EzraBrooks · Nov 4, 2026 · Nov 10, 2026 · Nov 10, 2026 · Nov 5, 2026 · Nov 10, 2026
diff --git a/.github/workflows/testpr.yaml b/.github/workflows/testpr.yaml
@@ -154,8 +154,9 @@ jobs:
       PLATFORM: ${{ matrix.target.platform }}
       # while uploads go to a test channel, packages already there aren't built again
       ROBOSTACK_UPLOAD_CHANNEL: ${{ vars.ROBOSTACK_UPLOAD_CHANNEL }}
-      # rattler-build writes to distros/<d>/work/output, or to CONDA_BLD_PATH (win-64)
-      CACHE_DIR: ${{ matrix.target.platform == 'win-64' && 'D:/bld/win-64' || format('distros/{0}/work/output/{1}', matrix.distro, matrix.target.platform) }}
+      # rattler-build writes to distros/<d>/work/output, or to CONDA_BLD_PATH (win-64); its
+      # <platform>/ and noarch/ (e.g. the compatibility packages) are the build cache
+      OUTPUT_DIR: ${{ matrix.target.platform == 'win-64' && 'D:/bld' || format('distros/{0}/work/output', matrix.distro) }}
     steps:
     - uses: actions/checkout@v6
       with:
@@ -226,7 +227,9 @@ jobs:
     - name: Restore build cache
       uses: actions/cache/restore@v5
       with:
-        path: ${{ env.CACHE_DIR }}
+        path: |
+          ${{ env.OUTPUT_DIR }}/${{ matrix.target.platform }}
+          ${{ env.OUTPUT_DIR }}/noarch
         key: ${{ runner.os }}-${{ matrix.distro }}-${{ matrix.target.platform }}-pr-${{ github.event.pull_request.number }}
         restore-keys: |
           ${{ runner.os }}-${{ matrix.distro }}-${{ matrix.target.platform }}-pr-${{ github.event.pull_request.number }}-
@@ -235,21 +238,21 @@ jobs:
     - name: Apply ci.yaml cache controls
       shell: bash -l {0}
       run: |
-        pixi run python tools/ci_config.py --cache-dir "$CACHE_DIR" --config "distros/$DISTRO/ci.yaml" --vinca "distros/$DISTRO/vinca.yaml"
-        mkdir -p "$CACHE_DIR"
-        pixi run rattler-index fs "$CACHE_DIR/.." --force
+        pixi run python tools/ci_config.py --output-dir "$OUTPUT_DIR" --platform "$PLATFORM" --config "distros/$DISTRO/ci.yaml" --vinca "distros/$DISTRO/vinca.yaml"
+        mkdir -p "$OUTPUT_DIR/$PLATFORM"
+        pixi run rattler-index fs "$OUTPUT_DIR" --force
 
     - name: See packages restored by cache
       shell: bash -l {0}
       run: |
         shopt -s nullglob
-        packages=("$CACHE_DIR"/*.conda)
+        packages=("$OUTPUT_DIR/$PLATFORM"/*.conda "$OUTPUT_DIR"/noarch/*.conda)
         echo "${#packages[@]} packages restored from the cache"
         for package in "${packages[@]}"; do basename "$package"; done
 
     - name: Estimate the build time
       shell: bash -l {0}
-      run: pixi run python tools/ci_estimate.py --recipes "distros/$DISTRO/work/recipes" --cache-dir "$CACHE_DIR" --platform "$PLATFORM"
+      run: pixi run python tools/ci_estimate.py --recipes "distros/$DISTRO/work/recipes" --output-dir "$OUTPUT_DIR" --platform "$PLATFORM"
 
