diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1d1ab8e..eed19b4 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -6,24 +6,23 @@ on:
       - main
     paths-ignore:
       - 'AUTHORS.md'
-      - 'CITATION.bib'
       - 'CONTRIBUTING.md'
       - 'LICENSE.md'
       - 'NEWS.md'
       - 'README.md'
-      - '.github/workflows/CompatHelper.yml'
+      - '.github/workflows/Downgrade.yml'
+      - '.github/workflows/FormatCheck.yml'
+      - '.github/workflows/SpellCheck.yml'
       - '.github/workflows/TagBot.yml'
+      - '.github/dependabot.yml'
       - '.gitignore'
   pull_request:
     paths-ignore:
-      - 'AUTHORS.md'
-      - 'CITATION.bib'
-      - 'CONTRIBUTING.md'
-      - 'LICENSE.md'
-      - 'NEWS.md'
-      - 'README.md'
-      - '.github/workflows/CompatHelper.yml'
+      - '.github/workflows/Downgrade.yml'
+      - '.github/workflows/FormatCheck.yml'
+      - '.github/workflows/SpellCheck.yml'
       - '.github/workflows/TagBot.yml'
+      - '.github/dependabot.yml'
       - '.gitignore'
   workflow_dispatch:
     inputs:
@@ -40,35 +39,172 @@ concurrency:
 
 jobs:
   test:
+    if: "!contains(github.event.head_commit.message, 'skip ci')"
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
       matrix:
-        julia-version: ['1.10', '1', 'nightly']
-        julia-arch: [x64, x86]
-        os: [ubuntu-latest, windows-latest]
+        julia-version:
+          - '1.10'
+          - '1'
+          - 'nightly'
+        julia-arch:
+          - x64
+          - x86
+        os:
+          - ubuntu-latest
+          - windows-latest
+        mpi-provider:
+          - JLL_MPI
+        t8code_version:
+          - '4.0.0'
+        t8code_snapshot:
+          - '26.07'
         include:
         - julia-version: '1.10'
           julia-arch: 'default'
           os: macos-latest
+          mpi-provider: JLL_MPI
+          t8code_version: '4.0.0'
+          t8code_snapshot: '26.07'
         - julia-version: '1'
           julia-arch: 'default'
           os: macos-latest
+          mpi-provider: JLL_MPI
+          t8code_version: '4.0.0'
+          t8code_snapshot: '26.07'
         - julia-version: 'nightly'
           julia-arch: 'default'
           os: macos-latest
+          mpi-provider: JLL_MPI
+          t8code_version: '4.0.0'
+          t8code_snapshot: '26.07'
+        - julia-version: '1.10'
+          julia-arch: 'x64'
+          os: ubuntu-latest
+          mpi-provider: SYSTEM_MPI
+          t8code_version: '4.0.0'
+          t8code_snapshot: '26.07'
+        - julia-version: '1'
+          julia-arch: 'x64'
+          os: ubuntu-latest
+          mpi-provider: SYSTEM_MPI
+          t8code_version: '4.0.0'
+          t8code_snapshot: '26.07'
+        - julia-version: 'nightly'
+          julia-arch: 'x64'
+          os: ubuntu-latest
+          mpi-provider: SYSTEM_MPI
+          t8code_version: '4.0.0'
+          t8code_snapshot: '26.07'
     steps:
-      - uses: actions/checkout@v7
-      - uses: julia-actions/setup-julia@v3
+      - name: Checkout repository
+        uses: actions/checkout@v7
+
+      - name: Set environment variables
+        shell: bash
+        run: |
+          echo "JULIA_MPI_PROVIDER=${{ matrix.mpi-provider }}" >> $GITHUB_ENV
+
+      - name: Enable Julia cache
+        uses: julia-actions/cache@v3
+
+      - name: Enable t8code cache
+        if: matrix.mpi-provider == 'SYSTEM_MPI'
+        id: cache-t8code
+        uses: actions/cache@v6
+        with:
+          path: ./t8code-local
+          key: ${{ matrix.os }}-${{ matrix.julia-arch }}-${{ matrix.t8code_version }}-${{ matrix.t8code_snapshot }}
+
+      - name: Install Julia
+        uses: julia-actions/setup-julia@v3
         with:
           version: ${{ matrix.julia-version }}
           arch: ${{ matrix.julia-arch }}
-      - uses: julia-actions/julia-buildpkg@v1
-      - uses: julia-actions/julia-runtest@v1
-        # with:
-        #   annotate: true
-        continue-on-error: false
+          show-versioninfo: true
+
+      - name: Install system MPI library
+        if: matrix.mpi-provider == 'SYSTEM_MPI'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y openmpi-bin libopenmpi-dev
