diff --git a/shared/src/collab/collab.schema.spec.ts b/shared/src/collab/collab.schema.spec.ts
index d309b89bc..893560fcf 100644
--- a/shared/src/collab/collab.schema.spec.ts
+++ b/shared/src/collab/collab.schema.spec.ts
@@ -1,5 +1,6 @@
 import {
   collabNoteCreateRequestSchema,
+  collabNoteUpdateRequestSchema,
   collabPollCreateRequestSchema,
   collabPollVoteRequestSchema,
   collabMessageCreateRequestSchema,
@@ -14,6 +15,35 @@ describe('collabNoteCreateRequestSchema', () => {
     expect(collabNoteCreateRequestSchema.safeParse({ title: '' }).success).toBe(false);
     expect(collabNoteCreateRequestSchema.safeParse({}).success).toBe(false);
   });
+
+  it('accepts explicit null for the optional fields (desktop null-clearing)', () => {
+    expect(
+      collabNoteCreateRequestSchema.safeParse({
+        title: 'Idea',
+        content: 'Body',
+        category: null,
+        color: '#6366f1',
+        website: null,
+      }).success,
+    ).toBe(true);
+  });
+});
+
+describe('collabNoteUpdateRequestSchema', () => {
+  it('accepts explicit null for the optional fields (desktop null-clearing)', () => {
+    expect(
+      collabNoteUpdateRequestSchema.safeParse({
+        title: 'Idea',
+        content: null,
+        category: null,
+        color: null,
+        website: null,
+        pinned: 1,
+      }).success,
+    ).toBe(true);
+    expect(collabNoteUpdateRequestSchema.safeParse({ pinned: true }).success).toBe(true);
+    expect(collabNoteUpdateRequestSchema.safeParse({ title: null }).success).toBe(false);
+  });
 });
 
 describe('collabPollCreateRequestSchema', () => {
diff --git a/shared/src/collab/collab.schema.ts b/shared/src/collab/collab.schema.ts
index 38ef7a941..b3a314ffe 100644
--- a/shared/src/collab/collab.schema.ts
+++ b/shared/src/collab/collab.schema.ts
@@ -13,20 +13,24 @@ import { z } from 'zod';
 
 export const collabNoteCreateRequestSchema = z.object({
   title: z.string().min(1),
-  content: z.string().optional(),
-  category: z.string().optional(),
-  color: z.string().optional(),
-  website: z.string().optional(),
+  // The desktop notes form clears optional fields by sending explicit null
+  // (the service coerces falsy to its defaults), so they are all nullable.
+  content: z.string().nullable().optional(),
+  category: z.string().nullable().optional(),
+  color: z.string().nullable().optional(),
+  website: z.string().nullable().optional(),
 });
 export type CollabNoteCreateRequest = z.infer<typeof collabNoteCreateRequestSchema>;
 
 export const collabNoteUpdateRequestSchema = z.object({
   title: z.string().optional(),
-  content: z.string().optional(),
-  category: z.string().optional(),
-  color: z.string().optional(),
+  // Same null-clearing protocol as create (the desktop form resends the whole
+  // note object, with cleared fields as explicit null).
+  content: z.string().nullable().optional(),
+  category: z.string().nullable().optional(),
+  color: z.string().nullable().optional(),
   pinned: z.union([z.boolean(), z.number()]).optional(),
-  website: z.string().optional(),
+  website: z.string().nullable().optional(),
 });
 export type CollabNoteUpdateRequest = z.infer<typeof collabNoteUpdateRequestSchema>;