     - name: Build recipes
       id: build-recipes
@@ -266,7 +269,7 @@ jobs:
         [ "$PLATFORM" != "win-64" ] && extra+=(--parallel-builds "3:$(getconf _NPROCESSORS_ONLN)")
         build=(python tools/robostack.py "$DISTRO" build --target-platform "$PLATFORM" "${extra[@]}")
         if [ "$PLATFORM" != "win-64" ]; then
-          build=(python tools/ci_build.py --cache-dir "$CACHE_DIR" --timeout 19800 -- "${build[@]}")
+          build=(python tools/ci_build.py --output-dir "$OUTPUT_DIR" --platform "$PLATFORM" --timeout 19800 -- "${build[@]}")
         fi
         pixi run "${build[@]}" 2>&1 | tee rattler-build.log
         status=${PIPESTATUS[0]}
@@ -288,7 +291,7 @@ jobs:
       continue-on-error: true
       shell: bash -l {0}
       run: |
-        pixi run abi-check --distro "$DISTRO" --platform "$PLATFORM" --pr-builds "$CACHE_DIR" --summary "abi-check-$DISTRO.md"
+        pixi run abi-check --distro "$DISTRO" --platform "$PLATFORM" --pr-builds "$OUTPUT_DIR/$PLATFORM" --summary "abi-check-$DISTRO.md"
         cat "abi-check-$DISTRO.md" >> "$GITHUB_STEP_SUMMARY"
 
     - name: Upload the ABI check
@@ -313,15 +316,17 @@ jobs:
       if: ${{ always() && runner.os == 'Windows' && steps.build-recipes.outcome == 'cancelled' }}
       shell: bash -l {0}
       run: |
-        newest=$(ls -t "$CACHE_DIR"/*.conda 2>/dev/null | head -1)
+        newest=$(ls -t "$OUTPUT_DIR/$PLATFORM"/*.conda "$OUTPUT_DIR"/noarch/*.conda 2>/dev/null | head -1)
         if [ -n "$newest" ]; then echo "Removing $newest"; rm -f "$newest"; fi
 
     - name: Save build cache
       id: save-cache
       if: ${{ always() && contains(fromJSON('["success","failure","cancelled"]'), steps.build-recipes.outcome) && (runner.os == 'Windows' || steps.build-recipes.outputs.cache-ready == 'true') }}
       uses: actions/cache/save@v5
       with:
-        path: ${{ env.CACHE_DIR }}
+        path: |
+          ${{ env.OUTPUT_DIR }}/${{ matrix.target.platform }}
+          ${{ env.OUTPUT_DIR }}/noarch
         key: ${{ runner.os }}-${{ matrix.distro }}-${{ matrix.target.platform }}-pr-${{ github.event.pull_request.number }}-${{ github.run_id }}-${{ github.run_attempt }}
 
     # Only the newest cache of a pull request/distribution/platform is restored; the ones

diff --git a/.scripts/build_unix.sh b/.scripts/build_unix.sh
@@ -40,7 +40,13 @@ pixi run -v rs "${ROBOSTACK_DISTRO}" build-ci "${recipe_args[@]}" --output-dir $
 
 # Check if it build something, this is a hotfix for the skips inside additional_recipes
 shopt -s nullglob
-conda_packages=( "${CONDA_BLD_PATH}/${target}"*/*.conda )
+if [[ -n "$target" ]]; then
+    # noarch packages (e.g. the compatibility packages) are uploaded from every platform;
+    # the first upload wins and the others skip
+    conda_packages=( "${CONDA_BLD_PATH}/${target}"*/*.conda "${CONDA_BLD_PATH}/noarch/"*.conda )
+else
+    conda_packages=( "${CONDA_BLD_PATH}/"*/*.conda )
+fi
 if (( ${#conda_packages[@]} > 0 )); then
     # Upload packages one-by-one; the upload task (tools/robostack.py) uploads them to
     # prefix.dev and anaconda.org and skips packages that are already there.

diff --git a/.scripts/build_win.bat b/.scripts/build_win.bat
@@ -37,17 +37,19 @@ for %%X in (%CURRENT_RECIPES%) do set "RECIPE_ARGS=!RECIPE_ARGS! --recipe %FEEDS
 pixi run -v rs %ROBOSTACK_DISTRO% build-ci !RECIPE_ARGS! --output-dir %CONDA_BLD_PATH%
 if errorlevel 1 exit 1
 
