Modernise CI, split out the docs build, and make the per-step paths allocation-free

.githooks/pre-push

@@ -0,0 +1,57 @@
+#!/bin/sh
+#
+# Run the test suite before a push, and refuse the push if it fails.
+#
+# Enable with
+#
+#     git config core.hooksPath .githooks
+#
+# and skip a single push with `SIMPLESPLINES_SKIP_TESTS=1 git push` — for a
+# documentation-only change, say, or when the failure is already known and being
+# pushed to a branch on purpose.
+
+set -eu
+
+# git feeds the hook one `<local ref> <local oid> <remote ref> <remote oid>` line per ref
+# being pushed, and an all-zero local oid means that ref is being deleted. Read them:
+# a push that only deletes has nothing to test, and a hook that exits without draining
+# leaves git writing into a closed pipe.
+refs=0
+content=0
+while read -r _local_ref local_oid _remote_ref _remote_oid; do
+    refs=$((refs + 1))
+    case "$local_oid" in
+        *[!0]*) content=1 ;;
+    esac
+done
+
+if [ "$refs" -gt 0 ] && [ "$content" -eq 0 ]; then
+    printf 'pre-push: nothing but ref deletions, skipping the test suite.\n' >&2
+    exit 0
+fi
+
+if [ "${SIMPLESPLINES_SKIP_TESTS:-0}" != "0" ]; then
+    printf 'pre-push: SIMPLESPLINES_SKIP_TESTS is set, skipping the test suite.\n' >&2
+    exit 0
+fi
+
+if ! command -v julia >/dev/null 2>&1; then
+    printf 'pre-push: julia is not on PATH, cannot run the test suite; refusing the push.\n' >&2
+    printf '          Set SIMPLESPLINES_SKIP_TESTS=1 to push anyway.\n' >&2
+    exit 1
+fi
+
+# git runs its hooks from the top level of the work tree, but asking rather than assuming
+# also gives the right answer in a linked worktree.
+root=$(git rev-parse --show-toplevel)
+
+printf 'pre-push: running the SimpleSplines test suite...\n' >&2
+
+if julia --project="$root" -e 'using Pkg; Pkg.test()'; then
+    printf 'pre-push: tests passed.\n' >&2
+    exit 0
+fi
+
+printf 'pre-push: tests FAILED; refusing the push.\n' >&2
+printf '          Set SIMPLESPLINES_SKIP_TESTS=1 to push anyway.\n' >&2
+exit 1

.github/dependabot.yml

@@ -5,3 +5,8 @@ updates:
     directory: "/" # Location of package manifests
     schedule:
       interval: "weekly"
+    # One pull request for all action bumps rather than one per action.
+    groups:
+      github-actions:
+        patterns:
+          - "*"

.github/workflows/CI.yml

@@ -16,65 +16,55 @@ jobs:
     name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }}
     runs-on: ${{ matrix.os }}
     timeout-minutes: 60
+    # A pre-release or nightly failure is information, not a broken build.
+    continue-on-error: ${{ matrix.experimental }}
     permissions: # needed to allow julia-actions/cache to proactively delete old caches that it has created
       actions: write
       contents: read
     strategy:
       fail-fast: false
       matrix:
+        # 'min' resolves the lower bound of the julia compat entry in Project.toml, so the
+        # matrix follows the declared support window instead of having to be edited alongside
+        # it; '1' is the current stable release.
         version:
-          - '1.10'
-          - '1.12'
-          - 'nightly'
+          - 'min'
+          - '1'
         os:
           - ubuntu-latest
           - macOS-latest
           - windows-latest
         arch:
-          - x64
+          # 'default' is the runner's native architecture, which is aarch64 on macOS-latest;
+          # a hardcoded 'x64' would test Julia under Rosetta there.
+          - default
+        experimental:
+          - false
+        include:
+          - version: 'lts'
+            os: ubuntu-latest
+            arch: default
+            experimental: false
+          - version: 'pre'
+            os: ubuntu-latest
+            arch: default
+            experimental: true
+          - version: 'nightly'
+            os: ubuntu-latest
+            arch: default
+            experimental: true
     steps:
-      - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v2
+      - uses: actions/checkout@v7
+      - uses: julia-actions/setup-julia@v3
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: julia-actions/cache@v2
+      - uses: julia-actions/cache@v3
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v4
+      - uses: codecov/codecov-action@v7
         with:
           files: lcov.info
           token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: false
-  docs:
-    name: Documentation
-    runs-on: ubuntu-latest
-    permissions:
-      actions: write # needed to allow julia-actions/cache to proactively delete old caches that it has created
-      contents: write
-      statuses: write
-    steps:
-      - uses: actions/checkout@v4
-      - uses: julia-actions/setup-julia@v2
-        with:
-          version: '1'
-      - uses: julia-actions/cache@v2
-      - name: Configure doc environment
-        shell: julia --project=docs --color=yes {0}
-        run: |
-          using Pkg
-          Pkg.develop(PackageSpec(path=pwd()))
-          Pkg.instantiate()
-      - uses: julia-actions/julia-buildpkg@v1
-      - uses: julia-actions/julia-docdeploy@v1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
-      - name: Run doctests
-        shell: julia --project=docs --color=yes {0}
-        run: |
-          using Documenter: DocMeta, doctest
-          using SimpleSplines
-          DocMeta.setdocmeta!(SimpleSplines, :DocTestSetup, :(using SimpleSplines); recursive=true)
-          doctest(SimpleSplines)

