diff --git a/.github/ISSUE_TEMPLATE/bug-report.yml b/.github/ISSUE_TEMPLATE/bug-report.yml
index 01bed0d..bc71300 100644
--- a/.github/ISSUE_TEMPLATE/bug-report.yml
+++ b/.github/ISSUE_TEMPLATE/bug-report.yml
@@ -48,10 +48,11 @@ body:
     attributes:
       label: "Runtime Environment"
       description: >
-        Please provide a description of the environment in which the error
-        occurred.
+        Please provide the versions of fiber, Python, and JAX (jax and jaxlib),
+        the operating system, and whether JAX is running on CPU or GPU.
       placeholder: >
-        Raspberry Pi 4 running Ubuntu 22.04 natively.
+        fiber 0.1.0, Python 3.14, jax 0.4.38 / jaxlib 0.4.38 on CUDA GPU,
+        Ubuntu 24.04.
     validations:
       required: true
 
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..1035b83
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,40 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v7
+
+      - name: Run Ruff linter
+        run: uvx ruff@0.16.5 check --output-format=github
+
+      - name: Run Ruff formatter
+        run: uvx ruff@0.16.5 format --check
+
+  lock:
+    name: Lockfile
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v7
+        with:
+          python-version: "3.14"
+
+      - name: Check that uv.lock is up to date
+        run: uv lock --check
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
new file mode 100644
index 0000000..3d85e85
--- /dev/null
+++ b/.github/workflows/format.yml
@@ -0,0 +1,31 @@
+name: Formatting (pre-commit)
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  pre-commit:
+    name: Format
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      - name: Setup Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: "3.14"
+
+      - name: Run pre-commit
+        uses: pre-commit/action@v3.0.1
+        id: precommit
+
+      - name: Upload pre-commit changes
+        if: failure() && steps.precommit.outcome == 'failure'
+        uses: rhaschke/upload-git-patch-action@main
+        with:
+          name: pre-commit
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..79af7ca
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,47 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+
+jobs:
+  release:
+    name: Build and publish release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7
+        with:
+          fetch-depth: 0
+
+      - name: Setup Python
+        uses: actions/setup-python@v7
+        with:
+          python-version: "3.14"
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v7
+
+      - name: Verify tag matches project version
+        run: |
+          version=$(python -c 'import tomllib, pathlib; print(tomllib.loads(pathlib.Path("pyproject.toml").read_text())["project"]["version"])')
+          if [ "v${version}" != "${GITHUB_REF_NAME}" ]; then
+            echo "::error::Tag ${GITHUB_REF_NAME} does not match pyproject.toml version v${version}"
+            exit 1
+          fi
+
+      - name: Build distributions
+        run: uv build
+
+      - name: Create GitHub release
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          prerelease=""
+          case "${GITHUB_REF_NAME}" in *-*) prerelease="--prerelease" ;; esac
+          gh release create "${GITHUB_REF_NAME}" dist/* \
+            --generate-notes --verify-tag ${prerelease}
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 55cd696..4575618 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,14 +1,16 @@
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.14.14
+    rev: v0.16.5
     hooks:
-      - id: ruff
+      - id: ruff-check
         args: ["--fix", "--exit-non-zero-on-fix"]
+      - id: ruff-format
 
   - repo: https://github.com/codespell-project/codespell
     rev: v2.4.1
     hooks:
       - id: codespell
+        args: ["-L", "groupt"]
 
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v6.0.0
diff --git a/README.md b/README.md
index 48e3bd8..eb192c7 100644
--- a/README.md
+++ b/README.md
@@ -71,7 +71,7 @@ the typed wrapper classes:
 ```python
 import fiber.numpy as fnp
 
-w_hat = fnp.skew3(w_vec)     # 3x3 skew-symmetric matrix
+w_hat = fnp.skew3(w_vec)  # 3x3 skew-symmetric matrix
 R_mat = fnp.so3.expm(w_hat)  # 3x3 rotation matrix
 ```
 
diff --git a/fiber/solvers/_euler.py b/fiber/solvers/_euler.py
index 5cdffcb..1ff9396 100644
--- a/fiber/solvers/_euler.py
+++ b/fiber/solvers/_euler.py
@@ -24,7 +24,7 @@
 import equinox as eqx
 from diffrax import RESULTS, AbstractItoSolver, AbstractTerm
 
-from .._custom_types import VF, Args, BoolScalarLike, DenseInfo, RealScalarLike
+from .._custom_types import VF, Args, BoolScalarLike, Control, DenseInfo, RealScalarLike
 from .._groups._element import AbstractTangentVector
 from .._local_interpolation import LocalLeftBundleInterpolation as LocalInterpolation
 from .._operations import rplus
@@ -35,7 +35,7 @@
 
 
 class LieEuler(AbstractItoSolver):
-    term_structure: ClassVar = AbstractTerm
+    term_structure: ClassVar = AbstractTerm[AbstractTangentVector, Control]
     interpolation_cls: ClassVar[Callable[..., LocalInterpolation]] = LocalInterpolation
 
     def order(self, terms):
diff --git a/fiber/solvers/_euler_heun.py b/fiber/solvers/_euler_heun.py
index 43d153e..69d791b 100644
--- a/fiber/solvers/_euler_heun.py
+++ b/fiber/solvers/_euler_heun.py
@@ -19,22 +19,29 @@
 # THE SOFTWARE.
 
