fix: don't miss blocks on batcher updates

crates/op-rbuilder/src/generator.rs

@@ -155,7 +155,16 @@ where
         // Adding 0.5 seconds as wiggle room since block times are shorter here.
         // TODO: A better long-term solution would be to implement cancellation logic
         // that cancels existing jobs when receiving new block building requests.
-        let deadline = job_deadline(attributes.timestamp()) + Duration::from_millis(500);
+        //
+        // When batcher's max channel duration is big enough (e.g. 10m), the
+        // sequencer would send an avalanche of FCUs/getBlockByNumber on
+        // each batcher update (with 10m channel it's ~800 FCUs at once).
+        // At such moment it can happen that the time b/w FCU and ensuing
+        // getPayload would be on the scale of ~2.5s. Therefore we should
+        // "remember" the payloads long enough to accommodate this corner-case
+        // (without it we are losing blocks). Postponing the deadline for 5s
+        // (not just 0.5s) because of that.
+        let deadline = job_deadline(attributes.timestamp()) + Duration::from_millis(5000);
 
         let deadline = Box::pin(tokio::time::sleep(deadline));
         let config = PayloadConfig::new(Arc::new(parent_header.clone()), attributes);