feat: fetch flow (#1068)

### What problem does this PR solve?
feat: fetch flow #918 
feat: save graph

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

web/src/pages/flow/constant.ts

@@ -1,6 +1,32 @@
+import { ModelVariableType } from '@/constants/knowledge';
+
 export enum Operator {
   Begin = 'Begin',
   Retrieval = 'Retrieval',
   Generate = 'Generate',
   Answer = 'Answer',
 }
+
+export const initialRetrievalValues = {
+  similarity_threshold: 0.2,
+  keywords_similarity_weight: 0.3,
+  top_n: 8,
+};
+
+export const initialBeginValues = {
+  prologue: `Hi! I'm your assistant, what can I do for you?`,
+};
+
+export const initialGenerateValues = {
+  parameters: ModelVariableType.Precise,
+  temperatureEnabled: false,
+  temperature: 0.1,
+  top_p: 0.3,
+  frequency_penalty: 0.7,
+  presence_penalty: 0.4,
+  max_tokens: 512,
+  prompt: `Please summarize the following paragraphs. Be careful with the numbers, do not make things up. Paragraphs as following:
+  {cluster_content}
+The above is the content you need to summarize.`,
+  cite: true,
+};