.github/workflows/CompatHelper.yml

@@ -3,10 +3,21 @@ on:
   schedule:
     - cron: 0 0 * * *
   workflow_dispatch:
+permissions:
+  actions: write # needed to allow julia-actions/cache to proactively delete old caches that it has created
+  contents: write
+  pull-requests: write
 jobs:
   CompatHelper:
     runs-on: ubuntu-latest
+    timeout-minutes: 30
     steps:
+      # The runner images no longer ship a Julia, so one has to be installed rather than
+      # assumed; without this the `julia -e` steps below fail before CompatHelper starts.
+      - uses: julia-actions/setup-julia@v3
+        with:
+          version: '1'
+      - uses: julia-actions/cache@v3
       - name: Pkg.add("CompatHelper")
         run: julia -e 'using Pkg; Pkg.add("CompatHelper")'
       - name: CompatHelper.main()

.github/workflows/Documenter.yml

@@ -0,0 +1,43 @@
+name: Documentation
+on:
+  push:
+    branches:
+      - main
+    tags: ['*']
+  pull_request:
+  workflow_dispatch:
+concurrency:
+  # Skip intermediate builds: always.
+  # Cancel intermediate builds: only if it is a pull request build.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+jobs:
+  build:
+    name: Documentation
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+    permissions:
+      actions: write # needed to allow julia-actions/cache to proactively delete old caches that it has created
+      contents: write
+      pull-requests: read
+      statuses: write
+    steps:
+      - uses: actions/checkout@v7
+      - uses: julia-actions/setup-julia@v3
+        with:
+          version: '1'
+      - uses: julia-actions/cache@v3
+      - uses: julia-actions/julia-buildpkg@v1
+      # julia-docdeploy resolves the docs environment against the checkout and instantiates
+      # it itself, so there is no separate step for that here.
+      - uses: julia-actions/julia-docdeploy@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
+      - name: Run doctests
+        shell: julia --project=docs --color=yes {0}
+        run: |
+          using Documenter: DocMeta, doctest
+          using SimpleSplines
+          DocMeta.setdocmeta!(SimpleSplines, :DocTestSetup, :(using SimpleSplines); recursive=true)
+          doctest(SimpleSplines)

.github/workflows/Register.yml

@@ -8,9 +8,10 @@ on:
 jobs:
   register:
     runs-on: ubuntu-latest
+    timeout-minutes: 30
     permissions:
-        contents: write
+      contents: write
     steps:
-      - uses: julia-actions/RegisterAction@latest
+      - uses: julia-actions/RegisterAction@v0.3.2
         with:
           token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/TagBot.yml

@@ -24,6 +24,7 @@ jobs:
   TagBot:
     if: github.event_name == 'workflow_dispatch' || github.actor == 'JuliaTagBot'
     runs-on: ubuntu-latest
+    timeout-minutes: 30
     steps:
       - uses: JuliaRegistries/TagBot@v1
         with:

