fix(custom-block): derive fields for disabled blocks so edits keep placeholders; reseed edit form after async load

Author: TheodoreSpeaks

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

@@ -99,6 +99,19 @@ export function CustomBlockDetail({ blockId, workspaceId, onBack }: CustomBlockD
   const [error, setError] = useState<string | null>(null)
   const [showDelete, setShowDelete] = useState(false)
 
+  // Edit mode may mount before `useCustomBlocks` has resolved this row, leaving the
+  // buffers empty. Reseed them the first time the block's identity loads (or when it
+  // changes) — keyed on `existing.id` so a later refetch of the SAME block doesn't
+  // clobber in-progress edits. (The icon reseeds itself via `currentImage`.)
+  const [seededId, setSeededId] = useState(existing?.id ?? null)
+  if (existing && existing.id !== seededId) {
+    setSeededId(existing.id)
+    setName(existing.name)
+    setDescription(existing.description ?? '')
+    setInputs(toCustomBlockInputs(existing.inputFields))
+    setOutputs(existing.exposedOutputs ?? [])
+  }
+
   const iconUpload = useProfilePictureUpload({
     currentImage: existing?.iconUrl ?? null,
     onError: (e) => setError(e),

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

@@ -180,11 +180,11 @@ export async function listCustomBlocksWithInputs(
       description: row.description,
       iconUrl: row.iconUrl,
       enabled: row.enabled,
-      // Field set derived live from the deployed Start; stored placeholders merged in.
-      inputFields: applyInputPlaceholders(
-        row.inputs,
-        row.enabled ? await deriveInputFields(row.workflowId) : []
-      ),
+      // Field set derived live from the deployed Start; stored placeholders merged
+      // in. Derive even for a disabled block — the source workflow's deployment is
+      // independent of the block's enabled flag, and the edit form needs the real
+      // fields so a save doesn't overwrite the block's stored placeholders.
+      inputFields: applyInputPlaceholders(row.inputs, await deriveInputFields(row.workflowId)),
       exposedOutputs: row.outputs ?? [],
     }))
   )