From 5a3a260e707ccfce7ec3c1f779f23fe8b0468175 Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 14:25:46 +0200
Subject: [PATCH 01/11] CI: revive workflows for Julia 1.12 (Ubuntu + Windows)

- checkout@v4 with recursive submodules; julia-actions v2 stack
- Julia 1.12 (matches [compat]/[sources]); drop macOS and stale 1.7
- non-blocking Codecov v4
- add opt-in julia-nightly.yml forward-guard (manual + weekly, non-gating)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml            | 73 ++++++++++++++---------------
 .github/workflows/julia-nightly.yml | 45 ++++++++++++++++++
 2 files changed, 80 insertions(+), 38 deletions(-)
 create mode 100644 .github/workflows/julia-nightly.yml

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index fb8467f..f58ae77 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -2,56 +2,53 @@ name: CI
 on:
   pull_request:
   push:
-    branches:
-      - master
-    tags: '*'
+    branches: [master]
+    tags: ['*']
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
 jobs:
   test:
-    name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
+    name: Julia ${{ matrix.version }} - ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     strategy:
-      fail-fast: true
+      fail-fast: false
       matrix:
-        include:
-          - os: windows-latest
-            arch: 'x64'
-            version: '1.7'
-          - os: ubuntu-latest
-            arch: 'x64'
-            version: '1.7'
-          - os: macos-latest
-            arch: 'x64'
-            version: '1.7'
+        version: ['1.12']
+        os: [ubuntu-latest, windows-latest]
+        arch: [x64]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
 
-      - uses: julia-actions/setup-julia@v1
+      - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
 
-      - uses: actions/cache@v1
-        env:
-          cache-name: cache-artifacts
-        with:
-          path: ~/.julia/artifacts
-          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
-          restore-keys: |
-            ${{ runner.os }}-test-${{ env.cache-name }}-
-            ${{ runner.os }}-test-
-            ${{ runner.os }}-
-      - name: Build
-        # Use bash always to avoid having to escape quotes for Windows
-        shell: bash
-        run: julia --compiled-modules=no --color=yes --project -e 'import Pkg; Pkg.Registry.add("General"); Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git")); Pkg.build(;verbose = true);Pkg.instantiate()'
+      - uses: julia-actions/cache@v2
 
-      - name: Test
-        uses: julia-actions/julia-runtest@v1
+      - name: Add registries + instantiate
+        shell: bash
+        run: |
+          julia --color=yes --project -e '
+            import Pkg
+            Pkg.Registry.add("General")
+            Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
+            Pkg.instantiate()
+            Pkg.build(; verbose=true)'
 
-      - name: Calculate process coverage
-        uses: julia-actions/julia-processcoverage@v1
+      - uses: julia-actions/julia-runtest@v1
 
-      - name: Coverage report
-        uses: codecov/codecov-action@v1
+      - uses: julia-actions/julia-processcoverage@v1
+      - uses: codecov/codecov-action@v4
         with:
-          file: lcov.info
+          files: lcov.info
+          fail_ci_if_error: false
+          token: ${{ secrets.CODECOV_TOKEN }}
diff --git a/.github/workflows/julia-nightly.yml b/.github/workflows/julia-nightly.yml
new file mode 100644
index 0000000..abb72ac
--- /dev/null
+++ b/.github/workflows/julia-nightly.yml
@@ -0,0 +1,45 @@
+name: Julia nightly
+# Forward-guard against the next Julia. Not part of PR gating: runs on a
+# weekly schedule and manual dispatch only, so a break here never blocks a
+# merge.
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '11 7 * * 1'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  test-nightly:
+    name: Julia ${{ matrix.version }} - ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ['nightly']
+        os: [ubuntu-latest, windows-latest]
+        arch: [x64]
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: ${{ matrix.version }}
+          arch: ${{ matrix.arch }}
+      - uses: julia-actions/cache@v2
+      - name: Add registries + instantiate
+        shell: bash
+        run: |
+          julia --color=yes --project -e '
+            import Pkg
+            Pkg.Registry.add("General")
+            Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
+            Pkg.instantiate()
+            Pkg.build(; verbose=true)'
+      - uses: julia-actions/julia-runtest@v1

From 424a2c99eff8e00f621f2c07998078f0e6f5389e Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 14:38:55 +0200
Subject: [PATCH 02/11] docs: add Documenter site (install + API) with Pages
 deploy

- docs/ scaffold: index, installation, examples, API reference
- API page pulls existing docstrings for OM.simulate/translate/flatten,
  library loaders, and result export
- docs.yml: build on PR, deploy to gh-pages on master/tags via GITHUB_TOKEN
- warnonly=true for initial deploys; tighten once API pages are complete

