Bake sccache into the SDK image and enable it via RUSTC_WRAPPER in CI and
the devcontainer (not repo-wide, so non-SDK builds are unaffected).
- container/Containerfile: install the sccache musl binary.
- ci.yml: RUSTC_WRAPPER=sccache, CARGO_INCREMENTAL=0, SCCACHE_DIR=/sccache,
cache size cap, plus a `sccache --show-stats` step per job.
- runner-config.example.yaml: bind-mount /var/cache/sccache into job
containers so the cache persists across runs and is shared between jobs.
- .devcontainer: enable sccache with a named cache volume.
Assisted-By: Claude Code (claude-opus-4)
Claude-Session: https://claude.ai/code/session_01NFpGtGTWUEYXLwZeZs2RAV
Signed-off-by: Stan Grams <sjg@haxx.space>
sjg
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