chore: seed sgclaw rust baseline

tests/pipe_handshake_test.rs

@@ -0,0 +1,41 @@
+mod common;
+
+use std::time::Duration;
+
+use common::MockTransport;
+use sgclaw::pipe::{perform_handshake, AgentMessage, BrowserMessage};
+
+#[test]
+fn handshake_reads_init_and_writes_init_ack() {
+    let transport = MockTransport::new(vec![BrowserMessage::Init {
+        version: "1.0".to_string(),
+        hmac_seed: "0123456789abcdef".to_string(),
+        capabilities: vec!["browser_action".to_string()],
+    }]);
+
+    let result = perform_handshake(&transport, Duration::from_secs(5)).unwrap();
+    let sent = transport.sent_messages();
+
+    assert_eq!(result.capabilities, vec!["browser_action"]);
+    assert_eq!(sent.len(), 1);
+    assert!(matches!(
+        &sent[0],
+        AgentMessage::InitAck {
+            version,
+            agent_id,
+            supported_actions
+        } if version == "1.0" && !agent_id.is_empty() && supported_actions.len() >= 4
+    ));
+}
+
+#[test]
+fn handshake_rejects_version_mismatch() {
+    let transport = MockTransport::new(vec![BrowserMessage::Init {
+        version: "9.9".to_string(),
+        hmac_seed: "0123456789abcdef".to_string(),
+        capabilities: vec![],
+    }]);
+
+    let err = perform_handshake(&transport, Duration::from_secs(5)).unwrap_err();
+    assert!(err.to_string().contains("unsupported protocol version"));
+}