diff --git a/.changeset/ord-2039.md b/.changeset/ord-2039.md
new file mode 100644
index 00000000..0cca7717
--- /dev/null
+++ b/.changeset/ord-2039.md
@@ -0,0 +1,5 @@
+---
+"@lifi/perps-sdk-provider-lighter": patch
+---
+
+Read Lighter order, client order and trade ids from the exact string fields, so ids above 2^53 no longer round in `Order.orderId`, `Order.clientOrderId`, `Fill.id`, `Fill.orderId` and the `getOrder` lookup.
diff --git a/packages/perps-sdk-provider-lighter/src/LighterProvider.ts b/packages/perps-sdk-provider-lighter/src/LighterProvider.ts
index 7c6511f6..dfe5343a 100644
--- a/packages/perps-sdk-provider-lighter/src/LighterProvider.ts
+++ b/packages/perps-sdk-provider-lighter/src/LighterProvider.ts
@@ -1617,7 +1617,7 @@ export const createLighterProvider = (
         // `accountOrders` reaches active and inactive rows alike, so a reused
         // client order index can match more than one row. Prefer the live one.
         const matches = orders
-          .filter((o) => String(o.client_order_index) === clientOrderIndex)
+          .filter((o) => o.client_order_id === clientOrderIndex)
           .flatMap((o) => mapDetail(o) ?? [])
         const hit =
           matches.find((o) => isActiveOrderStatus(o.status)) ?? matches[0]
@@ -1627,8 +1627,7 @@ export const createLighterProvider = (
         return hit
       }
 
-      const byOrderIndex = (o: LtOrder): boolean =>
-        String(o.order_index) === params.id
+      const byOrderIndex = (o: LtOrder): boolean => o.order_id === params.id
 
       const active = await retryOnRevoked(params.address, token, (t) =>
         fetchActiveOrders(
diff --git a/packages/perps-sdk-provider-lighter/src/LighterProvider.unit.spec.ts b/packages/perps-sdk-provider-lighter/src/LighterProvider.unit.spec.ts
index c8818be1..b65e36cd 100644
--- a/packages/perps-sdk-provider-lighter/src/LighterProvider.unit.spec.ts
+++ b/packages/perps-sdk-provider-lighter/src/LighterProvider.unit.spec.ts
@@ -342,6 +342,7 @@ const TRADES_RESPONSE = {
   trades: [
     {
       trade_id: 7,
+      trade_id_str: '7',
       tx_hash: '0xfeed',
       type: 'trade',
       market_id: 0,
@@ -350,6 +351,10 @@ const TRADES_RESPONSE = {
       usd_amount: '25000',
       ask_id: 11,
       bid_id: 22,
+      ask_id_str: '11',
+      bid_id_str: '22',
+      ask_client_id_str: '0',
+      bid_client_id_str: '0',
       ask_account_id: 99,
       bid_account_id: 42,
       is_maker_ask: true,
@@ -3171,7 +3176,7 @@ describe('LighterProvider — getOrders pagination contract', () => {
     order_index: orderIndex,
     client_order_index: 0,
     order_id: String(orderIndex),
-    client_order_id: String(orderIndex),
+    client_order_id: '0',
     market_index: 0,
     owner_account_index: 42,
     initial_base_amount: '0.1',
@@ -5352,6 +5357,11 @@ describe('LighterProvider — getOrder', () => {
 })
 
 describe('LighterProvider — one-call order reads', () => {
+  // A market 33 order index above 2^53: `JSON.parse` rounds the numeric twin
+  // to ...276, so only the string twin carries the exact id.
+  const UNSAFE_ORDER_ID = '9570149379440277'
+  const UNSAFE_ORDER_ID_PARSED = 9570149379440276
+
   const TWO_MARKETS_RESPONSE = {
     markets: [
       MARKETS_RESPONSE.markets[0],
@@ -5461,8 +5471,8 @@ describe('LighterProvider — one-call order reads', () => {
           code: 0,
           next_cursor: '',
           orders: [
-            makeOrder({ order_index: 900, market_index: 0 }),
-            makeOrder({ order_index: 901, market_index: 1 }),
+            makeOrder({ order_index: 900, order_id: '900', market_index: 0 }),
+            makeOrder({ order_index: 901, order_id: '901', market_index: 1 }),
           ],
         })
       }
@@ -5496,7 +5506,9 @@ describe('LighterProvider — one-call order reads', () => {
         return respond({
           code: 0,
           next_cursor: '',
-          orders: [makeOrder({ order_index: 901, market_index: 1 })],
+          orders: [
+            makeOrder({ order_index: 901, order_id: '901', market_index: 1 }),
+          ],
         })
       }
       return undefined
@@ -5516,7 +5528,12 @@ describe('LighterProvider — one-call order reads', () => {
   it('resolves an active order by client order index through one accountOrders request', async () => {
     overrideFetch((u) =>
       u.includes('/api/v1/accountOrders')
-        ? respond({ code: 200, orders: [makeOrder({ client_order_index: 7 })] })
+        ? respond({
+            code: 200,
+            orders: [
+              makeOrder({ client_order_index: 7, client_order_id: '7' }),
+            ],
+          })
         : undefined
     )
 
