fix(api): fetch relay swaps first, and never idle while the queue has work

After launch the Ref fetch loop slept ten seconds between batches of
twenty, oldest first: 1,574 relay swaps — real 1Click trades through the
pool — waited behind thousands of an arbitrage bot's direct calls, which
the re-read had queued and which mostly fail, draining at about six a
minute. The page's pool swaps and price chart ran hours behind.

The queue now serves the relay's entries first, then the least-retried,
newest first, and loops straight on while batches (now fifty) come back
full; FastNEAR's pacing is the only limit, about a hundred a minute.

Refs #37, #39

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015pkwBsR54NRmZyU4QVhvfj

.sqlx/query-27db80d44ed3461395ff90a0fc77e443354f720243e45d1a6c62ed466b49696f.json

@@ -1,6 +1,6 @@
 {
   "db_name": "PostgreSQL",
-  "query": "\n            select tx_hash, signer, near_height, trader, attempts from ref_pending\n            where chain = $1 and near_height <= $2\n            order by near_height limit $3\n            ",
+  "query": "\n            select tx_hash, signer, near_height, trader, attempts from ref_pending\n            where chain = $1 and near_height <= $2\n            -- The relay's first: each is a solver's swap through the pool, near\n            -- certain, where a direct call is as often a bot's failed attempt.\n            -- Then the least-retried, newest first, so the page stays current\n            -- and a backlog fills in behind it rather than ahead of it.\n            order by (signer = 'intents.near') desc, attempts, near_height desc\n            limit $3\n            ",
   "describe": {
     "columns": [
       {
@@ -44,5 +44,5 @@
       false
     ]
   },
-  "hash": "3de8c1993770595fd108c10eeba83f0c0107e0aa24dfd440ac3841320efb6615"
+  "hash": "27db80d44ed3461395ff90a0fc77e443354f720243e45d1a6c62ed466b49696f"
 }

crates/blackbeard-api/src/refdcl.rs

@@ -42,7 +42,10 @@ pub const READS: &str = "Ref DCL pools holding the asset — liquidity and limit
 /// enough for the pool's receipt, which runs a block or two after the relay's.
 const FETCH_AFTER_BLOCKS: u64 = 20;
 
-/// How often the queue is worked.
+/// Queued transactions taken per pass.
+const FETCH_BATCH: i64 = 50;
+
+/// How often the queue is worked when it is empty.
 const FETCH_INTERVAL: Duration = Duration::from_secs(10);
 
 /// Attempts before a queued transaction is given up on.
@@ -100,8 +103,14 @@ async fn fetch(chain: Arc<ChainRuntime>, store: Store, near: NearClient, config:
     let Some(asset_contract) = config.token_contract().map(str::to_owned) else {
         return;
     };
+    let mut backlog = false;
     loop {
-        tokio::time::sleep(FETCH_INTERVAL).await;
+        // Straight on while the last batch was full: the wait is for an empty
+        // queue, never for one with work in it. After launch it slept ten
+        // seconds between batches of twenty while 1,574 relay swaps waited.
+        if !backlog {
+            tokio::time::sleep(FETCH_INTERVAL).await;
+        }
         let tip = match near.heights().await {
             Ok((tip, _)) => tip,
             Err(e) => {
@@ -110,10 +119,13 @@ async fn fetch(chain: Arc<ChainRuntime>, store: Store, near: NearClient, config:
             }
         };
         let due = match store
-            .due_ref_pending(&id, tip.saturating_sub(FETCH_AFTER_BLOCKS), 20)
+            .due_ref_pending(&id, tip.saturating_sub(FETCH_AFTER_BLOCKS), FETCH_BATCH)
             .await
         {
-            Ok(d) => d,
+            Ok(d) => {
+                backlog = d.len() as i64 == FETCH_BATCH;
+                d
+            }
             Err(e) => {
                 tracing::warn!(chain = %id, error = %e, "ref queue unreadable");
                 continue;

crates/blackbeard-data/src/store.rs

@@ -3334,7 +3334,12 @@ impl Store {
             r#"
             select tx_hash, signer, near_height, trader, attempts from ref_pending
             where chain = $1 and near_height <= $2
-            order by near_height limit $3
+            -- The relay's first: each is a solver's swap through the pool, near
+            -- certain, where a direct call is as often a bot's failed attempt.
+            -- Then the least-retried, newest first, so the page stays current
+            -- and a backlog fills in behind it rather than ahead of it.
+            order by (signer = 'intents.near') desc, attempts, near_height desc
+            limit $3
             "#,
             chain.as_str(),
             height as i64,