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/docs.yml | 45 ++++++++++++++++++++++++++++
 docs/Project.toml          |  9 ++++++
 docs/make.jl               | 27 +++++++++++++++++
 docs/src/api.md            | 32 ++++++++++++++++++++
 docs/src/examples.md       | 32 ++++++++++++++++++++
 docs/src/index.md          | 22 ++++++++++++++
 docs/src/installation.md   | 61 ++++++++++++++++++++++++++++++++++++++
 7 files changed, 228 insertions(+)
 create mode 100644 .github/workflows/docs.yml
 create mode 100644 docs/Project.toml
 create mode 100644 docs/make.jl
 create mode 100644 docs/src/api.md
 create mode 100644 docs/src/examples.md
 create mode 100644 docs/src/index.md
 create mode 100644 docs/src/installation.md

diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
new file mode 100644
index 0000000..557ec19
--- /dev/null
+++ b/.github/workflows/docs.yml
@@ -0,0 +1,45 @@
+name: Documentation
+on:
+  push:
+    branches: [master]
+    tags: ['*']
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: write        # deploydocs pushes the built site to the gh-pages branch
+  statuses: write
+
+jobs:
+  docs:
+    name: Build and deploy docs
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - uses: julia-actions/setup-julia@v2
+        with:
+          version: '1.12'
+
+      - uses: julia-actions/cache@v2
+
+      - name: Instantiate docs environment
+        shell: bash
+        run: |
+          julia --project=docs --color=yes -e '
+            import Pkg
+            Pkg.Registry.add("General")
+            Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
+            Pkg.instantiate()'
+
+      - name: Build and deploy
+        shell: bash
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
+        run: julia --project=docs --color=yes docs/make.jl
diff --git a/docs/Project.toml b/docs/Project.toml
new file mode 100644
index 0000000..a8b459b
--- /dev/null
+++ b/docs/Project.toml
@@ -0,0 +1,9 @@
+[deps]
+Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+OM = "2f925a0b-2436-437b-858e-49aee461894b"
+
+[sources]
+OM = {path = ".."}
+
+[compat]
+Documenter = "1"
diff --git a/docs/make.jl b/docs/make.jl
new file mode 100644
index 0000000..3bd870b
--- /dev/null
+++ b/docs/make.jl
@@ -0,0 +1,27 @@
+using Documenter
+using OM
+
+makedocs(
+    sitename = "OM.jl",
+    authors = "John Tinnerholm and contributors",
+    modules = [OM],
+    format = Documenter.HTML(
+        prettyurls = get(ENV, "CI", "false") == "true",
+        canonical = "https://JKRT.github.io/OM.jl",
+    ),
+    pages = [
+        "Home" => "index.md",
+        "Installation" => "installation.md",
+        "Examples" => "examples.md",
+        "API reference" => "api.md",
+    ],
+    # Keep the first deploys from hard-failing on as-yet-undocumented bindings
+    # or cross-reference gaps; tighten to `false` once the API pages are filled.
+    warnonly = true,
+)
+
+deploydocs(
+    repo = "github.com/JKRT/OM.jl.git",
+    devbranch = "master",
+    push_preview = true,
+)
diff --git a/docs/src/api.md b/docs/src/api.md
new file mode 100644
index 0000000..e1b3be3
--- /dev/null
+++ b/docs/src/api.md
@@ -0,0 +1,32 @@
+# API reference
+
+The public API is called through the `OM` module (functions are qualified,
+e.g. `OM.simulate`).
+
+## Simulation and translation
+
+```@docs
+OM.simulate
+OM.translate
+OM.flatten
+OM.getMTKProblem
+OM.resimulate
+```
+
+## Libraries
+
+```@docs
+OM.loadLibrary
+OM.loadPackage
+OM.loadInstalledLibrary
+OM.installLibrary
+OM.libraries
+```
+
+## Output and inspection
+
+```@docs
+OM.exportCSV
+OM.writeModelToFile
+OM.exportModelica
+```
diff --git a/docs/src/examples.md b/docs/src/examples.md
new file mode 100644
index 0000000..11fbd15
--- /dev/null
+++ b/docs/src/examples.md
@@ -0,0 +1,32 @@
+# Examples
+
+## A simple pendulum
+
+```julia
+using OM
+sol = OM.simulate("Modelica.Mechanics.MultiBody.Examples.Elementary.Pendulum";
+                  MSL_Version = "MSL:3.2.3", stopTime = 1.0)
+```
+
+## Translate without simulating
+
+Build the in-memory model (frontend + backend) and inspect or solve it later:
+
+```julia
+OM.translate("Modelica.Electrical.Analog.Examples.DifferenceAmplifier";
+             MSL_Version = "MSL:3.2.3")
+prob = OM.getMTKProblem("Modelica.Electrical.Analog.Examples.DifferenceAmplifier")
+```
+
+## Flatten only (frontend)
+
+```julia
+(flatModel, functions) = OM.flatten("Modelica.Mechanics.MultiBody.Examples.Elementary.Pendulum")
+```
+
+## Export results
+
+```julia
+sol = OM.simulate("Modelica....SomeModel"; MSL_Version = "MSL:3.2.3", stopTime = 1.0)
+OM.exportCSV(sol, "result.csv")
+```
diff --git a/docs/src/index.md b/docs/src/index.md
new file mode 100644
index 0000000..c749815
--- /dev/null
+++ b/docs/src/index.md
@@ -0,0 +1,22 @@
+# OM.jl
+
+OM.jl is a Modelica compiler written in Julia. It takes Modelica models
+(including the Modelica Standard Library), flattens and lowers them through a
+Julia frontend and backend, and simulates them via the
+[SciML](https://sciml.ai) / ModelingToolkit ecosystem.
+
+The typical user flow is a single call:
+
+```julia
+using OM
+sol = OM.simulate("Modelica.Mechanics.MultiBody.Examples.Elementary.Pendulum";
+                  MSL_Version = "MSL:3.2.3", stopTime = 1.0)
+```
+
+- **[Installation](installation.md)** — how to get OM.jl and its submodules set up.
+- **[Examples](examples.md)** — worked simulations.
+- **[API reference](api.md)** — the public functions (`simulate`, `translate`,
+  `flatten`, library loading, result export).
+
+The pipeline is FRONTEND (parse → SCode → instantiate → type → flatten) →
+BACKEND (BDAE → SimCode → code generation) → SIMULATE.
diff --git a/docs/src/installation.md b/docs/src/installation.md
new file mode 100644
index 0000000..afc59c1
--- /dev/null
+++ b/docs/src/installation.md
@@ -0,0 +1,61 @@
+# Installation
+
+OM.jl is a multi-package project: the compiler stages live in sibling
+sub-packages (`OMFrontend.jl`, `OMBackend.jl`, `OMParser.jl`, …) that the
+top-level `OM` package references through `Project.toml` `[sources]` paths.
+Those sub-packages are git **submodules**, so they must be checked out.
+
+## Requirements
+
+- **Julia ≥ 1.12** (the project's `[compat]` pins `julia = "1.12"`, and the
+  `[sources]` table requires Julia ≥ 1.11).
+- Git.
+
+## Clone with submodules
+
+```bash
+git clone --recurse-submodules https://github.com/JKRT/OM.jl.git
+cd OM.jl
+```
+
+If you already cloned without `--recurse-submodules`:
+
+```bash
+git submodule update --init --recursive
+```
+
+## Instantiate
+
+OM.jl depends on packages registered in the General registry **and** in the
+OpenModelica registry, so add both before instantiating:
+
+```julia
+julia --project -e '
+  import Pkg
+  Pkg.Registry.add("General")
+  Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
+  Pkg.instantiate()
+  Pkg.build(; verbose = true)'
+```
+
+## First run
+
+```julia
+using OM
+sol = OM.simulate("Modelica.Mechanics.MultiBody.Examples.Elementary.Pendulum";
+                  MSL_Version = "MSL:3.2.3", stopTime = 1.0)
+```
+
+The first call compiles a large dependency tree (ModelingToolkit,
+DifferentialEquations); subsequent runs in the same session are fast.
+
+## Other MSL versions and third-party libraries
+
+`MSL_Version` selects the bundled serialized MSL (3.2.3 or 4.0.0). To use an
+installed-but-unbundled version or a third-party library, load it through the
+general loader and pass the returned key:
+
+```julia
+key = OM.loadInstalledLibrary("Modelica"; version = "4.1.0")
+OM.simulate("Modelica....SomeModel"; libraries = [key])
+```