@@ -5542,6 +5559,7 @@ describe('LighterProvider — one-call order reads', () => {
             orders: [
               makeOrder({
                 client_order_index: 8,
+                client_order_id: '8',
                 status: 'filled',
                 remaining_base_amount: '0',
                 filled_base_amount: '0.1',
@@ -5572,10 +5590,17 @@ describe('LighterProvider — one-call order reads', () => {
             orders: [
               makeOrder({
                 client_order_index: 7,
+                client_order_id: '7',
                 order_index: 800,
+                order_id: '800',
                 status: 'canceled',
               }),
-              makeOrder({ client_order_index: 7, order_index: 901 }),
+              makeOrder({
+                client_order_index: 7,
+                client_order_id: '7',
+                order_index: 901,
+                order_id: '901',
+              }),
             ],
           })
         : undefined
@@ -5594,7 +5619,12 @@ describe('LighterProvider — one-call order reads', () => {
   it('ignores an accountOrders row whose client order index differs', async () => {
     overrideFetch((u) =>
       u.includes('/api/v1/accountOrders')
-        ? respond({ code: 200, orders: [makeOrder({ client_order_index: 9 })] })
+        ? respond({
+            code: 200,
+            orders: [
+              makeOrder({ client_order_index: 9, client_order_id: '9' }),
+            ],
+          })
         : undefined
     )
 
@@ -5649,6 +5679,54 @@ describe('LighterProvider — one-call order reads', () => {
     expect(requestsTo('/api/v1/accountOrders')).toEqual([])
   })
 
+  it('matches a bare order id above 2^53 on order_id, not the rounded order_index', async () => {
+    overrideFetch((u) =>
+      u.includes('/api/v1/accountActiveOrders')
+        ? respond({
+            code: 0,
+            next_cursor: '',
+            orders: [
+              makeOrder({
+                order_index: UNSAFE_ORDER_ID_PARSED,
+                order_id: UNSAFE_ORDER_ID,
+              }),
+            ],
+          })
+        : undefined
+    )
+
+    const order = await (await boundProvider()).getOrder({
+      address: ADDRESS,
+      id: UNSAFE_ORDER_ID,
+    })
+
+    expect(order.orderId).toBe(UNSAFE_ORDER_ID)
+    expect(requestsTo('/api/v1/accountInactiveOrders')).toEqual([])
+  })
+
+  it('matches a client order index above 2^53 on client_order_id', async () => {
+    overrideFetch((u) =>
+      u.includes('/api/v1/accountOrders')
+        ? respond({
+            code: 200,
+            orders: [
+              makeOrder({
+                client_order_index: UNSAFE_ORDER_ID_PARSED,
+                client_order_id: UNSAFE_ORDER_ID,
+              }),
+            ],
+          })
+        : undefined
+    )
+
+    const order = await (await boundProvider()).getOrder({
+      address: ADDRESS,
+      id: `${LIGHTER_CLIENT_ORDER_INDEX_ID_PREFIX}${UNSAFE_ORDER_ID}`,
+    })
+
+    expect(order.clientOrderId).toBe(UNSAFE_ORDER_ID)
+  })
+
   it('falls back to the inactive orders for an order_index that no longer rests', async () => {
     overrideFetch((u) => {
       if (u.includes('/api/v1/accountActiveOrders')) {
@@ -5693,6 +5771,7 @@ describe('LighterProvider — getFills logos and realized PnL', () => {
   // 50000 → realized PnL (50000 - 40000) × 1 = 10000.
   const REDUCING_TRADE = {
     trade_id: 9,
+    trade_id_str: '9',
     tx_hash: '0xfeed',
     type: 'trade',
     market_id: 0,
@@ -5701,6 +5780,10 @@ describe('LighterProvider — getFills logos and realized PnL', () => {
     usd_amount: '50000',
     ask_id: 7,
     bid_id: 8,
+    ask_id_str: '7',
+    bid_id_str: '8',
+    ask_client_id_str: '0',
+    bid_client_id_str: '0',
     ask_account_id: 42,
     bid_account_id: 0,
     is_maker_ask: false,
@@ -5771,6 +5854,7 @@ describe('LighterProvider — getFills unresolvable market rows', () => {
   const tradeRow = (tradeId: number, marketId: number) => ({
     ...TRADES_RESPONSE.trades[0],
     trade_id: tradeId,
+    trade_id_str: String(tradeId),
     market_id: marketId,
   })
 