-:: Check if .conda files exist in the win-64 directory
-if exist "%CONDA_BLD_PATH%\win-64\*.conda" (
-    echo Found .conda files, starting upload...
-    rem Upload packages one-by-one; the upload task (tools/robostack.py) uploads them to
-    rem prefix.dev and anaconda.org and skips packages that are already there.
-    for %%F in ("%CONDA_BLD_PATH%\win-64\*.conda") do (
+:: Upload the win-64 and noarch packages one-by-one; the upload task (tools/robostack.py)
+:: uploads them to prefix.dev and anaconda.org and skips packages that are already there
+:: (noarch ones, e.g. the compatibility packages, are uploaded from every platform).
+set FOUND=0
+for %%D in (win-64 noarch) do (
+    for %%F in ("%CONDA_BLD_PATH%\%%D\*.conda") do (
+        set FOUND=1
         echo Uploading %%~fF
         pixi run rs %ROBOSTACK_DISTRO% upload "%%~fF"
         if errorlevel 1 exit 1
     )
-) else (
-    echo Warning: No .conda files found in %CONDA_BLD_PATH%\win-64
+)
+if "!FOUND!" == "0" (
+    echo Warning: No .conda files found in %CONDA_BLD_PATH%\win-64 or %CONDA_BLD_PATH%\noarch
     echo This might be due to all the packages being skipped
 )
diff --git a/AGENTS.md b/AGENTS.md
@@ -21,6 +21,10 @@ to read without Claude):
   into `distros/<d>/`.
 - Run everything per distribution with `pixi run rs <distro> <task>`, from the
   repository root. Package names are `ros2-<pkg>` (dashes), e.g. `ros2-rsl`.
+- lyrical builds packages with Python content for Python 3.12-3.14 and the others once
+  (`conditional_python_dependency`, see README "Python versions"). A built-once package
+  that fails its `package_contents` test ships Python after all: add `python` to its
+  `add_host` in `patch/dependencies.yaml`.
 - Never edit `conda_build_config.yaml` by hand: change `shared/pinning/` or the
   distribution's `distro.yaml`, then `pixi run rs <distro> render-pinning` (CI checks it).
 - A change outside `distros/` rebuilds every distribution in CI; keep such PRs focused.
@@ -51,6 +55,7 @@ pixi run rs <d> build --continue-on-failure     # everything missing on the chan
 pixi run rs <d> check-patches [--recipe ros2-<pkg>]
 pixi run rs <d> check-deps                      # pin conflicts, before building anything
 pixi run rs <d> gap-report                      # recipes without artifacts and vice versa
+pixi run rs <d> python-audit [--elf]            # per-Python vs built-once recipes against the published packages
 pixi run rs add-package <pkg>... [<d>...]       # select packages (as the bot does)
 pixi run rs check                               # sanity checks (CI)
 ```

diff --git a/README.md b/README.md
@@ -16,7 +16,8 @@ distribution comes from the channel. The older names keep working: for every pac
 there is also a small `ros-<distro>-<package>` package that just depends on
 `ros2-<package>` of the same version (vinca's `package_name_mode: both` in
 `shared/vinca.yaml`), so existing environments and instructions such as
-`pixi add ros-jazzy-desktop` don't break.
+`pixi add ros-jazzy-desktop` don't break. These are `noarch` packages, built once for
+all platforms: each platform's build uploads them, and whichever comes first wins.
 
 **A package is missing?** Open a *Package request* issue. robostack-bot opens a pull
 request that adds it to the build, and a maintainer reviews it.
@@ -106,6 +107,16 @@ pixi run rs check                             # sanity checks (also run in CI)
 of a distribution uses `full_rebuild: true` there. A new build number goes into its
 `pkg_additional_info.yaml` (one package) or `vinca.yaml` (everything).
 
+**Python versions:** a distribution's `pinning_overrides` can list several Pythons, as
+lyrical does for 3.12-3.14. With `conditional_python_dependency: true` in its
+`vinca.yaml`, only packages with Python content (Python modules, rosidl Python bindings,
+extensions) get python in host/run and are built once per Python; the others are built