From 7d2aac672c39c2a4f7dc8cf7da206bae1bdc3291 Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 15:34:25 +0200
Subject: [PATCH 03/11] CI: build native libs before precompile (fixes OMParser
 load)

instantiate auto-precompiles, but OMBackend's precompile workload loads
OMParser whose native .so is produced by the build step. Disable
auto-precompile during instantiate, run Pkg.build, then Pkg.precompile so
the downloaded parser libraries exist first. Applied to CI, nightly, docs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml            | 11 +++++++++--
 .github/workflows/docs.yml          |  8 ++++++--
 .github/workflows/julia-nightly.yml |  7 +++++--
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index f58ae77..e05c8ca 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -34,15 +34,22 @@ jobs:
 
       - uses: julia-actions/cache@v2
 
-      - name: Add registries + instantiate
+      - name: Add registries, build native libs, precompile
         shell: bash
+        # Build BEFORE precompile: OMParser downloads its native shared
+        # libraries in the build step, and OMBackend's precompile workload
+        # loads OMParser. Disable auto-precompile during instantiate, build,
+        # then precompile so the native libs exist first.
+        env:
+          JULIA_PKG_PRECOMPILE_AUTO: '0'
         run: |
           julia --color=yes --project -e '
             import Pkg
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(; verbose=true)'
+            Pkg.build(; verbose=true)
+            Pkg.precompile()'
 
       - uses: julia-actions/julia-runtest@v1
 
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 557ec19..c121ad6 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -10,7 +10,7 @@ concurrency:
   cancel-in-progress: true
 
 permissions:
-  contents: write        # deploydocs pushes the built site to the gh-pages branch
+  contents: write
   statuses: write
 
 jobs:
@@ -30,12 +30,16 @@ jobs:
 
       - name: Instantiate docs environment
         shell: bash
+        env:
+          JULIA_PKG_PRECOMPILE_AUTO: '0'
         run: |
           julia --project=docs --color=yes -e '
             import Pkg
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
-            Pkg.instantiate()'
+            Pkg.instantiate()
+            Pkg.build(; verbose=true)
+            Pkg.precompile()'
 
