pybamm-team · martinjrobins · Jun 28, 2026 · Jun 29, 2026 · Jun 30, 2026 · Jul 1, 2026
@@ -14,6 +14,7 @@
 - PyBaMM and `pybammsolvers` now develop in a single repository — a UV workspace under `packages/` — while continuing to release independently to PyPI. Release tags are namespaced (`pybamm-v*` and `pybammsolvers-v*`), and PyBaMM's CI now tests against the in-repo solver on every platform. The published `pybamm` package and its dependency on `pybammsolvers` are unchanged for users. See `RELEASE.md` for the release model. ([#5512](https://github.com/pybamm-team/PyBaMM/issues/5512))
 - Legacy BPX v0.x files/objects now load again: `bpx` itself detects and converts them to the v1.x schema on a best-effort basis (with a `UserWarning`), so `ParameterValues.create_from_bpx`/`create_from_bpx_obj` no longer raise a `ValidationError`. PyBaMM officially supports `bpx>=1`. ([#5574](https://github.com/pybamm-team/PyBaMM/pull/5574))
 - `create_from_bpx`/`create_from_bpx_obj` now also accept BPX files that omit `State` fields (or the whole `State` section): the ambient/initial temperatures default to the reference temperature and the initial electrolyte concentration to 1000 mol.m-3 (logged), while opt-in fields (initial hysteresis state, heat transfer coefficient) are left for the model to default. ([#5574](https://github.com/pybamm-team/PyBaMM/pull/5574))
+- add `pybamm.LossSolver` that constructs a loss function from a `pybamm.Simulation` [(#5625)](https://github.com/pybamm-team/PyBaMM/pull/5652)
 
 ## Bug fixes
 
@@ -245,6 +246,7 @@ as initial conditions. ([#5311](https://github.com/pybamm-team/PyBaMM/pull/5311)
 - Fixed a bug in 2D concatenatations for quantities that vary in the `tb` direction ([#5310](https://github.com/pybamm-team/PyBaMM/pull/5310))
 
 # Breaking changes
+
 - Removes default constants added to  `ParameterValues` on construction. **Only breaking if you rely on this functionality in custom models, parameters, etc.** ([#5336](https://github.com/pybamm-team/PyBaMM/pull/5336))
 
 # [v25.10.2](https://github.com/pybamm-team/PyBaMM/tree/v25.10.2) - 2025-11-27
@@ -296,12 +298,12 @@ as initial conditions. ([#5311](https://github.com/pybamm-team/PyBaMM/pull/5311)
 - Fix Bruggeman coefficient computation from BPX porosity and transport efficiency instead of hard-coding, remove redundant values, and add a unit test for verification. ([#5196](https://github.com/pybamm-team/PyBaMM/pull/5196))
 
 ## Breaking changes
+
 - Updates the hysteresis decay rate parameters to a "true" hysteresis decay rate which changes the interpretation of the units of the hysteresis decay rate parameters. ([#5217](https://github.com/pybamm-team/PyBaMM/pull/5217))
 - Changed fundamental variable for all SEI models from thickness to concentration ([#4869](https://github.com/pybamm-team/PyBaMM/pull/4869))
 
 # [v25.8.0](https://github.com/pybamm-team/PyBaMM/tree/v25.8.0) - 2025-08-04
 
-
 ## Features
 
 - Added `plot_3d_cross_section` & `plot_3d_heatmap` functions to support plotting for 3D thermal simulations. ([#5130](https://github.com/pybamm-team/PyBaMM/pull/5130))
@@ -326,7 +328,7 @@ as initial conditions. ([#5311](https://github.com/pybamm-team/PyBaMM/pull/5311)
 - Fixed non-deterministic plotting CI issues ([#5150](https://github.com/pybamm-team/PyBaMM/pull/5150))
 - Fix non-deterministic ShapeError in 3D FEM gradient method ([#5143](https://github.com/pybamm-team/PyBaMM/pull/5143))
 - Fixes negative electrode boundary values for half-cell voltage contributions. ([#5139](https://github.com/pybamm-team/PyBaMM/pull/5139))
-- Makes `A_cc` L_z * L_y * number of layers ([#5138](https://github.com/pybamm-team/PyBaMM/pull/5138))
+- Makes `A_cc` L_z *L_y* number of layers ([#5138](https://github.com/pybamm-team/PyBaMM/pull/5138))
 - Fixes `TimeIntegral` expression node summation when dependent on an input parameter. ([#5119](https://github.com/pybamm-team/PyBaMM/pull/5119))
 - Fixed a bug that ignored the default duration of drive cycles for `CRate` steps and a bug that overwrote custom `period` arguments for drive cycles. ([#5090](https://github.com/pybamm-team/PyBaMM/pull/5090))
 - Converts sensitivities to numpy objects, fixing bug in `DiscreteTimeSum` sensitivity calculation ([#5037](https://github.com/pybamm-team/PyBaMM/pull/5037))
@@ -335,7 +337,6 @@ as initial conditions. ([#5311](https://github.com/pybamm-team/PyBaMM/pull/5311)
 - Fixed a bug where simplifications cause heavisides to evaluate as booleans ([#4893](https://github.com/pybamm-team/PyBaMM/pull/4893))
 - Fixed a bug in the `WyciskOpenCircuitPotential` model where the differential capacity was not being evaluated correctly. ([#4893](https://github.com/pybamm-team/PyBaMM/pull/4893))
 
