diff --git a/CLAUDE.md b/CLAUDE.md
index 2f67c40..1f21cfb 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -69,7 +69,8 @@ globals, and 17-boot.js runs an IIFE last to bootstrap the app.
 | `15-event-listeners.js` | 6 | global keydown (Esc closes modals/drawer) |
 | `16-clock.js` | 20 | UTC clock IIFE for header |
 | `17-boot.js` | 33 | init IIFE: load trades, wallet popup OR `render() + fetchExpiryPrices() + cloudPull → autoLoadChain` |
-| `18-chain-sync.js` | 579 | Rysk + Hypersurface chain sync: `autoLoadChain`, `syncRysk`, `syncHypersurface`, `resolveRyskOutcomes`, `resolveHsfcOutcomes`, `fetchRyskExpiryPrices`, `applyCloseTrade`, `autoDetectOutcomes` (stale-detection only), `migrateCloseTrades`. Routes through `/api/chain-sync` proxy. `hasProxy()` returns false on `file://` |
+| `18-chain-sync.js` | ~530 | Rysk + Hypersurface chain sync: `autoLoadChain`, `syncRysk`, `syncHypersurface`, `resolveRyskOutcomes`, `resolveHsfcOutcomes`, `fetchRyskExpiryPrices`, `autoDetectOutcomes` (stale-detection only), `migrateCloseTrades`. Routes through `/api/chain-sync` proxy. `hasProxy()` returns false on `file://` |
+| `18b-chain-apply.js` | ~55 | `applyCloseTrade(tradesArray, closeTrade)` → boolean; `applyImportedTrades(tradesArray, openTrades, closeTrades, synced)` → `{added, closedCount, corrected}`. Pure helpers extracted from chain-sync: dedup by txHash, open/close split, close-trade matching, OPEN→EXPIRED correction. Both dual-exported for Node tests |
 
 **Line numbers above are approximate** — they shift as the code evolves. Use them
 as starting anchors, not exact addresses. Re-grep if a function moved.
@@ -116,7 +117,7 @@ typecheck step — plain JS, no TS.
     `getContext`, `scrollIntoView`. Returns `{ window, teardown }`; jsdom tests
     must call `t.after(teardown)` to release the clock interval.
 - **Dual-export pattern** (used by `02-utils.js`, `04b-lot-engine.js`,
-  `05-compute.js`, `05a-merge-open-lots.js`): a guarded footer
+  `05-compute.js`, `05a-merge-open-lots.js`, `18b-chain-apply.js`): a guarded footer
   `if (typeof module !== 'undefined' && module.exports) module.exports = {...}`.
   No-op in the browser; `require()`-able from Node tests. `build.py` does no
   stripping — the footer ships into `hyperwheel.html` and is harmless.
diff --git a/src/js/18-chain-sync.js b/src/js/18-chain-sync.js
index b66069b..dfbc2fa 100644
--- a/src/js/18-chain-sync.js
+++ b/src/js/18-chain-sync.js
@@ -164,37 +164,11 @@ async function syncRysk(address) {
     throw e;
   }
 
-  const synced    = loadSynced();
-  const newTrades = [];
-  let   corrected = 0;
-
-  for (const r of (positions || [])) {
-    if (r.txHash && synced.has(r.txHash)) {
-      // Already imported — correct OPEN→EXPIRED if now past expiry.
-      // resolveRyskOutcomes will then set the definitive ASSIGNED/CALLED/EXPIRED.
-      const nowTs    = Math.floor(Date.now() / 1000);
-      const expiryTs = r.expiry || 0;
-      if (expiryTs > 0 && expiryTs < nowTs) {
-        const existing = trades.find(t => t.txHash === r.txHash);
-        if (existing && existing.outcome === 'OPEN') {
-          existing.outcome = 'EXPIRED';
-          corrected++;
-        }
-      }
-      continue;
-    }
-    const t = parseRyskTrade(r);
-    if (!t) continue;
-    newTrades.push(t);
-    if (r.txHash) synced.add(r.txHash);
-  }
-
-  // Split: open trades imported first, then close trades applied against them
-  const openTrades  = newTrades.filter(t => !t.isClose);
-  const closeTrades = newTrades.filter(t =>  t.isClose);
-  let closedCount = 0;
-  openTrades.forEach(t => trades.push(t));
-  closeTrades.forEach(t => { if (applyCloseTrade(t)) closedCount++; });
+  const synced      = loadSynced();
+  const allTrades   = (positions || []).map(parseRyskTrade).filter(Boolean);
+  const openTrades  = allTrades.filter(t => !t.isClose);
+  const closeTrades = allTrades.filter(t =>  t.isClose);
+  const { added, closedCount, corrected } = applyImportedTrades(trades, openTrades, closeTrades, synced);
 
