Archive build logs as lightweight evidence

README.md

@@ -20,6 +20,7 @@ Supported options are `--local`, `--cpu {aarch64,arm,x86_64}`, `--no-fetch`, and
 Each build is one permanent Castle application transaction. Read `out/current/build.json` for its finalized state. On `PASS`, the current package is described by `out/current/package.json` and is at `out/current/kam-mobile.apk`.
 
 `build/<build_id>/` is transient working state. Its useful logs are `build/<build_id>/logs/compile.log`, `build/<build_id>/logs/package.log`, and, when apksigner is available and invoked, `build/<build_id>/logs/signature.log`.
+After every completed build, the compact logs and final `build.json` are copied to the tracked `build-evidence/<build_id>/` directory. It never contains the temporary application, compiler cache, or APK.
 
 ## Source and resources