fix(bedrock_mantle): route xai.grok-4.3 via /openai/v1 frontier path

[marty-sullivan]

Relevant issues

Follow-up fix to #31916, which added bedrock_mantle/xai.grok-4.3 but routed it on the standard /v1 base. Original SigV4 issue: #31196.

Pre-Submission checklist

• I have added meaningful tests
• My PR passes all CI/CD checks (e.g., lint, format, unit tests)
• My PR's scope is as isolated as possible; it only solves 1 specific problem

Screenshots / Proof of Fix

bedrock_mantle routing is data-driven from the price map: mantle_base_segment() returns openai/v1 only when the model's entry has use_openai_responses_path: true, else v1. #31916 added grok-4.3 without the flag (by analogy to gpt-oss), so it routed to the standard /v1 base.

But xAI Grok is a third-party frontier model on Bedrock Mantle and is served on the /openai/v1 base (like gpt-5.x and gemma-4), not the /v1 path used by open-weights models such as gpt-oss. Live behavior against bedrock-mantle.<region>.api.aws (real SigV4 calls, no mocks):

• Before (grok on /v1/chat/completions): {"error":{"code":"access_denied","message":"Berm is not enabled for this account","type":"permission_denied_error"}}
• After (this change — grok on /openai/v1): 200 OK, normal completion (finish_reason present, reasoning + output tokens billed).

AWS docs confirm the /openai/v1 prefix is required for these frontier models; omitting it returns a 404/validation error.

Type

🐛 Bug Fix

Changes

• Add "use_openai_responses_path": true to the bedrock_mantle/xai.grok-4.3 entry in model_prices_and_context_window.json and its backup, so mantle_base_segment() returns openai/v1.
• Update test_registry_returns_native_config_for_xai_grok to assert use_openai_path is True (with a comment explaining grok is a frontier model on /openai/v1).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[marty-sullivan]

@greptileai

[greptile-apps]

Greptile Summary

This PR fixes a routing bug for bedrock_mantle/xai.grok-4.3 where missing the use_openai_responses_path flag caused requests to hit the standard /v1 base instead of the required /openai/v1 frontier path, resulting in an "access denied" error from the Bedrock Mantle service.

• Adds "use_openai_responses_path": true to the bedrock_mantle/xai.grok-4.3 entry in both model_prices_and_context_window.json and its backup, using the existing data-driven flag mechanism shared by gpt-5.x and gemma-4 entries.
• Updates test_registry_returns_native_config_for_xai_grok to assert use_openai_path is True, correctly reflecting the fixed behavior rather than the prior buggy routing; an explanatory comment documents why grok is a frontier model requiring the /openai/v1 path.

Confidence Score: 5/5

Narrow, data-only fix adding a single flag to two JSON files and updating one test assertion to match corrected behavior; no logic changes, no new code paths.

The change touches only two JSON price-map files (kept in sync) and a single test assertion. The flag mechanism being used is well-tested and already in production use for other frontier models. The test update correctly reflects the fixed routing rather than masking a regression.

No files require special attention.

Important Files Changed

Filename	Overview
model_prices_and_context_window.json	Adds use_openai_responses_path: true to bedrock_mantle/xai.grok-4.3; change is minimal, correct, and consistent with the existing flag pattern used by gpt-5.x and gemma-4 entries.
litellm/model_prices_and_context_window_backup.json	Mirrors the same use_openai_responses_path: true addition to the backup JSON, keeping both files in sync as expected.
tests/test_litellm/llms/bedrock_mantle/test_bedrock_mantle_responses_transformation.py	Flips test_registry_returns_native_config_for_xai_grok assertion from False to True with an explanatory comment; the previous assertion was testing the buggy behavior, so this update correctly reflects the fix rather than weakening coverage. No real network calls are introduced.

_{Reviews (2): Last reviewed commit: "fix(bedrock_mantle): route xai.grok-4.3 ..." | Re-trigger Greptile}

[marty-sullivan]

Both failing checks are unrelated to this change. auth-and-jwt fails on the pre-existing wildcard access bug tracked in #33030 (fix open in #33031); the same two bedrockz test cases fail on unrelated PRs against other bases, including the docs-only #33049. osv-scan started failing repo-wide today because PYSEC-2026-2253 through PYSEC-2026-2257 were published for pillow 12.2.0, which uv.lock pins; they are fixed in pillow 12.3.0