       - name: Build and deploy
         shell: bash
diff --git a/.github/workflows/julia-nightly.yml b/.github/workflows/julia-nightly.yml
index abb72ac..9b3ea2b 100644
--- a/.github/workflows/julia-nightly.yml
+++ b/.github/workflows/julia-nightly.yml
@@ -33,13 +33,16 @@ jobs:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
       - uses: julia-actions/cache@v2
-      - name: Add registries + instantiate
+      - name: Add registries, build native libs, precompile
         shell: bash
+        env:
+          JULIA_PKG_PRECOMPILE_AUTO: '0'
         run: |
           julia --color=yes --project -e '
             import Pkg
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(; verbose=true)'
+            Pkg.build(; verbose=true)
+            Pkg.precompile()'
       - uses: julia-actions/julia-runtest@v1

From 469ed6dec8e2085dc3d112a4b46a30bed8a221bc Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 15:38:32 +0200
Subject: [PATCH 04/11] CI: build only native-artifact packages, skip OMBackend
 build.jl

OMBackend's deps/build.jl is a standalone-dev script (Pkg.add of registry
deps + rebuild of OMParser/OMFrontend). In the OM umbrella it is redundant
and its build sandbox resolves relative ../DAE.jl sources to a nonexistent
sibling path. OMBackend has no native artifact, so build only OMParser,
OMRuntimeExternalC, OMFrontend; OMBackend is still precompiled normally.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml            | 2 +-
 .github/workflows/docs.yml          | 2 +-
 .github/workflows/julia-nightly.yml | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index e05c8ca..0e4d977 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -48,7 +48,7 @@ jobs:
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(; verbose=true)
+            Pkg.build(["OMParser", "OMRuntimeExternalC", "OMFrontend"]; verbose=true)
             Pkg.precompile()'
 
       - uses: julia-actions/julia-runtest@v1
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index c121ad6..5afac46 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -38,7 +38,7 @@ jobs:
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(; verbose=true)
+            Pkg.build(["OMParser", "OMRuntimeExternalC", "OMFrontend"]; verbose=true)
             Pkg.precompile()'
 
       - name: Build and deploy
diff --git a/.github/workflows/julia-nightly.yml b/.github/workflows/julia-nightly.yml
index 9b3ea2b..c8e8a8f 100644
--- a/.github/workflows/julia-nightly.yml
+++ b/.github/workflows/julia-nightly.yml
@@ -43,6 +43,6 @@ jobs:
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(; verbose=true)
+            Pkg.build(["OMParser", "OMRuntimeExternalC", "OMFrontend"]; verbose=true)
             Pkg.precompile()'
       - uses: julia-actions/julia-runtest@v1

From cb7bef7c5868f99d95cec22816decc2ba58e41d7 Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 15:46:35 +0200
Subject: [PATCH 05/11] CI: build only OMParser + OMRuntimeExternalC (native
 artifacts)

OMFrontend's build.jl (like OMBackend's) is a standalone-dev script that
Pkg.add's deps from git master, clobbering the umbrella's path sources -
it re-resolved OMParser to git#master, dropping the just-built native lib and
breaking precompile. Build only the two packages that download genuine native
artifacts and whose builds don't clobber sources; OMFrontend/OMBackend are
precompiled normally.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml            | 2 +-
 .github/workflows/docs.yml          | 2 +-
 .github/workflows/julia-nightly.yml | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 0e4d977..e03ea27 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -48,7 +48,7 @@ jobs:
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(["OMParser", "OMRuntimeExternalC", "OMFrontend"]; verbose=true)
+            Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
             Pkg.precompile()'
 
       - uses: julia-actions/julia-runtest@v1
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 5afac46..c654c03 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -38,7 +38,7 @@ jobs:
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(["OMParser", "OMRuntimeExternalC", "OMFrontend"]; verbose=true)
+            Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
             Pkg.precompile()'
 
       - name: Build and deploy
diff --git a/.github/workflows/julia-nightly.yml b/.github/workflows/julia-nightly.yml
index c8e8a8f..ba9b00a 100644
--- a/.github/workflows/julia-nightly.yml
+++ b/.github/workflows/julia-nightly.yml
@@ -43,6 +43,6 @@ jobs:
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
             Pkg.instantiate()
-            Pkg.build(["OMParser", "OMRuntimeExternalC", "OMFrontend"]; verbose=true)
+            Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
             Pkg.precompile()'
       - uses: julia-actions/julia-runtest@v1

From b70e18b159ddad4be0cc9e9f066e1d8ebb4ca390 Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 16:35:17 +0200
Subject: [PATCH 06/11] CI: sibling-checkout + Pkg.develop layout (mirror
 OMFrontend CI)

Submodule-recursive + committed-Manifest fought the project's design:
OMParser's native lib (git-ignored, downloaded at build) wasn't found at
precompile, and submodule pointers are unreliable. Adopt OMFrontend.jl's
proven pattern: check out OM and every sub-package as siblings, Pkg.develop
them via ../<name>.jl, build only the native-artifact packages
(OMParser/OMRuntimeExternalC), resolve, precompile, then run tests. No
submodules used, so submodule-pointer drift is irrelevant.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml | 56 +++++++++++++++++++++++++++++++++-------
 1 file changed, 47 insertions(+), 9 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index e03ea27..3849675 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -12,10 +12,16 @@ concurrency:
 permissions:
   contents: read
 
