Add snapshot_callback support to Pipeline.run

[mpangrazzi]

Related Issues

• fixes #https://github.com/deepset-ai/haystack-private/issues/236

Proposed Changes:

Added a snapshot_callback parameter to Pipeline.run() that allows users to provide a custom handler for pipeline snapshots instead of the default file-saving behavior. Currently, when a breakpoint is triggered or an error occurs during pipeline execution, snapshots are always saved to JSON files on disk.

This is limiting for users who want to e.g. save snapshots to a database or send snapshots to a remote service.

How did you test it?

unit tests, manual verification

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	Review	Updated (UTC)
haystack-docs	Ignored	Preview	Dec 16, 2025 1:05pm

[coveralls]

Pull Request Test Coverage Report for Build 20240621513

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 29 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.006%) to 92.139%

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Files with Coverage Reduction	New Missed Lines	%
core/pipeline/pipeline.py	10	91.74%
core/pipeline/breakpoint.py	19	89.29%

Totals
Change from base Build 20238602779:	0.006%
Covered Lines:	14136
Relevant Lines:	15342

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💛 - Coveralls

[mpangrazzi]

Closing this, will reimplement on top of this refactor when it will be merged.