CI - NEW FEATURE - Add a pre-commit formatting workflow, disabled for now

Adds a Format and Hygiene workflow that runs the repository's own pre-commit
suite (JuliaFormatter plus the file-hygiene hooks) so contributors who have not
run `pre-commit install` are still caught. It is wired to workflow_dispatch
only: the repository has pre-existing formatting drift that must be cleaned up
first, which is out of scope here. Running it manually from the Actions tab
shows the current damage; uncommenting the pull_request trigger enables it as
a gate.

The julia-formatter hook is `language: system`, so it shells out to whatever
JuliaFormatter is in the default depot environment rather than the one implied
by the pinned hook revision. The workflow therefore installs JuliaFormatter
v1.0.62 explicitly, matching the rev in .pre-commit-config.yaml, so CI and
local runs agree.

Also disables coverage instrumentation in the test job. julia-runtest enables
it by default, but nothing consumes the .cov files: they are gitignored and
never uploaded. Instrumenting compute-heavy numerical code for output that is
discarded is pure cost.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019tFBCa5iBXyb7xp8LxqBJx

Author: Claude

.github/workflows/format.yaml

@@ -0,0 +1,65 @@
+name: Format and Hygiene
+
+# Runs the repository's pre-commit suite (JuliaFormatter + file hygiene) so that
+# contributors who have not run `pre-commit install` locally are still caught.
+#
+# DISABLED as a pull request gate for now: the repository has pre-existing
+# formatting drift that has to be cleaned up first. Until then, run this
+# manually from the Actions tab ("Run workflow") to see the current damage.
+#
+# To enable it as a gate, uncomment the `pull_request` trigger below. If the
+# test suite's `Tests` job is a required status check, add `pre-commit` too.
+on:
+  workflow_dispatch:
+  # pull_request:
+  #   branches:
+  #     - main
+  #     - develop
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  pre-commit:
+    name: pre-commit
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          # Matches default_language_version in .pre-commit-config.yaml
+          python-version: '3.10'
+
+      - name: Set up Julia
+        uses: julia-actions/setup-julia@v2
+        with:
+          version: '1.11'
+
+      # The julia-formatter hook is `language: system`: it shells out to
+      # `julia -e 'import JuliaFormatter: format; format(ARGS)'` and therefore
+      # uses whatever JuliaFormatter lives in the default depot environment.
+      # Pin it to the same version .pre-commit-config.yaml pins the hook repo
+      # to, otherwise CI and local pre-commit runs disagree on formatting.
+      - name: Install JuliaFormatter
+        run: julia -e 'using Pkg; Pkg.add(PackageSpec(name="JuliaFormatter", version="1.0.62"))'
+
+      - name: Cache pre-commit environments
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/pre-commit
+          key: pre-commit-${{ runner.os }}-py3.10-${{ hashFiles('.pre-commit-config.yaml') }}
+          restore-keys: |
+            pre-commit-${{ runner.os }}-py3.10-
+
+      - name: Run pre-commit
+        run: |
+          python -m pip install --upgrade pre-commit
+          pre-commit run --all-files --show-diff-on-failure --color=always

.github/workflows/test.yaml

@@ -107,8 +107,14 @@ jobs:
       - name: Build Julia packages
         uses: julia-actions/julia-buildpkg@v1
 
+      # Coverage instrumentation is off: nothing consumes the .cov files (they are
+      # gitignored and never uploaded), and instrumenting slows compute-heavy
+      # numerical code noticeably. Set coverage: true and add a Codecov upload
+      # step together if coverage reporting is ever wanted.
       - name: Run tests
         uses: julia-actions/julia-runtest@v1
+        with:
+          coverage: false
 
   # Stable check that is present on every pull request, whether or not the suite
   # ran. Point branch protection at this job so skipped runs do not block merges.