Frontend Query & Mutation

Intent

• Keep API hooks in controllers/API/queries/{domain}/ as the organized source of truth.
• Use UseRequestProcessor for consistent retry, invalidation, and error handling.
• Use Axios api instance for all HTTP calls (never raw fetch for REST).
• Use performStreamingRequest() for streaming operations (build, chat).
• Keep cache invalidation in mutation onSettled callbacks.

Architecture Overview

Langflow uses Axios + TanStack React Query v5 for data fetching. There is no oRPC or contract layer. The architecture is:

Component
  -> API hook (controllers/API/queries/{domain}/use-{verb}-{resource}.ts)
    -> UseRequestProcessor (controllers/API/services/request-processor.ts)
      -> useQuery / useMutation (TanStack React Query)
        -> queryFn / mutationFn
          -> api.get/post/patch/delete (Axios instance from controllers/API/api.tsx)

Key Files

File	Purpose
controllers/API/api.tsx	Axios instance, ApiInterceptor component, performStreamingRequest()
controllers/API/services/request-processor.ts	UseRequestProcessor hook wrapping useQuery/useMutation with retry defaults
controllers/API/helpers/constants.ts	URL constants (URLs) and getURL() helper
controllers/API/queries/{domain}/	Domain-organized query and mutation hooks
types/api/index.ts	useQueryFunctionType, useMutationFunctionType type helpers
stores/	Zustand stores for client-side state

Workflow

1. Identify the change surface.
   • Read references/query-patterns.md for hook structure, naming, URL patterns, and query/mutation call-site shape.
   • Read references/runtime-rules.md for conditional queries, invalidation, error handling, and streaming.
   • Read both references when a task spans hook creation and runtime behavior.
2. Implement the hook following existing patterns.
   • Use UseRequestProcessor for query() and mutate() wrappers.
   • Use the api Axios instance for all HTTP calls.
   • Use getURL() for constructing API paths.
   • Type the hook with useQueryFunctionType or useMutationFunctionType.
3. Preserve Langflow conventions.
   • Query keys are arrays with the hook name: ["useGetFlows"].
   • Mutations invalidate related queries in onSettled.
   • Zustand store updates happen in the query/mutation function, not in components.
   • UseRequestProcessor provides default retry (5 for queries, 3 for mutations) with exponential backoff.

Files Commonly Touched

• controllers/API/queries/{domain}/use-get-*.ts (query hooks)
• controllers/API/queries/{domain}/use-post-*.ts (create mutations)
• controllers/API/queries/{domain}/use-patch-*.ts (update mutations)
• controllers/API/queries/{domain}/use-delete-*.ts (delete mutations)
• controllers/API/helpers/constants.ts (URL constants)
• types/api/index.ts (API type definitions)
• stores/ (Zustand store updates triggered by queries)

References

• Use references/query-patterns.md for hook structure, naming conventions, directory layout, and anti-patterns.
• Use references/runtime-rules.md for conditional queries, invalidation, mutate versus mutateAsync, error handling, and streaming requests.

Treat this skill as the single query and mutation entry point for Langflow frontend work. Keep detailed rules in the reference files instead of duplicating them in project docs.