diff --git a/packages/perps-sdk-provider-lighter/src/contract.decimal.unit.spec.ts b/packages/perps-sdk-provider-lighter/src/contract.decimal.unit.spec.ts
index 0e93702e..960fa105 100644
--- a/packages/perps-sdk-provider-lighter/src/contract.decimal.unit.spec.ts
+++ b/packages/perps-sdk-provider-lighter/src/contract.decimal.unit.spec.ts
@@ -249,7 +249,7 @@ const ACTIVE_ORDERS = {
     {
       order_index: 88,
       client_order_index: 0,
-      order_id: 'lt-88',
+      order_id: '88',
       client_order_id: '0',
       market_index: BTC_MARKET_ID,
       owner_account_index: ACCOUNT_INDEX,
@@ -284,7 +284,7 @@ const ACTIVE_ORDERS = {
     {
       order_index: 89,
       client_order_index: 0,
-      order_id: 'lt-89',
+      order_id: '89',
       client_order_id: '0',
       market_index: BTC_MARKET_ID,
       owner_account_index: ACCOUNT_INDEX,
@@ -323,6 +323,7 @@ const TRADES = {
   trades: [
     {
       trade_id: 7,
+      trade_id_str: '7',
       tx_hash: '0xabc',
       type: 'trade',
       market_id: BTC_MARKET_ID,
@@ -331,6 +332,10 @@ const TRADES = {
       usd_amount: '0.047',
       ask_id: 100,
       bid_id: 200,
+      ask_id_str: '100',
+      bid_id_str: '200',
+      ask_client_id_str: '0',
+      bid_client_id_str: '0',
       ask_account_id: 0,
       bid_account_id: ACCOUNT_INDEX,
       is_maker_ask: false,
diff --git a/packages/perps-sdk-provider-lighter/src/getOrders.unit.spec.ts b/packages/perps-sdk-provider-lighter/src/getOrders.unit.spec.ts
index 23c8328d..17519b82 100644
--- a/packages/perps-sdk-provider-lighter/src/getOrders.unit.spec.ts
+++ b/packages/perps-sdk-provider-lighter/src/getOrders.unit.spec.ts
@@ -45,7 +45,7 @@ const MARKET: Market = {
 const order = (overrides: Partial<LtOrder> = {}): LtOrder => ({
   order_index: 88,
   client_order_index: 0,
-  order_id: 'lt-88',
+  order_id: '88',
   client_order_id: '0',
   market_index: 1,
   owner_account_index: 42,
@@ -141,10 +141,16 @@ describe('Lighter getOrders lifecycle reads', () => {
       order(),
       order({
         order_index: 90,
+        order_id: '90',
         filled_base_amount: '0',
         filled_quote_amount: '0',
       }),
-      order({ type: 'twap-sub', order_index: 89, parent_order_id: '88' }),
+      order({
+        type: 'twap-sub',
+        order_index: 89,
+        order_id: '89',
+        parent_order_id: '88',
+      }),
     ])
     const result = await provider.getOrders({ address: ADDRESS, marketId: '1' })
     expect(result.orders).toMatchObject([
@@ -178,8 +184,13 @@ describe('Lighter getOrders lifecycle reads', () => {
       [],
       [
         order({ status: 'filled' }),
-        order({ type: 'limit', order_index: 91, status: 'canceled-expired' }),
-        order({ order_index: 92, status: 'canceled' }),
+        order({
+          type: 'limit',
+          order_index: 91,
+          order_id: '91',
+          status: 'canceled-expired',
+        }),
+        order({ order_index: 92, order_id: '92', status: 'canceled' }),
       ],
       'next-page'
     )
@@ -213,8 +224,11 @@ describe('Lighter getOrders lifecycle reads', () => {
 