+env:
+  # OM's Project.toml lives in the OM.jl subdir of the workspace; pin it so the
+  # cache action and inline julia calls key off the same project.
+  JULIA_PROJECT: OM.jl
+
 jobs:
   test:
     name: Julia ${{ matrix.version }} - ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
+    timeout-minutes: 120
     strategy:
       fail-fast: false
       matrix:
@@ -23,9 +29,26 @@ jobs:
         os: [ubuntu-latest, windows-latest]
         arch: [x64]
     steps:
-      - uses: actions/checkout@v4
+      # OM and every sub-package are checked out as SIBLINGS in the workspace.
+      # The packages' [sources] reference ../<name>.jl, and we Pkg.develop them
+      # explicitly below. This mirrors OMFrontend.jl's working CI and avoids the
+      # submodule-pointer + nested-path issues entirely.
+      - name: Checkout OM.jl
+        uses: actions/checkout@v4
         with:
-          submodules: recursive
+          path: OM.jl
+      - { name: Checkout Absyn.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/Absyn.jl,              ref: master, path: Absyn.jl } }
+      - { name: Checkout ArrayUtil.jl,          uses: actions/checkout@v4, with: { repository: JKRT/ArrayUtil.jl,                 ref: master, path: ArrayUtil.jl } }
+      - { name: Checkout DAE.jl,                uses: actions/checkout@v4, with: { repository: JKRT/DAE.jl,                       ref: master, path: DAE.jl } }
+      - { name: Checkout DoubleEnded.jl,        uses: actions/checkout@v4, with: { repository: OpenModelica/DoubleEnded.jl,        ref: master, path: DoubleEnded.jl } }
+      - { name: Checkout ImmutableList.jl,      uses: actions/checkout@v4, with: { repository: OpenModelica/ImmutableList.jl,      ref: master, path: ImmutableList.jl } }
+      - { name: Checkout ListUtil.jl,           uses: actions/checkout@v4, with: { repository: JKRT/ListUtil.jl,                   ref: master, path: ListUtil.jl } }
+      - { name: Checkout MetaModelica.jl,       uses: actions/checkout@v4, with: { repository: OpenModelica/MetaModelica.jl,       ref: master, path: MetaModelica.jl } }
+      - { name: Checkout OMBackend.jl,          uses: actions/checkout@v4, with: { repository: JKRT/OMBackend.jl,                 ref: master, path: OMBackend.jl } }
+      - { name: Checkout OMFrontend.jl,         uses: actions/checkout@v4, with: { repository: OpenModelica/OMFrontend.jl,         ref: master, path: OMFrontend.jl } }
+      - { name: Checkout OMParser.jl,           uses: actions/checkout@v4, with: { repository: OpenModelica/OMParser.jl,           ref: master, path: OMParser.jl } }
+      - { name: Checkout OMRuntimeExternalC.jl, uses: actions/checkout@v4, with: { repository: OpenModelica/OMRuntimeExternalC.jl, ref: master, path: OMRuntimeExternalC.jl } }
+      - { name: Checkout SCode.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/SCode.jl,              ref: master, path: SCode.jl } }
 
       - uses: julia-actions/setup-julia@v2
         with:
@@ -33,13 +56,16 @@ jobs:
           arch: ${{ matrix.arch }}
 
       - uses: julia-actions/cache@v2
+        with:
+          cache-name: om-ci
 
-      - name: Add registries, build native libs, precompile
+      - name: Develop siblings, build native libs, precompile
         shell: bash
-        # Build BEFORE precompile: OMParser downloads its native shared
-        # libraries in the build step, and OMBackend's precompile workload
-        # loads OMParser. Disable auto-precompile during instantiate, build,
-        # then precompile so the native libs exist first.
+        working-directory: OM.jl
+        # Disable auto-precompile so the native-lib build runs before precompile
+        # (OMParser/OMRuntimeExternalC download shared libs in their build step).
+        # Build only those two: OMBackend/OMFrontend build.jl are standalone-dev
+        # scripts that Pkg.add deps from git and clobber the dev'd path sources.
         env:
           JULIA_PKG_PRECOMPILE_AUTO: '0'
         run: |
@@ -47,13 +73,25 @@ jobs:
             import Pkg
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
-            Pkg.instantiate()
+            siblings = [
+              "../Absyn.jl", "../ArrayUtil.jl", "../DAE.jl", "../DoubleEnded.jl",
+              "../ImmutableList.jl", "../ListUtil.jl", "../MetaModelica.jl",
+              "../OMBackend.jl", "../OMFrontend.jl", "../OMParser.jl",
+              "../OMRuntimeExternalC.jl", "../SCode.jl",
+            ]
+            Pkg.develop([Pkg.PackageSpec(path = p) for p in siblings])
             Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
+            Pkg.resolve()
             Pkg.precompile()'
 
