fix(custom-blocks): reserve system output names and hide own block from command modal (#5667)

* fix(custom-blocks): reserve system output names and hide own block from command modal

* fix(mothership): constrain custom block image icons in subagent tool rows

* improvement(custom-blocks): allow result as an exposed output name

Author: TheodoreSpeaks

apps/sim/app/workspace/[workspaceId]/home/components/message-content/components/agent-group/tool-call-item.tsx

@@ -93,7 +93,13 @@ export function ToolCallItem({
   return (
     <div className='flex items-center gap-[6px] pl-6'>
       {BlockIcon && (
-        <BlockIcon className='size-[14px] flex-shrink-0' style={getBareIconStyle(BlockIcon)} />
+        // Size via inline style: a custom block's image icon carries a trailing
+        // `size-full` that defeats size *classes* (it fills tiled surfaces), so a
+        // class-only size renders the uploaded icon at natural size here.
+        <BlockIcon
+          className='size-[14px] flex-shrink-0'
+          style={{ width: 14, height: 14, ...getBareIconStyle(BlockIcon) }}
+        />
       )}
       {isExecuting ? (
         <ShimmerText className='text-[13px] [--shimmer-rest:var(--text-secondary)]'>

apps/sim/app/workspace/[workspaceId]/w/components/sidebar/components/search-modal/search-modal.tsx

@@ -97,6 +97,7 @@ export function SearchModal({
   const params = useParams()
   const router = useRouter()
   const workspaceId = params.workspaceId as string
+  const currentWorkflowId = params.workflowId as string | undefined
   const inputRef = useRef<HTMLInputElement>(null)
   const [mounted, setMounted] = useState(false)
   const { navigateToSettings } = useSettingsNavigation()
@@ -581,23 +582,25 @@ export function SearchModal({
    */
   const filteredBlocks = useMemo(() => {
     if (!isOnWorkflowPage) return []
+    // A custom block is hidden on its own source workflow's canvas — placing it
+    // there recurses (same exclusion as the toolbar).
     return filterAndCap(
-      blocks,
+      blocks.filter((b) => !b.sourceWorkflowId || b.sourceWorkflowId !== currentWorkflowId),
       (b) => b.name,
       deferredSearch,
       (b) => b.searchValue
     )
-  }, [isOnWorkflowPage, blocks, deferredSearch])
+  }, [isOnWorkflowPage, blocks, deferredSearch, currentWorkflowId])
 
   const filteredTools = useMemo(() => {
     if (!isOnWorkflowPage) return []
     return filterAndCap(
-      tools,
+      tools.filter((t) => !t.sourceWorkflowId || t.sourceWorkflowId !== currentWorkflowId),
       (t) => t.name,
       deferredSearch,
       (t) => t.searchValue
     )
-  }, [isOnWorkflowPage, tools, deferredSearch])
+  }, [isOnWorkflowPage, tools, deferredSearch, currentWorkflowId])
 
   const filteredTriggers = useMemo(() => {
     if (!isOnWorkflowPage) return []

apps/sim/blocks/custom/build-config.test.ts

@@ -8,6 +8,7 @@ import {
   CUSTOM_BLOCK_TILE_COLOR,
   type CustomBlockRow,
   isCustomBlockType,
+  isReservedOutputName,
 } from '@/blocks/custom/build-config'
 import type { BlockIcon } from '@/blocks/types'
 
@@ -33,6 +34,18 @@ describe('isCustomBlockType', () => {
   })
 })
 
