The macOS CI workflow has a failing job in repository QIICR/dcmqi caused by the dependency cache being treated as valid when the restored cache contents are incomplete or corrupt.

Context:

• Failing workflow run: C/C++ CI macOS
• Workflow file: .github/workflows/cmake-macos.yml
• Failing job URL: https://github.com/QIICR/dcmqi/actions/runs/26633738915/job/78517899566
• Commit analyzed: 495da82985f89a039fd8816ed23b83396c5be809

Observed failure:

• The workflow restores cached DCMTK, ITK, and zlib directories and then configures dcmqi using the cached dependency path.
• The job log shows WARNING: Cache entry deserialization failed, entry ignored and later CMake fails inside SlicerExecutionModel because ITKConfig.cmake cannot be found.
• Root CMakeLists.txt requires find_package(ITK NO_MODULE REQUIRED) and find_package(DCMTK NO_MODULE REQUIRED), so the cached path is only valid if the restored build directories actually contain those package config files.

Please create a pull request that updates .github/workflows/cmake-macos.yml to make the cache usage robust.

Required changes:

1. Add a validation step after cache restore/reporting that verifies the restored cache is actually usable before taking the cached configure path.
   • Check for ${{ github.workspace }}/dcmqi-build/ITK-build/ITKConfig.cmake
   • Check for ${{ github.workspace }}/dcmqi-build/DCMTK-build/DCMTKConfig.cmake
   • Check that ${{ github.workspace }}/dcmqi-build/zlib-install/include and ${{ github.workspace }}/dcmqi-build/zlib-install/lib exist
   • Expose an output like cache_ok=true|false
2. Change the Configure dcmqi w/ cached DCMTK/ITK/ZLIB step so it only runs when both:
   • steps.cache-dcmtk-itk-zlib.outputs.cache-hit == 'true'
   • cache validation output indicates the cache is usable
3. Change the Configure dcmqi w/o cached DCMTK/ITK/ZLIB step so it runs when either:
   • cache was missed, or
   • cache validation failed
4. Tighten cache reuse to reduce reuse of stale/incompatible caches:
   • bump the cache namespace from cache-dcmtk-itk-zlib to something versioned like cache-dcmtk-itk-zlib-v2
   • remove the broad restore-keys fallback, or otherwise avoid restoring arbitrary older caches from the same prefix
5. Keep the change focused on fixing the failing macOS CI cache behavior. Avoid unrelated refactors.

Please make the PR title concise and descriptive, explaining that it validates and tightens the macOS dependency cache in CI.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Please find a solution for this failing job. Use the logs, job definition, and any referenced files where the failure occurred. Keep your response focused on the solution and include code suggestions when appropriate.

Assistant: The failure is caused by an invalid cache restore that reports a cache hit but does not restore a usable ITK package layout.

What failed

The macOS workflow takes the cached-deps path when cache-hit == 'true' and configures dcmqi with:

• -DDCMTK_DIR=${{ github.workspace }}/dcmqi-build/DCMTK-build
• -DITK_DIR=${{ github.workspace }}/dcmqi-build/ITK-build
• -DZLIB_ROOT=${{ github.workspace }}/dcmqi-build/zlib-install

But during the build, SlicerExecutionModel fails in CMake with:

• By not providing "FindITK.cmake"... asked CMake to find a package configuration file provided by "ITK"
• missing ITKConfig.cmake / itk-config.cmake

That means the restored cache did not contain a valid ITK-build tree, even though the workflow treated it as usable. The log also shows:

• WARNING: Cache entry deserialization failed, entry ignored

So the job is effectively using a broken/partial cache state.

Relevant files:

• Workflow: https://github.com/QIICR/dcmqi/blob/495da82985f89a039fd8816ed23b83396c5be809/.github/workflows/cmake-macos.yml
• Root CMake dependency lookup: https://github.com/QIICR/dcmqi/blob/495da82985f89a039fd8816ed23b83396c5be809/CMakeLists.txt

Why this happens

In CMakeLists.txt, non-superbuild configuration requires a valid ITK package:

• find_package(ITK NO_MODULE REQUIRED) at CMakeLists.txt:276

The cached workflow path assumes ${{ github.workspace }}/dcmqi-build/ITK-build contains ITKConfig.cmake, but the cache restore warning indicates that assumption is false for this run.

Solution

Make the workflow validate the cache contents before taking the cached-deps path. If ITKConfig.cmake or DCMTKConfig.cmake is missing, force the full superbuild instead of using the cache.

Recommended workflow change

In .github/workflows/cmake-macos.yml, replace the current cache-hit-only gating with a validation step.

Add a validation step after Report cache status

    - name: Validate cached dependency config files
      id: validate-cache
      run: |
        CACHE_OK=true

        if [ ! -f "${{ github.workspace }}/dcmqi-build/ITK-build/ITKConfig.cmake" ]; t...

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