diff --git a/src/main.rs b/src/main.rs
index a464023..5a9614d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -515,18 +515,33 @@ async fn launch() -> _ {
     }
 
     // Background task: incrementally materialise new 1-hour OHLCV buckets as blocks arrive.
-    // The full historical backfill above already ran; this task only handles the tail.
+    // After a version wipe this is also what repopulates history, since the synchronous
+    // backfill above is skipped in that case.
     // Only processes buckets older than 3 hours (well beyond BCH reorg depth).
     {
         let ohlcv_write = dbpool.cauldron_w.clone();
         let ohlcv_read = dbpool.cauldron_r.clone();
         let ohlcv_state_bg = ohlcv_state.clone();
+        let ohlcv_ibd = ibd_state.clone();
         tokio::spawn(async move {
             // Batch size: 1 day per SQL call to keep each write short.
             const BATCH_SECS: i64 = 24 * 3600;
             // Safety margin: only materialise buckets older than this many seconds.
             const SAFETY_SECS: i64 = 3 * 3600;
 
+            // Wait for IBD before materialising anything.
+            //
+            // The synchronous backfill above waits too, but it is skipped whenever
+            // `ohlcv_wiped` is set — which includes every fresh database, since a missing
+            // version key reads as stale.  Without this the task would sweep from the
+            // first trade all the way to `now - 3h` while indexing is still years behind,
+            // writing nothing, contending with block writes for the cauldron write lock,
+            // and advancing `materialized_end` to roughly now against an empty table — at
+            // which point `candlesticks()` would take the fast path over nothing.
+            while !ohlcv_ibd.initial_sync_complete.load(Ordering::Relaxed) {
+                tokio::time::sleep(Duration::from_secs(1)).await;
+            }
+
             loop {
                 let now = crate::timeutil::time_now();
                 // Floor to 1-hour boundary, 3 hours ago.