AUTHORS.md

@@ -0,0 +1,19 @@
+# Authors
+
+SimpleSplines' development is coordinated by a group of *principal developers*, who are also
+its main contributors and who can be contacted in case of questions about SimpleSplines. In
+addition, there are *contributors* who have provided substantial additions or modifications.
+Together, these two groups form "The SimpleSplines Authors" as mentioned in the
+[LICENSE](LICENSE.md) file.
+
+## Principal Developers
+
+* [Michael Kraus](https://www.michael-kraus.org/),
+  Max Planck Institute for Plasma Physics, Garching, Germany
+
+## Contributors
+
+Everyone who has contributed to SimpleSplines, the principal developers above included, in
+alphabetical order:
+
+* Michael Kraus

CHANGELOG.md

@@ -86,17 +86,97 @@ was the difference between 6.0 ms and 0.4 ms for assembling one Hessian.
 
 The constant assemblies — `mass_matrix`, `stiffness_matrix`, `derivative_matrix` and any
 `mixed_matrix` — are memoised on first use. They do not depend on the field, but a downstream
-time integrator asks for them inside every Newton iteration of every step.
+time integrator asks for them inside every Newton iteration of every step. `basis_integrals`
+is one of these constants too, and is now assembled with the quadrature and returned by
+reference rather than recomputed per call.
+
+The paths a time integrator actually runs per step allocate nothing. Evaluation is
+allocation-free at any degree and derivative order on any mesh; a `CirculantMass` solve is
+allocation-free; and `l2_projection!` is now allocation-free end to end on a uniform mesh,
+the `f ⊙ w` product going into a buffer held by the quadrature and the load vector being
+formed with `mul!` straight into the output. The buffer is taken only when the product lands
+in the quadrature's element type, so a wider sample — a complex `f` — is still projected,
+through a product of its own, rather than narrowed into it. On a non-uniform mesh a CHOLMOD
+temporary remains, CHOLMOD having no in-place `ldiv!`.
+
+That buffer is mutable state on a struct that reads as immutable, as the memoising `cache`
+behind `mixed_matrix` already was, so the `SplineQuadrature` docstring now warns that one
+quadrature must not be shared between threads.
 
 ### Dependencies
 
 `BSplineKit` was dropped: the basis is implemented here, and its variable-coefficient
 assemblies do not map onto that package's Galerkin interface. `FFTW` and `SparseArrays` were
 added for the above, and `CompactBasisFunctions` for the shared `Basis` hierarchy.
 
+### Repository and CI
+
+The documentation build moved out of `CI.yml` into its own `Documenter.yml` workflow, so that
+a docs failure and a test failure are separate signals and the docs job is not queued behind
+the test matrix. The README gained a badge for it.
+
+The workflows were brought up to current action versions — `actions/checkout@v7`,
+`julia-actions/setup-julia@v3`, `julia-actions/cache@v3`, `codecov/codecov-action@v7` — and
+the test matrix now names Julia versions by alias rather than by number:
+
+- `min` resolves the lower bound of the `julia` compat entry, so the matrix tracks the
+  declared support window instead of having to be edited alongside it;
+- `lts` and `1` cover the long-term-support and current stable releases;
+- `pre` and `nightly` run on Linux only and are `continue-on-error`, since an upcoming-release
+  failure is information rather than a broken build.
+
+`arch` is now `default` rather than `x64`, which is what tests Julia natively on the ARM64
+macOS runners instead of under Rosetta.
+
+`AUTHORS.md` was added and `LICENSE` renamed to `LICENSE.md`, whose copyright line now names
+"The SimpleSplines Authors" and points at it.
+
+The `pre-push` hook the README asks the reader to enable now exists in `.githooks/`. It runs
+the test suite and refuses the push if it fails; `SIMPLESPLINES_SKIP_TESTS=1` overrides it.
+
 ### Fixed
 
