Fix guardrails for passthrough endpoint

[Sameerlite]

Relevant issues

Fixes #18106
Fixes #17477

Pre-Submission checklist

Please complete all items before asking a LiteLLM maintainer to review your PR

• I have Added testing in the tests/litellm/ directory, Adding at least 1 test is a hard requirement - see details
• My PR passes all unit tests on make test-unit
• My PR's scope is as isolated as possible, it only solves 1 specific problem

CI (LiteLLM team)

CI status guideline:

• 50-55 passing tests: main is stable with minor issues.
• 45-49 passing tests: acceptable but needs attention
• <= 40 passing tests: unstable; be careful with your merges and assess the risk.

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Type

🐛 Bug Fix

Changes

• Passthrough routes now properly report their call type instead of None
• Guardrails gracefully handle passthrough endpoints with early returns
• Response type validation works with TypedDict types by catching the TypeError and allowing passthrough responses through (which are raw httpx.Response objects, not LiteLLM response types)

Manual Testing

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Project	Deployment	Review	Updated (UTC)
litellm	Ready	Preview, Comment	Dec 18, 2025 2:37pm

[mallapraveen]

@Sameerlite is this going to be merged? Will be ready for Saturday release?

[Sameerlite]

@mallapraveen Yes, it was failing some mypy test. Just fixed. Will get merged today and will be in Sat release