K, which incorporates both implicit damping :math:hD and implicit position stiffness :math:h^2 K. Under this integrator mjData.qacc is the discrete step map :math:(v^+ - v)/h, and joint, tendon and actuator stiffness and damping join the solver's metric, making passive springs and actuator position gains stable at timesteps far beyond the explicit stability limit. Constraint rows are treated implicitly as well: :at:solref spring--dampers are evaluated at the end of the step, so constraints are stable at any timeconst; under this integrator the :ref:refsafe<option-flag-refsafe> flag replaces contact and limit rows stiffer than the timestep can resolve by the stiffest zero-restitution row instead of clamping timeconst. The actuator-gain treatment resolves the stiff-servo timestep limitation of :issue:3443 (analysis contributed by :github:user:qiayuanl). See the :ref:integrator documentation<geIntegrators> for semantics and current limitations.

.. admonition:: Breaking API changes :class: attention

  Removed the implicit flex effective-metric special case under ``implicit``/``implicitfast`` with the ``CG``
  solver, introduced in 3.11.0. This behavior now requires ``integrator="discrete"`` (with a primal solver:
  ``CG`` or ``Newton``), which additionally treats joint damping and stiffness implicitly inside the solve. Models
  relying on the old behavior should set :ref:`integrator<option-integrator>` to ``discrete``; models with flex
  elasticity or passive flex contact under ``implicit``/``implicitfast`` now raise a runtime error carrying this
  migration note.

5. :commit:0b4e17747 Restored clamping of non-positive pivots in the sparse inertia factorization, along with the associated mjWARN_INERTIA warning. The guard was inadvertently dropped in the 3.3.0 conversion of qLD to CSR format; since then, models with singular mass matrices silently produced non-finite accelerations, typically surfacing as divergence warnings and automatic resets.
6. :commit:c9d997610 Added single-shot :ref:multicontact<coMultiCCD> for collisions with cylinder geoms.
7. :commit:10eeb8289 The Newton solver with :ref:elliptic cones<option-cone> now rebuilds the cone-augmented Hessian factor with a single refactorization instead of per-contact rank-1 updates when a flop-count model predicts this is faster. Scenes with many simultaneously sliding contacts speed up by 1.4-2x on average and 3-4x on the slowest steps. Contribution by :github:user:kevinzakka.

Compiler ^^^^^^^^ 8. :commit:2a3957558 Custom text fields (:ref:custom/text<custom-text>) in MJCF now accept their values inside a <![CDATA[ ... ]]> block in addition to the data attribute. When saving a model via :ref:mj_saveXML, custom

... (truncated)

Commits

• 123347c Update changelog for the 3.13.0 release.
• 5cc54f3 Add Googler @​mention to failure alerts.
• 297f5fc Merge pull request #3267 from njfletcher215:order-siblings-deterministically
• 9f42b35 Keep the authored damping ratio in the discrete refsafe row.
• 6b5c05d Remove trailing underscore from local variable.
• a6cb503 Import NVIDIA Warp 1.17.0
• 4990fa5 Merge pull request #3541 from proudhare:fix/ph-issue-3540
• a90ca41 Enable MultiCCD by default in MuJoCo global settings.
• d1da09a Enable island rendering draw mode.
• 2944f5e Introduce internal mjPacked32 struct in engine_collision_driver.c to handle p...
• Additional commits viewable in compare view

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