Add optional reference photo conditioning to Flux generation

server/utils/studioQueue.ts

@@ -1149,6 +1149,9 @@ async function startStudioEditJob(item: StudioJob) {
       }
       : null
     const refId = payload.referenceStillId
+    if (refId && !existsSync(stillPath(item.ownerKey, refId))) {
+      throw new Error('The reference photo is missing from the library')
+    }
     const reference = refId && existsSync(stillPath(item.ownerKey, refId))
       ? {
         filename: payload.referenceStillFilename || 'image2.png',
@@ -1230,7 +1233,7 @@ async function startStudioEditJob(item: StudioJob) {
         engine: v2Engine,
         task: payload.v2Task || (graphMode === 'generate' ? 't2i' : 'scene'),
         image: graphMode === 'generate' ? null : image,
-        reference: graphMode === 'compose' ? reference : null,
+        reference: graphMode === 'compose' || (graphMode === 'generate' && v2Engine === 'flux') ? reference : null,
         mask,
         prompt: payload.prompt,
         negative: payload.negative || '',