 from collections.abc import Callable
-from typing import ClassVar
+from typing import ClassVar, cast
 
 import equinox as eqx
 from diffrax import RESULTS, AbstractStratonovichSolver, AbstractTerm, MultiTerm
+from diffrax._term import WrapTerm
 
-from .._custom_types import VF, Args, BoolScalarLike, DenseInfo, RealScalarLike
-from .._groups import AbstractTangentVector
+from .._custom_types import VF, Args, BoolScalarLike, Control, DenseInfo, RealScalarLike
+from .._groups import AbstractCotangentVector, AbstractTangentVector
 from .._local_interpolation import LocalLeftBundleInterpolation as LocalInterpolation
 from .._operations import rplus
 from ._term import SharpTerm
 
 type _ErrorEstimate = None
 type _SolverState = None
-type _Terms = MultiTerm[tuple[SharpTerm, AbstractTerm]]
 type _V = AbstractTangentVector
 
+_Terms = MultiTerm[
+    tuple[
+        SharpTerm[AbstractCotangentVector],
+        AbstractTerm[AbstractCotangentVector, Control],
+    ]
+]
+
 
 class EulerHeun(AbstractStratonovichSolver):
     term_structure: ClassVar = _Terms
@@ -72,20 +79,20 @@ def step(
         del solver_state, made_jump
 
         drift, diffusion = terms.terms
+        dual_metric = cast(SharpTerm, cast(WrapTerm, drift).term).dual_metric
+
         dt = drift.contr(t0, t1)
         dw = diffusion.contr(t0, t1)
 
         f0 = drift.vf_prod(t0, y0, args, dt)
-        h0 = diffusion.prod(diffusion.vf(t0, y0, args), dw)
-        h0 = drift.term.dual_metric(y0, h0)  # type: ignore
+        h0 = diffusion.vf_prod(t0, y0, args, dw)
 
-        y_prime = y0 + h0
+        y_prime = y0 + dual_metric(y0, h0)  # type: ignore[reportOperatorIssue]
         h_prime = diffusion.vf_prod(t0, y_prime, args, dw)
-        h_prime = drift.term.dual_metric(y_prime, h_prime)  # type: ignore
 
-        vf = f0 + 0.5 * (h0 + h_prime)
-        y1 = y0 + vf
-        y1 = eqx.tree_at(lambda w: w.point.value, y1, rplus(y0.point, f0).value)
+        k = f0 + 0.5 * (h0 + h_prime)
+        y1 = y0 + dual_metric(y0, k)  # type: ignore[reportOperatorIssue]
+        y1 = eqx.tree_at(lambda w: w.point.value, y1, rplus(y0.point, y0 * dt).value)
 
         dense_info = {"y0": y0, "y1": y1}
         return y1, None, dense_info, None, RESULTS.successful
@@ -94,7 +101,8 @@ def func(
         self,
         terms: _Terms,
         t0: RealScalarLike,
-        y0: AbstractTangentVector,
+        y0: _V,
         args: Args,
     ) -> VF:
-        return terms.vf(t0, y0, args)
+        drift, diffusion = terms.terms
+        return drift.vf(t0, y0, args), diffusion.vf(t0, y0, args)
diff --git a/fiber/solvers/_variational_integrator.py b/fiber/solvers/_variational_integrator.py
index a372beb..8e08287 100644
--- a/fiber/solvers/_variational_integrator.py
+++ b/fiber/solvers/_variational_integrator.py
@@ -40,10 +40,16 @@
 
 type _ErrorEstimate = None
 type _SolverState = None
-type _Terms = MultiTerm[tuple[ImplicitVariationalTerm, VariationalDiffusionTerm]]
 type _V = AbstractTangentVector
 type _CV = AbstractCotangentVector
 
+_Terms = MultiTerm[
+    tuple[
+        ImplicitVariationalTerm[AbstractCotangentVector],
+        VariationalDiffusionTerm[AbstractCotangentVector],
+    ]
+]
+
 
 def _implicit_relation(v: Array, solver_args: Args) -> Array:
     implicit_step, y_prime, t1, vector_cls, integrator_args, dt = solver_args
diff --git a/pyproject.toml b/pyproject.toml
index 7bd2189..467989b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,3 +1,7 @@
+[build-system]
+requires = ["flit_core >=3.8.0,<4"]
+build-backend = "flit_core.buildapi"
+
 [project]
 name = "fiber"
 version = "0.1.0"
diff --git a/uv.lock b/uv.lock
index 84d4478..5fa164b 100644
--- a/uv.lock
+++ b/uv.lock
@@ -47,7 +47,7 @@ wheels = [
 [[package]]
 name = "fiber"
 version = "0.1.0"
-source = { virtual = "." }
+source = { editable = "." }
 dependencies = [
     { name = "diffrax" },
     { name = "equinox" },