### Summary
Closes#17848.
This replaces #17958 with a smaller implementation focused on the
original requirement. The previous PR gradually expanded beyond the
necessary scope; the optional custom endpoint extension is intentionally
excluded from this version.
- Add request-scoped Bedrock API key authentication to the Python
Bedrock adapters and Go chat runtime.
- Discover and persist models available to API key instances, so users
do not need to manually enter the model type, model name, or maximum
token count.
- Add API Key mode to the existing Bedrock settings UI and refresh the
model and default-model lists after instance changes.
- Preserve selected models during credential-only updates while keeping
the existing SigV4 authentication modes unchanged.
- Return a clear error for unsupported API-key reranking.
- Document instance-scoped authentication and short-term API key
guidance.
## What
Adds a reranker connector for the **Bedrock** factory, which previously
offered
chat/embedding/CV models but no reranker — selecting a Bedrock rerank
model
raised `Factory not in rerank model`.
## How
`BedrockRerank` calls the `bedrock-agent-runtime` Rerank API. It reuses
the same
JSON key protocol as `BedrockEmbed` (`auth_mode` / `bedrock_region` /
`bedrock_ak` / `bedrock_sk`, with `access_key_secret` / `iam_role` /
`assume_role` modes). Documents are truncated to the model window
(Cohere Rerank
v3.5 ~2k of its shared 4k window, Amazon Rerank v1 8k) on top of
Bedrock's own
internal truncation. Scores are returned in `[0, 1]`, so the shared
`Base.similarity` normalization applies unchanged.
Verified against `amazon.rerank-v1:0` and `cohere.rerank-v3-5:0` in
`eu-central-1`.
> Note: this PR adds the connector only. Bedrock rerank models can be
selected by
> adding the relevant entries to `conf/llm_factories.json` under the
Bedrock
> provider; that catalog change is intentionally left out of this PR.
## Tests
`test/unit_test/rag/llm/test_bedrock_rerank.py` — boto3 is mocked (no
AWS call):
score-by-index mapping, per-model document truncation, model ARN
construction,
auth-mode validation and the empty-input short-circuit. `pytest` green
alongside
the existing reranker normalization suite.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
