Tolerate Cache Fails During GitHub Action Runs

[dchansen06]

Cache Fails Fine

Problem and Scope

Cache is not perfect and occasionally dies, but it is not key just really nice

Description

Treat sccache like ccache and ensure the CI/CD jobs are not dependent on it passing

Gotchas and Limitations

Manually must check in and ensure GitHub Action cache is working still

Testing

• HOOTL testing
• HITL testing
• Human tested

Testing Details

Ran with ccache, sccache, and neither locally

Larger Impact

Less intrusive CI/CD jobs

Additional Context and Ticket

Resolves #496

[Copilot]

Pull request overview

This PR aims to make CI runs resilient to intermittent GitHub Actions cache / sccache issues (Issue #496) by making cache-related steps non-fatal and moving sccache enablement into CMake so builds can proceed even when caching infrastructure flakes.

Changes:

• Add automatic sccache compiler launcher configuration in CMakeLists.txt (similar structure to existing ccache setup).
• Ignore the local sccache/ directory in .gitignore.
• Update the UnitTests HOOTL workflow to tolerate failures in cache and sccache setup/start steps and stop forcing -DCMAKE_C_COMPILER_LAUNCHER=sccache in CI.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 2 comments.

File	Description
CMakeLists.txt	Auto-detects and configures sccache as a compiler launcher (and sets SCCACHE_DIR).
.gitignore	Adds sccache/ to ignored build/cache artifacts.
.github/workflows/UnitTestsHOOTL.yml	Makes cache and sccache setup steps non-fatal and removes hard-forcing sccache via a CMake CLI flag.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.