+describe('isReservedOutputName', () => {
+  it('rejects the system output fields case-insensitively', () => {
+    expect(isReservedOutputName('cost')).toBe(true)
+    expect(isReservedOutputName('Cost')).toBe(true)
+    expect(isReservedOutputName(' success ')).toBe(true)
+    expect(isReservedOutputName('error')).toBe(true)
+    expect(isReservedOutputName('result')).toBe(false)
+    expect(isReservedOutputName('cost_2')).toBe(false)
+    expect(isReservedOutputName('summary')).toBe(false)
+  })
+})
+
 describe('buildCustomBlockConfig', () => {
   const fields: WorkflowInputField[] = [
     { name: 'title', type: 'string' },
@@ -47,6 +60,7 @@ describe('buildCustomBlockConfig', () => {
     const config = buildCustomBlockConfig(row, fields, { icon })
     expect(config.type).toBe('custom_block_abc123')
     expect(config.name).toBe('Invoice Parser')
+    expect(config.sourceWorkflowId).toBe('wf-1')
     expect(config.category).toBe('tools')
     expect(config.bgColor).toBe(CUSTOM_BLOCK_TILE_COLOR)
     expect(config.hideFromToolbar).toBeUndefined()

apps/sim/blocks/custom/build-config.ts

@@ -62,6 +62,20 @@ export const RESERVED_PARAMS = new Set([
   'advancedMode',
 ])
 
+/**
+ * Output names the block projects itself (`success`/`error` from `buildOutputs`,
+ * `cost` from the executor's billing aggregation). A user-named exposed output
+ * must never shadow these — an output literally named `cost` would clobber the
+ * billed cost. `result` is deliberately NOT reserved: it only exists as a system
+ * field when no outputs are curated, which cannot co-occur with a named output.
+ */
+export const RESERVED_OUTPUT_NAMES = new Set(['success', 'error', 'cost'])
+
+/** Whether an exposed-output name collides with a system output field. */
+export function isReservedOutputName(name: string): boolean {
+  return RESERVED_OUTPUT_NAMES.has(name.trim().toLowerCase())
+}
+
 /** Map a Start input field type to the editor sub-block type used to collect it. */
 function subBlockTypeForField(fieldType: string): SubBlockType {
   switch (fieldType) {
@@ -122,6 +136,7 @@ export function buildCustomBlockConfig(
     type: row.type,
     name: row.name,
     description: row.description,
+    sourceWorkflowId: row.workflowId,
     category: 'tools',
     longDescription:
       'A published workflow packaged as a reusable, self-contained block. Fill its input ' +

apps/sim/blocks/types.ts

@@ -468,6 +468,12 @@ export interface BlockConfig<T extends ToolResponse = ToolResponse> {
     }
   }
   hideFromToolbar?: boolean
+  /**
+   * For published custom blocks only: the bound source workflow's id. Discovery
+   * surfaces use it to hide a workflow's own block on that workflow's canvas
+   * (placing it would recurse).
+   */
+  sourceWorkflowId?: string
   /**
    * Marks an unreleased block. Preview blocks are hidden from every discovery
    * surface (toolbar, search, mentions, copilot/VFS, docs) in every environment —

apps/sim/ee/custom-blocks/components/custom-block-detail.tsx

@@ -32,7 +32,11 @@ import { saveDiscardActions } from '@/app/workspace/[workspaceId]/settings/compo
 import { SettingsPanel } from '@/app/workspace/[workspaceId]/settings/components/settings-panel'
 import { useProfilePictureUpload } from '@/app/workspace/[workspaceId]/settings/hooks/use-profile-picture-upload'
 import { useSettingsUnsavedGuard } from '@/app/workspace/[workspaceId]/settings/hooks/use-settings-unsaved-guard'
-import type { CustomBlockInput, CustomBlockOutput } from '@/blocks/custom/build-config'
+import {
+  type CustomBlockInput,
+  type CustomBlockOutput,
+  isReservedOutputName,
+} from '@/blocks/custom/build-config'
 import { SettingRow } from '@/ee/components/setting-row'
 import {
   useCustomBlocks,
@@ -56,12 +60,12 @@ const decodeOutput = (value: string) => {
     : { blockId: value.slice(0, i), path: value.slice(i + OUTPUT_SEP.length) }
 }
 
