fix: workflow loop node break conditions (#15549)

web/app/components/workflow/nodes/loop/default.ts

   checkValid(payload: LoopNodeType, t: any) {
     let errorMessages = ''
 
-    if (!errorMessages && (!payload.break_conditions || payload.break_conditions.length === 0))
-      errorMessages = t(`${i18nPrefix}.fieldRequired`, { field: t('workflow.nodes.loop.breakCondition') })
-
     payload.break_conditions!.forEach((condition) => {
       if (!errorMessages && (!condition.variable_selector || condition.variable_selector.length === 0))
         errorMessages = t(`${i18nPrefix}.fieldRequired`, { field: t(`${i18nPrefix}.fields.variable`) })

web/app/components/workflow/nodes/loop/panel.tsx

       <div>
         <Field
           title={<div className='pl-3'>{t(`${i18nPrefix}.breakCondition`)}</div>}
+          tooltip={t(`${i18nPrefix}.breakConditionTip`)}
         >
           <ConditionWrap
             nodeId={id}

web/app/components/workflow/nodes/loop/use-config.ts

 import { LogicalOperator } from './types'
 import type { HandleAddCondition, HandleAddSubVariableCondition, HandleRemoveCondition, HandleToggleConditionLogicalOperator, HandleToggleSubVariableConditionLogicalOperator, HandleUpdateCondition, HandleUpdateSubVariableCondition, LoopNodeType } from './types'
 import useIsVarFileAttribute from './use-is-var-file-attribute'
+import { useStore } from '@/app/components/workflow/store'
 
 const DELIMITER = '@@@@@'
 const useConfig = (id: string, payload: LoopNodeType) => {
   const { nodesReadOnly: readOnly } = useNodesReadOnly()
   const { isNodeInLoop } = useIsNodeInLoop(id)
   const isChatMode = useIsChatMode()
+  const conversationVariables = useStore(s => s.conversationVariables)
 
   const { inputs, setInputs } = useNodeCrud<LoopNodeType>(id, payload)
 
   const beforeNodes = getBeforeNodesInSameBranch(id)
   const loopChildrenNodes = getLoopNodeChildren(id)
   const canChooseVarNodes = [...beforeNodes, ...loopChildrenNodes]
-  const childrenNodeVars = toNodeOutputVars(loopChildrenNodes, isChatMode)
+  const childrenNodeVars = toNodeOutputVars(loopChildrenNodes, isChatMode, undefined, [], conversationVariables)
 
   // single run
   const loopInputKey = `${id}.input_selector`

web/i18n/en-US/workflow.ts

       loop_other: '{{count}} Loops',
       currentLoop: 'Current Loop',
       breakCondition: 'Loop Termination Condition',
+      breakConditionTip: 'Only variables within loops with termination conditions and conversation variables can be referenced.',
       loopMaxCount: 'Maximum Loop Count',
       loopMaxCountError: 'Please enter a valid maximum loop count, ranging from 1 to {{maxCount}}',
       errorResponseMethod: 'Error Response Method',

web/i18n/zh-Hans/workflow.ts

       loop_other: '{{count}} 个循环',
       currentLoop: '当前循环',
       breakCondition: '循环终止条件',
+      breakConditionTip: '支持引用终止条件循环内的变量和会话变量。',
       loopMaxCount: '最大循环次数',
       loopMaxCountError: '请输入正确的 最大循环次数，范围为 1 到 {{maxCount}}',
       errorResponseMethod: '错误响应方法',