   // Resolve outcomes from Rysk oracle settlement prices (authoritative — no CoinGecko needed).
   let posOutcomeChanged = false;
@@ -204,13 +178,13 @@ async function syncRysk(address) {
     // expiry-prices query failed — outcomes stay as EXPIRED; retry on next sync
   }
 
-  if (openTrades.length > 0 || closedCount > 0 || corrected > 0 || posOutcomeChanged) {
+  if (added + closedCount + corrected > 0 || posOutcomeChanged) {
     save();
     render();
     saveSynced(synced);
   }
 
-  return { imported: newTrades.length, corrected, skipped: (positions || []).length - newTrades.length - corrected };
+  return { imported: added, corrected, skipped: (positions || []).length - allTrades.length };
 }
 
 // ── HYPERSURFACE SYNC ─────────────────────────────────────
@@ -363,38 +337,19 @@ async function syncHypersurface(address) {
 
   const synced    = loadSynced();
   const newTrades = [];
-  let   corrected = 0;
 
   // Each trade can have multiple legs; each leg becomes one trade entry
   for (const trade of trades_raw) {
     for (const leg of (trade.legs || [])) {
-      const key = (trade.createdTransaction || trade.id || '') + '-' + (leg.id || '');
-      if (key && synced.has(key)) {
-        // Already imported — correct OPEN→EXPIRED if now past expiry
-        const oToken   = leg.oToken;
-        const expiryTs = oToken ? parseInt(oToken.expiryTimestamp || '0') : 0;
-        const nowTs    = Math.floor(Date.now() / 1000);
-        if (expiryTs > 0 && expiryTs < nowTs) {
-          const existing = trades.find(t => t.txHash === key);
-          if (existing && existing.outcome === 'OPEN') {
-            existing.outcome = 'EXPIRED';
-            corrected++;
-          }
-        }
-        continue;
-      }
       const t = parseHsfcLeg(trade, leg);
       if (!t) continue;
       newTrades.push(t);
-      if (key) synced.add(key);
     }
   }
 
   const openTrades  = newTrades.filter(t => !t.isClose);
   const closeTrades = newTrades.filter(t =>  t.isClose);
-  let closedCount = 0;
-  openTrades.forEach(t => trades.push(t));
-  closeTrades.forEach(t => { if (applyCloseTrade(t)) closedCount++; });
+  const { added, closedCount, corrected } = applyImportedTrades(trades, openTrades, closeTrades, synced);
 
   // Resolve HSFC outcomes from on-chain Position data (authoritative — no CoinGecko needed).
   // positions(account, amount_lt:"0") = short positions (options the user sold).
@@ -412,35 +367,17 @@ async function syncHypersurface(address) {
     // positions query failed — outcomes stay as EXPIRED; will retry on next sync
   }
 
-  if (openTrades.length > 0 || closedCount > 0 || corrected > 0 || posOutcomeChanged) {
+  if (added + closedCount + corrected > 0 || posOutcomeChanged) {
     save();
     render();
     saveSynced(synced);
   }
 
   const totalLegs = trades_raw.reduce((n, t) => n + (t.legs || []).length, 0);
-  return { imported: openTrades.length, closed: closedCount, skipped: totalLegs - newTrades.length };
-}
-
-// ── CLOSE TRADE HANDLING ──────────────────────────────────
-// When a user buys back an option they sold, it arrives as a separate
-// trade entry with isClose=true. Instead of importing it as a row,
-// find the matching open trade and mark it CLOSED with closeCost set.
-
-function applyCloseTrade(closeTrade) {
-  const match = trades.find(t =>
-    t.asset   === closeTrade.asset &&
-    t.type    === closeTrade.type &&
-    t.expiry  === closeTrade.expiry &&
-    Math.abs(t.strike - closeTrade.strike) < 0.01 &&
-    t.outcome === 'OPEN'
-  );
-  if (!match) return false;
-  match.outcome   = 'CLOSED';
-  match.closeCost = Math.abs(closeTrade.premium);
-  return true;
+  return { imported: added, closed: closedCount, skipped: totalLegs - newTrades.length };
 }
 
