diff --git a/CLAUDE.md b/CLAUDE.md
index 6f74cd60a..04e18dee4 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -20,6 +20,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 ### Testing
 
 - E2E tests are in `tests/e2e/` directory
+- Regression tests for GitHub issues go in `tests/regression/test/` as `issue-{number}.test.ts`
 
 ### ZenStack CLI Commands
 
diff --git a/packages/orm/src/client/crud/dialects/base-dialect.ts b/packages/orm/src/client/crud/dialects/base-dialect.ts
index 0f204817f..3ab2d4979 100644
--- a/packages/orm/src/client/crud/dialects/base-dialect.ts
+++ b/packages/orm/src/client/crud/dialects/base-dialect.ts
@@ -34,6 +34,7 @@ import {
     requireIdFields,
     requireModel,
     requireTypeDef,
+    tmpAlias,
 } from '../../query-utils';
 
 export abstract class BaseCrudDialect<Schema extends SchemaDef> {
@@ -298,7 +299,7 @@ export abstract class BaseCrudDialect<Schema extends SchemaDef> {
             }
         }
 
-        const joinAlias = `${modelAlias}$${field}`;
+        const joinAlias = tmpAlias(`${modelAlias}$${field}`);
         const joinPairs = buildJoinPairs(
             this.schema,
             model,
@@ -307,7 +308,7 @@ export abstract class BaseCrudDialect<Schema extends SchemaDef> {
             field,
             joinAlias,
         );
-        const filterResultField = `${field}$filter`;
+        const filterResultField = tmpAlias(`${field}$flt`);
 
         const joinSelect = this.eb
             .selectFrom(`${fieldDef.type} as ${joinAlias}`)
@@ -383,7 +384,7 @@ export abstract class BaseCrudDialect<Schema extends SchemaDef> {
 
         // evaluating the filter involves creating an inner select,
         // give it an alias to avoid conflict
-        const relationFilterSelectAlias = `${modelAlias}$${field}$filter`;
+        const relationFilterSelectAlias = tmpAlias(`${modelAlias}$${field}$flt`);
 
         const buildPkFkWhereRefs = (eb: ExpressionBuilder<any, any>) => {
             const m2m = getManyToManyRelation(this.schema, model, field);
@@ -1083,7 +1084,7 @@ export abstract class BaseCrudDialect<Schema extends SchemaDef> {
                             );
                             const sort = this.negateSort(value._count, negated);
                             result = result.orderBy((eb) => {
-                                const subQueryAlias = `${modelAlias}$orderBy$${field}$count`;
+                                const subQueryAlias = tmpAlias(`${modelAlias}$ob$${field}$ct`);
                                 let subQuery = this.buildSelectModel(relationModel, subQueryAlias);
                                 const joinPairs = buildJoinPairs(this.schema, model, modelAlias, field, subQueryAlias);
                                 subQuery = subQuery.where(() =>
@@ -1099,7 +1100,7 @@ export abstract class BaseCrudDialect<Schema extends SchemaDef> {
                         }
                     } else {
                         // order by to-one relation
-                        const joinAlias = `${modelAlias}$orderBy$${index}`;
+                        const joinAlias = tmpAlias(`${modelAlias}$ob$${index}`);
                         result = result.leftJoin(`${relationModel} as ${joinAlias}`, (join) => {
                             const joinPairs = buildJoinPairs(this.schema, model, modelAlias, field, joinAlias);
                             return join.on((eb) =>
diff --git a/packages/orm/src/client/crud/dialects/lateral-join-dialect-base.ts b/packages/orm/src/client/crud/dialects/lateral-join-dialect-base.ts
index 65f2d9cec..94f29b20a 100644
--- a/packages/orm/src/client/crud/dialects/lateral-join-dialect-base.ts
+++ b/packages/orm/src/client/crud/dialects/lateral-join-dialect-base.ts
@@ -11,6 +11,7 @@ import {
     requireField,
     requireIdFields,
     requireModel,
+    tmpAlias,
 } from '../../query-utils';
 import { BaseCrudDialect } from './base-dialect';
 
