fix(ai): normalize SDK objects before truncating messages

[saschabuehrle]

Fixes #5350

truncate_messages_by_size() currently calls json.dumps() on the raw messages input. That breaks when SDK/Pydantic objects (e.g. OpenAI response tool call objects) are present.

This change normalizes messages first via _normalize_data(..., unpack=False) before doing any JSON size calculations/truncation logic.

It also adds a regression test covering a pydantic-like object with model_dump().

Greetings, saschabuehrle

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

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Entries from this PR are highlighted with a left border (blockquote style).

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New Features ✨

• (asgi) Add option to disable suppressing chained exceptions by alexander-alderman-webb in #5714
• (logging) Separate ignore lists for events/breadcrumbs and sentry logs by sl0thentr0py in #5698

Bug Fixes 🐛

Anthropic

• Set exception info on streaming span when applicable by alexander-alderman-webb in #5683
• Patch AsyncStream.close() and AsyncMessageStream.close() to finish spans by alexander-alderman-webb in #5675
• Patch Stream.close() and MessageStream.close() to finish spans by alexander-alderman-webb in #5674

Other

• (ai) Normalize SDK objects before truncating messages by saschabuehrle in #5779

• (starlette) Catch Jinja2Templates ImportError by alexander-alderman-webb in #5741

Documentation 📚

• Add note on AI PRs to CONTRIBUTING.md by sentrivana in #5696

Internal Changes 🔧

• Add -latest alias for each integration test suite by sentrivana in #5706
• Use date-based branch names for toxgen PRs by sentrivana in #5704
• 🤖 Update test matrix with new releases (03/19) by github-actions in #5703
• Add client report tests for span streaming by sentrivana in #5677

Other

• Update CHANGELOG.md by sentrivana in #5685

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Normalization converts None values to string "None"

High Severity

Calling _normalize_data(messages, unpack=False) before truncation corrupts None values in message dicts. The _normalize_data fallback at line 488 converts any non-primitive (including None) to str(data), turning None into the string "None". This is very common in practice — OpenAI assistant messages with tool calls have "content": null. The existing parameterized test with content=None will also fail since it asserts result[0]["content"] is content.

Additional Locations (1)

• sentry_sdk/ai/utils.py#L487-L488