feat(web_ui): defer operator /compact to turn end, run when idle too

hive-ag3nt/src/turn.rs

@@ -150,8 +150,9 @@ pub enum TurnOutcome {
     /// as `result_kind = "compacted"` in turn stats so the stats page can
     /// distinguish normal turns from turns that triggered a compaction.
     Compacted,
-    /// claude saw "Prompt is too long" — the session needs compacting.
-    /// Run `compact_session()` then retry the same wake-up prompt.
+    /// claude saw "Prompt is too long" and even a reactive compact + retry
+    /// (inside [`InfiniteSession::run`]) couldn't bring it back under the
+    /// window. Rare; the serve loop treats it like `Ok` (acks the turn).
     PromptTooLong,
     /// The Anthropic API refused the request due to a rate limit, per-account
     /// usage cap, or exhausted credit balance. The serve loop should park for
@@ -282,7 +283,7 @@ pub async fn drive_turn(prompt: &str, files: &TurnFiles, bus: &Bus) -> TurnOutco
         });
         result = session.run(&config, prompt, &sink).await;
     }
-    match result {
+    let outcome = match result {
         Ok(progress) => {
             if progress.created {
                 // Fresh session minted this turn → flag it so the bin loop
@@ -299,7 +300,19 @@ pub async fn drive_turn(prompt: &str, files: &TurnFiles, bus: &Bus) -> TurnOutco
             }
         }
         Err(e) => error_to_turn(e),
+    };
+    // Operator `/compact` (`POST /api/compact`) deferred to the turn boundary:
+    // run it now that the turn is done, so it works mid-turn rather than only
+    // when the agent is idle. Only on a healthy turn — no point spawning a
+    // compaction after a rate-limited / auth-failed / crashed one.
+    if bus.take_compact() && matches!(outcome, TurnOutcome::Ok | TurnOutcome::Compacted) {
+        bus.emit(LiveEvent::Note {
+            text: "operator: /compact — running at turn end".into(),
+        });
+        let _ = session.compact(&config, &sink).await;
+        return TurnOutcome::Compacted;
     }
+    outcome
 }
 
 /// Pre-turn auto-reset check. If context is large AND the prompt cache has
@@ -377,30 +390,32 @@ pub fn emit_turn_end(bus: &Bus, outcome: &TurnOutcome) {
     }
 }
 
-/// Operator-initiated `/compact` on the durable session (from the web UI).
-/// Resume-only via [`InfiniteSession::compact`]: a missing session is a
-/// harmless no-op (never mints an empty session just to compact it). Surfaces
-/// the result as a Note and the usual `TurnOutcome`.
-pub async fn compact_session(files: &TurnFiles, bus: &Bus) -> TurnOutcome {
+/// Service a pending operator `/compact` (`Bus::request_compact`) while the
+/// agent is idle — the serve loop calls this when a `recv` returns no message,
+/// so a queued `/compact` runs even when no turn is driving. (The in-flight
+/// case is handled at the end of [`drive_turn`].) Resume-only via
+/// [`InfiniteSession::compact`]: a missing session is a harmless no-op. Returns
+/// `true` if a compaction ran.
+pub async fn run_pending_compact(files: &TurnFiles, bus: &Bus) -> bool {
+    if !bus.take_compact() {
+        return false;
+    }
     bus.emit(LiveEvent::Note {
-        text: "running /compact on the session".into(),
+        text: "operator: /compact — running on idle session".into(),
     });
+    bus.set_state(crate::events::TurnState::Compacting);
     let config = claude_config(bus, files);
     let sink = BusSink::new(bus);
     match infinite_session(bus).compact(&config, &sink).await {
-        Ok(()) => {
-            bus.emit(LiveEvent::Note {
-                text: "/compact done".into(),
-            });
-            TurnOutcome::Compacted
-        }
-        Err(e) => {
-            bus.emit(LiveEvent::Note {
-                text: format!("/compact failed: {e}"),
-            });
-            error_to_turn(e)
-        }
+        Ok(()) => bus.emit(LiveEvent::Note {
+            text: "/compact done".into(),
+        }),
+        Err(e) => bus.emit(LiveEvent::Note {
+            text: format!("/compact failed: {e}"),
+        }),
     }
+    bus.set_state(crate::events::TurnState::Idle);
+    true
 }
 
 /// The constant session title for this agent. `HIVE_SESSION_TITLE` overrides