Add _to_trace_dict for image content and file content

[sjrl]

Related Issues

• fixes issue in platform for sending large binary objects to the tracing backend

Proposed Changes:

Follow the same strategy used in ByteStream and for tracing backends only send a placeholder for the binary data.

How did you test it?

Added unit tests

Notes for the reviewer

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	Mar 31, 2026 7:33am

[coveralls]

Pull Request Test Coverage Report for Build 23785870335

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.004%) to 92.903%

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Totals
Change from base Build 23754030523:	0.004%
Covered Lines:	15878
Relevant Lines:	17091

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💛 - Coveralls

[anakin87]

I have no problems with introducing these methods.

But I am not fully sure that this fixes the logging issue.

@sjrl @Amnah199 feel free to share your impressions.

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EDIT: we mean tracing, not logging

[anakin87]

Can you also change this code

haystack/haystack/dataclasses/chat_message.py

Lines 561 to 565 in 01b11aa

	if isinstance(part, ImageContent):
	serialized_part["image"]["base64_image"] = f"Base64 string ({len(part.base64_image)} characters)"
	elif isinstance(part, FileContent):
	serialized_part["file"]["base64_data"] = f"Base64 string ({len(part.base64_data)} characters)"
	serialized["content"].append(serialized_part)

to use the newly introduced methods (for consistency)?

[sjrl]

Can you also change this code

haystack/haystack/dataclasses/chat_message.py

Lines 561 to 565 in 01b11aa

	if isinstance(part, ImageContent):
	serialized_part["image"]["base64_image"] = f"Base64 string ({len(part.base64_image)} characters)"
	elif isinstance(part, FileContent):
	serialized_part["file"]["base64_data"] = f"Base64 string ({len(part.base64_data)} characters)"
	serialized["content"].append(serialized_part)

to use the newly introduced methods (for consistency)?

Done in 96d44e3

[anakin87]

Looks good!