feat(vector-stores): support Bedrock retrievalConfiguration passthrough

[Sameerlite]

Route vector store search extra_body into provider transformers and handle Bedrock retrievalConfiguration explicitly so only intended provider-specific fields are forwarded.

Fixes LIT-2482

Relevant issues

Linear ticket

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Screenshots / Proof of Fix

Type

🆕 New Feature
🐛 Bug Fix

Changes

[greptile-apps]

Greptile Summary

This PR threads extra_body through to all vector store provider transformers and adds explicit handling in the Bedrock transformer to extract and deep-copy retrievalConfiguration (supporting both camelCase and snake_case keys), merge it with standard params, and cast the result for the request body. All other providers accept the new parameter for interface compliance but ignore it. The previously flagged shallow-copy mutation and undocumented override behaviors are fully addressed: deepcopy prevents caller mutation, verbose_logger.debug logs any conflict between extra_body and standard params, and three new tests verify the non-mutation and override semantics end-to-end.

Confidence Score: 5/5

Safe to merge — no P0/P1 issues; all previously flagged concerns (shallow copy mutation, silent override) have been addressed with deepcopy, debug logging, and targeted tests.

The deep copy correctly prevents caller mutation, standard-params-win override is explicitly logged and covered by tests, the interface change is consistent across all 12 provider files, and new tests exercise all three key scenarios. No regressions for non-Bedrock providers since extra_body was never forwarded to transformers before this PR.

No files require special attention.

Important Files Changed

Filename	Overview
litellm/llms/bedrock/vector_stores/transformation.py	Core Bedrock transformer: uses deepcopy to safely extract retrievalConfiguration from extra_body, logs conflicts, and passes the full config through to Bedrock via cast(). All previous concerns (shallow copy mutation, silent override) are addressed.
litellm/llms/base_llm/vector_store/transformation.py	Adds extra_body parameter to abstract and default implementations of transform_search_vector_store_request; interface change is consistent across the class hierarchy.
litellm/llms/custom_httpx/llm_http_handler.py	Threads extra_body through to both sync and async transform_search_vector_store_request call sites; straightforward plumbing change.
tests/test_litellm/llms/bedrock/vector_stores/test_bedrock_vector_store_transformation.py	Adds three new tests covering: extra_body passthrough with irrelevant fields excluded, no mutation of caller's extra_body when max_num_results overrides, and no mutation when filters override. Good coverage of previously flagged concerns.

Sequence Diagram

sequenceDiagram
    participant Caller
    participant llm_http_handler
    participant BedrockTransformer
    participant BedrockAPI

    Caller->>llm_http_handler: vector_store_search(query, extra_body, optional_params)
    llm_http_handler->>BedrockTransformer: transform_search_vector_store_request(query, optional_params, extra_body)
    Note over BedrockTransformer: deepcopy(extra_body["retrievalConfiguration"])
    Note over BedrockTransformer: Merge max_num_results → numberOfResults (standard param wins)
    Note over BedrockTransformer: Merge filters → filter (standard param wins)
    Note over BedrockTransformer: cast(BedrockKBRetrievalConfiguration, retrieval_config)
    BedrockTransformer-->>llm_http_handler: (url, request_body)
    llm_http_handler->>BedrockAPI: POST /knowledgebases/{id}/retrieve
    BedrockAPI-->>llm_http_handler: retrievalResults
    llm_http_handler-->>Caller: VectorStoreSearchResponse

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_{Reviews (3): Last reviewed commit: "Fix tests" | Re-trigger Greptile}

[codecov]

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