   it('combines active and terminal filters without retaining unrequested statuses', async () => {
     const { provider, requests } = await setup(
-      [order(), order({ order_index: 89, filled_base_amount: '0' })],
-      [order({ order_index: 90, status: 'filled' })]
+      [
+        order(),
+        order({ order_index: 89, order_id: '89', filled_base_amount: '0' }),
+      ],
+      [order({ order_index: 90, order_id: '90', status: 'filled' })]
     )
     const result = await provider.getOrders({
       address: ADDRESS,
@@ -231,7 +245,7 @@ describe('Lighter getOrders lifecycle reads', () => {
   it('does not repeat the active snapshot on a mixed history continuation page', async () => {
     const { provider, requests } = await setup(
       [order()],
-      [order({ order_index: 90, status: 'filled' })]
+      [order({ order_index: 90, order_id: '90', status: 'filled' })]
     )
     const result = await provider.getOrders({
       address: ADDRESS,
@@ -287,7 +301,12 @@ describe('Lighter getOrders lifecycle reads', () => {
       [],
       [
         order({ status: 'filled' }),
-        order({ order_index: 91, market_index: 999, status: 'filled' }),
+        order({
+          order_index: 91,
+          order_id: '91',
+          market_index: 999,
+          status: 'filled',
+        }),
       ]
     )
     const result = await provider.getOrders({
@@ -300,7 +319,14 @@ describe('Lighter getOrders lifecycle reads', () => {
   it('keeps a history row whose market is delisted', async () => {
     const { provider } = await setup(
       [],
-      [order({ order_index: 91, market_index: 2, status: 'filled' })],
+      [
+        order({
+          order_index: 91,
+          order_id: '91',
+          market_index: 2,
+          status: 'filled',
+        }),
+      ],
       '',
       [MARKET, { ...MARKET, id: '2', isDelisted: true }]
     )
@@ -324,7 +350,7 @@ describe('Lighter getOrders lifecycle reads', () => {
   it('uses the same order shape for list reads and single-order reads', async () => {
     const { provider } = await setup(
       [],
-      [order({ status: 'filled', client_order_index: 7 })]
+      [order({ status: 'filled', client_order_index: 7, client_order_id: '7' })]
     )
     const params: ProviderGetOrdersParams = {
       address: ADDRESS,
diff --git a/packages/perps-sdk-provider-lighter/src/types/fill.ts b/packages/perps-sdk-provider-lighter/src/types/fill.ts
index 7e62e891..a4eb2d5b 100644
--- a/packages/perps-sdk-provider-lighter/src/types/fill.ts
+++ b/packages/perps-sdk-provider-lighter/src/types/fill.ts
@@ -16,6 +16,7 @@
  */
 export type LtTrade = {
   trade_id: number
+  trade_id_str: string
   tx_hash: string
   type: string
   market_id: number
@@ -24,6 +25,10 @@ export type LtTrade = {
   usd_amount: string
   ask_id: number
   bid_id: number
+  ask_id_str: string
+  bid_id_str: string
+  ask_client_id_str: string
+  bid_client_id_str: string
   ask_account_id: number
   bid_account_id: number
   is_maker_ask: boolean
diff --git a/packages/perps-sdk-provider-lighter/src/utils/mapFill.ts b/packages/perps-sdk-provider-lighter/src/utils/mapFill.ts
index f579d43a..5b5720a1 100644
--- a/packages/perps-sdk-provider-lighter/src/utils/mapFill.ts
+++ b/packages/perps-sdk-provider-lighter/src/utils/mapFill.ts
@@ -161,8 +161,8 @@ export const mapFill = (
       : tickToFeeAmount(trade.usd_amount, feeTick, integratorFeeTick)
 
   return {
-    id: trade.trade_id.toString(),
-    orderId: String(isBuyer ? trade.bid_id : trade.ask_id),
+    id: trade.trade_id_str,
+    orderId: isBuyer ? trade.bid_id_str : trade.ask_id_str,
     market,
     side: isBuyer ? OrderSide.BUY : OrderSide.SELL,
     type: OrderType.LIMIT,
diff --git a/packages/perps-sdk-provider-lighter/src/utils/mapFill.unit.spec.ts b/packages/perps-sdk-provider-lighter/src/utils/mapFill.unit.spec.ts
index e14f2fe1..f09b89cb 100644
--- a/packages/perps-sdk-provider-lighter/src/utils/mapFill.unit.spec.ts
+++ b/packages/perps-sdk-provider-lighter/src/utils/mapFill.unit.spec.ts
@@ -52,8 +52,14 @@ const PLACEHOLDER_TX_HASH =
 const SETTLED_TX_HASH =
   '3981a9639035409777f73feb18bb96c6c07fa55127863e58f2319691924a59b0e448ab560c1b135d'
 
