feat: quality of life improvement for pipeline building

[sjrl]

Related Issues

• fixes #issue-number

Proposed Changes:

Add Pipeline.connect_many() to connect multiple (sender, receiver) pairs in one call. Pipeline.add_component() and Pipeline.add_components() now return the pipeline, allowing pipeline-building methods to be chained.

Before

Pipeline construction requires separate calls for every component and connection:

pipeline = Pipeline()

pipeline.add_component("retriever", retriever)
pipeline.add_component("prompt_builder", prompt_builder)
pipeline.add_component("llm", llm)

pipeline.connect("retriever", "prompt_builder.documents")
pipeline.connect("prompt_builder", "llm")

After

Components and connections can be added in batches and chained fluently:

pipeline = (
    Pipeline()
    .add_components({"retriever": retriever, "prompt_builder": prompt_builder, "llm": llm})
    .connect_many([("retriever", "prompt_builder.documents"), ("prompt_builder", "llm")])
)

How did you test it?

New tests

Notes for the reviewer

The motivation was to find ways to streamline the code building experience for pipelines in Haystack and help reduce boiler plate by not needing to repeat the same function calls many times.

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have added unit tests and updated the docstrings.
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I have documented my code.
• I have added a release note file, following the contributors guidelines.
• I have run pre-commit hooks and fixed any issue.

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
haystack-docs	Ignored	Preview	Aug 21, 2026 12:51pm

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Coverage report

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File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/core/pipeline
base.py
pipeline.py
Project Total

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