hive-agent: let an agent compact from 40% context usage instead of 66%

hive-agent/src/todo_server.rs

@@ -39,7 +39,7 @@ use crate::todos::{Todo, Todos};
 /// effective context window, an agent-initiated compact is refused (nothing
 /// meaningful to reclaim yet, and it'd just burn a compaction pass on a
 /// near-empty session).
-const COMPACT_MIN_USAGE_FRACTION: f64 = 0.66;
+const COMPACT_MIN_USAGE_FRACTION: f64 = 0.40;
 
 /// Pause after a failed `accept`, so a failure that persists (fd exhaustion)
 /// does not turn the accept loop into a busy spin.
@@ -982,6 +982,22 @@ mod tests {
         assert!(low.take_compact().is_none(), "a refusal queues nothing");
     }
 
+    #[test]
+    fn the_compact_floor_is_forty_percent_of_the_window() {
+        let (_dir, todos, _) = stores();
+        let wake = Notify::new();
+        let under = bus_with_context(39);
+        let resp = dispatch(compact_req(None), &todos, &wake, None, &under);
+        assert!(
+            matches!(&resp, Response::Err { message } if message.contains("40%")),
+            "{resp:?}"
+        );
+        let at = bus_with_context(40);
+        let resp = dispatch(compact_req(None), &todos, &wake, None, &at);
+        assert!(matches!(resp, Response::Ok), "{resp:?}");
+        assert!(at.take_compact().is_some(), "the floor itself is allowed");
+    }
+
     #[test]
     fn compact_above_the_floor_queues_the_request_with_its_wake_prompt() {
         let (_dir, todos, _) = stores();