+// ── MIGRATION ─────────────────────────────────────────────
 // Migration: clean up already-imported negative-premium OPEN trades
 // (synced before this fix was deployed).
 function migrateCloseTrades() {
diff --git a/src/js/18b-chain-apply.js b/src/js/18b-chain-apply.js
new file mode 100644
index 0000000..19b6418
--- /dev/null
+++ b/src/js/18b-chain-apply.js
@@ -0,0 +1,56 @@
+// ── CHAIN APPLY ───────────────────────────────────────────────────────────────
+// Pure helpers for importing chain trades into the local trades array.
+// Parameterised on `tradesArray` rather than the global `trades` — safe to
+// require() from Node tests with no browser context.
+
+function applyCloseTrade(tradesArray, closeTrade) {
+  const match = tradesArray.find(t =>
+    t.asset   === closeTrade.asset &&
+    t.type    === closeTrade.type &&
+    t.expiry  === closeTrade.expiry &&
+    Math.abs(t.strike - closeTrade.strike) < 0.01 &&
+    t.outcome === 'OPEN'
+  );
+  if (!match) return false;
+  match.outcome   = 'CLOSED';
+  match.closeCost = Math.abs(closeTrade.premium);
+  return true;
+}
+
+// Apply a batch of pre-parsed chain trades to tradesArray.
+// openTrades / closeTrades are split by the caller; synced Set is mutated
+// in-place. Returns { added, closedCount, corrected }.
+function applyImportedTrades(tradesArray, openTrades, closeTrades, synced) {
+  let added = 0, closedCount = 0, corrected = 0;
+
+  for (const t of openTrades) {
+    if (t.txHash && synced.has(t.txHash)) continue;
+    const trade = Object.assign({}, t);
+    delete trade.isClose;
+    tradesArray.push(trade);
+    if (t.txHash) synced.add(t.txHash);
+    added++;
+  }
+
+  for (const t of closeTrades) {
+    if (t.txHash && synced.has(t.txHash)) continue;
+    if (applyCloseTrade(tradesArray, t)) closedCount++;
+    if (t.txHash) synced.add(t.txHash);
+  }
+
+  // Correct any OPEN trade whose expiry date is now in the past — covers
+  // pre-existing stale trades as well as newly added ones.
+  const todayStr = new Date().toISOString().split('T')[0];
+  for (const t of tradesArray) {
+    if (t.outcome === 'OPEN' && t.expiry && t.expiry < todayStr) {
+      t.outcome = 'EXPIRED';
+      corrected++;
+    }
+  }
+
+  return { added, closedCount, corrected };
+}
+
+if (typeof module !== 'undefined' && module.exports) {
+  module.exports = { applyCloseTrade, applyImportedTrades };
+}
diff --git a/test/unit/chain-apply.test.js b/test/unit/chain-apply.test.js
new file mode 100644
index 0000000..4895fea
--- /dev/null
+++ b/test/unit/chain-apply.test.js
@@ -0,0 +1,105 @@
+const test = require('node:test');
+const assert = require('node:assert');
+const { applyCloseTrade, applyImportedTrades } = require('../../src/js/18b-chain-apply.js');
+
+const PAST_DATE   = '2020-01-01';
+const FUTURE_DATE = '2099-12-31';
+
+// ── applyCloseTrade ──────────────────────────────────────────────────────────
+
+test('applyCloseTrade: matches OPEN trade and sets CLOSED + closeCost', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 10, outcome: 'OPEN' },
+  ];
+  const result = applyCloseTrade(arr, { asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 3 });
+  assert.strictEqual(result, true);
+  assert.strictEqual(arr[0].outcome, 'CLOSED');
+  assert.strictEqual(arr[0].closeCost, 3);
+});
+
+test('applyCloseTrade: no match on strike → returns false, no mutation', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 10, outcome: 'OPEN' },
+  ];
