CARGO_TARGET_DIR=/cargo-target redirects all build output away from the in-tree `<crate>/target/` path, so `cp $BUILD/target/release/...` fails after a successful compile. Mirror alpha-perception-template's correct pattern: `cp $CARGO_TARGET_DIR/release/...`. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>