From 07cc828c0804326050922fd0b2b03607b2ffa1e9 Mon Sep 17 00:00:00 2001
From: sainathr19 <gsnr1925@gmail.com>
Date: Wed, 19 Aug 2026 16:10:37 +0530
Subject: [PATCH] fix: don't let the batch event scan block the status display
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refresh() awaited fetchStatus and fetchBatches together via Promise.all.
fetchBatches scans from_block=0 to "latest" on its first call — against a
contract deployed near the chain's current tip, that's a huge paginated
range with zero matching events, taking many RPC round-trips to exhaust.
While it was in flight, setStatus never ran, so the UI stayed blank even
though fetchStatus itself resolves instantly. The 10s poll interval also
kept starting a fresh overlapping scan on top of the still-running one.

Decouple the batch scan from status/plan, and guard it so a slow scan
can't be restarted by the next poll tick before it finishes.
---
 ui/src/App.jsx | 37 ++++++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/ui/src/App.jsx b/ui/src/App.jsx
index 5741284..4f5c9fd 100644
--- a/ui/src/App.jsx
+++ b/ui/src/App.jsx
@@ -81,9 +81,16 @@ export default function App() {
   // two contracts' feeds, and its cursor would skip blocks on the new one.
   const feedGenerationRef = useRef(0);
 
+  // A from-block-0 event scan against a contract deployed near the chain's
+  // current tip can take many paginated RPC round-trips to reach "latest".
+  // It must never gate the status/plan display, and a slow scan must not be
+  // restarted from under itself by the next poll tick.
+  const batchScanInFlightRef = useRef(false);
+
   useEffect(() => {
     feedGenerationRef.current += 1;
     nextFromBlockRef.current = 0;
+    batchScanInFlightRef.current = false;
     setBatches([]);
   }, [provider, address]);
 
@@ -91,23 +98,39 @@ export default function App() {
     if (!address) return;
     const generation = feedGenerationRef.current;
     try {
-      const [nextStatus, { newBatches, nextFromBlock }] = await Promise.all([
+      const [nextStatus, nextPlan] = await Promise.all([
         fetchStatus(provider, address),
-        fetchBatches(provider, address, nextFromBlockRef.current),
+        commitment ? fetchPlan(provider, address, commitment) : Promise.resolve(null),
       ]);
-      const nextPlan = commitment ? await fetchPlan(provider, address, commitment) : null;
       if (generation !== feedGenerationRef.current) return;
-      nextFromBlockRef.current = nextFromBlock;
       setStatus(nextStatus);
-      if (newBatches.length > 0) {
-        setBatches((prev) => [...newBatches.reverse(), ...prev]);
-      }
       setPlan(nextPlan);
       setError("");
     } catch (refreshError) {
       if (generation !== feedGenerationRef.current) return;
       setError(String(refreshError.message ?? refreshError));
     }
+
+    if (batchScanInFlightRef.current) return;
+    batchScanInFlightRef.current = true;
+    try {
+      const { newBatches, nextFromBlock } = await fetchBatches(
+        provider,
+        address,
+        nextFromBlockRef.current,
+      );
+      if (generation !== feedGenerationRef.current) return;
+      nextFromBlockRef.current = nextFromBlock;
+      if (newBatches.length > 0) {
+        setBatches((prev) => [...newBatches.reverse(), ...prev]);
+      }
+    } catch (batchError) {
+      if (generation === feedGenerationRef.current) {
+        console.error("fetchBatches failed:", batchError);
+      }
+    } finally {
+      batchScanInFlightRef.current = false;
+    }
   }, [provider, address, commitment]);
 
   useEffect(() => {