feat(bedrock): support Bearer token auth for Bedrock-compatible proxies

[vidgewong]

Summary

Some enterprise environments expose Bedrock-compatible endpoints behind corporate proxies that authenticate via Bearer tokens rather than AWS SigV4. These proxies use the same path format (/model/{model}/invoke) but accept Authorization: Bearer <token> instead of SigV4-signed requests.

This PR adds support for this pattern without affecting existing workflows.

Changes

• agent/anthropic_adapter.py: When both AWS_BEARER_TOKEN_BEDROCK and ANTHROPIC_BEDROCK_BASE_URL env vars are set, creates a subclass of AnthropicBedrock that overrides _prepare_request() to inject Bearer auth instead of SigV4 signing. When these vars are not set, behavior is unchanged.

• agent/bedrock_adapter.py: Extends is_anthropic_bedrock_model() to also match claude-* model names (Anthropic native format), not just anthropic.claude-* (Bedrock foundation model IDs). Proxies often use the shorter name format.

Safety

• Both changes are additive and gated behind environment variable checks
• Existing Bedrock (SigV4), Anthropic native, and OpenRouter flows are unaffected
• The Bearer path only activates when both AWS_BEARER_TOKEN_BEDROCK and ANTHROPIC_BEDROCK_BASE_URL are set simultaneously

Use Case

Enterprise users whose IT provides a Bedrock-compatible API gateway (e.g. genai-nexus.api.corpinter.net) with Bearer token auth can now use Hermes without needing direct AWS credentials:

# ~/.hermes/config.yaml
model:
  default: claude-opus-4.6
  provider: bedrock

# ~/.hermes/.env
AWS_BEARER_TOKEN_BEDROCK=<your-token>
ANTHROPIC_BEDROCK_BASE_URL=https://your-proxy.example.com

Test Plan

• Verified Bearer token auth works with a corporate Bedrock proxy
• Verified standard SigV4 Bedrock path is not affected (env vars unset)
• Verified non-Bedrock providers (Anthropic native, OpenRouter) unaffected

[alt-glitch]

Likely duplicate of #17162, which adds the same Bearer token auth for Bedrock-compatible proxies to the same files (agent/anthropic_adapter.py, agent/bedrock_adapter.py). Also related to #24507 (Converse API routing for bearer auth) and #26531 (api_mode detection fix for bearer). The approach differs slightly (#17162 uses SDK api_key param vs this PR's _prepare_request override), but the feature is the same.

[lordbuffcloud]

LGTM. The Bearer-token branch for Bedrock-compatible proxies is small and targeted, and the model-classification tweak for bare proxy names lines up with the intended routing path. I smoke-tested the new branch locally with a mocked AnthropicBedrock SDK: it produced an Authorization: Bearer header and preserved the existing default headers/timeouts, and the bedrock model-detection tests still passed.

[vidgewong]

Hi, is there anything else needed for this to be merged?

[RamsAI-bot]

For anyone tracking bearer-token Bedrock support: the two PRs that look closest to a complete fix for native Bedrock are #24507 (main-loop Converse routing + AWS_BEARER_TOKEN_BEDROCK → AWS_BEARER_TOKEN promotion) and #28085 (auxiliary dual-path Converse client). They were verified to compose cleanly (cherry-pick, 0 conflicts) and together cover both the main loop and auxiliary tasks (title generation / compression; vision still has a separate gap).

Relative to this PR: this targets a different use case — Bedrock-compatible corporate proxies via ANTHROPIC_BEDROCK_BASE_URL — so it's complementary to the native-Bedrock fixes above rather than overlapping.

[RamsAI-bot]

Update — the aux vision gap noted in my comment above is now resolved by #28085's second commit (acd5de2da), verified working against real bearer-token Bedrock. So #24507 + #28085 (in full) now cover the main loop and all aux tasks — title generation, compression, and vision — under AWS_BEARER_TOKEN_BEDROCK.

[teknium1]

Thanks for targeting the corporate Bedrock-proxy case; current main still lacks this specific AnthropicBedrock bearer path.

Problems

• The new bearer constructor at agent/anthropic_adapter.py:813 omits max_retries=0. Current main deliberately disables SDK retries at agent/anthropic_adapter.py:865-867, with coverage at tests/agent/test_anthropic_adapter.py:219-224; this branch should preserve that behavior.
• The PR changes only production files and has no regression coverage for the custom URL/auth branch. It also relies on the SDK-private _prepare_request override at agent/anthropic_adapter.py:803-804.
• The endpoint is exposed only through a new non-secret environment variable. Bedrock already has a config surface (hermes_cli/config.py:1523-1529); related #17162 is useful reference for a config-backed endpoint spanning Anthropic and Converse paths.

Suggested changes

• Preserve max_retries=0 and add branch-specific tests for the bearer header, custom URL, unset-env SigV4 behavior, and claude-* routing.
• Move the endpoint into Bedrock configuration/docs and validate the supported SDK auth mechanism rather than leaving a private-method override untested.

Automated hermes-sweeper review.

[teknium1]

Please pass max_retries=0 here as well. Current main disables Anthropic SDK retries for the normal Bedrock client (agent/anthropic_adapter.py:865-867) so Hermes's outer retry loop remains authoritative; the bearer branch otherwise regresses that invariant.