-
 ## Breaking changes
 
 - Changed behavior of drive cycle steps in `pybamm.Experiment`s to treat each time point as a discontinuity, consistent with how input interpolants work. This ensures more accurate simulation of drive cycles with rapid changes. ([#5141](https://github.com/pybamm-team/PyBaMM/pull/5141))
@@ -344,7 +345,6 @@ as initial conditions. ([#5311](https://github.com/pybamm-team/PyBaMM/pull/5311)
 - Removed support for Python 3.9 ([#5052](https://github.com/pybamm-team/PyBaMM/pull/5052))
 - In OCP hysteresis models, users need to explicitly give the equilibrium, delithiation, and lithiation OCPs when using a hysteresis model. E.g., you must provide all three of "Negative electrode OCP [V]", "Negative electrode delithiation OCP [V]", and "Negative electrode lithiation OCP [V]". ([#4893](https://github.com/pybamm-team/PyBaMM/pull/4893))
 
-
 # [v25.6.0](https://github.com/pybamm-team/PyBaMM/tree/v25.6.0) - 2025-05-27
 
 ## Features
@@ -502,6 +502,7 @@ package to install PyBaMM with only the required dependencies. ([conda-forge/pyb
 - Removed the `start_step_offset` setting and disabled minimum `dt` warnings for drive cycles with the (`IDAKLUSolver`). ([#4416](https://github.com/pybamm-team/PyBaMM/pull/4416))
 
 ## Bug Fixes
+
 - Added error for binary operators on two concatenations with different numbers of children. Previously, the extra children were dropped. Also fixed bug where Q_rxn was dropped from the total heating term in half-cell models. ([#4562](https://github.com/pybamm-team/PyBaMM/pull/4562))
 - Fixed bug where Q_rxn was set to 0 for the negative electrode in half-cell models. ([#4557](https://github.com/pybamm-team/PyBaMM/pull/4557))
 - Fixed bug in post-processing solutions with infeasible experiments using the (`IDAKLUSolver`). ([#4541](https://github.com/pybamm-team/PyBaMM/pull/4541))
@@ -1269,7 +1270,7 @@ This release introduces:
 - Added `NewmanTobias` li-ion battery model ([#1423](https://github.com/pybamm-team/PyBaMM/pull/1423))
 - Added `plot_voltage_components` to easily plot the component overpotentials that make up the voltage ([#1419](https://github.com/pybamm-team/PyBaMM/pull/1419))
 - Made `QuickPlot` more customizable and added an example ([#1419](https://github.com/pybamm-team/PyBaMM/pull/1419))
-- `Solution` objects can now be created by stepping _different_ models ([#1408](https://github.com/pybamm-team/PyBaMM/pull/1408))
+- `Solution` objects can now be created by stepping *different* models ([#1408](https://github.com/pybamm-team/PyBaMM/pull/1408))
 - Added Yang et al 2017 model that couples irreversible lithium plating, SEI growth and change in porosity which produces a transition from linear to nonlinear degradation pattern of lithium-ion battery over extended cycles([#1398](https://github.com/pybamm-team/PyBaMM/pull/1398))
 - Added support for Python 3.9 and dropped support for Python 3.6. Python 3.6 may still work but is now untested ([#1370](https://github.com/pybamm-team/PyBaMM/pull/1370))
 - Added the electrolyte overpotential and Ohmic losses for full conductivity, including surface form ([#1350](https://github.com/pybamm-team/PyBaMM/pull/1350))

@@ -105,7 +105,7 @@ def install_locked(session, *, extras=None, groups=None):
 def run_coverage(session):
     """Run the coverage tests and generate an XML report."""
     set_environment_variables(PYBAMM_ENV, session=session)
-    install_locked(session, extras=["all", "jax"], groups=["dev"])
+    install_locked(session, extras=["all", "jax", "pydiffsol"], groups=["dev"])
     # Using plugin here since coverage runs unit tests on linux with latest python version.
     if "CI" in os.environ:
         session.install("pytest-github-actions-annotate-failures")
@@ -147,7 +147,7 @@ def run_doctests(session):
 def run_unit(session):
     """Run the unit tests."""
     set_environment_variables(PYBAMM_ENV, session=session)
-    install_locked(session, extras=["all", "jax"], groups=["dev"])
+    install_locked(session, extras=["all", "jax", "pydiffsol"], groups=["dev"])
     session.run("python", "-m", "pytest", "-m", "unit", "packages/pybamm/tests")
 
