diff --git a/packages/orm/src/client/contract.ts b/packages/orm/src/client/contract.ts
index 4a451e203..4d54c2e49 100644
--- a/packages/orm/src/client/contract.ts
+++ b/packages/orm/src/client/contract.ts
@@ -28,15 +28,20 @@ import type {
     FindUniqueArgs,
     GroupByArgs,
     GroupByResult,
+    OmitWhere,
     ProcedureFunc,
     SelectSubset,
+    SelectSubsetWithWhere,
     SimplifiedPlainResult,
     Subset,
+    SubsetWithWhere,
     TypeDefResult,
     UpdateArgs,
     UpdateManyAndReturnArgs,
     UpdateManyArgs,
     UpsertArgs,
+    WhereInput,
+    WhereUniqueInput,
 } from './crud-types';
 import type { Diagnostics } from './diagnostics';
 import type { ClientOptions, QueryOptions } from './options';
@@ -405,8 +410,8 @@ export type AllModelOperations<
                * });
                * ```
                */
-              updateManyAndReturn<T extends UpdateManyAndReturnArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-                  args: Subset<T, UpdateManyAndReturnArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+              updateManyAndReturn<T extends OmitWhere<UpdateManyAndReturnArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+                  args: { where?: WhereInput<Schema, Model, Options> } & SubsetWithWhere<T, OmitWhere<UpdateManyAndReturnArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>,
               ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>[]>;
           });
 
@@ -498,8 +503,8 @@ type CommonModelOperations<
      * }); // result: `{ _count: { posts: number } }`
      * ```
      */
-    findMany<T extends FindManyArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args?: SelectSubset<T, FindManyArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    findMany<T extends OmitWhere<FindManyArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args?: { where?: WhereInput<Schema, Model, Options> } & SelectSubset<T, FindManyArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>[]>;
 
     /**
@@ -508,8 +513,8 @@ type CommonModelOperations<
      * @returns a single entity or null if not found
      * @see {@link findMany}
      */
-    findUnique<T extends FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args: SelectSubset<T, FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    findUnique<T extends OmitWhere<FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args: { where: WhereUniqueInput<Schema, Model, Options> } & SelectSubset<T, FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult> | null>;
 
     /**
@@ -518,8 +523,8 @@ type CommonModelOperations<
      * @returns a single entity
      * @see {@link findMany}
      */
-    findUniqueOrThrow<T extends FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args: SelectSubset<T, FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    findUniqueOrThrow<T extends OmitWhere<FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args: { where: WhereUniqueInput<Schema, Model, Options> } & SelectSubset<T, FindUniqueArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>>;
 
     /**
@@ -528,8 +533,8 @@ type CommonModelOperations<
      * @returns a single entity or null if not found
      * @see {@link findMany}
      */
-    findFirst<T extends FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args?: SelectSubset<T, FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    findFirst<T extends OmitWhere<FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args?: { where?: WhereInput<Schema, Model, Options> } & SelectSubset<T, FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult> | null>;
 
     /**
@@ -538,8 +543,8 @@ type CommonModelOperations<
      * @returns a single entity
      * @see {@link findMany}
      */
-    findFirstOrThrow<T extends FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args?: SelectSubset<T, FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    findFirstOrThrow<T extends OmitWhere<FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args?: { where?: WhereInput<Schema, Model, Options> } & SelectSubset<T, FindFirstArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>>;
 
     /**
@@ -744,8 +749,8 @@ type CommonModelOperations<
      * });
      * ```
      */
-    update<T extends UpdateArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args: SelectSubset<T, UpdateArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    update<T extends OmitWhere<UpdateArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args: { where: WhereUniqueInput<Schema, Model, Options> } & SelectSubsetWithWhere<T, OmitWhere<UpdateArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>>;
 
     /**
@@ -768,8 +773,8 @@ type CommonModelOperations<
      *     limit: 10
      * });
      */
-    updateMany<T extends UpdateManyArgs<Schema, Model, Options, ExtQueryArgs>>(
-        args: Subset<T, UpdateManyArgs<Schema, Model, Options, ExtQueryArgs>>,
+    updateMany<T extends OmitWhere<UpdateManyArgs<Schema, Model, Options, ExtQueryArgs>>>(
+        args: { where?: WhereInput<Schema, Model, Options> } & SubsetWithWhere<T, OmitWhere<UpdateManyArgs<Schema, Model, Options, ExtQueryArgs>>>,
     ): ZenStackPromise<Schema, BatchResult>;
 
     /**
@@ -792,8 +797,8 @@ type CommonModelOperations<
      * });
      * ```
      */
-    upsert<T extends UpsertArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args: SelectSubset<T, UpsertArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    upsert<T extends OmitWhere<UpsertArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args: { where: WhereUniqueInput<Schema, Model, Options> } & SelectSubsetWithWhere<T, OmitWhere<UpsertArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>>;
 
     /**
@@ -815,8 +820,8 @@ type CommonModelOperations<
      * }); // result: `{ id: string; email: string }`
      * ```
      */
-    delete<T extends DeleteArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>(
-        args: SelectSubset<T, DeleteArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
+    delete<T extends OmitWhere<DeleteArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>>(
+        args: { where: WhereUniqueInput<Schema, Model, Options> } & SelectSubset<T, DeleteArgs<Schema, Model, Options, ExtQueryArgs, ExtResult>>,
     ): ZenStackPromise<Schema, SimplifiedPlainResult<Schema, Model, T, Options, ExtResult>>;
 