-/** Derive a unique, friendly output name from a dot-path, avoiding collisions. */
+/** Derive a unique, friendly output name from a dot-path, avoiding collisions and reserved names. */
 function deriveOutputName(path: string, taken: Set<string>): string {
   const base = (path.split('.').pop() || path).replace(/[^a-zA-Z0-9_]/g, '_')
   let name = base
   let n = 2
-  while (taken.has(name)) name = `${base}_${n++}`
+  while (taken.has(name) || isReservedOutputName(name)) name = `${base}_${n++}`
   taken.add(name)
   return name
 }
@@ -360,6 +364,11 @@ export function CustomBlockDetail({ blockId, workspaceId, onBack }: CustomBlockD
       setError('Output names must be unique')
       return
     }
+    const reserved = exposedOutputs.find((o) => isReservedOutputName(o.name))
+    if (reserved) {
+      setError(`"${reserved.name}" is a reserved output name (success, error, cost)`)
+      return
+    }
     // Only the placeholder and required flag are authored; the field set/name/type
     // are always derived from the deployed Start. Persist only non-empty overrides.
     const inputPlaceholders = visibleInputs

apps/sim/executor/handlers/workflow/workflow-handler.test.ts

@@ -518,6 +518,45 @@ describe('WorkflowBlockHandler', () => {
       })
     })
   })
+
+  describe('projectCustomBlockOutput', () => {
+    const childResult = {
+      success: true,
+      output: { data: 'whole result' },
+      logs: [{ blockId: 'b1', success: true, output: { data: { x: 42 }, price: 999 } }],
+    }
+
+    it('maps each curated output to its named field plus system fields', () => {
+      const result = (handler as any).projectCustomBlockOutput(
+        childResult,
+        [{ blockId: 'b1', path: 'data.x', name: 'answer' }],
+        0.5
+      )
+
+      expect(result).toEqual({ answer: 42, success: true, cost: { total: 0.5 } })
+    })
+
+    it('never lets an exposed output named cost clobber the billed cost', () => {
+      const result = (handler as any).projectCustomBlockOutput(
+        childResult,
+        [{ blockId: 'b1', path: 'price', name: 'cost' }],
+        0.5
+      )
+
+      expect(result.cost).toEqual({ total: 0.5 })
+      expect(result.success).toBe(true)
+    })
+
+    it('exposes the whole child result when no outputs are curated', () => {
+      const result = (handler as any).projectCustomBlockOutput(childResult, [], 0.5)
+
+      expect(result).toEqual({
+        success: true,
+        result: { data: 'whole result' },
+        cost: { total: 0.5 },
+      })
+    })
+  })
 })
 
 describe('remapCustomBlockInputKeys', () => {

apps/sim/executor/handlers/workflow/workflow-handler.ts

@@ -888,14 +888,15 @@ export class WorkflowBlockHandler implements BlockHandler {
       return { success: true, result: executionResult.output ?? {}, ...cost }
     }
     const logs = executionResult.logs ?? []
-    const output: Record<string, unknown> = { success: true, ...cost }
+    const output: Record<string, unknown> = {}
     for (const { blockId, path, name } of exposedOutputs) {
       const log =
         [...logs].reverse().find((l) => l.blockId === blockId && l.success) ??
         [...logs].reverse().find((l) => l.blockId === blockId)
       output[name] = log ? getValueAtPath(log.output, path) : undefined
     }
-    return output as BlockOutput
+    // System fields spread last — pre-validation rows may still name an output cost/success.
+    return { ...output, success: true, ...cost } as BlockOutput
   }
 
   private mapChildOutputToParent(

apps/sim/lib/api/contracts/custom-blocks.ts

@@ -1,6 +1,7 @@
 import { z } from 'zod'
 import { workflowIdSchema, workspaceIdSchema } from '@/lib/api/contracts/primitives'
 import { defineRouteContract } from '@/lib/api/contracts/types'
+import { isReservedOutputName } from '@/blocks/custom/build-config'
 
 const inputFieldSchema = z.object({
   /** Stable per-field id — preserved so client block configs key sub-blocks on it
@@ -36,6 +37,21 @@ const exposedOutputSchema = z.object({
   name: z.string().min(1).max(60),
 })
 
