bash+openssl signer (raw-64-byte ed25519 over exact bytes, base64 .sig — the plugin-index format) with the pinned-key cross-check, manifest-then-sig upload order, and a live-feed self-verify. announce.yml re-hashes the installer against its sidecar and fail-closes without UPDATE_MANIFEST_KEY; pre-release tags never enter the stable feed. windows-host.yml grows a Linux canary-manifest job. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>