diff --git a/README.md b/README.md
index a9ef191..0175d19 100644
--- a/README.md
+++ b/README.md
@@ -83,6 +83,8 @@ Flutter UI (Dart)
       │
 flutter_rust_bridge (FFI)
       │
+Proprietary engine (Rust)
+      │
    mailcore (Rust)
    ├── IMAP client
    ├── SMTP client
@@ -96,7 +98,7 @@ The UI layer never blocks: all network and crypto operations run in Rust, commun
 | Layer | Technology |
 |---|---|
 | UI | Flutter / Dart |
-| Core engine | Rust (`mailcore`) |
+| Core engine | Rust (Proprietary + `mailcore`) |
 | FFI bridge | flutter_rust_bridge |
 | Cryptography | sequoia-openpgp |
 | Local storage | SQLite |
@@ -118,7 +120,7 @@ The source is published here for transparency and community audit. It is license
 
 **What stays proprietary:**
 
-The PGP/Sequoia integration, advanced privacy features, and the Flutter UI (`korax/`) are not published. A second Rust library — `mailmore` — will eventually hold additional proprietary engine capabilities.
+The PGP/Sequoia integration, advanced privacy features, the proprietary Rust engine, and the Flutter UI (`korax/`) are not published.
 
 ---