CI: coverage from Julia 1 on ubuntu, save the cache only from a job that succeeds

.github/workflows/CI.yml

@@ -16,7 +16,7 @@
 #
 # `min` resolves the lower bound of *this* package's `[compat] julia` entry and `1` the current
 # stable release, so one identical matrix still tests the right versions in a tree whose compat
-# floors are 1.10 and 1.11. The check names therefore never change — not when a package raises its
+# floors are 1.10, 1.11 and 1.12. The check names therefore never change — not when a package raises its
 # floor, and not when Julia releases. That is what lets harness ci-protection use one static list.
 #
 # `pre` and `nightly` are advisory (`experimental: true` + `continue-on-error`): a failure in an
@@ -57,8 +57,10 @@ jobs:
         env:
             # Instrument and upload coverage in a single matrix entry only. Uploading from all six
             # makes Codecov merge six reports of the same scope per run, and the merged percentage
-            # then moves for reasons that are not code changes.
-            COVERAGE: ${{ matrix.version == 'min' && matrix.os == 'ubuntu-latest' }}
+            # then moves for reasons that are not code changes. The entry is `1`, not `min`:
+            # instrumentation makes the job that carries the coverage the slowest of the matrix,
+            # and `min` is already the slowest Julia.
+            COVERAGE: ${{ matrix.version == '1' && matrix.os == 'ubuntu-latest' }}
             # Two threads, everywhere: a runner has more than one core, and a suite with a threading
             # test is otherwise silently single-threaded.
             JULIA_NUM_THREADS: 2
@@ -94,6 +96,11 @@ jobs:
                   version: ${{ matrix.version }}
                   arch: ${{ matrix.arch }}
             - uses: julia-actions/cache@v3
+              with:
+                  # Save only from a job that succeeds. A cancelled or failed job saves a partial
+                  # cache, the next run of the branch restores it, and that job then precompiles
+                  # some 300 packages again.
+                  save-always: false
             - uses: julia-actions/julia-buildpkg@v1
             - uses: julia-actions/julia-runtest@v1
               with:

CHANGELOG.md

@@ -24,6 +24,7 @@ breaking release).
 
 ### Changed
 
+- **CI uploads coverage from the `Julia 1 - ubuntu-latest` job instead of `Julia min`, and a test job saves the Julia cache only when it succeeds.**
 - **The package needs Julia 1.12 or later** (`[compat] julia = "1.12"`, was `"1.11"`). On Julia 1.11.9, the gradient of an `LNNLoss` with respect to the network parameters stops with `StackOverflowError` in type inference ("Internal error: during type inference of … Encountered stack overflow") on macOS and Windows; the `Julia min` job on Linux passes. The overflow comes from SymbolicUtils 4.49.0, whose `rrule` for `SymbolicUtils.Code.create_array` returns an exactly typed tuple of tangents, one per array element; Zygote's reverse pass through the generated Hessian of `lagrangian_acceleration` is then inferred far deeper. With the 4.48.0 rule restored, or in a task with a 64 MB stack, the same gradient passes on 1.11.9; Julia 1.12.7 and 1.13.1 pass it on the root task. This closes #327: the `Julia min` jobs on macOS and Windows had failed in the *Lagrangian Neural Network* testset since 2026-10-01, and every testset after it was never run there.
 - **`test/Project.toml` has no `[compat]` entry for a dependency of the package.** The entries for AbstractNeuralNetworks, GeometricOptimizers, HDF5, KernelAbstractions, LinearAlgebra, NeuralNetworkParameters, Random and Zygote are gone: the test environment contains the package, so the bounds of `Project.toml` apply there, and an entry in `test/Project.toml` can only repeat or narrow them. `NeuralNetworkParameters = "0.3"` was narrower than the package's `"0.3, 0.4"`.
 - **The test suite follows one flat layout.** `test/runtests.jl` is one list of `@safetestset "<label>" include("<path>")` lines in the groups `core`, `slow` and `metal`, selected by `ARGS`; with no arguments it runs `core` and `slow`, and `metal` too on an Apple-silicon Mac, so `Pkg.test()` and CI run every test they ran before. The 14 nested `test/<subject>/runtests.jl` drivers are gone. A test file sits where the source it tests sits: `test/attention/` and `test/transformers/` went into `test/layers/`, `test/architectures/` and `test/kernels/`; `test/reduced_order_modeling/` into `test/architectures/` and `test/reduced_system/`; `test/losses/training_method_losses.jl` into `test/loss/`; the tests that span the package, the docstring examples among them, into `test/integration/`; and `aqua.jl`, `exports.jl` and `reachability.jl` into `test/quality/`. `test/docstrings/layers_and_architectures.jl`, named in *Added* above, is now `test/integration/docstrings/layers_and_architectures.jl`. `test/layers/sympnet_upscaling.jl` is in `slow`. Thirteen files that drew random numbers without a seed now call `Random.seed!(1234)`. The shared helper of the two gradient-structure tests is `test/helpers/network_parameters_gradient_structure.jl`, and its `@test_broken` names issue #319.