+// A market 33 order index above 2^53: `JSON.parse` rounds the numeric twin to
+// ...276, so only the `_str` twin carries the exact id.
+const UNSAFE_ORDER_ID = '9570149379440277'
+const UNSAFE_ORDER_ID_PARSED = 9570149379440276
+
 const baseTrade = (overrides: Partial<LtTrade> = {}): LtTrade => ({
   trade_id: 7,
+  trade_id_str: '7',
   tx_hash: '0xabc',
   type: 'trade',
   market_id: 1,
@@ -62,6 +68,10 @@ const baseTrade = (overrides: Partial<LtTrade> = {}): LtTrade => ({
   usd_amount: NOTIONAL,
   ask_id: 100,
   bid_id: 200,
+  ask_id_str: '100',
+  bid_id_str: '200',
+  ask_client_id_str: '0',
+  bid_client_id_str: '0',
   ask_account_id: 0,
   bid_account_id: ACCOUNT_INDEX,
   is_maker_ask: false,
@@ -81,10 +91,17 @@ const baseTrade = (overrides: Partial<LtTrade> = {}): LtTrade => ({
 })
 
 describe('mapFill (Lighter)', () => {
-  it('stringifies trade_id into Fill.id', () => {
+  it('reads Fill.id from trade_id_str, not the rounded trade_id', () => {
     expect(
-      mapValidFill(baseTrade({ trade_id: 7 }), ACCOUNT_INDEX, MARKET).id
-    ).toBe('7')
+      mapValidFill(
+        baseTrade({
+          trade_id: UNSAFE_ORDER_ID_PARSED,
+          trade_id_str: UNSAFE_ORDER_ID,
+        }),
+        ACCOUNT_INDEX,
+        MARKET
+      ).id
+    ).toBe(UNSAFE_ORDER_ID)
   })
 
   it('carries the resolved market identity onto the fill verbatim', () => {
@@ -444,33 +461,35 @@ describe('mapFill (Lighter)', () => {
     })
   })
 
-  describe('orderId selects bid_id / ask_id by viewer side', () => {
-    it('buyer path: viewer on bid → orderId from bid_id', () => {
+  describe('orderId selects bid_id_str / ask_id_str by viewer side', () => {
+    it('buyer path: viewer on bid → orderId from bid_id_str', () => {
       const fill = mapValidFill(
         baseTrade({
           bid_account_id: ACCOUNT_INDEX,
           ask_account_id: 0,
-          bid_id: 42,
-          ask_id: 99,
+          bid_id: UNSAFE_ORDER_ID_PARSED,
+          bid_id_str: UNSAFE_ORDER_ID,
+          ask_id_str: '99',
         }),
         ACCOUNT_INDEX,
         MARKET
       )
-      expect(fill.orderId).toBe('42')
+      expect(fill.orderId).toBe(UNSAFE_ORDER_ID)
     })
 
-    it('seller path: viewer on ask → orderId from ask_id', () => {
+    it('seller path: viewer on ask → orderId from ask_id_str', () => {
       const fill = mapValidFill(
         baseTrade({
           ask_account_id: ACCOUNT_INDEX,
           bid_account_id: 0,
-          bid_id: 42,
-          ask_id: 77,
+          ask_id: UNSAFE_ORDER_ID_PARSED,
+          ask_id_str: UNSAFE_ORDER_ID,
+          bid_id_str: '42',
         }),
         ACCOUNT_INDEX,
         MARKET
       )
-      expect(fill.orderId).toBe('77')
+      expect(fill.orderId).toBe(UNSAFE_ORDER_ID)
     })
   })
 
diff --git a/packages/perps-sdk-provider-lighter/src/utils/mapOrder.ts b/packages/perps-sdk-provider-lighter/src/utils/mapOrder.ts
index 2bdc2b78..2efb543e 100644
--- a/packages/perps-sdk-provider-lighter/src/utils/mapOrder.ts
+++ b/packages/perps-sdk-provider-lighter/src/utils/mapOrder.ts
@@ -20,6 +20,9 @@ import { LIGHTER_PROVIDER_KEY } from '../constants.js'
 import type { LtOrder } from '../types/index.js'
 import { rowTimestampToIsoStringOrUndefined } from './rowTimestamp.js'
 
