fix(shared): align todo contracts with the wire format the client sends

The optional metadata fields (category, due_date, description,
assigned_user_id — plus priority on update) now accept explicit null: the
client clears fields by sending null, which the schemas rejected. checked
accepts the legacy 0/1 numeric form alongside boolean (the integration net
pins it). Drops the client-side casts that papered over the too-narrow
types.

shared/src/todo/todo.schema.spec.ts

@@ -17,6 +17,18 @@ describe('todoCreateItemRequestSchema', () => {
     // priority is numeric (matches the service), not a string
     expect(todoCreateItemRequestSchema.safeParse({ name: 'X', priority: 'high' }).success).toBe(false);
   });
+
+  it('accepts explicit null on the optional metadata fields (client clears with null)', () => {
+    expect(
+      todoCreateItemRequestSchema.safeParse({
+        name: 'X',
+        category: null,
+        due_date: null,
+        description: null,
+        assigned_user_id: null,
+      }).success,
+    ).toBe(true);
+  });
 });
 
 describe('todoUpdateItemRequestSchema', () => {
@@ -24,6 +36,25 @@ describe('todoUpdateItemRequestSchema', () => {
     expect(todoUpdateItemRequestSchema.safeParse({}).success).toBe(true);
     expect(todoUpdateItemRequestSchema.safeParse({ checked: true }).success).toBe(true);
   });
+
+  it('accepts checked as 0/1 (legacy numeric form) but rejects other numbers', () => {
+    expect(todoUpdateItemRequestSchema.safeParse({ checked: 1 }).success).toBe(true);
+    expect(todoUpdateItemRequestSchema.safeParse({ checked: 0 }).success).toBe(true);
+    expect(todoUpdateItemRequestSchema.safeParse({ checked: 2 }).success).toBe(false);
+  });
+
+  it('accepts explicit null on the nullable fields (bodyKeys clear protocol)', () => {
+    expect(
+      todoUpdateItemRequestSchema.safeParse({
+        category: null,
+        due_date: null,
+        description: null,
+        assigned_user_id: null,
+        priority: null,
+      }).success,
+    ).toBe(true);
+    expect(todoUpdateItemRequestSchema.safeParse({ name: null }).success).toBe(false);
+  });
 });
 
 describe('todoReorderRequestSchema', () => {

shared/src/todo/todo.schema.ts

@@ -12,22 +12,27 @@ import { z } from 'zod';
 
 export const todoCreateItemRequestSchema = z.object({
   name: z.string().min(1),
-  category: z.string().optional(),
-  due_date: z.string().optional(),
-  description: z.string().optional(),
-  assigned_user_id: z.number().optional(),
+  // The client clears optional fields by sending explicit null (the service
+  // coerces falsy to its defaults), so every optional metadata field is nullable.
+  category: z.string().nullable().optional(),
+  due_date: z.string().nullable().optional(),
+  description: z.string().nullable().optional(),
+  assigned_user_id: z.number().nullable().optional(),
   priority: z.number().optional(),
 });
 export type TodoCreateItemRequest = z.infer<typeof todoCreateItemRequestSchema>;
 
 export const todoUpdateItemRequestSchema = z.object({
   name: z.string().optional(),
-  checked: z.boolean().optional(),
-  category: z.string().optional(),
-  due_date: z.string().optional(),
-  description: z.string().optional(),
-  assigned_user_id: z.number().optional(),
-  priority: z.number().optional(),
+  // The legacy route accepted both boolean and 0/1 for checked — both stay valid.
+  checked: z.union([z.boolean(), z.number().int().min(0).max(1)]).optional(),
+  // Nullable fields follow the bodyKeys protocol: a key present with null
+  // clears the field, an omitted key leaves it unchanged.
+  category: z.string().nullable().optional(),
+  due_date: z.string().nullable().optional(),
+  description: z.string().nullable().optional(),
+  assigned_user_id: z.number().nullable().optional(),
+  priority: z.number().nullable().optional(),
 });
 export type TodoUpdateItemRequest = z.infer<typeof todoUpdateItemRequestSchema>;