+
+      - name: Install t8code
+        if: matrix.mpi-provider == 'SYSTEM_MPI' && steps.cache-t8code.outputs.cache-hit != 'true'
+        run: |
+          T8CODE_RELEASE=${{ matrix.t8code_version }}
+          mkdir t8code-local
+          cd t8code-local
+          wget https://github.com/DLR-AMR/t8code/releases/download/v${T8CODE_RELEASE}-${{ matrix.t8code_snapshot }}/T8CODE-${T8CODE_RELEASE}-Source.tar.gz
+          tar xf T8CODE-${T8CODE_RELEASE}-Source.tar.gz
+          mkdir build
+          cd build
+          cmake \
+              -DCMAKE_C_COMPILER=mpicc \
+              -DCMAKE_CXX_COMPILER=mpicxx \
+              -DCMAKE_BUILD_TYPE=Release \
+              -DCMAKE_INSTALL_PREFIX="$PWD/../prefix" \
+              -DT8CODE_BUILD_TESTS=OFF \
+              -DBUILD_GMOCK=OFF \
+              -DINSTALL_GTEST=OFF \
+              -DT8CODE_BUILD_TUTORIALS=OFF \
+              -DT8CODE_BUILD_EXAMPLES=OFF \
+              -DT8CODE_BUILD_BENCHMARKS=OFF \
+              -DT8CODE_ENABLE_MPI=ON \
+              -DT8CODE_BUILD_FORTRAN_INTERFACE=ON \
+              ../T8CODE-${T8CODE_RELEASE}-Source
+          make -j 2
+          make install
+
+      - name: Configure MPI.jl
+        if: matrix.mpi-provider == 'SYSTEM_MPI'
+        shell: julia --color=yes --project=. {0}
+        run: |
+          using Pkg
+          Pkg.instantiate()
+
+          # Use system MPI
+          using MPIPreferences
+          MPIPreferences.use_system_binary(; force = true)
+
+      - name: Configure T8code.jl
+        if: matrix.mpi-provider == 'SYSTEM_MPI'
+        shell: julia --color=yes --project=. {0}
+        run: |
+          using Preferences, UUIDs
+          set_preferences!(
+           UUID("d0cc0030-9a40-4274-8435-baadcfd54fa1"), # UUID of T8code.jl
+           "libt8" => abspath("./t8code-local/prefix/lib/libt8.so"), force = true)
+          set_preferences!(
+           UUID("d0cc0030-9a40-4274-8435-baadcfd54fa1"), # UUID of T8code.jl
+           "libp4est" => abspath("./t8code-local/prefix/lib/libp4est.so"), force = true)
+          set_preferences!(
+           UUID("d0cc0030-9a40-4274-8435-baadcfd54fa1"), # UUID of T8code.jl
+           "libsc" => abspath("./t8code-local/prefix/lib/libsc.so"), force = true)
+
+      # Add an explicit precompile step where we expect t8code_jll to fail
+      # https://github.com/DLR-AMR/T8code.jl/pull/143#issuecomment-5783271942
+      - name: Precompile (nightly)
+        if: matrix.mpi-provider == 'SYSTEM_MPI' && matrix.julia-version == 'nightly'
+        shell: julia --code-coverage=@/home/runner/work/T8code.jl/T8code.jl --color=yes --warn-overwrite=yes --depwarn=yes --inline=yes --startup-file=no --track-allocation=none --check-bounds=yes --compiled-modules=yes --depwarn=yes --project=. {0}
+        run: |
+          using Pkg
+          Pkg.precompile(; skip_dependents=false)
+        continue-on-error: true
+
+      - name: Precompile
+        if: matrix.mpi-provider == 'SYSTEM_MPI' && matrix.julia-version != 'nightly'
+        shell: julia --code-coverage=@/home/runner/work/T8code.jl/T8code.jl --color=yes --warn-overwrite=yes --depwarn=yes --inline=yes --startup-file=no --track-allocation=none --check-bounds=yes --compiled-modules=yes --depwarn=yes --project=. {0}
+        run: |
+          using Pkg
+          Pkg.precompile()
+        continue-on-error: true
+
+      - name: Run Julia tests
+        uses: julia-actions/julia-runtest@v1
+
       # Enable tmate debugging of manually-triggered workflows if the input option was provided
       - name: Setup tmate session
         uses: mxschmitt/action-tmate@v3
-        if: ${{ github.event_name == 'workflow_dispatch' && inputs.debug_enabled }}
+        if: github.event_name == 'workflow_dispatch' && inputs.debug_enabled
diff --git a/NEWS.md b/NEWS.md
new file mode 100644
index 0000000..38b0ca0
--- /dev/null
+++ b/NEWS.md
@@ -0,0 +1,18 @@
+# Changelog
+
+T8code.jl follows the interpretation of
+[semantic versioning (semver)](https://julialang.github.io/Pkg.jl/dev/compatibility/#Version-specifier-format-1)
+used in the Julia ecosystem. Notable changes will be documented in this file
+for human readability.