 - `QuadratureRules` compat was `"0.1"`, which could not co-resolve with
   `CompactBasisFunctions`; it is now `"0.2"`.
 - `LinearAlgebra` compat was `"1.12.0"` alongside `julia = "1.10"`, which contradicted the
   1.10 row of the CI matrix; it is now `"1"`.
+- `docs/Project.toml` pinned `CompactBasisFunctions` to an absolute path on a developer's
+  machine through a `[sources]` entry. That path does not exist on a CI runner, so the
+  documentation build could only ever have succeeded locally; the entry is removed and the
+  dependency now resolves from the registry.
+- `CompatHelper.yml` invoked `julia` without installing it. The runner images no longer ship
+  a Julia, so the workflow failed before CompatHelper started; it now sets Julia up first.
+
+## Open Issues
+
+### `weighted_matrix` allocates a fresh matrix per call
+
+`weighted_matrix` is the one assembly that cannot be memoised — it depends on the field, so a
+downstream time integrator asks for a *different* one inside every Newton iteration of every
+step, which is exactly the call pattern under which allocation matters most. Measured at
+`N = 128`, `p = 3`, `nq = 5`:
+
+| | bytes |
+|:--|--:|
+| `f .* q.w` temporary | 5 kB |
+| `Φₐ * Diagonal(f ⊙ w)` | 47 kB |
+| `(Φₐ D) * Φᵦᵀ` sparse-sparse product | 208 kB |
+| **total per call** | **260 kB** |
+
+The `f ⊙ w` temporary is the same one `l2_projection!` no longer pays and could be removed the
+same way, with the buffer the quadrature already holds. The other 255 kB are not a temporary
+at all: they are the result, a freshly built `SparseMatrixCSC` with its `colptr`, `rowval` and
+`nzval` allocated and its structure recomputed from scratch.
+
+That structure does not depend on `f`. For a fixed `(a, b)` the sparsity pattern of
+`Φₐ diag(f ⊙ w) Φᵦᵀ` is the same for every coefficient — a basis function overlaps only the
+`2p+1` others whose supports meet its own — so the pattern could be assembled once per
+`(a, b)`, cached beside the `mixed_matrix` results, and only `nzval` refilled per
+call. That turns 260 kB into zero.
+
+What it needs is an in-place entry point, `weighted_matrix!(A, q, f, a, b)`, since the present
+signature has nowhere to write. Callers holding a matrix across steps would use it and callers
+wanting a value would keep the allocating form. Deferred rather than done because it widens
+the API, and because the sparse triple product would have to be written out by hand against
+the cached pattern instead of delegating to `SparseArrays`, which is the part that needs to be
+got right rather than merely written.

LICENSE → LICENSE.md

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2025 Michael Kraus
+Copyright (c) 2025-present The SimpleSplines Authors (see [AUTHORS.md](AUTHORS.md))
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -3,6 +3,7 @@
 [![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](https://JuliaDEC.github.io/SimpleSplines.jl/stable/)
 [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://JuliaDEC.github.io/SimpleSplines.jl/dev/)
 [![Build Status](https://github.com/JuliaDEC/SimpleSplines.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/JuliaDEC/SimpleSplines.jl/actions/workflows/CI.yml?query=branch%3Amain)
+[![Documentation](https://github.com/JuliaDEC/SimpleSplines.jl/actions/workflows/Documenter.yml/badge.svg?branch=main)](https://github.com/JuliaDEC/SimpleSplines.jl/actions/workflows/Documenter.yml?query=branch%3Amain)
 [![Coverage](https://codecov.io/gh/JuliaDEC/SimpleSplines.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/JuliaDEC/SimpleSplines.jl)
 [![PkgEval](https://JuliaCI.github.io/NanosoldierReports/pkgeval_badges/S/SimpleSplines.svg)](https://JuliaCI.github.io/NanosoldierReports/pkgeval_badges/S/SimpleSplines.html)
 
@@ -19,3 +20,15 @@ To run the test suite before every push, enable the repository's git hooks:
 ```sh
 git config core.hooksPath .githooks
 ```
+
+`.githooks/pre-push` refuses the push if the suite fails. To push regardless — a
+documentation-only change, or a failure that is already known — set
+
+```sh
+SIMPLESPLINES_SKIP_TESTS=1 git push
+```
+
+## License
+
+SimpleSplines is licensed under the [MIT License](LICENSE.md). See [AUTHORS.md](AUTHORS.md)
+for the list of authors the copyright refers to.