fix(websearch): wrap agentic loop response in fake stream for streaming requests

[vokako]

Summary

When websearch_interception is enabled and a client sends a streaming request via /v1/messages, the handler converts stream=True to stream=False internally to execute the search. After the agentic loop completes, the non-streaming dict response was returned directly to the client expecting SSE events, resulting in empty streams.

Root Cause

In _call_agentic_completion_hooks(), the FakeAnthropicMessagesStreamIterator wrapping code only executes when no agentic loop ran. When the agentic loop does run, all return paths return the dict directly without wrapping.

Fix

Added _maybe_wrap_in_fake_stream() helper that checks the websearch_interception_converted_stream flag and wraps dict responses in FakeAnthropicMessagesStreamIterator. Applied to all return paths in _call_agentic_completion_hooks:

• async_run_agentic_loop (legacy path)
• _execute_anthropic_agentic_plan (plan-based path)
• plan.response_override
• plan.terminate

Testing

• Unit tests added for _maybe_wrap_in_fake_stream()
• Verified with anthropic SDK client.messages.stream() + websearch tool:
  • Before fix: stream completes with 0 text chars (no events received)
  • After fix: stream correctly delivers text_delta events and message_stop

Changes

• litellm/llms/custom_httpx/llm_http_handler.py: Added _maybe_wrap_in_fake_stream() method, wrapped all agentic loop return paths
• tests/test_litellm/integrations/websearch_interception/test_websearch_streaming_wrap.py: Unit tests

[codecov]

Codecov Report

❌ Patch coverage is 55.55556% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
litellm/llms/custom_httpx/llm_http_handler.py	55.55%	8 Missing ⚠️

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[greptile-apps]

Greptile Summary

This PR fixes a bug where streaming requests routed through websearch_interception received an empty stream after an agentic loop completed, because every early-return path inside _call_agentic_completion_hooks returned the raw dict directly instead of wrapping it in FakeAnthropicMessagesStreamIterator.

• Extracts a _maybe_wrap_in_fake_stream() helper that checks websearch_interception_converted_stream in logging_obj.model_call_details and wraps dict responses; non-dict values (already-streaming objects, None) are returned unchanged.
• Applies the helper to all four agentic-loop return paths: async_run_agentic_loop, _execute_anthropic_agentic_plan, plan.response_override, and plan.terminate.
• Adds focused unit tests covering the flag-true/false, non-dict, and None-logging-obj cases; no real network calls.

Confidence Score: 4/5

The change is safe to merge; it fixes a clearly broken streaming path without touching any other request flow.

All four agentic-loop exit paths are correctly guarded. The isinstance(response, dict) check prevents double-wrapping when a recursive agentic iteration already returned an iterator. The only gap is that the no-loop-ran fallback at the bottom of _call_agentic_completion_hooks still inlines the same detection logic instead of delegating to the new helper, leaving duplicate code that could drift.

The inline duplication in _call_agentic_completion_hooks around lines 4929-4966 should be cleaned up.

Important Files Changed

Filename	Overview
litellm/llms/custom_httpx/llm_http_handler.py	Adds _maybe_wrap_in_fake_stream() helper and applies it to all four agentic-loop return paths; the existing no-loop path at the bottom of the function still inlines the same logic rather than delegating to the helper.
tests/test_litellm/integrations/websearch_interception/test_websearch_streaming_wrap.py	New unit tests for _maybe_wrap_in_fake_stream; all four branches covered, mock-only with no real network calls.

Comments Outside Diff (1)

1. litellm/llms/custom_httpx/llm_http_handler.py, line 4929-4966 (link)

   The "no agentic loop ran" fallback at the end of _call_agentic_completion_hooks duplicates the same flag-check and wrapping logic that was just extracted into _maybe_wrap_in_fake_stream. Using the helper here too would remove the duplication and make future maintenance easier — any change to the wrapping logic only needs to happen in one place.

_{Reviews (1): Last reviewed commit: "fix(websearch): wrap agentic loop respon..." | Re-trigger Greptile}

[mateo-berri]

This has been merged. We've credited you for this change. Thank you so much for your contribution!