+
+
+## Changes in the v0.9 lifecycle
+
+#### Added
+
+- Added `ExplicitImports` tests
+
+#### Changed
+
+- Updated to `Clang.jl` version 0.19
+- Based on t8code's July release 
diff --git a/test/Project.toml b/test/Project.toml
index 7ceb184..d72741d 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -6,8 +6,9 @@ MPIPreferences = "3da0fdf6-3ccc-4f1b-acd9-58baa6c99267"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-Aqua = "0.7, 0.8"
+Aqua = "0.8"
 ExplicitImports = "1.15"
 MPI = "0.20.6"
 MPIPreferences = "0.1.6"
 Test = "1"
+julia = "1.10"
diff --git a/test/test_all.jl b/test/test_all.jl
index cfc21da..787120d 100644
--- a/test/test_all.jl
+++ b/test/test_all.jl
@@ -17,6 +17,13 @@ comm = MPI.COMM_WORLD
 CI_ON_WINDOWS = (get(ENV, "GITHUB_ACTIONS", false) == "true") && Sys.iswindows()
 CI_ON_MACOS = (get(ENV, "GITHUB_ACTIONS", false) == "true") && Sys.isapple()
 
+# When run in CI, check if we are running with system MPI or Julia artifacts
+JULIA_MPI_PROVIDER = get(ENV, "JULIA_MPI_PROVIDER", "JLL_MPI")
+
+@testset "MPI" begin
+    include("test_mpi.jl")
+end
+
 @testset "init" begin
     include("test_init.jl")
 end
diff --git a/test/test_aqua.jl b/test/test_aqua.jl
index 89cbeb9..48a5d04 100644
--- a/test/test_aqua.jl
+++ b/test/test_aqua.jl
@@ -5,8 +5,22 @@ using ExplicitImports: test_explicit_imports
 using Test
 using T8code
 
+# When run in CI, check if we are running with system MPI or Julia artifacts
+JULIA_MPI_PROVIDER = get(ENV, "JULIA_MPI_PROVIDER", "JLL_MPI")
+
 @testset "Aqua.jl" begin
-    Aqua.test_all(T8code)
+    # in case we are running with system MPI t8code_jll will not be loaded
+    if JULIA_MPI_PROVIDER == "SYSTEM_MPI"
+        stale_deps_ignore = (ignore = [:t8code_jll],)
+        test_persistent_tasks = false
+    else
+        stale_deps_ignore = ()
+        test_persistent_tasks = true
+    end
+
+    Aqua.test_all(T8code;
+                  persistent_tasks = test_persistent_tasks,
+                  stale_deps = stale_deps_ignore)
 end
 
 @testset "ExplicitImports.jl" begin
diff --git a/test/test_init.jl b/test/test_init.jl
index 88d9e6b..a22a539 100644
--- a/test/test_init.jl
+++ b/test/test_init.jl
@@ -1,7 +1,3 @@
-@testset "T8code.uses_mpi" begin
-    @test T8code.uses_mpi() == true
-end
-
 @testset "T8code.init" begin
     @test_nowarn T8code.Libt8.sc_init(comm, 0, 1, C_NULL, SC_LP_DEFAULT)
     @test_nowarn t8_init(SC_LP_DEFAULT)
diff --git a/test/test_mpi.jl b/test/test_mpi.jl
new file mode 100644
index 0000000..3390d66
--- /dev/null
+++ b/test/test_mpi.jl
@@ -0,0 +1,8 @@
+@testset "Conditional loading of t8code_jll" begin
+    t8code_jll_loaded = any(m -> nameof(m) === :t8code_jll, values(Base.loaded_modules))
+    @test (JULIA_MPI_PROVIDER == "SYSTEM_MPI") != t8code_jll_loaded
+end
+
+@testset "T8code.uses_mpi" begin
+    @test T8code.uses_mpi() == true
+end