@@ -31,7 +32,7 @@ export abstract class LateralJoinDialectBase<Schema extends SchemaDef> extends B
         parentAlias: string,
         payload: true | FindArgs<Schema, GetModels<Schema>, any, true>,
     ): SelectQueryBuilder<any, any, any> {
-        const relationResultName = `${parentAlias}$${relationField}`;
+        const relationResultName = tmpAlias(`${parentAlias}$${relationField}`);
         const joinedQuery = this.buildRelationJSON(
             model,
             query,
@@ -56,7 +57,7 @@ export abstract class LateralJoinDialectBase<Schema extends SchemaDef> extends B
 
         return qb.leftJoinLateral(
             (eb) => {
-                const relationSelectName = `${resultName}$sub`;
+                const relationSelectName = tmpAlias(`${resultName}$sub`);
                 const relationModelDef = requireModel(this.schema, relationModel);
 
                 let tbl: SelectQueryBuilder<any, any, any>;
diff --git a/packages/orm/src/client/crud/dialects/mysql.ts b/packages/orm/src/client/crud/dialects/mysql.ts
index 45e4aaea1..e9ca2e4aa 100644
--- a/packages/orm/src/client/crud/dialects/mysql.ts
+++ b/packages/orm/src/client/crud/dialects/mysql.ts
@@ -306,7 +306,7 @@ export class MySqlCrudDialect<Schema extends SchemaDef> extends LateralJoinDiale
         return this.eb.exists(
             this.eb
                 .selectFrom(sql`JSON_TABLE(${receiver}, '$[*]' COLUMNS(value JSON PATH '$'))`.as('$items'))
-                .select(this.eb.lit(1).as('$t'))
+                .select(this.eb.lit(1).as('_'))
                 .where(buildFilter(this.eb.ref('$items.value'))),
         );
     }
diff --git a/packages/orm/src/client/crud/dialects/postgresql.ts b/packages/orm/src/client/crud/dialects/postgresql.ts
index 62b19d3d6..5f962dbb5 100644
--- a/packages/orm/src/client/crud/dialects/postgresql.ts
+++ b/packages/orm/src/client/crud/dialects/postgresql.ts
@@ -352,7 +352,7 @@ export class PostgresCrudDialect<Schema extends SchemaDef> extends LateralJoinDi
         return this.eb.exists(
             this.eb
                 .selectFrom(this.eb.fn('jsonb_array_elements', [receiver]).as('$items'))
-                .select(this.eb.lit(1).as('$t'))
+                .select(this.eb.lit(1).as('_'))
                 .where(buildFilter(this.eb.ref('$items.value'))),
         );
     }
diff --git a/packages/orm/src/client/crud/dialects/sqlite.ts b/packages/orm/src/client/crud/dialects/sqlite.ts
index 93d4f547d..95e2910f8 100644
--- a/packages/orm/src/client/crud/dialects/sqlite.ts
+++ b/packages/orm/src/client/crud/dialects/sqlite.ts
@@ -25,6 +25,7 @@ import {
     requireField,
     requireIdFields,
     requireModel,
+    tmpAlias,
 } from '../../query-utils';
 import { BaseCrudDialect } from './base-dialect';
 
@@ -201,7 +202,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
         const relationModel = relationFieldDef.type as GetModels<Schema>;
         const relationModelDef = requireModel(this.schema, relationModel);
 
-        const subQueryName = `${parentAlias}$${relationField}`;
+        const subQueryName = tmpAlias(`${parentAlias}$${relationField}`);
         let tbl: SelectQueryBuilder<any, any, any>;
 
         if (this.canJoinWithoutNestedSelect(relationModelDef, payload)) {
@@ -214,7 +215,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
             // need to make a nested select on relation model
             tbl = eb.selectFrom(() => {
                 // nested query name
-                const selectModelAlias = `${parentAlias}$${relationField}$sub`;
+                const selectModelAlias = tmpAlias(`${parentAlias}$${relationField}$sub`);
 
