Batch like accounts together by prefix before any mismatches

runTrade now draws each batch from a single account-type prefix group
(largest group first) instead of slicing across prefixes; a group's
remainder fires alone on a later tick. copyTrade fills open slots with
accounts matching the positioned accounts' prefix before mismatched ones.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/auto-trade.ts

@@ -255,6 +255,7 @@ export async function runTrade(action: 'Buy' | 'Sell' | 'Auto', symbol: string)
         daysTraded: number;
         plan: DayPlan;
         isExtraDay: boolean;
+        prefix: string;
     };
 
     const allEligible: EligibleItem[] = [];
@@ -281,6 +282,7 @@ export async function runTrade(action: 'Buy' | 'Sell' | 'Auto', symbol: string)
                 firmName: firm.name, client, acc, contract,
                 cash: ev.cash, dailyPnL: ev.dailyPnL, daysTraded: ev.daysTraded,
                 plan: ev.plan, isExtraDay: ev.isExtraDay,
+                prefix: getAccountConfig(acc.id).accountType?.prefix ?? '',
             });
         }
     }));
@@ -292,8 +294,21 @@ export async function runTrade(action: 'Buy' | 'Sell' | 'Auto', symbol: string)
 
     // Take only the first batch — all fired simultaneously, no rolling pool.
     // Remaining accounts wait for the next tick (which only fires once all positions are flat).
-    const batch = allEligible.slice(0, maxConcurrent);
+    // Like accounts trade together: a batch is drawn from a single prefix group
-    console.log(`[auto-trade] ${allEligible.length} eligible account(s) — firing batch of ${batch.length}`);
+    // (largest group first), never mixed across prefixes — a group's remainder
+    // fires as a smaller batch on a later tick instead of being padded from
+    // another prefix. E.g. 4×FTDFY, 5×MFFUEV, 7×MFFUSF at limit 5 fires as
+    // batches of 5, 5, 4, 2.
+    const groups = new Map<string, EligibleItem[]>();
+    for (const item of allEligible) {
+        const group = groups.get(item.prefix);
+        if (group) group.push(item);
+        else groups.set(item.prefix, [item]);
+    }
+    const [batchPrefix, batchGroup] = [...groups.entries()]
+        .sort((a, b) => b[1].length - a[1].length || a[0].localeCompare(b[0]))[0];
+    const batch = batchGroup.slice(0, maxConcurrent);
+    console.log(`[auto-trade] ${allEligible.length} eligible account(s) across ${groups.size} prefix group(s) — firing batch of ${batch.length} ${batchPrefix || '(no prefix)'}`);
 
     // ── Phase 2: fire the batch simultaneously ──
     const tradeResults = await Promise.allSettled(batch.map(async (item) => {
@@ -414,6 +429,7 @@ export async function copyTrade() {
     let positionedCount = 0;
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     let positionedClient: any = null;
+    const positionedPrefixes = new Set<string>();
 
     for (const firm of firms) {
         const client = clients.get(firm.id);
@@ -422,6 +438,8 @@ export async function copyTrade() {
             const pos = client.positions[acc.id];
             if (!pos) continue;
             positionedCount++;
+            const prefix = getAccountConfig(acc.id).accountType?.prefix;
+            if (prefix) positionedPrefixes.add(prefix);
             if (!resolvedAction) {
                 resolvedAction = pos.netPos > 0 ? 'Buy' : 'Sell';
                 positionContractId = pos.contractId;
@@ -482,6 +500,7 @@ export async function copyTrade() {
         contract: { name: string; tickSize: number };
         cash: { amount: number; realizedPnL: number };
         plan: DayPlan;
+        prefix: string;
     };
     const eligible: CopyItem[] = [];
 
@@ -509,11 +528,18 @@ export async function copyTrade() {
             // copyTrade has no extra-day branch — those accounts wait for the scheduler
             if (ev.isExtraDay) { console.log(`[copy-trade] ${acc.name}: extra-day account — skip`); continue; }
 
-            eligible.push({ firmName: firm.name, client, acc, contract, cash: ev.cash, plan: ev.plan });
+            eligible.push({
+                firmName: firm.name, client, acc, contract, cash: ev.cash, plan: ev.plan,
+                prefix: getAccountConfig(acc.id).accountType?.prefix ?? '',
+            });
         }
     }));
 
-    const batch = eligible.slice(0, slotsAvailable);
+    // Fill the open slots with accounts whose prefix matches the already-positioned
+    // accounts before falling back to mismatched prefixes.
+    const matchesPositioned = (item: CopyItem) => positionedPrefixes.has(item.prefix);
+    const ordered = [...eligible.filter(matchesPositioned), ...eligible.filter((i) => !matchesPositioned(i))];
+    const batch = ordered.slice(0, slotsAvailable);
     if (batch.length === 0) {
         console.log('[copy-trade] no eligible accounts to copy to');
         return [];