-      - uses: julia-actions/julia-runtest@v1
+      - name: Test
+        shell: bash
+        working-directory: OM.jl
+        run: julia --color=yes --code-coverage=user --project=. -e 'include("test/runtests.jl")'
 
       - uses: julia-actions/julia-processcoverage@v1
+        with:
+          directories: OM.jl/src
       - uses: codecov/codecov-action@v4
         with:
           files: lcov.info

From 3a4ce2138beeceff23263deacd35abf2ff70fc4f Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 17:10:12 +0200
Subject: [PATCH 07/11] CI: run tests from OM.jl/test (runtests.jl guards
 pwd==@__DIR__)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 3849675..513ceb2 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -86,8 +86,8 @@ jobs:
 
       - name: Test
         shell: bash
-        working-directory: OM.jl
-        run: julia --color=yes --code-coverage=user --project=. -e 'include("test/runtests.jl")'
+        working-directory: OM.jl/test     # runtests.jl guards pwd() == @__DIR__
+        run: julia --color=yes --code-coverage=user --project=.. -e 'include("runtests.jl")'
 
       - uses: julia-actions/julia-processcoverage@v1
         with:

From d5178fc96ae4012a32b07f0236307766b195435e Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 17:13:44 +0200
Subject: [PATCH 08/11] CI: add test-only deps (ADTypes, Sundials, Logging,
 Test) to env

runtests.jl/testUtils.jl 'using' these but OM declares only Test in [extras];
include(runtests.jl) on the main project does not merge [targets]. Promote
them to direct deps in the CI env (already resolved transitively).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 513ceb2..ecae7a3 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -80,6 +80,9 @@ jobs:
               "../OMRuntimeExternalC.jl", "../SCode.jl",
             ]
             Pkg.develop([Pkg.PackageSpec(path = p) for p in siblings])
+            # Test-only deps used by test/testUtils.jl but absent from OM [deps]
+            # (already in the resolved manifest transitively; promote to direct).
+            Pkg.add(["ADTypes", "Sundials", "Logging", "Test"])
             Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
             Pkg.resolve()
             Pkg.precompile()'

From 724b21862cade82bf4773488d6f24bac9b38ad8c Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 17:17:08 +0200
Subject: [PATCH 09/11] CI: drop coverage steps for now (not relevant while
 reviving CI)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/CI.yml | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index ecae7a3..f05779f 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -90,13 +90,4 @@ jobs:
       - name: Test
         shell: bash
         working-directory: OM.jl/test     # runtests.jl guards pwd() == @__DIR__
-        run: julia --color=yes --code-coverage=user --project=.. -e 'include("runtests.jl")'
-
-      - uses: julia-actions/julia-processcoverage@v1
-        with:
-          directories: OM.jl/src
-      - uses: codecov/codecov-action@v4
-        with:
-          files: lcov.info
-          fail_ci_if_error: false
-          token: ${{ secrets.CODECOV_TOKEN }}
+        run: julia --color=yes --project=.. -e 'include("runtests.jl")'

From 2e4c6257223062024df0709f0ee2d8a6e2ddf6e7 Mon Sep 17 00:00:00 2001
From: JKRT <jtinnerholm@gmail.com>
Date: Sat, 13 Jun 2026 18:11:02 +0200
Subject: [PATCH 10/11] CI: propagate sibling-checkout pattern to nightly +
 docs workflows

Same proven recipe as CI.yml (sibling checkouts, Pkg.develop, native-only
build, no coverage). nightly: weekly/dispatch on Julia nightly. docs: builds
the Documenter site against the dev'd OM. (nightly/docs not act-validated;
CI.yml is the act-proven one.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .github/workflows/docs.yml          | 34 ++++++++++++++--
 .github/workflows/julia-nightly.yml | 62 +++++++++++++++++++++++++----
 2 files changed, 84 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index c654c03..70ae5c2 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -17,19 +17,36 @@ jobs:
   docs:
     name: Build and deploy docs
     runs-on: ubuntu-latest
+    timeout-minutes: 120
     steps:
-      - uses: actions/checkout@v4
+      - name: Checkout OM.jl
+        uses: actions/checkout@v4
         with:
-          submodules: recursive
+          path: OM.jl
+      - { name: Checkout Absyn.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/Absyn.jl,              ref: master, path: Absyn.jl } }
+      - { name: Checkout ArrayUtil.jl,          uses: actions/checkout@v4, with: { repository: JKRT/ArrayUtil.jl,                 ref: master, path: ArrayUtil.jl } }
+      - { name: Checkout DAE.jl,                uses: actions/checkout@v4, with: { repository: JKRT/DAE.jl,                       ref: master, path: DAE.jl } }
+      - { name: Checkout DoubleEnded.jl,        uses: actions/checkout@v4, with: { repository: OpenModelica/DoubleEnded.jl,        ref: master, path: DoubleEnded.jl } }
+      - { name: Checkout ImmutableList.jl,      uses: actions/checkout@v4, with: { repository: OpenModelica/ImmutableList.jl,      ref: master, path: ImmutableList.jl } }
+      - { name: Checkout ListUtil.jl,           uses: actions/checkout@v4, with: { repository: JKRT/ListUtil.jl,                   ref: master, path: ListUtil.jl } }
+      - { name: Checkout MetaModelica.jl,       uses: actions/checkout@v4, with: { repository: OpenModelica/MetaModelica.jl,       ref: master, path: MetaModelica.jl } }
+      - { name: Checkout OMBackend.jl,          uses: actions/checkout@v4, with: { repository: JKRT/OMBackend.jl,                 ref: master, path: OMBackend.jl } }
+      - { name: Checkout OMFrontend.jl,         uses: actions/checkout@v4, with: { repository: OpenModelica/OMFrontend.jl,         ref: master, path: OMFrontend.jl } }
+      - { name: Checkout OMParser.jl,           uses: actions/checkout@v4, with: { repository: OpenModelica/OMParser.jl,           ref: master, path: OMParser.jl } }
+      - { name: Checkout OMRuntimeExternalC.jl, uses: actions/checkout@v4, with: { repository: OpenModelica/OMRuntimeExternalC.jl, ref: master, path: OMRuntimeExternalC.jl } }
+      - { name: Checkout SCode.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/SCode.jl,              ref: master, path: SCode.jl } }
 
