Update PTY write handling in ProcessRegistry to ensure data is encoded as bytes before writing. This change improves compatibility with string inputs and clarifies the expected data type in comments.

tools/process_registry.py

@@ -538,10 +538,11 @@ class ProcessRegistry:
         if session.exited:
             return {"status": "already_exited", "error": "Process has already finished"}
 
-        # PTY mode -- write through pty handle
+        # PTY mode -- write through pty handle (expects bytes)
         if hasattr(session, '_pty') and session._pty:
             try:
-                session._pty.write(data)
+                pty_data = data.encode("utf-8") if isinstance(data, str) else data
+                session._pty.write(pty_data)
                 return {"status": "ok", "bytes_written": len(data)}
             except Exception as e:
                 return {"status": "error", "error": str(e)}