A Haystack pipeline can be perfectly wired and still unsafe.

The retriever returns documents.

The ranker ranks them.

The prompt builder formats them.

The generator answers.

Every component did its job.

But if untrusted text moved through the pipeline as ordinary context, the trust boundary was lost.

That is the problem this post is about.

Not bad Python.

Not broken pipeline wiring.

Not a missing prompt instruction.

A valid component connection only says:

this value fits the next component

Enter fullscreen mode

Exit fullscreen mode

It does not say:

this value is safe to influence the next component

Enter fullscreen mode

Exit fullscreen mode

That difference matters in RAG and agentic systems.

This post shows how to add a trust boundary to a Haystack pipeline with Omega Walls.

The core idea:

Type-safe is not trust-safe.

Why Haystack is a good place to think about boundaries

Haystack makes AI pipelines explicit.

A pipeline is built from components: retrievers, prompt builders,…