add agent-facing compact tool gated on context usage

hive-agent-sock/src/lib.rs

@@ -83,6 +83,14 @@ pub enum Request {
     /// reminder-activity chart data (was `hive-core-agent-sock`'s
     /// `ReminderRollup` against the broker; now served from the local store).
     ReminderRollup { since_secs: u64 },
+    /// Agent self-service request to compact the current session, mirroring
+    /// the operator's `/compact` dashboard button. Gated server-side: only
+    /// honoured when the last completed turn's context usage is above 66%
+    /// of the effective context window — below that, `Response::Err`
+    /// explains why and takes no action. On a pass, queues the same
+    /// deferred `compact_pending` flag the operator's button sets (consumed
+    /// at the next turn boundary), so it never races a live claude process.
+    Compact,
 }
 
 /// A response on the in-agent socket. Serialised with a `kind` tag,