                 // select all fields
                 let selectModelQuery = this.buildModelSelect(relationModel, selectModelAlias, payload, true);
@@ -268,7 +269,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
                                 const subJson = this.buildCountJson(
                                     relationModel,
                                     eb,
-                                    `${parentAlias}$${relationField}`,
+                                    tmpAlias(`${parentAlias}$${relationField}`),
                                     value,
                                 );
                                 return [sql.lit(field), subJson];
@@ -279,7 +280,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
                                         relationModel,
                                         eb,
                                         field,
-                                        `${parentAlias}$${relationField}`,
+                                        tmpAlias(`${parentAlias}$${relationField}`),
                                         value,
                                     );
                                     return [sql.lit(field), subJson];
@@ -305,7 +306,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
                                 relationModel,
                                 eb,
                                 field,
-                                `${parentAlias}$${relationField}`,
+                                tmpAlias(`${parentAlias}$${relationField}`),
                                 value,
                             );
                             return [sql.lit(field), subJson];
@@ -440,7 +441,7 @@ export class SqliteCrudDialect<Schema extends SchemaDef> extends BaseCrudDialect
         return this.eb.exists(
             this.eb
                 .selectFrom(this.eb.fn('json_each', [receiver]).as('$items'))
-                .select(this.eb.lit(1).as('$t'))
+                .select(this.eb.lit(1).as('_'))
                 .where(buildFilter(this.eb.ref('$items.value'))),
         );
     }
diff --git a/packages/orm/src/client/crud/operations/base.ts b/packages/orm/src/client/crud/operations/base.ts
index 0314bcf95..e38ca4369 100644
--- a/packages/orm/src/client/crud/operations/base.ts
+++ b/packages/orm/src/client/crud/operations/base.ts
@@ -260,23 +260,23 @@ export abstract class BaseOperationHandler<Schema extends SchemaDef> {
                     .exists(
                         this.dialect
                             .buildSelectModel(model, model)
-                            .select(sql.lit(1).as('$t'))
+                            .select(sql.lit(1).as('_'))
                             .where(() => this.dialect.buildFilter(model, model, filter)),
                     )
-                    .as('exists'),
+                    .as('$exists'),
             )
             .modifyEnd(this.makeContextComment({ model, operation: 'read' }));
 
-        let result: { exists: number | boolean }[] = [];
+        let result: { $exists: number | boolean }[] = [];
         const compiled = kysely.getExecutor().compileQuery(query.toOperationNode(), createQueryId());
         try {
             const r = await kysely.getExecutor().executeQuery(compiled);
-            result = r.rows as { exists: number | boolean }[];
+            result = r.rows as { $exists: number | boolean }[];
         } catch (err) {
             throw createDBQueryError(`Failed to execute query: ${err}`, err, compiled.sql, compiled.parameters);
         }
 
-        return !!result[0]?.exists;
+        return !!result[0]?.$exists;
     }
 
     protected async read(
diff --git a/packages/orm/src/client/executor/temp-alias-transformer.ts b/packages/orm/src/client/executor/temp-alias-transformer.ts
new file mode 100644
index 000000000..1a66a260a
--- /dev/null
+++ b/packages/orm/src/client/executor/temp-alias-transformer.ts
@@ -0,0 +1,27 @@
+import { IdentifierNode, OperationNodeTransformer, type OperationNode, type QueryId } from 'kysely';
+import { TEMP_ALIAS_PREFIX } from '../query-utils';
+
+/**
+ * Kysely node transformer that replaces temporary aliases created during query construction with
+ * shorter names while ensuring the same temp alias gets replaced with the same name.
+ */
+export class TempAliasTransformer extends OperationNodeTransformer {
+    private aliasMap = new Map<string, string>();
+
+    run<T extends OperationNode>(node: T): T {
+        this.aliasMap.clear();
+        return this.transformNode(node);
+    }
+
+    protected override transformIdentifier(node: IdentifierNode, queryId?: QueryId): IdentifierNode {
+        if (node.name.startsWith(TEMP_ALIAS_PREFIX)) {
+            let mapped = this.aliasMap.get(node.name);
+            if (!mapped) {
+                mapped = `$$t${this.aliasMap.size + 1}`;
+                this.aliasMap.set(node.name, mapped);
+            }
+            return IdentifierNode.create(mapped);
+        }
+        return super.transformIdentifier(node, queryId);
+    }
+}
diff --git a/packages/orm/src/client/executor/zenstack-query-executor.ts b/packages/orm/src/client/executor/zenstack-query-executor.ts
index 4fa8b1896..b0aab7627 100644
--- a/packages/orm/src/client/executor/zenstack-query-executor.ts
+++ b/packages/orm/src/client/executor/zenstack-query-executor.ts
@@ -39,6 +39,7 @@ import { createDBQueryError, createInternalError, ORMError } from '../errors';
 import type { AfterEntityMutationCallback, OnKyselyQueryCallback } from '../plugin';
 import { requireIdFields, stripAlias } from '../query-utils';
 import { QueryNameMapper } from './name-mapper';
+import { TempAliasTransformer } from './temp-alias-transformer';
 import type { ZenStackDriver } from './zenstack-driver';
 
 type MutationQueryNode = InsertQueryNode | UpdateQueryNode | DeleteQueryNode;
@@ -620,10 +621,24 @@ In such cases, ZenStack cannot reliably determine the IDs of the mutated entitie
             }) as string;
     }
 
