diff --git a/lib/sea/SeaArrowIpc.ts b/lib/sea/SeaArrowIpc.ts
index 95071895..6e09dcb4 100644
--- a/lib/sea/SeaArrowIpc.ts
+++ b/lib/sea/SeaArrowIpc.ts
@@ -162,6 +162,12 @@ function arrowTypeToTTypeId(field: Field<DataType>): TTypeId {
       return TTypeId.TIMESTAMP_TYPE;
     case 'DECIMAL':
       return TTypeId.DECIMAL_TYPE;
+    // INTERVAL — surface as STRING_TYPE to match the Thrift backend and the
+    // Python kernel connector, both of which report interval columns with a
+    // string type code. The cell value is already rendered to the canonical
+    // interval string (e.g. "2-6" / "3 12:30:15.000000000") by
+    // ArrowResultConverter, which keys off the Arrow value type (not this
+    // synthesized TTypeId), so value formatting is unaffected.
     case 'INTERVAL':
     case 'INTERVAL DAY':
     case 'INTERVAL DAY TO HOUR':
@@ -173,11 +179,10 @@ function arrowTypeToTTypeId(field: Field<DataType>): TTypeId {
     case 'INTERVAL MINUTE':
     case 'INTERVAL MINUTE TO SECOND':
     case 'INTERVAL SECOND':
-      return TTypeId.INTERVAL_DAY_TIME_TYPE;
     case 'INTERVAL YEAR':
     case 'INTERVAL YEAR TO MONTH':
     case 'INTERVAL MONTH':
-      return TTypeId.INTERVAL_YEAR_MONTH_TYPE;
+      return TTypeId.STRING_TYPE;
     case 'ARRAY':
       return TTypeId.ARRAY_TYPE;
     case 'MAP':
@@ -198,10 +203,12 @@ function arrowTypeToTTypeId(field: Field<DataType>): TTypeId {
   if (DataType.isInt(arrowType)) {
     // Duration columns are rewritten to Int64 with a
     // `databricks.arrow.duration_unit` metadata marker (see
-    // `SeaArrowIpcDurationFix.ts`). Surface them as INTERVAL_DAY_TIME
-    // so the converter formats them back into the thrift string form.
+    // `SeaArrowIpcDurationFix.ts`). Surface them as STRING_TYPE (matching the
+    // Thrift backend and Python kernel) — the converter still formats the
+    // value into the thrift INTERVAL DAY-TIME string via the duration_unit
+    // metadata, independent of this type code.
     if (arrowType.bitWidth === 64 && field.metadata.has(DURATION_UNIT_METADATA_KEY)) {
-      return TTypeId.INTERVAL_DAY_TIME_TYPE;
+      return TTypeId.STRING_TYPE;
     }
     switch (arrowType.bitWidth) {
       case 8:
@@ -233,8 +240,10 @@ function arrowTypeToTTypeId(field: Field<DataType>): TTypeId {
   // pairs which the converter formats to thrift's `"Y-M"` / day-time
   // strings.
   if (DataType.isInterval(arrowType)) {
-    // unit 0 = YEAR_MONTH, unit 1 = DAY_TIME, unit 2 = MONTH_DAY_NANO
-    return arrowType.unit === 0 ? TTypeId.INTERVAL_YEAR_MONTH_TYPE : TTypeId.INTERVAL_DAY_TIME_TYPE;
+    // Surface native Arrow interval types as STRING_TYPE too (Thrift / Python
+    // kernel parity). The converter formats the value to the thrift "Y-M" /
+    // day-time string from the Arrow value, independent of this type code.
+    return TTypeId.STRING_TYPE;
   }
   if (DataType.isList(arrowType)) return TTypeId.ARRAY_TYPE;
   if (DataType.isMap(arrowType)) return TTypeId.MAP_TYPE;
diff --git a/lib/sea/SeaErrorMapping.ts b/lib/sea/SeaErrorMapping.ts
index b17d594a..1dcd693a 100644
--- a/lib/sea/SeaErrorMapping.ts
+++ b/lib/sea/SeaErrorMapping.ts
@@ -147,6 +147,20 @@ export function mapKernelErrorToJsError(kErr: KernelErrorShape): ErrorWithSqlSta
       error = new ParameterError(message);
       break;
 
+    case 'SqlError': {
+      // A server-reported SQL execution failure (kernel `SqlError`, e.g. a
+      // bad query, missing table, divide-by-zero, invalid cast). The Thrift
+      // backend surfaces the same situation as `OperationStateError(Error)`
+      // when the operation reaches ERROR_STATE (see DBSQLOperation), so map
+      // SqlError to the same class for backend parity. OperationStateError
+      // extends HiveDriverError, so existing `instanceof HiveDriverError`
+      // catches are unaffected.
+      const stateError = new OperationStateError(OperationStateErrorCode.Error);
+      stateError.message = message;
+      error = stateError;
+      break;
+    }
+
     // All remaining kernel ErrorCode variants map to the base driver error class.
     // M0 intentionally does not introduce new error classes; M1 may add nuance.
     case 'NotFound':
@@ -156,7 +170,6 @@ export function mapKernelErrorToJsError(kErr: KernelErrorShape): ErrorWithSqlSta
     case 'Internal':
     case 'InvalidStatementHandle':
     case 'NetworkError':
-    case 'SqlError':
       error = new HiveDriverError(message);
       break;
 
diff --git a/tests/unit/sea/SeaIntervalParity.test.ts b/tests/unit/sea/SeaIntervalParity.test.ts
index bee5a5b9..c0cab289 100644
--- a/tests/unit/sea/SeaIntervalParity.test.ts
+++ b/tests/unit/sea/SeaIntervalParity.test.ts
@@ -403,12 +403,15 @@ describe('SeaOperationBackend — INTERVAL parity with thrift', () => {
     const backend = new SeaOperationBackend({ statement: stub, context: new ClientContextStub() });
 
     // Round-trip the metadata to confirm we synthesise the right TTypeId.
+    // Interval columns are surfaced as STRING_TYPE — matching the Thrift
+    // backend and the Python kernel connector, both of which report interval
+    // columns with a string type code. The value is still rendered to the
+    // canonical interval string (asserted below), which is what makes this
+    // "interval parity with thrift".
     const metadata = await backend.getResultMetadata();
     expect(metadata.schema?.columns?.[0]?.typeDesc.types?.[0]?.primitiveEntry?.type).to.equal(
-      // INTERVAL_DAY_TIME_TYPE = 30 in TCLIService_types
-      // We assert by importing the enum below to avoid magic numbers.
       // eslint-disable-next-line global-require, @typescript-eslint/no-var-requires
-      require('../../../thrift/TCLIService_types').TTypeId.INTERVAL_DAY_TIME_TYPE,
+      require('../../../thrift/TCLIService_types').TTypeId.STRING_TYPE,
     );
 
     const rows = await backend.fetchChunk({ limit: 100 });