+/**
+ * Publish/update variant: rejects reserved system output names (`success`,
+ * `error`, `cost`) that would shadow the block's own projected fields. The
+ * read schema stays lenient so rows that predate this validation still parse.
+ */
+const exposedOutputWriteSchema = exposedOutputSchema.extend({
+  name: z
+    .string()
+    .min(1)
+    .max(60)
+    .refine((name) => !isReservedOutputName(name), {
+      message: 'Output name is reserved (success, error, cost)',
+    }),
+})
+
 export const customBlockSchema = z.object({
   id: z.string(),
   organizationId: z.string(),
@@ -87,7 +103,7 @@ export const publishCustomBlockBodySchema = z.object({
   /** Per-input placeholder hints keyed by Start field id; the field set itself is always derived from the deployment. */
   inputs: z.array(inputPlaceholderSchema).max(50).optional(),
   /** Curated outputs; omit/empty to expose the child's whole result. */
-  exposedOutputs: z.array(exposedOutputSchema).max(50).optional(),
+  exposedOutputs: z.array(exposedOutputWriteSchema).max(50).optional(),
 })
 
 export type PublishCustomBlockBody = z.input<typeof publishCustomBlockBodySchema>
@@ -104,7 +120,7 @@ export const updateCustomBlockBodySchema = z
     /** A URL (https or internal serve path) sets/replaces the icon; `null` clears it (default icon). */
     iconUrl: iconUrlSchema.nullable().optional(),
     inputs: z.array(inputPlaceholderSchema).max(50).optional(),
-    exposedOutputs: z.array(exposedOutputSchema).max(50).optional(),
+    exposedOutputs: z.array(exposedOutputWriteSchema).max(50).optional(),
   })
   .refine((v) => Object.keys(v).length > 0, { message: 'At least one field is required' })
 

apps/sim/lib/workflows/custom-blocks/operations.test.ts

@@ -0,0 +1,67 @@
+/**
+ * @vitest-environment node
+ */
+import { describe, expect, it, vi } from 'vitest'
+
+vi.mock('@/lib/billing/core/subscription', () => ({
+  isOrganizationOnEnterprisePlan: vi.fn(),
+}))
+
+vi.mock('@/lib/core/config/feature-flags', () => ({
+  isFeatureEnabled: vi.fn(),
+}))
+
+vi.mock('@/lib/workflows/input-format', () => ({
+  extractInputFieldsFromBlocks: vi.fn(),
+}))
+
+vi.mock('@/lib/workflows/persistence/utils', () => ({
+  loadDeployedWorkflowState: vi.fn(),
+}))
+
+vi.mock('@/lib/workspaces/permissions/utils', () => ({
+  getWorkspaceWithOwner: vi.fn(),
+}))
+
+import {
+  CustomBlockValidationError,
+  publishCustomBlock,
+  updateCustomBlock,
+} from '@/lib/workflows/custom-blocks/operations'
+
+const publishParams = {
+  organizationId: 'org-1',
+  workspaceId: 'ws-1',
+  workflowId: 'wf-1',
+  userId: 'user-1',
+  name: 'Enrich Lead',
+  description: '',
+}
+
+describe('reserved exposed-output names', () => {
+  it('publishCustomBlock rejects an output named cost', async () => {
+    await expect(
+      publishCustomBlock({
+        ...publishParams,
+        exposedOutputs: [{ blockId: 'b1', path: 'price', name: 'cost' }],
+      })
+    ).rejects.toThrow(CustomBlockValidationError)
+  })
+
+  it('publishCustomBlock rejects reserved names case-insensitively', async () => {
+    await expect(
+      publishCustomBlock({
+        ...publishParams,
+        exposedOutputs: [{ blockId: 'b1', path: 'content', name: 'Success' }],
+      })
+    ).rejects.toThrow('"Success" is a reserved output name (success, error, cost)')
+  })
+
+  it('updateCustomBlock rejects a reserved output name', async () => {
+    await expect(
+      updateCustomBlock('cb-1', {
+        exposedOutputs: [{ blockId: 'b1', path: 'content', name: 'error' }],
+      })
+    ).rejects.toThrow(CustomBlockValidationError)
+  })
+})