 

@@ -12,19 +12,19 @@ maintainers = [{ name = "The PyBaMM Team", email = "pybamm@pybamm.org" }]
 requires-python = ">=3.10, <3.15"
 readme = { file = "README.md", content-type = "text/markdown" }
 classifiers = [
-    "Development Status :: 5 - Production/Stable",
-    "Intended Audience :: Developers",
-    "Intended Audience :: Science/Research",
-    "License :: OSI Approved :: BSD License",
-    "Programming Language :: Python",
-    "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.10",
-    "Programming Language :: Python :: 3.11",
-    "Programming Language :: Python :: 3.12",
-    "Programming Language :: Python :: 3.13",
-    "Programming Language :: Python :: 3.14",
-    "Topic :: Scientific/Engineering",
+  "Development Status :: 5 - Production/Stable",
+  "Intended Audience :: Developers",
+  "Intended Audience :: Science/Research",
+  "License :: OSI Approved :: BSD License",
+  "Programming Language :: Python",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3 :: Only",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
+  "Programming Language :: Python :: 3.14",
+  "Topic :: Scientific/Engineering",
 ]
 dependencies = [
     "pybammsolvers>=0.8.0,<0.9.0",
@@ -53,66 +53,68 @@ Changelog = "https://github.com/pybamm-team/PyBaMM/blob/main/CHANGELOG.md"
 # For example notebooks
 examples = ["jupyter"]
 plot = [
-    # Note: matplotlib is loaded for debug plots, but to ensure PyBaMM runs
-    # on systems without an attached display, it should never be imported
-    # outside of plot() methods.
-    "matplotlib>=3.6.0",
+  # Note: matplotlib is loaded for debug plots, but to ensure PyBaMM runs
+  # on systems without an attached display, it should never be imported
+  # outside of plot() methods.
+  "matplotlib>=3.6.0",
 ]
 cite = ["pybtex>=0.25.0"]
-# For diffsl export integration tests
-pydiffsol = ["pydiffsol>=0.5.2"]
+# For diffsl tests
+pydiffsol = ["pydiffsol>=0.6.1"]
 # Battery Parameter eXchange format
 bpx = ["bpx>=1.1.1,<1.2.0"]
 # Low-overhead progress bars
 tqdm = ["tqdm"]
-jax = ["jax>=0.7.0, <0.9.0; python_version >= '3.11' and (sys_platform != 'darwin' or platform_machine != 'x86_64')"]
+jax = [
+  "jax>=0.7.0, <0.9.0; python_version >= '3.11' and (sys_platform != 'darwin' or platform_machine != 'x86_64')",
+]
 # Contains all optional dependencies, except for jax, and dev dependencies
 all = [
-    "scikit-fem>=8.1.0",
-    "meshio>=5.3.0",
-    "pybamm[examples,plot,cite,bpx,tqdm]",
+  "scikit-fem>=8.1.0",
+  "meshio>=5.3.0",
+  "pybamm[examples,plot,cite,bpx,tqdm]",
 ]
 
 [dependency-groups]
 docs = [
-    "sphinx>=6",
-    "sphinx_rtd_theme>=0.5",
-    "pydata-sphinx-theme",
-    "sphinx_design",
-    "sphinx-copybutton",
-    "myst-parser",
-    "sphinx-inline-tabs",
-    "sphinxcontrib-bibtex",
-    "sphinx-autobuild",
-    "sphinx-last-updated-by-git",
-    "nbsphinx",
-    "ipykernel",
-    "ipywidgets",
-    "sphinx-gallery",
-    "sphinx-docsearch",
+  "sphinx>=6",
+  "sphinx_rtd_theme>=0.5",
+  "pydata-sphinx-theme",
+  "sphinx_design",
+  "sphinx-copybutton",
+  "myst-parser",
+  "sphinx-inline-tabs",
+  "sphinxcontrib-bibtex",
+  "sphinx-autobuild",
+  "sphinx-last-updated-by-git",
+  "nbsphinx",
+  "ipykernel",
+  "ipywidgets",
+  "sphinx-gallery",
+  "sphinx-docsearch",
 ]
 dev = [
-    # For working with pre-commit hooks
-    "pre-commit",
-    # For code style checks: linting and auto-formatting
-    "ruff",
-    # For running testing sessions
-    "nox",
-    # For coverage
-    "pytest-cov",
-    # For doctest
-    "pytest-doctestplus",
-    # pytest and its plugins
-    "pytest>=9.0",
-    "pytest-xdist",
-    "pytest-mock",
-    "pytest-snapshot",
-    # For testing Jupyter notebooks
-    "nbmake",
-    # To access the metadata for python packages
-    "importlib-metadata; python_version < '3.10'",
-    # For property based testing
-    "hypothesis",
+  # For working with pre-commit hooks
+  "pre-commit",
+  # For code style checks: linting and auto-formatting
+  "ruff",
+  # For running testing sessions
+  "nox",
+  # For coverage
+  "pytest-cov",
+  # For doctest
+  "pytest-doctestplus",
+  # pytest and its plugins
+  "pytest>=9.0",
+  "pytest-xdist",
+  "pytest-mock",
+  "pytest-snapshot",
+  # For testing Jupyter notebooks
+  "nbmake",
+  # To access the metadata for python packages
+  "importlib-metadata; python_version < '3.10'",
+  # For property based testing
+  "hypothesis",
 ]
 