+// Lighter sends client index 0 as the string "0" for an order placed without one.
+const NO_CLIENT_ORDER_ID = '0'
+
 const mapOrderType = (type: string): Order['type'] => {
   switch (type.replace(/-/g, '_')) {
     case 'market':
@@ -142,10 +145,10 @@ export const mapOrder = (
       : undefined
   const status = mapOrderStatus(order)
   const base: OrderBase = {
-    orderId: String(order.order_index),
-    ...(order.client_order_index === 0
+    orderId: order.order_id,
+    ...(order.client_order_id === NO_CLIENT_ORDER_ID
       ? {}
-      : { clientOrderId: String(order.client_order_index) }),
+      : { clientOrderId: order.client_order_id }),
     market,
     side: order.is_ask ? OrderSide.SELL : OrderSide.BUY,
     status,
@@ -218,12 +221,12 @@ export const mapOrderUpdates = (
       wsLog.droppedRow(
         LIGHTER_PROVIDER_KEY,
         'order',
-        `${raw.order_index}: ${error.message}`
+        `${raw.order_id}: ${error.message}`
       )
       continue
     }
     if (!isActiveOrderStatus(status)) {
-      terminated.push(String(raw.order_index))
+      terminated.push(raw.order_id)
     }
     if (order !== undefined) {
       orders.push(order)
diff --git a/packages/perps-sdk-provider-lighter/src/utils/mapOrder.unit.spec.ts b/packages/perps-sdk-provider-lighter/src/utils/mapOrder.unit.spec.ts
index 19c36475..745cf182 100644
--- a/packages/perps-sdk-provider-lighter/src/utils/mapOrder.unit.spec.ts
+++ b/packages/perps-sdk-provider-lighter/src/utils/mapOrder.unit.spec.ts
@@ -29,10 +29,15 @@ const MARKET: MarketDisplay = {
   },
 }
 
+// A market 33 order index above 2^53: `JSON.parse` rounds the numeric twin to
+// ...276, so only the string twin carries the exact id.
+const UNSAFE_ORDER_ID = '9570149379440277'
+const UNSAFE_ORDER_ID_PARSED = 9570149379440276
+
 const baseOrder = (overrides: Partial<LtOrder> = {}): LtOrder => ({
   order_index: 1,
   client_order_index: 0,
-  order_id: 'lt-1',
+  order_id: '1',
   client_order_id: '0',
   market_index: 1,
   owner_account_index: 42,
@@ -67,13 +72,30 @@ const baseOrder = (overrides: Partial<LtOrder> = {}): LtOrder => ({
 
 describe('mapOrder (Lighter)', () => {
   it('separates the venue id and client id and omits an absent client id', () => {
-    const order = mapOrder(baseOrder({ client_order_index: 77 }), MARKET)
+    const order = mapOrder(
+      baseOrder({ client_order_index: 77, client_order_id: '77' }),
+      MARKET
+    )
     expect(order?.orderId).toBe('1')
     expect(order?.clientOrderId).toBe('77')
     expect(mapOrder(baseOrder(), MARKET)).not.toHaveProperty('clientOrderId')
     expect(order).not.toHaveProperty('explorerLink')
   })
 
+  it('reads orderId and clientOrderId from the string ids, not the rounded indexes', () => {
+    const order = mapOrder(
+      baseOrder({
+        order_index: UNSAFE_ORDER_ID_PARSED,
+        order_id: UNSAFE_ORDER_ID,
+        client_order_index: UNSAFE_ORDER_ID_PARSED,
+        client_order_id: UNSAFE_ORDER_ID,
+      }),
+      MARKET
+    )
+    expect(order?.orderId).toBe(UNSAFE_ORDER_ID)
+    expect(order?.clientOrderId).toBe(UNSAFE_ORDER_ID)
+  })
+
   it('maps a parent-dependent trigger with its parent id', () => {
     expect(
       mapOrder(
@@ -384,9 +406,10 @@ describe('mapOrderUpdates (Lighter)', () => {
     const result = mapOrderUpdates(
       [
         baseOrder(),
-        baseOrder({ order_index: 2, status: 'filled' }),
+        baseOrder({ order_index: 2, order_id: '2', status: 'filled' }),
         baseOrder({
           order_index: 3,
+          order_id: '3',
           type: 'take-profit',
           trigger_status: 'parent-order',
           parent_order_id: '1',
@@ -408,8 +431,8 @@ describe('mapOrderUpdates (Lighter)', () => {
     const warn = vi.spyOn(console, 'warn').mockImplementation(() => {})
     const result = mapOrderUpdates(
       [
-        baseOrder({ order_index: 7, type: 'unknown' }),
-        baseOrder({ order_index: 8 }),
+        baseOrder({ order_index: 7, order_id: '7', type: 'unknown' }),
+        baseOrder({ order_index: 8, order_id: '8' }),
       ],
       () => MARKET
     )
@@ -438,12 +461,39 @@ describe('mapOrderUpdates (Lighter)', () => {
   it('skips rows with no registered market but retains terminal eviction ids', () => {
     expect(
       mapOrderUpdates(
-        [baseOrder(), baseOrder({ order_index: 2, status: 'filled' })],
+        [
+          baseOrder(),
+          baseOrder({ order_index: 2, order_id: '2', status: 'filled' }),
+        ],
         () => undefined
       )
     ).toEqual({ orders: [], terminated: ['2'] })
   })
 
