recv: cap batch size at 5, default stays 1 (#2150 clarified)

hive-ag3nt/src/serve_common.rs

@@ -31,9 +31,13 @@ pub fn format_wake_prompt(
     let pending = if unread == 0 {
         String::new()
     } else {
+        // Suggested batch size is clamped to the server-side recv cap
+        // (see `RECV_BATCH_MAX` in hive-c0re) so the hint never asks
+        // for more than one round-trip can deliver.
+        let batch = unread.min(5);
         format!(
             "\n\n({unread} more message(s) pending in your inbox — call `mcp__hyperhive__recv` \
-             with `max: {unread}` to drain them all in one round-trip before acting. If the \
+             with `max: {batch}` to drain the next batch before acting. If the \
              backlog is stale/already handled, `ack_until(up_to: <highest [msg #N] seen>)` \
              clears everything up to that id in one call instead.)"
         )