       - uses: julia-actions/setup-julia@v2
         with:
           version: '1.12'
 
       - uses: julia-actions/cache@v2
+        with:
+          cache-name: om-docs
 
-      - name: Instantiate docs environment
+      - name: Instantiate docs env (sibling develop + native build)
         shell: bash
+        working-directory: OM.jl
         env:
           JULIA_PKG_PRECOMPILE_AUTO: '0'
         run: |
@@ -37,12 +54,21 @@ jobs:
             import Pkg
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
-            Pkg.instantiate()
+            siblings = [
+              "../Absyn.jl", "../ArrayUtil.jl", "../DAE.jl", "../DoubleEnded.jl",
+              "../ImmutableList.jl", "../ListUtil.jl", "../MetaModelica.jl",
+              "../OMBackend.jl", "../OMFrontend.jl", "../OMParser.jl",
+              "../OMRuntimeExternalC.jl", "../SCode.jl",
+            ]
+            Pkg.develop([Pkg.PackageSpec(path = p) for p in siblings])
+            Pkg.develop(Pkg.PackageSpec(path = "."))
             Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
+            Pkg.resolve()
             Pkg.precompile()'
 
       - name: Build and deploy
         shell: bash
+        working-directory: OM.jl
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
diff --git a/.github/workflows/julia-nightly.yml b/.github/workflows/julia-nightly.yml
index ba9b00a..5903282 100644
--- a/.github/workflows/julia-nightly.yml
+++ b/.github/workflows/julia-nightly.yml
@@ -1,7 +1,6 @@
 name: Julia nightly
-# Forward-guard against the next Julia. Not part of PR gating: runs on a
-# weekly schedule and manual dispatch only, so a break here never blocks a
-# merge.
+# Forward-guard against the next Julia. Not part of PR gating: weekly +
+# manual dispatch only, so a break here never blocks a merge.
 on:
   workflow_dispatch:
   schedule:
@@ -14,10 +13,16 @@ concurrency:
 permissions:
   contents: read
 