+  const result = applyCloseTrade(arr, { asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 35, premium: 3 });
+  assert.strictEqual(result, false);
+  assert.strictEqual(arr[0].outcome, 'OPEN');
+});
+
+test('applyCloseTrade: non-OPEN trade is not matched', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 10, outcome: 'EXPIRED' },
+  ];
+  const result = applyCloseTrade(arr, { asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 3 });
+  assert.strictEqual(result, false);
+});
+
+// ── applyImportedTrades ──────────────────────────────────────────────────────
+
+test('applyImportedTrades: pushes open trade and strips isClose field', () => {
+  const arr = [];
+  const synced = new Set();
+  const open = [{ id: 1, asset: 'HYPE', type: 'PUT', expiry: FUTURE_DATE, outcome: 'OPEN', isClose: false, txHash: 'tx1' }];
+  const { added } = applyImportedTrades(arr, open, [], synced);
+  assert.strictEqual(added, 1);
+  assert.strictEqual(arr.length, 1);
+  assert.strictEqual('isClose' in arr[0], false, 'isClose must be stripped from pushed trade');
+  assert.ok(synced.has('tx1'));
+});
+
+test('applyImportedTrades: already-synced txHash is skipped', () => {
+  const arr = [];
+  const synced = new Set(['tx1']);
+  const open = [{ id: 1, asset: 'HYPE', type: 'PUT', expiry: FUTURE_DATE, outcome: 'OPEN', isClose: false, txHash: 'tx1' }];
+  const { added } = applyImportedTrades(arr, open, [], synced);
+  assert.strictEqual(added, 0);
+  assert.strictEqual(arr.length, 0);
+});
+
+test('applyImportedTrades: close trade matches open → CLOSED, closedCount: 1', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 10, outcome: 'OPEN' },
+  ];
+  const synced = new Set();
+  const close = [{ asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 30, premium: 3, isClose: true, txHash: 'tx-c' }];
+  const { closedCount } = applyImportedTrades(arr, [], close, synced);
+  assert.strictEqual(closedCount, 1);
+  assert.strictEqual(arr[0].outcome, 'CLOSED');
+  assert.strictEqual(arr[0].closeCost, 3);
+  assert.ok(synced.has('tx-c'));
+});
+
+test('applyImportedTrades: unknown close trade with no match → closedCount: 0', () => {
+  const arr = [];
+  const synced = new Set();
+  const close = [{ asset: 'HYPE', type: 'PUT', expiry: '2026-05-01', strike: 99, premium: 3, isClose: true, txHash: 'tx-c' }];
+  const { closedCount } = applyImportedTrades(arr, [], close, synced);
+  assert.strictEqual(closedCount, 0);
+});
+
+test('applyImportedTrades: OPEN RYSK trade with past expiry corrected to EXPIRED', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: PAST_DATE, outcome: 'OPEN', platform: 'RYSK' },
+  ];
+  const { corrected } = applyImportedTrades(arr, [], [], new Set());
+  assert.strictEqual(corrected, 1);
+  assert.strictEqual(arr[0].outcome, 'EXPIRED');
+});
+
+test('applyImportedTrades: OPEN HSFC trade with past expiry corrected to EXPIRED', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: PAST_DATE, outcome: 'OPEN', platform: 'HSFC' },
+  ];
+  const { corrected } = applyImportedTrades(arr, [], [], new Set());
+  assert.strictEqual(corrected, 1);
+  assert.strictEqual(arr[0].outcome, 'EXPIRED');
+});
+
+test('applyImportedTrades: OPEN trade with future expiry is not corrected', () => {
+  const arr = [
+    { id: 1, asset: 'HYPE', type: 'PUT', expiry: FUTURE_DATE, outcome: 'OPEN', platform: 'RYSK' },
+  ];
+  const { corrected } = applyImportedTrades(arr, [], [], new Set());
+  assert.strictEqual(corrected, 0);
+  assert.strictEqual(arr[0].outcome, 'OPEN');
+});