     /**
@@ -838,8 +843,8 @@ type CommonModelOperations<
      * });
      * ```
      */
-    deleteMany<T extends DeleteManyArgs<Schema, Model, Options, ExtQueryArgs>>(
-        args?: Subset<T, DeleteManyArgs<Schema, Model, Options, ExtQueryArgs>>,
+    deleteMany<T extends OmitWhere<DeleteManyArgs<Schema, Model, Options, ExtQueryArgs>>>(
+        args?: { where?: WhereInput<Schema, Model, Options> } & Subset<T, DeleteManyArgs<Schema, Model, Options, ExtQueryArgs>>,
     ): ZenStackPromise<Schema, BatchResult>;
 
     /**
diff --git a/packages/orm/src/client/crud-types.ts b/packages/orm/src/client/crud-types.ts
index e739575dd..8c8108089 100644
--- a/packages/orm/src/client/crud-types.ts
+++ b/packages/orm/src/client/crud-types.ts
@@ -1104,6 +1104,42 @@ export type SelectSubset<T, U> = {
       ? 'Please either choose `select` or `omit`.'
       : {});
 
+/**
+ * Strips the `where` field from an args type so the remaining fields can be used as
+ * the generic type parameter `T` in CRUD methods, allowing `where` to be typed directly
+ * and benefit from TypeScript's excess property checking.
+ * @internal
+ */
+export type OmitWhere<T> = Omit<T, 'where'>;
+
+/**
+ * Like {@link Subset} but maps the `where` key to `unknown` (instead of `never`) when
+ * `where` is not present in `U`. This is used in CRUD method signatures where `where`
+ * is separately typed as `{ where: WhereXxxInput }`: because TypeScript infers T from
+ * the full argument object (including the `where` field), a naive `Subset<T, OmitWhere<U>>`
+ * would produce `where: never` in the mapped result, collapsing the `where` type in the
+ * intersection to `never`. Mapping to `unknown` instead gives
+ * `{ where: W } & { where: unknown }` = `{ where: W }`, preserving both the correct type
+ * and TypeScript's excess-property checking on `where`.
+ * @internal
+ */
+export type SubsetWithWhere<T, U> = {
+    [key in keyof T]: key extends keyof U ? T[key] : key extends 'where' ? unknown : never;
+};
+
+/**
+ * Like {@link SelectSubset} but maps the `where` key to `unknown` (instead of `never`) when
+ * `where` is not present in `U`. See {@link SubsetWithWhere} for the rationale.
+ * @internal
+ */
+export type SelectSubsetWithWhere<T, U> = {
+    [key in keyof T]: key extends keyof U ? T[key] : key extends 'where' ? unknown : never;
+} & (T extends { select: any; include: any }
+    ? 'Please either choose `select` or `include`.'
+    : T extends { select: any; omit: any }
+      ? 'Please either choose `select` or `omit`.'
+      : {});
+
 type ToManyRelationFilter<
     Schema extends SchemaDef,
     Model extends GetModels<Schema>,
diff --git a/tests/e2e/orm/schemas/delegate/typecheck.ts b/tests/e2e/orm/schemas/delegate/typecheck.ts
index 76e36115f..c17981818 100644
--- a/tests/e2e/orm/schemas/delegate/typecheck.ts
+++ b/tests/e2e/orm/schemas/delegate/typecheck.ts
@@ -176,11 +176,48 @@ async function queryBuilder() {
     client.$qb.selectFrom('Video').select(['viewCount']).execute();
 }
 
+async function whereEPC() {
+    // unknown fields in `where` clause should produce a TypeScript error
+    await client.asset.findMany({
+        where: {
+            viewCount: 1,
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+    });
+
+    await client.asset.findFirst({
+        where: {
+            viewCount: 1,
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+    });
+
+    // valid fields should not produce errors
+    await client.asset.findMany({
+        where: {
+            viewCount: { gt: 0 },
+        },
+    });
+
+    // unknown fields in `where` clause for update should also produce TypeScript errors
+    await client.asset.update({
+        where: {
+            id: 1,
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+        data: { viewCount: 2 },
+    });
+}
+
 async function main() {
     await create();
     await update();
     await find();
     await queryBuilder();
+    await whereEPC();
 }
 
 main();
diff --git a/tests/e2e/orm/schemas/typing/typecheck.ts b/tests/e2e/orm/schemas/typing/typecheck.ts
index 9f8b2aa86..d28059153 100644
--- a/tests/e2e/orm/schemas/typing/typecheck.ts
+++ b/tests/e2e/orm/schemas/typing/typecheck.ts
@@ -220,6 +220,30 @@ async function find() {
     console.log(u.posts[0]?.author?.role);
     // @ts-expect-error
     console.log(u.posts[0]?.author?.email);
+
+    // unknown fields in `where` clause should produce TypeScript errors
+    await client.user.findMany({
+        where: {
+            email: 'test@test.com',
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+    });
+
+    await client.user.findFirst({
+        where: {
+            email: 'test@test.com',
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+    });
+
+    // valid where fields should not produce errors
+    await client.user.findMany({
+        where: {
+            email: { contains: '@test.com' },
+        },
+    });
 }
 
 async function create() {
@@ -554,6 +578,35 @@ async function update() {
             email: 'alex@zenstack.dev',
         },
     });
+
+    // unknown fields in `where` clause should produce TypeScript errors for update/upsert/updateMany
+    await client.user.update({
+        where: {
+            id: 1,
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+        data: { name: 'Alex' },
+    });
+
+    await client.user.upsert({
+        where: {
+            id: 1,
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+        create: { name: 'Alex', email: 'alex@zenstack.dev' },
+        update: { name: 'Alex New' },
+    });
+
+    await client.user.updateMany({
+        where: {
+            email: 'test@test.com',
+            // @ts-expect-error notExistsColumn is not a valid field
+            notExistsColumn: 1,
+        },
+        data: { name: 'Alex' },
+    });
 }
 
 async function del() {