Provides symmetric encryption and decryption of secrets using AES-GCM. The class is self-contained, uses a single key from environment, and can be extracted into any Python project needing secure secret storage. Demonstrates proper use of nonce, ciphertext, and tag concatenation.

Defines a configurable retry policy model with nine strategies (exponential, linear, fixed, with/without jitter) and a `compute_delay()` method. The model is reusable across any system requiring retry logic, and the enum-based strategy selection with parameterized backoff is a clean pattern.

Resolves placeholders like `${{node.outputs.field}}` and `${{store.key}}` in input strings at runtime. The logic is isolated, handles nested references, and can be reused in any workflow system needing dynamic input resolution. Demonstrates careful parsing and error handling.

Implements `UvicornTestServer`, a reusable test fixture that starts a Uvicorn server in a separate thread for integration testing. The pattern is generic and can be extracted for any FastAPI or ASGI application test suite. Handles server lifecycle, port allocation, and graceful shutdown.

A React component that renders a workflow execution graph using React Flow. It converts API data into layered nodes and edges, supports status-based styling, and opens detail modals. The component is self-contained with clear props and can be adapted for any directed graph visualization in a React application.