Wire every Image v2 LoRA, including Concept, through one sampler chain.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/utils/loras.ts

@@ -386,17 +386,6 @@ function linkRef(value: unknown): [string, number] | null {
     : null
 }
 
-function currentModelClipFeeds(graph: WorkflowGraph) {
-  const prompt = Object.values(graph).find(node => node.class_type === 'CLIPTextEncode' && linkRef(node.inputs.clip))
-  const modelNode = Object.values(graph).find(node => MODEL_FEED_CLASSES.has(node.class_type) && linkRef(node.inputs.model))
-  const model = linkRef(modelNode?.inputs.model)
-  const clip = linkRef(prompt?.inputs.clip)
-  return {
-    model: model && graph[model[0]] ? model : null,
-    clip: clip && graph[clip[0]] ? clip : null
-  }
-}
-
 export function assertImageV2LoraStack(stack: unknown, engine: 'flux' | 'krea') {
   const items = normalizeLoraStack(stack)
   if (engine !== 'krea') return items
@@ -407,16 +396,40 @@ export function assertImageV2LoraStack(stack: unknown, engine: 'flux' | 'krea')
   return items
 }
 
+function stripExistingLoraLoaders(graph: WorkflowGraph) {
+  const remaining = new Set(
+    Object.entries(graph)
+      .filter(([, node]) => node.class_type === LORA_LOADER)
+      .map(([id]) => id)
+  )
+  while (remaining.size) {
+    const id = [...remaining].find(candidate => (
+      ![...remaining].some(other => other !== candidate && linkSource(graph[other]?.inputs.model) === candidate)
+    )) || [...remaining][0]
+    bypassLoraNode(graph, id)
+    remaining.delete(id)
+  }
+}
+
+function modelConsumers(graph: WorkflowGraph) {
+  return Object.values(graph).filter(node => MODEL_FEED_CLASSES.has(node.class_type) && linkRef(node.inputs.model))
+}
+
+function clipConsumers(graph: WorkflowGraph) {
+  return Object.values(graph).filter(node => node.class_type === 'CLIPTextEncode' && linkRef(node.inputs.clip))
+}
+
 /**
- * Append a user LoRA chain after the current model/CLIP feed.
- * Flux v2 already has Concept/Consistency loaders; this stacks after those.
- * Empty stack is a no-op. Klein LoRAs on a Krea graph throw.
+ * Replace any template LoRA loaders with the posted chain, in list order.
+ * Strength 0 skips that card (off). Empty chain leaves UNET/CLIP wired straight to the sampler.
  */
 export function applyImageV2UserLoras(
   graph: WorkflowGraph,
   stack?: unknown,
   engine: 'flux' | 'krea' = 'flux'
 ) {
+  stripExistingLoraLoaders(graph)
+
   const xaigen = isXaigenStudio()
   const items = normalizeLoraStack(stack)
     .filter(item => xaigen || !isXaigenOnlyLora(item.name))
@@ -424,8 +437,7 @@ export function applyImageV2UserLoras(
       ...item,
       name: resolveUserLoraName(item.name, 'image')
     }))
-    .filter(item => item.name && (xaigen || !isXaigenOnlyLora(item.name)) && !alreadyHasLora(graph, item.name))
-  if (!items.length) return [] as LoraStackItem[]
+    .filter(item => item.name && (xaigen || !isXaigenOnlyLora(item.name)) && (item.strengthModel !== 0 || item.strengthClip !== 0))
 
   if (engine === 'krea') {
     const klein = items.find(item => isKleinImageLora(item.name))
@@ -434,48 +446,54 @@ export function applyImageV2UserLoras(
     }
   }
 
-  const feeds = currentModelClipFeeds(graph)
-  const modelFrom = feeds.model || (graph['4'] ? ['4', 0] as [string, number] : null)
-  const clipFrom = feeds.clip || (graph['5'] ? ['5', 0] as [string, number] : null)
+  const guiders = modelConsumers(graph)
+  const encodes = clipConsumers(graph)
+  const modelFrom = linkRef(guiders[0]?.inputs.model) || (graph['4'] ? ['4', 0] as [string, number] : null)
+  const clipFrom = linkRef(encodes[0]?.inputs.clip) || (graph['5'] ? ['5', 0] as [string, number] : null)
   if (!modelFrom || !clipFrom) {
     throw createError({ statusCode: 500, statusMessage: 'v2 graph has no model/CLIP feed for user LoRAs.' })
   }
+  if (!items.length) return [] as LoraStackItem[]
+  if (!guiders.length || !encodes.length) {
+    throw createError({
+      statusCode: 500,
+      statusMessage: 'Image v2 LoRA chain is not connected to the sampler. Refusing to run without those adapters.'
+    })
+  }
 
-  const firstId = 'user:lora:0'
-  graph[firstId] = {
-    class_type: LORA_LOADER,
-    inputs: {
-      lora_name: items[0].name,
-      strength_model: items[0].strengthModel,
-      strength_clip: items[0].strengthClip,
-      model: modelFrom,
-      clip: clipFrom
-    },
-    _meta: { title: items.length === 1 ? 'User LoRA' : 'User LoRA 1' }
-  }
-  for (const [id, node] of Object.entries(graph)) {
-    if (id === firstId) continue
-    for (const [key, value] of Object.entries(node.inputs)) {
-      if (!Array.isArray(value)) continue
-      if (value[0] === modelFrom[0] && value[1] === modelFrom[1]) node.inputs[key] = [firstId, 0]
-      else if (value[0] === clipFrom[0] && value[1] === clipFrom[1]) node.inputs[key] = [firstId, 1]
+  let model: [string, number] = modelFrom
+  let clip: [string, number] = clipFrom
+  const ids: string[] = []
+  for (const [index, item] of items.entries()) {
+    const nodeId = String(70 + index)
+    if (graph[nodeId]) {
+      throw createError({ statusCode: 500, statusMessage: `v2 graph already has node ${nodeId}. Refusing to overwrite it with a LoRA.` })
     }
-  }
-  let sourceId = firstId
-  for (const [index, item] of items.slice(1).entries()) {
-    const nodeId = `user:lora:${index + 1}`
-    injectAfter(graph, sourceId, nodeId, {
+    graph[nodeId] = {
       class_type: LORA_LOADER,
       inputs: {
         lora_name: item.name,
         strength_model: item.strengthModel,
         strength_clip: item.strengthClip,
-        model: [sourceId, 0],
-        clip: [sourceId, 1]
+        model,
+        clip
       },
-      _meta: { title: `User LoRA ${index + 2}` }
+      _meta: { title: items.length === 1 ? 'LoRA' : `LoRA ${index + 1}` }
+    }
+    ids.push(nodeId)
+    model = [nodeId, 0]
+    clip = [nodeId, 1]
+  }
+  for (const node of guiders) node.inputs.model = model
+  for (const node of encodes) node.inputs.clip = clip
+
+  const hooked = guiders.every(node => linkRef(node.inputs.model)?.[0] === ids[ids.length - 1])
+    && encodes.every(node => linkRef(node.inputs.clip)?.[0] === ids[ids.length - 1])
+  if (!hooked) {
+    throw createError({
+      statusCode: 500,
+      statusMessage: 'Image v2 LoRA chain is not connected to the sampler. Refusing to run without those adapters.'
     })
-    sourceId = nodeId
   }
   return items
 }