+    private processQueryNode<Node extends RootOperationNode>(query: Node): Node {
+        let result = query;
+        result = this.processNameMapping(result);
+        result = this.processTempAlias(result);
+        return result;
+    }
+
     private processNameMapping<Node extends RootOperationNode>(query: Node): Node {
         return this.nameMapper?.transformNode(query) ?? query;
     }
 
+    private processTempAlias<Node extends RootOperationNode>(query: Node): Node {
+        if (this.options.useCompactAliasNames === false) {
+            return query;
+        }
+        return new TempAliasTransformer().run(query);
+    }
+
     private createClientForConnection(connection: DatabaseConnection, inTx: boolean) {
         const innerExecutor = this.withConnectionProvider(new SingleConnectionProvider(connection));
         innerExecutor.suppressMutationHooks = true;
@@ -650,8 +665,8 @@ In such cases, ZenStack cannot reliably determine the IDs of the mutated entitie
         queryId?: QueryId,
         parameters?: readonly unknown[],
     ) {
-        // no need to handle mutation hooks, just proceed
-        const finalQuery = this.processNameMapping(query);
+        // run query node processors: name mapping, temp alias renaming, etc.
+        const finalQuery = this.processQueryNode(query);
 
         // inherit the original queryId
         let compiledQuery = this.compileQuery(finalQuery, queryId ?? createQueryId());
diff --git a/packages/orm/src/client/options.ts b/packages/orm/src/client/options.ts
index 2061ebafa..4601598b2 100644
--- a/packages/orm/src/client/options.ts
+++ b/packages/orm/src/client/options.ts
@@ -197,6 +197,12 @@ export type ClientOptions<Schema extends SchemaDef> = QueryOptions<Schema> & {
      * `@@validate`, etc. Defaults to `true`.
      */
     validateInput?: boolean;
+
+    /**
+     * Whether to use compact alias names (e.g., "$t1", "$t2") when transforming ORM queries to SQL.
+     * Defaults to `true`.
+     */
+    useCompactAliasNames?: boolean;
 } & (HasComputedFields<Schema> extends true
         ? {
               /**
diff --git a/packages/orm/src/client/query-utils.ts b/packages/orm/src/client/query-utils.ts
index fb9c39bea..0ea7ea58a 100644
--- a/packages/orm/src/client/query-utils.ts
+++ b/packages/orm/src/client/query-utils.ts
@@ -427,3 +427,16 @@ export function extractFieldName(node: OperationNode) {
         return undefined;
     }
 }
+
+export const TEMP_ALIAS_PREFIX = '$$_';
+
+/**
+ * Create an alias name for a temporary table or column name.
+ */
+export function tmpAlias(name: string) {
+    if (!name.startsWith(TEMP_ALIAS_PREFIX)) {
+        return `${TEMP_ALIAS_PREFIX}${name}`;
+    } else {
+        return name;
+    }
+}
diff --git a/packages/plugins/policy/src/expression-transformer.ts b/packages/plugins/policy/src/expression-transformer.ts
index 3b31bd05c..2a237c5cb 100644
--- a/packages/plugins/policy/src/expression-transformer.ts
+++ b/packages/plugins/policy/src/expression-transformer.ts
@@ -403,7 +403,7 @@ export class ExpressionTransformer<Schema extends SchemaDef> {
 
         return this.transform(expr.left, {
             ...context,
-            memberSelect: SelectionNode.create(AliasNode.create(predicateResult, IdentifierNode.create('$t'))),
+            memberSelect: SelectionNode.create(AliasNode.create(predicateResult, IdentifierNode.create('_'))),
             memberFilter: predicateFilter,
         });
     }
@@ -776,7 +776,7 @@ export class ExpressionTransformer<Schema extends SchemaDef> {
 
         return {
             ...receiver,
-            selections: [SelectionNode.create(AliasNode.create(currNode!, IdentifierNode.create('$t')))],
+            selections: [SelectionNode.create(AliasNode.create(currNode!, IdentifierNode.create('_')))],
         };
     }
 
