integration: LlamaIndex Workflow Checkpointer using @durable_async

[sdageltc]

Description

LlamaIndex recently released event-driven Workflows (llama-index-core). Integrating LetItLoop allows developers to make LlamaIndex Workflows crash-resilient with zero external database dependencies.

Proposed Architecture

Implement a custom LlamaIndex step handler or decorator that maps LlamaIndex workflow step events to LetItLoop @durable_async and async_step().

Acceptance Criteria

• Clean example in examples/cookbooks/llamaindex_durable_workflow.py.
• Deterministic mock test in tests/test_cookbooks.py.
• Low-latency benchmark (<1ms fast-forward on resume).

Feel free to open a draft PR or discuss implementation ideas here!