chore: import upstream snapshot with attribution

apps/sim/app/workspace/[workspaceId]/providers/custom-blocks-loader.tsx

@@ -0,0 +1,55 @@
+'use client'
+
+import { useEffect } from 'react'
+import { useParams } from 'next/navigation'
+import { buildCustomBlockConfig } from '@/blocks/custom/build-config'
+import { hydrateClientCustomBlocks } from '@/blocks/custom/client-overlay'
+import { getCustomBlockIcon } from '@/blocks/custom/custom-block-icon'
+import { useWhitelabelSettings } from '@/ee/whitelabeling/hooks/whitelabel'
+import { useCustomBlocks } from '@/hooks/queries/custom-blocks'
+
+/**
+ * Hydrates the client custom-block registry overlay from the active workspace's
+ * org custom blocks. Mounted once in the workspace layout so every surface that
+ * resolves blocks synchronously — the canvas, the block palette, copilot mentions,
+ * and the Access Control "Blocks" list — sees custom blocks. Re-hydrates on
+ * workspace switch (the query key changes) and on any publish/edit/unpublish.
+ */
+export function CustomBlocksLoader() {
+  const params = useParams()
+  const workspaceId = params?.workspaceId as string | undefined
+  const { data } = useCustomBlocks(workspaceId)
+
+  // Blocks with no uploaded icon fall back to the org's whitelabel logo, then the
+  // default glyph. All blocks share the org, so read it off the first row.
+  const { data: whitelabel } = useWhitelabelSettings(data?.[0]?.organizationId)
+  const fallbackIconUrl = whitelabel?.logoUrl ?? null
+
+  useEffect(() => {
+    hydrateClientCustomBlocks(
+      // Disabled blocks stay resolvable (so a still-placed instance renders on the
+      // canvas and survives serialization instead of vanishing) but are hidden from
+      // the palette so no new instance can be placed; a run fails loudly server-side.
+      (data ?? []).map((block) => {
+        const effectiveIcon = block.iconUrl || fallbackIconUrl
+        return buildCustomBlockConfig(
+          {
+            type: block.type,
+            name: block.name,
+            description: block.description,
+            workflowId: block.workflowId,
+            exposedOutputs: block.exposedOutputs,
+          },
+          block.inputFields,
+          {
+            icon: getCustomBlockIcon(block.iconUrl, fallbackIconUrl),
+            bgColor: effectiveIcon ? 'transparent' : undefined,
+            hideFromToolbar: !block.enabled,
+          }
+        )
+      })
+    )
+  }, [data, fallbackIconUrl])
+
+  return null
+}