probe: use the store binary outside the checkout

Author: speak-agent

.github/workflows/probe-old-engine-msvc-sysroot.yml

@@ -22,6 +22,10 @@ jobs:
         shell: bash
         run: |
           export MCPP_VENDORED_XLINGS="$XLINGS_BIN"
+          # $MCPP is the project-scoped shim, which resolves only inside this
+          # checkout; the probes run elsewhere, so they use the store binary.
+          MCPP=$(find "$(cygpath -u "$USERPROFILE")/.xlings/data/xpkgs/xim-x-mcpp/2026.9.21.3" -name mcpp.exe | head -1)
+          echo "store binary: $MCPP"
           "$MCPP" --version
           "$MCPP" self config --mirror GLOBAL
           reg="$(cygpath -u "$MCPP_HOME")/registry/data/xpkgs"