+  it('evicts and warns with the string order id, not the rounded index', () => {
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {})
+    const result = mapOrderUpdates(
+      [
+        baseOrder({
+          order_index: UNSAFE_ORDER_ID_PARSED,
+          order_id: UNSAFE_ORDER_ID,
+          status: 'filled',
+        }),
+        baseOrder({
+          order_index: UNSAFE_ORDER_ID_PARSED,
+          order_id: UNSAFE_ORDER_ID,
+          type: 'unknown',
+        }),
+      ],
+      () => MARKET
+    )
+    expect(result.terminated).toEqual([UNSAFE_ORDER_ID])
+    expect(warn).toHaveBeenCalledWith(
+      `[lighter:ws] skipping order row: ${UNSAFE_ORDER_ID}: Unknown Lighter order type: unknown`
+    )
+    warn.mockRestore()
+  })
+
   it('skips a pre-book row with no registered market and evicts nothing', () => {
     expect(
       mapOrderUpdates([baseOrder({ status: 'in-progress' })], () => undefined)
diff --git a/packages/perps-sdk-provider-lighter/src/websocket/LighterWsProvider.unit.spec.ts b/packages/perps-sdk-provider-lighter/src/websocket/LighterWsProvider.unit.spec.ts
index 04e299c6..8068dc90 100644
--- a/packages/perps-sdk-provider-lighter/src/websocket/LighterWsProvider.unit.spec.ts
+++ b/packages/perps-sdk-provider-lighter/src/websocket/LighterWsProvider.unit.spec.ts
@@ -12,6 +12,7 @@ import {
 } from '../constants.js'
 import { lighterProvider } from '../LighterProvider.js'
 import type { LtWsUserStatsMessage } from '../types/index.js'
+import { mapFill, mapOrder } from '../utils/index.js'
 import { LighterWsProvider, lighterWsProvider } from './LighterWsProvider.js'
 
 type LighterWsProviderInternals = {
@@ -43,8 +44,8 @@ const marketsFailureResponse = () =>
 const RAW_ORDER = {
   order_index: 1,
   client_order_index: 0,
-  order_id: 'ord1',
-  client_order_id: '',
+  order_id: '1',
+  client_order_id: '0',
   market_index: 0,
   owner_account_index: 42,
   initial_base_amount: '1.0',
@@ -72,6 +73,7 @@ const RAW_ORDER = {
 
 const RAW_TRADE = {
   trade_id: 1,
+  trade_id_str: '1',
   tx_hash: '0xabc',
   type: 'trade',
   market_id: 0,
@@ -80,6 +82,10 @@ const RAW_TRADE = {
   usd_amount: '25000',
   ask_id: 1,
   bid_id: 2,
+  ask_id_str: '1',
+  bid_id_str: '2',
+  ask_client_id_str: '0',
+  bid_client_id_str: '0',
   ask_account_id: 99,
   bid_account_id: 42,
   is_maker_ask: true,
@@ -115,6 +121,10 @@ const RAW_POSITION = {
 
 const TEST_ADDR = '0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef'
 const ACCOUNT_IDX = 42
+// A market 33 order index above 2^53: `JSON.parse` rounds the numeric twin to
+// ...276, so only the string twin carries the exact id.
+const UNSAFE_ORDER_ID = '9570149379440277'
+const UNSAFE_ORDER_ID_PARSED = 9570149379440276
 const LAST_FUNDING_PAYMENT_TIME = 1704067200000
 const NEXT_FUNDING_PAYMENT_TIME = 1704070800000
 
