fix logging assistant messages

src/mind/log.rs

@@ -41,6 +41,8 @@ impl ConversationLog {
             .context("serializing entry for log")?;
         writeln!(file, "{}", line)
             .context("writing to conversation log")?;
+        file.sync_all()
+            .context("syncing conversation log")?;
         Ok(())
     }