+once, without a `python_abi` dependency, and fail their build if they ship
+`site-packages` content or a CPython extension anyway. When vinca's guess from
+`package.xml` is wrong, add `python` to the package's `add_host` (or `remove_host`) in
+`patch/dependencies.yaml`. `pixi run rs <distro> python-audit [--elf]` compares the
+guess with the published packages and lists the misses.
+
 **Building only some distributions in a PR:** a PR builds the distributions it changes,
 and all of them as soon as it touches anything outside `distros/<distro>/`. To limit
 that (e.g. a humble rebuild that also changes `shared/` or `tools/`), add the label

diff --git a/distros/lyrical/conda_build_config.yaml b/distros/lyrical/conda_build_config.yaml
@@ -1000,23 +1000,26 @@ pythia8:
 python:
   # conda-forge supports only 3.14+ for win-arm64 and linux-riscv64
   # part of a zip_keys: python, is_python_min
+  - 3.12.* *_cpython   # [not ((win and arm64) or riscv64)]
+  - 3.13.* *_cp313     # [not ((win and arm64) or riscv64)]
   - 3.14.* *_cp314
-  - 3.12.* *_cpython
 python_impl:
   - cpython
 
   # ros-lyrical specific (distros/lyrical/distro.yaml)
 python_min:
   # minimum supported python version per CFEP-25
   # bump to next minor version when we drop python versions
-  - '3.11'             # [not ((win and arm64) or riscv64)]
+  - '3.12'             # [not ((win and arm64) or riscv64)]
   - '3.14'             # [(win and arm64) or riscv64]
 is_freethreading:
   - false
 is_python_min:
   # part of a zip_keys: python, is_python_min
-  - false
-  - false
+  - true               # [not ((win and arm64) or riscv64)]
+  - false              # [not ((win and arm64) or riscv64)]
+  - false              # [not ((win and arm64) or riscv64)]
+  - true               # [(win and arm64) or riscv64]
 is_abi3:
   - true
 pytorch:

diff --git a/distros/lyrical/distro.yaml b/distros/lyrical/distro.yaml
@@ -7,10 +7,21 @@ upload_to: [prefix, anaconda]
 read_from: prefix
 rosdistro_sync: lyrical/2026-10-05
 pinning_overrides:
-  # build every python package for 3.14 (the shared default) and 3.12;
-  # is_python_min is zipped with python, so it needs one entry per version
-  python: [3.14.* *_cp314, 3.12.* *_cpython]
-  is_python_min: [false, false]
+  # Lyrical supports Python 3.12-3.14 (REP 2000). Packages with Python content are
+  # built for each (vinca.yaml: conditional_python_dependency), the others once.
+  # conda-forge has only 3.14+ for win-arm64 and linux-riscv64, so those get one variant.
+  python:
+    - 3.12.* *_cpython # [not ((win and arm64) or riscv64)]
+    - 3.13.* *_cp313   # [not ((win and arm64) or riscv64)]
+    - 3.14.* *_cp314
+  is_python_min:
+    - true             # [not ((win and arm64) or riscv64)]
+    - false            # [not ((win and arm64) or riscv64)]
+    - false            # [not ((win and arm64) or riscv64)]
+    - true             # [(win and arm64) or riscv64]
+  python_min:
+    - '3.12'           # [not ((win and arm64) or riscv64)]
+    - '3.14'           # [(win and arm64) or riscv64]
   # every pyqt6 6.11.0 build on conda-forge needs qt6-main <=6.11.2, but the shared
   # `6.11` pin resolves to 6.11.3, whose run export (>=6.11.3) rules pyqt6 out: the
   # rqt packages then can't be installed with python_qt_binding. The published

diff --git a/distros/lyrical/vinca.yaml b/distros/lyrical/vinca.yaml
@@ -3,7 +3,12 @@ ros_distro: lyrical
 patch_dir: patch
 rosdistro_snapshot: rosdistro_snapshot.yaml
 rosdistro_additional_recipes: rosdistro_additional_recipes.yaml
-build_number: 30
+build_number: 31
+# Only packages with Python content get python in host/run, and with it the Python
+# variants of distro.yaml (cp312-cp314); the others are built once, without a
+# python_abi dependency. Override the classification per package with python in
+# add_host (or remove_host) in patch/dependencies.yaml.
+conditional_python_dependency: true
 
 mutex_package:
   version: 0.22.0