+env:
+  # OM's Project.toml lives in the OM.jl subdir of the workspace; pin it so the
+  # cache action and inline julia calls key off the same project.
+  JULIA_PROJECT: OM.jl
+
 jobs:
   test-nightly:
     name: Julia ${{ matrix.version }} - ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
+    timeout-minutes: 120
     strategy:
       fail-fast: false
       matrix:
@@ -25,16 +30,43 @@ jobs:
         os: [ubuntu-latest, windows-latest]
         arch: [x64]
     steps:
-      - uses: actions/checkout@v4
+      # OM and every sub-package are checked out as SIBLINGS in the workspace.
+      # The packages' [sources] reference ../<name>.jl, and we Pkg.develop them
+      # explicitly below. This mirrors OMFrontend.jl's working CI and avoids the
+      # submodule-pointer + nested-path issues entirely.
+      - name: Checkout OM.jl
+        uses: actions/checkout@v4
         with:
-          submodules: recursive
+          path: OM.jl
+      - { name: Checkout Absyn.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/Absyn.jl,              ref: master, path: Absyn.jl } }
+      - { name: Checkout ArrayUtil.jl,          uses: actions/checkout@v4, with: { repository: JKRT/ArrayUtil.jl,                 ref: master, path: ArrayUtil.jl } }
+      - { name: Checkout DAE.jl,                uses: actions/checkout@v4, with: { repository: JKRT/DAE.jl,                       ref: master, path: DAE.jl } }
+      - { name: Checkout DoubleEnded.jl,        uses: actions/checkout@v4, with: { repository: OpenModelica/DoubleEnded.jl,        ref: master, path: DoubleEnded.jl } }
+      - { name: Checkout ImmutableList.jl,      uses: actions/checkout@v4, with: { repository: OpenModelica/ImmutableList.jl,      ref: master, path: ImmutableList.jl } }
+      - { name: Checkout ListUtil.jl,           uses: actions/checkout@v4, with: { repository: JKRT/ListUtil.jl,                   ref: master, path: ListUtil.jl } }
+      - { name: Checkout MetaModelica.jl,       uses: actions/checkout@v4, with: { repository: OpenModelica/MetaModelica.jl,       ref: master, path: MetaModelica.jl } }
+      - { name: Checkout OMBackend.jl,          uses: actions/checkout@v4, with: { repository: JKRT/OMBackend.jl,                 ref: master, path: OMBackend.jl } }
+      - { name: Checkout OMFrontend.jl,         uses: actions/checkout@v4, with: { repository: OpenModelica/OMFrontend.jl,         ref: master, path: OMFrontend.jl } }
+      - { name: Checkout OMParser.jl,           uses: actions/checkout@v4, with: { repository: OpenModelica/OMParser.jl,           ref: master, path: OMParser.jl } }
+      - { name: Checkout OMRuntimeExternalC.jl, uses: actions/checkout@v4, with: { repository: OpenModelica/OMRuntimeExternalC.jl, ref: master, path: OMRuntimeExternalC.jl } }
+      - { name: Checkout SCode.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/SCode.jl,              ref: master, path: SCode.jl } }
+
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
+
       - uses: julia-actions/cache@v2
-      - name: Add registries, build native libs, precompile
+        with:
+          cache-name: om-nightly
+
+      - name: Develop siblings, build native libs, precompile
         shell: bash
+        working-directory: OM.jl
+        # Disable auto-precompile so the native-lib build runs before precompile
+        # (OMParser/OMRuntimeExternalC download shared libs in their build step).
+        # Build only those two: OMBackend/OMFrontend build.jl are standalone-dev
+        # scripts that Pkg.add deps from git and clobber the dev'd path sources.
         env:
           JULIA_PKG_PRECOMPILE_AUTO: '0'
         run: |
@@ -42,7 +74,21 @@ jobs:
             import Pkg
             Pkg.Registry.add("General")
             Pkg.Registry.add(Pkg.RegistrySpec(url="https://github.com/OpenModelica/OpenModelicaRegistry.git"))
-            Pkg.instantiate()
+            siblings = [
+              "../Absyn.jl", "../ArrayUtil.jl", "../DAE.jl", "../DoubleEnded.jl",
+              "../ImmutableList.jl", "../ListUtil.jl", "../MetaModelica.jl",
+              "../OMBackend.jl", "../OMFrontend.jl", "../OMParser.jl",
+              "../OMRuntimeExternalC.jl", "../SCode.jl",
+            ]
+            Pkg.develop([Pkg.PackageSpec(path = p) for p in siblings])
+            # Test-only deps used by test/testUtils.jl but absent from OM [deps]
+            # (already in the resolved manifest transitively; promote to direct).
+            Pkg.add(["ADTypes", "Sundials", "Logging", "Test"])
             Pkg.build(["OMParser", "OMRuntimeExternalC"]; verbose=true)
+            Pkg.resolve()
             Pkg.precompile()'
-      - uses: julia-actions/julia-runtest@v1
+
+      - name: Test
+        shell: bash
+        working-directory: OM.jl/test     # runtests.jl guards pwd() == @__DIR__
+        run: julia --color=yes --project=.. -e 'include("runtests.jl")'

From f040c5f3eff6d1caf4879d4d0f93503c385883c4 Mon Sep 17 00:00:00 2001
From: JKRT_CLAUDE_ACCOUNT <t9wgnbfpnd@privaterelay.appleid.com>
Date: Mon, 15 Jun 2026 09:04:38 +0200
Subject: [PATCH 11/11] CI: install BLAS / LAPACK / gfortran runtime on Linux
 (#45)

---
 .github/workflows/CI.yml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index f05779f..4cdc283 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -50,6 +50,17 @@ jobs:
       - { name: Checkout OMRuntimeExternalC.jl, uses: actions/checkout@v4, with: { repository: OpenModelica/OMRuntimeExternalC.jl, ref: master, path: OMRuntimeExternalC.jl } }
       - { name: Checkout SCode.jl,              uses: actions/checkout@v4, with: { repository: OpenModelica/SCode.jl,              ref: master, path: SCode.jl } }
 
+      # libSimulationRuntimeC.so in the OMRuntimeExternalC.jl libs-v0.1.0
+      # Linux zip has DT_NEEDED entries for liblapack.so.3, libblas.so.3 and
+      # libgfortran.so.5. ubuntu-24.04 does not ship those by default, so
+      # dlopen fails and every MSL / Spice3 / external-builtin test that goes
+      # through structural_simplify chains down to it. The Windows
+      # x86_64-mingw32 zip ships its own MinGW DLLs (libgfortran-5.dll,
+      # libopenblas.dll, ...) so no install step is needed there.
+      - name: Install OMC runtime system deps (Linux)
+        if: runner.os == 'Linux'
+        run: sudo apt-get update && sudo apt-get install -y --no-install-recommends liblapack3 libblas3 libgfortran5
+
       - uses: julia-actions/setup-julia@v2
         with:
           version: ${{ matrix.version }}