@@ -508,6 +518,7 @@ describe('LighterWsProvider', () => {
           trades: [
             {
               trade_id: 16164557907,
+              trade_id_str: '16164557907',
               size: '0.1336',
               price: '2181.83',
               is_maker_ask: false,
@@ -815,7 +826,12 @@ describe('LighterWsProvider', () => {
                 remaining_base_amount: '0.4',
                 filled_base_amount: '0.6',
               },
-              { ...RAW_ORDER, order_index: 2, status: 'canceled-expired' },
+              {
+                ...RAW_ORDER,
+                order_index: 2,
+                order_id: '2',
+                status: 'canceled-expired',
+              },
             ],
           },
         })
@@ -845,10 +861,11 @@ describe('LighterWsProvider', () => {
           channel: `account_all_orders:${ACCOUNT_IDX}`,
           orders: {
             '99': [
-              { ...RAW_ORDER, order_index: 3, market_index: 99 },
+              { ...RAW_ORDER, order_index: 3, order_id: '3', market_index: 99 },
               {
                 ...RAW_ORDER,
                 order_index: 4,
+                order_id: '4',
                 market_index: 99,
                 status: 'canceled-expired',
               },
@@ -869,7 +886,12 @@ describe('LighterWsProvider', () => {
       const listener = vi.fn()
       inject(p, `orderUpdates:${TEST_ADDR}`, listener)
 
-      const ethOrder = { ...RAW_ORDER, order_id: 'ord2', market_index: 1 }
+      const ethOrder = {
+        ...RAW_ORDER,
+        order_index: 2,
+        order_id: '2',
+        market_index: 1,
+      }
       ;(p as any).handleMessage(
         JSON.stringify({
           type: 'update/account_all_orders',
@@ -906,6 +928,69 @@ describe('LighterWsProvider', () => {
       p.close()
     })
 
+    it('emits the exact ids above 2^53 that the REST mappers produce', async () => {
+      const p = makeProvider()
+      await seedAccountAndMarkets(p)
+      const fillListener = vi.fn()
+      const orderListener = vi.fn()
+      inject(p, `fills:${TEST_ADDR}`, fillListener)
+      inject(p, `orderUpdates:${TEST_ADDR}`, orderListener)
+
+      // The wire carries the exact numeric twin; `JSON.parse` rounds it.
+      const toWire = (frame: unknown): string =>
+        JSON.stringify(frame).replaceAll(
+          String(UNSAFE_ORDER_ID_PARSED),
+          UNSAFE_ORDER_ID
+        )
+      const tradeFrame = toWire({
+        type: 'update/account_all_trades',
+        channel: `account_all_trades:${ACCOUNT_IDX}`,
+        trades: {
+          '0': [
+            {
+              ...RAW_TRADE,
+              trade_id: UNSAFE_ORDER_ID_PARSED,
+              trade_id_str: UNSAFE_ORDER_ID,
+              bid_id: UNSAFE_ORDER_ID_PARSED,
+              bid_id_str: UNSAFE_ORDER_ID,
+            },
+          ],
+        },
+      })
+      const orderFrame = toWire({
+        type: 'update/account_all_orders',
+        channel: `account_all_orders:${ACCOUNT_IDX}`,
+        orders: {
+          '0': [
+            {
+              ...RAW_ORDER,
+              order_index: UNSAFE_ORDER_ID_PARSED,
+              order_id: UNSAFE_ORDER_ID,
+              client_order_index: UNSAFE_ORDER_ID_PARSED,
+              client_order_id: UNSAFE_ORDER_ID,
+            },
+          ],
+        },
+      })
+      const internals = p as unknown as LighterWsProviderInternals
+      internals.handleMessage(tradeFrame)
+      internals.handleMessage(orderFrame)
+
+      const [fill] = fillListener.mock.calls[0][0].data
+      expect(fill.id).toBe(UNSAFE_ORDER_ID)
+      expect(fill.orderId).toBe(UNSAFE_ORDER_ID)
+      expect(fill).toEqual(
+        mapFill(JSON.parse(tradeFrame).trades['0'][0], ACCOUNT_IDX, fill.market)
+      )
+      const [order] = orderListener.mock.calls[0][0].data.orders
+      expect(order.orderId).toBe(UNSAFE_ORDER_ID)
+      expect(order.clientOrderId).toBe(UNSAFE_ORDER_ID)
+      expect(order).toEqual(
+        mapOrder(JSON.parse(orderFrame).orders['0'][0], order.market)
+      )
+      p.close()
+    })
+
     it('emits fills with empty array on initial subscribed snapshot (trades: [])', async () => {
       const p = makeProvider()
       await seedAccountAndMarkets(p)