fix: enforce workflow validation before deploy and run

The deploy endpoint only validated schedule data but never checked
workflow state (block types, edges, tool references). The Run button
had validation hardcoded to `false`. Redeployments (Update) skipped
all pre-deploy checks entirely.

Changes:
- Backend: call validateWorkflowState() before deploying to reject
  workflows with unknown block types, dangling edges, or invalid
  tool references (returns 400 with details)
- Frontend panel: replace hardcoded `hasValidationErrors = false`
  with a check that blocks are connected via edges
- Frontend deploy hook: run pre-deploy checks for redeployments too,
  not just first deploys

Fixes #3444

This PR was authored by Claude Opus 4.6 (AI), operated by @MaxwellCalkin

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: MaxwellCalkin

apps/sim/app/api/workflows/[id]/deploy/route.ts

@@ -20,6 +20,7 @@ import {
   createSchedulesForDeploy,
   validateWorkflowSchedules,
 } from '@/lib/workflows/schedules'
+import { validateWorkflowState } from '@/lib/workflows/sanitization/validation'
 import { validateWorkflowPermissions } from '@/lib/workflows/utils'
 import { createErrorResponse, createSuccessResponse } from '@/app/api/workflows/utils'
 import type { WorkflowState } from '@/stores/workflows/workflow/types'
@@ -134,6 +135,21 @@ export async function POST(request: NextRequest, { params }: { params: Promise<{
       return createErrorResponse('Failed to load workflow state', 500)
     }
 
+    // Validate workflow state (block types, edges, tool references)
+    const workflowValidation = validateWorkflowState({
+      blocks: normalizedData.blocks,
+      edges: normalizedData.edges,
+      loops: normalizedData.loops,
+      parallels: normalizedData.parallels,
+    } as WorkflowState)
+    if (!workflowValidation.valid) {
+      const errorSummary = workflowValidation.errors.join('; ')
+      logger.warn(
+        `[${requestId}] Workflow validation failed for ${id}: ${errorSummary}`
+      )
+      return createErrorResponse(`Workflow validation failed: ${errorSummary}`, 400)
+    }
+
     const scheduleValidation = validateWorkflowSchedules(normalizedData.blocks)
     if (!scheduleValidation.isValid) {
       logger.warn(

apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/deploy/hooks/use-deployment.ts

@@ -28,16 +28,13 @@ export function useDeployment({
 
   /**
    * Handle deploy button click
-   * First deploy: calls API to deploy, then opens modal on success
-   * Already deployed: opens modal directly (validation happens on Update in modal)
+   * First deploy: runs pre-deploy checks, calls API to deploy, then opens modal on success
+   * Already deployed: runs pre-deploy checks, then opens modal (redeployment happens in modal)
    */
   const handleDeployClick = useCallback(async () => {
     if (!workflowId) return { success: false, shouldOpenModal: false }
 
-    if (isDeployed) {
-      return { success: true, shouldOpenModal: true }
-    }
-
+    // Always run pre-deploy checks, even for redeployments
     const { blocks, edges, loops, parallels } = useWorkflowStore.getState()
     const liveBlocks = mergeSubblockState(blocks, workflowId)
     const checkResult = runPreDeployChecks({
@@ -56,6 +53,10 @@ export function useDeployment({
       return { success: false, shouldOpenModal: false }
     }
 
+    if (isDeployed) {
+      return { success: true, shouldOpenModal: true }
+    }
+
     setIsDeploying(true)
     try {
       const response = await fetch(`/api/workflows/${workflowId}/deploy`, {

apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/panel.tsx

@@ -356,7 +356,11 @@ export const Panel = memo(function Panel() {
   // Compute run button state
   const canRun = userPermissions.canRead // Running only requires read permissions
   const isLoadingPermissions = userPermissions.isLoading
-  const hasValidationErrors = false // TODO: Add validation logic if needed
+
+  // Validate workflow has connected blocks (at least one edge means blocks are wired together)
+  const hasEdges = useWorkflowStore((state) => state.edges.length > 0)
+  const hasValidationErrors = hasBlocks && !hasEdges
+
   const isWorkflowBlocked = isExecuting || hasValidationErrors
   const isButtonDisabled = !isExecuting && (isWorkflowBlocked || (!canRun && !isLoadingPermissions))