fix(dynamodb): treat a number as exact only when its string form round-trips

A decimal like 1.0000000000000000001 parses to a safe integer, so the safe-integer
shortcut dropped its digits. Return a JS number only when String(parsed) equals the
DynamoDB value (and it is not an unsafe integer); item output is unchanged.

Author: waleedlatif1

apps/sim/lib/internal/dynamodb/client.test.ts

@@ -81,6 +81,7 @@ describe('DynamoDB item unmarshalling', () => {
         bin: { B: new Uint8Array([104, 105]) },
         age: { N: '42' },
         ratio: { N: '0.12345678901234567890123' },
+        nearOne: { N: '1.0000000000000000001' },
       },
     })
     const firstPage = await queryItems(pageClient, 'Users', 'pk = :pk', {
@@ -93,6 +94,7 @@ describe('DynamoDB item unmarshalling', () => {
       bin: { B: 'aGk=' },
       age: 42,
       ratio: { N: '0.12345678901234567890123' },
+      nearOne: { N: '1.0000000000000000001' },
     })
 
     let sentStartKey: unknown
@@ -110,6 +112,7 @@ describe('DynamoDB item unmarshalling', () => {
       bin: { B: new Uint8Array([104, 105]) },
       age: { N: '42' },
       ratio: { N: '0.12345678901234567890123' },
+      nearOne: { N: '1.0000000000000000001' },
     })
     pageClient.destroy()
     client.destroy()

apps/sim/lib/internal/dynamodb/client.ts

@@ -23,10 +23,8 @@ type DynamoDBReturnValues = 'NONE' | 'ALL_OLD' | 'UPDATED_OLD' | 'ALL_NEW' | 'UP
  */
 function unwrapNumber(value: string): number | NumberValue {
   const parsed = Number(value)
-  if (Number.isSafeInteger(parsed)) return parsed
-  if (Number.isFinite(parsed) && !Number.isInteger(parsed) && String(parsed) === value) {
-    return parsed
-  }
+  const exact = Number.isFinite(parsed) && String(parsed) === value
+  if (exact && (!Number.isInteger(parsed) || Number.isSafeInteger(parsed))) return parsed
   return NumberValue.from(value)
 }