 [project.entry-points."pybamm_parameter_sets"]
@@ -159,21 +161,29 @@ build.hooks.vcs.version-file = "src/pybamm/_version.py"
 # pyproject. Without this, setuptools_scm looks for .git in packages/pybamm/,
 # fails, and falls back to 0.0.0.
 root = "../.."
-git_describe_command = ["git", "describe", "--dirty", "--tags", "--long", "--match", "pybamm-v*"]
+git_describe_command = [
+  "git",
+  "describe",
+  "--dirty",
+  "--tags",
+  "--long",
+  "--match",
+  "pybamm-v*",
+]
 tag_regex = '^pybamm-v(?P<version>[0-9].*)$'
 
 [tool.repo-review]
 ignore = [
-    "MY",     # ignore all MyPy setting checks (MY101, MY103, MY104, MY105, MY106)
-    "PP004",  # ignore the check that prevents an upper cap on Python requires
-    "PP308",  # ignore the explicit pytest summary flag (-ra) check
-    "PC140",  # ignore missing type checker in pre-commit
-    "PC160",  # ignore missing spell checker in pre-commit
-    "PC180",  # ignore missing markdown formatter in pre-commit
-    "RF102",  # ignore the missing isort selection in Ruff configuration
-    "PP006",  # ignore dev dependency group should be defined
-    "NOX201", # ignore set a script block with dependencies in your noxfile
-    "NOX202", # ignore noxfile has a shebang line
+  "MY",     # ignore all MyPy setting checks (MY101, MY103, MY104, MY105, MY106)
+  "PP004",  # ignore the check that prevents an upper cap on Python requires
+  "PP308",  # ignore the explicit pytest summary flag (-ra) check
+  "PC140",  # ignore missing type checker in pre-commit
+  "PC160",  # ignore missing spell checker in pre-commit
+  "PC180",  # ignore missing markdown formatter in pre-commit
+  "RF102",  # ignore the missing isort selection in Ruff configuration
+  "PP006",  # ignore dev dependency group should be defined
+  "NOX201", # ignore set a script block with dependencies in your noxfile
+  "NOX202", # ignore noxfile has a shebang line
 ]
 
 # NOTE: The shared [tool.ruff] config was hoisted to the repo-root pyproject.toml
@@ -188,14 +198,14 @@ testpaths = ["tests"]
 console_output_style = "progress"
 xfail_strict = true
 filterwarnings = [
-    "error",
-    # ignore internal nbmake warnings
-    'ignore:unclosed \<socket.socket:ResourceWarning',
-    'ignore:unclosed event loop \<:ResourceWarning',
-    # ignore warnings generated while running tests
-    "ignore::DeprecationWarning",
-    "ignore::UserWarning",
-    "ignore::RuntimeWarning",
+  "error",
+  # ignore internal nbmake warnings
+  'ignore:unclosed \<socket.socket:ResourceWarning',
+  'ignore:unclosed event loop \<:ResourceWarning',
+  # ignore warnings generated while running tests
+  "ignore::DeprecationWarning",
+  "ignore::UserWarning",
+  "ignore::RuntimeWarning",
 ]
 
 # Logging configuration
@@ -218,7 +228,7 @@ disable_error_code = ["call-overload", "operator"]
 
 [[tool.mypy.overrides]]
 module = [
-    "pybamm.models.base_model.*",
-    "pybamm.models.full_battery_models.base_battery_model.*",
+  "pybamm.models.base_model.*",
+  "pybamm.models.full_battery_models.base_battery_model.*",
 ]
 disable_error_code = "attr-defined"