[Md. Shalah Uddin (shanto462)]

Motivation & Context

BedrockEmbeddingClient built its runtime client with region_name=boto3_session.region_name or resolved_region, so a provided session's region won over an explicit region or BEDROCK_REGION. Its region attribute was always the configured region or us-east-1, even when requests went to the session's region or to the region boto3 resolved from its own configuration. BedrockChatClient already resolves the region in the expected order (#9249).

Description & Review Guide

• What are the major changes? The embedding client now resolves the region as region / BEDROCK_REGION, then the session's region (or boto3's own configuration when no session is passed, as before), then us-east-1, and uses that same value for the runtime client and for client.region. Both region docstrings describe this order. Regression tests mirror the chat client's from Python: fix(bedrock): use the boto3 session's region in BedrockChatClient #9249: a parametrized session test (session region, region argument wins, BEDROCK_REGION wins, default), a test that boto3's default region is reported, and a test that a pre-built client still ignores the session.
• What is the impact of these changes? A client created with an explicit region and a session in another region now sends requests to the explicit region, like the chat client; passing no region keeps the session's region. client.region now matches the region in use. Nothing changes when a pre-built client is passed, and credentials handling is unchanged.
• What do you want reviewers to focus on? Without a session, the embedding client still lets boto3 resolve the region from its own configuration (environment, config file), as its docstring has always said. The chat client pins us-east-1 in that case; I left that difference alone so this PR does not change the no-session behavior of either client.

Related Issue

Fixes #9348

No other open PR covers this issue.

AI Assistance

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Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR links to an agreed issue with no competing open PR, or the Related Issue section documents a trivial-change or repository-automation exception.
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

🟢 Approval recommended

The implementation matches the documented behavior and includes focused regression coverage.

0 open findings

What changed in this PR

Aligns Bedrock embedding region resolution with the intended precedence while preserving boto3 defaults.

Changes:

• Prioritizes configured regions over session regions.
• Keeps client.region consistent with the runtime region.
• Adds regression coverage and updates docstrings.

File	Description
_embedding_client.py	Corrects region resolution and documentation.
test_bedrock_embedding_client.py	Tests region precedence, boto3 defaults, and prebuilt clients.

🧠 Review effort: Balanced

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