fix(zoho-desk): stop posting null for untouched update_ticket fields

`filterUndefined` strips only `undefined`, but an untouched subBlock never
arrives as `undefined`: the workflow serializer initializes every subBlock value
to `null` (stores/workflows/utils.ts) and extractBlockParams writes those nulls
straight into tool params, with nothing between the serializer and request.body
filtering them.

Reproduced against the real serializer and block with only `status` set:

  basic     {"subject":null,"status":"Closed"}
  advanced  {"subject":null,"status":"Closed","priority":null,...,"cf":null}

`subject` leaks even in basic mode because it declares no `mode`, so
shouldSerializeSubBlock never drops it. Zoho documents subject as a writable
field, so every status-only edit either failed the PATCH or blanked the ticket's
subject; in advanced mode the whole update surface nulled out, including `cf`.

Two things hid this. The empty-PATCH guard was unreachable from the block (the
body always carried at least `subject`), and the existing test called buildBody
with fields *absent* rather than null - the shape the block never produces - so
it could not fail on the real path.

Replaces filterUndefined with a local omitUnset that drops undefined, null, and
'' (a cleared input means "leave unchanged", not "set to empty"). Adds three
tests using the real serializer shape, all verified to fail before the fix.

Also fixes the same null-blindness in the block's param mapping, where
Number(null) === 0 injected from=0 on every operation, and corrects the shared
limit placeholder, which claimed max 100 while list_threads allows 200.

Author: waleedlatif1

apps/sim/blocks/blocks/zoho-desk.ts

@@ -322,7 +322,7 @@ export const ZohoDeskBlock: BlockConfig<ZohoDeskResponse> = {
       id: 'limit',
       title: 'Limit',
       type: 'short-input',
-      placeholder: 'Max results (max 100)',
+      placeholder: 'Max results (tickets/comments 100, threads 200)',
       condition: {
         field: 'operation',
         value: ['list_tickets', 'list_comments', 'list_threads'],
@@ -371,11 +371,14 @@ export const ZohoDeskBlock: BlockConfig<ZohoDeskResponse> = {
         // Zoho documents from >= 0 and limit >= 1 as integers; a negative or
         // fractional value reaches the API as an opaque provider error, so drop
         // anything outside those bounds here rather than round-tripping it.
-        if (rawFrom !== undefined && rawFrom !== '') {
+        // `null` is checked explicitly: the serializer initializes untouched
+        // subBlocks to null, and Number(null) is 0 — which would otherwise inject
+        // from=0 on every operation instead of leaving the param unset.
+        if (rawFrom !== undefined && rawFrom !== null && rawFrom !== '') {
           const from = Number(rawFrom)
           if (Number.isInteger(from) && from >= 0) result.from = from
         }
-        if (rawLimit !== undefined && rawLimit !== '') {
+        if (rawLimit !== undefined && rawLimit !== null && rawLimit !== '') {
           const limit = Number(rawLimit)
           if (Number.isInteger(limit) && limit >= 1) result.limit = limit
         }

apps/sim/tools/zoho_desk/update_ticket.test.ts

@@ -19,4 +19,39 @@ describe('zohoDeskUpdateTicketTool request body', () => {
       subject: 'Hi',
     })
   })
+
+  // The workflow serializer initializes every untouched subBlock to `null` (not
+  // `undefined`) and writes those nulls into tool params, so this - not the
+  // fields-absent case above - is the shape the block actually produces. A
+  // status-only edit must not post `subject: null` and blank the ticket.
+  it('drops untouched fields that arrive as null from the serializer', () => {
+    const serializedParams = {
+      ...base,
+      subject: null,
+      status: 'Closed',
+      priority: null,
+      assigneeId: null,
+      departmentId: null,
+      category: null,
+      subCategory: null,
+      dueDate: null,
+      description: null,
+      resolution: null,
+      classification: null,
+      customFields: null,
+    }
+    expect(buildBody(serializedParams)).toEqual({ status: 'Closed' })
+  })
+
+  it('drops fields the user cleared to an empty string', () => {
+    expect(buildBody({ ...base, status: 'Closed', subject: '' })).toEqual({ status: 'Closed' })
+  })
+
+  // The empty-PATCH guard must be reachable from the real serializer shape, not
+  // only from the synthetic fields-absent case.
+  it('throws when every updatable field is null', () => {
+    expect(() => buildBody({ ...base, subject: null, status: null, priority: null })).toThrow(
+      /no fields to update/i
+    )
+  })
 })

apps/sim/tools/zoho_desk/update_ticket.ts

@@ -1,4 +1,3 @@
-import { filterUndefined } from '@sim/utils/object'
 import type { ToolConfig } from '@/tools/types'
 import type { ZohoDeskResponse, ZohoDeskUpdateTicketParams } from '@/tools/zoho_desk/types'
 import { ZOHO_DESK_TICKET_PROPERTIES } from '@/tools/zoho_desk/types'
@@ -9,6 +8,26 @@ import {
   requireZohoDeskId,
 } from '@/tools/zoho_desk/utils'
 
+/**
+ * Drop keys the caller did not set, so a PATCH only carries real edits.
+ *
+ * Deliberately NOT `filterUndefined`: that helper strips `undefined` only, but
+ * an untouched subBlock does not arrive as `undefined` - the workflow serializer
+ * initializes every subBlock value to `null` and writes those nulls straight
+ * into tool params. A status-only update therefore reached Zoho as
+ * `{"subject": null, "status": "Closed"}`, which either fails the PATCH or
+ * blanks the ticket's subject. Empty strings are treated the same way: an input
+ * the user cleared means "leave unchanged", not "set to empty".
+ */
+function omitUnset(fields: Record<string, unknown>): Record<string, unknown> {
+  const result: Record<string, unknown> = {}
+  for (const [key, value] of Object.entries(fields)) {
+    if (value === undefined || value === null || value === '') continue
+    result[key] = value
+  }
+  return result
+}
+
 export const zohoDeskUpdateTicketTool: ToolConfig<ZohoDeskUpdateTicketParams, ZohoDeskResponse> = {
   id: 'zoho_desk_update_ticket',
   name: 'Zoho Desk Update Ticket',
@@ -122,7 +141,7 @@ export const zohoDeskUpdateTicketTool: ToolConfig<ZohoDeskUpdateTicketParams, Zo
     method: 'PATCH',
     headers: (params) => buildZohoDeskHeaders(params),
     body: (params) => {
-      const body = filterUndefined({
+      const body = omitUnset({
         subject: params.subject,
         status: params.status,
         priority: params.priority,