diff --git a/packages/plugins/policy/src/policy-handler.ts b/packages/plugins/policy/src/policy-handler.ts
index 25545cfc8..aa46be502 100644
--- a/packages/plugins/policy/src/policy-handler.ts
+++ b/packages/plugins/policy/src/policy-handler.ts
@@ -825,13 +825,13 @@ export class PolicyHandler<Schema extends SchemaDef> extends OperationNodeTransf
         const queryA = eb
             .selectFrom(m2m.firstModel)
             .where(eb(eb.ref(`${m2m.firstModel}.${m2m.firstIdField}`), '=', aValue))
-            .select(() => new ExpressionWrapper(filterA).as('$t'));
+            .select(() => new ExpressionWrapper(filterA).as('_'));
 
         const filterB = this.buildPolicyFilter(m2m.secondModel, undefined, 'update');
         const queryB = eb
             .selectFrom(m2m.secondModel)
             .where(eb(eb.ref(`${m2m.secondModel}.${m2m.secondIdField}`), '=', bValue))
-            .select(() => new ExpressionWrapper(filterB).as('$t'));
+            .select(() => new ExpressionWrapper(filterB).as('_'));
 
         // select both conditions in one query
         const queryNode: SelectQueryNode = {
diff --git a/tests/regression/test/issue-2378.test.ts b/tests/regression/test/issue-2378.test.ts
new file mode 100644
index 000000000..2bafd992f
--- /dev/null
+++ b/tests/regression/test/issue-2378.test.ts
@@ -0,0 +1,104 @@
+import { createTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+
+describe('Regression for issue #2378', () => {
+    it('deep nested include should not generate alias names exceeding 63 bytes', async () => {
+        const db = await createTestClient(
+            `
+model RepositoryCases {
+    id         Int       @id @default(autoincrement())
+    templateId Int
+    template   Templates @relation(fields: [templateId], references: [id])
+}
+
+model Templates {
+    id         Int                      @id @default(autoincrement())
+    cases      RepositoryCases[]
+    caseFields TemplateCaseAssignment[]
+}
+
+model TemplateCaseAssignment {
+    id          Int        @id @default(autoincrement())
+    templateId  Int
+    template    Templates  @relation(fields: [templateId], references: [id])
+    caseFieldId Int
+    caseField   CaseFields @relation(fields: [caseFieldId], references: [id])
+}
+
+model CaseFields {
+    id           Int                      @id @default(autoincrement())
+    assignments  TemplateCaseAssignment[]
+    fieldOptions CaseFieldAssignment[]
+}
+
+model CaseFieldAssignment {
+    id            Int          @id @default(autoincrement())
+    caseFieldId   Int
+    caseField     CaseFields   @relation(fields: [caseFieldId], references: [id])
+    fieldOptionId Int
+    fieldOption   FieldOptions @relation(fields: [fieldOptionId], references: [id])
+}
+
+model FieldOptions {
+    id          Int                   @id @default(autoincrement())
+    value       String
+    assignments CaseFieldAssignment[]
+}
+            `,
+        );
+
+        // seed data: RepositoryCases -> Templates -> TemplateCaseAssignment -> CaseFields -> CaseFieldAssignment -> FieldOptions
+        await db.repositoryCases.create({
+            data: {
+                template: {
+                    create: {
+                        caseFields: {
+                            create: {
+                                caseField: {
+                                    create: {
+                                        fieldOptions: {
+                                            create: {
+                                                fieldOption: {
+                                                    create: { value: 'option1' },
+                                                },
+                                            },
+                                        },
+                                    },
+                                },
+                            },
+                        },
+                    },
+                },
+            },
+        });
+
+        // 5-level deep include that previously generated aliases exceeding 63 bytes
+        const result = await db.repositoryCases.findFirst({
+            where: { id: 1 },
+            include: {
+                template: {
+                    include: {
+                        caseFields: {
+                            include: {
+                                caseField: {
+                                    include: {
+                                        fieldOptions: {
+                                            include: {
+                                                fieldOption: true,
+                                            },
+                                        },
+                                    },
+                                },
+                            },
+                        },
+                    },
+                },
+            },
+        });
+
+        expect(result).toBeTruthy();
+        expect(result.template.caseFields).toHaveLength(1);
+        expect(result.template.caseFields[0].caseField.fieldOptions).toHaveLength(1);
+        expect(result.template.caseFields[0].caseField.fieldOptions[0].fieldOption.value).toBe('option1');
+    });
+});