Summary

Claude Platform on AWS is not fully supported today. We currently support Amazon Bedrock via Claude Code's existing Bedrock path, for example:

CLAUDE_CODE_USE_BEDROCK=1, AWS_PROFILE, AWS_REGION, and optional awsAuthRefresh such as aws sso login --profile cc.

That is a separate integration from Claude Platform on AWS. Claude Platform on AWS uses the Anthropic AWS gateway, ANTHROPIC_AWS_WORKSPACE_ID, AWS SigV4 or ANTHROPIC_AWS_API_KEY, and the official platform-specific SDK client.

Docs:

• https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws
• https://platform.claude.com/docs/en/api/sdks/typescript

Current status

• Amazon Bedrock should remain supported through the existing CLAUDE_CODE_USE_BEDROCK backend.
• Claude Platform on AWS should be treated as not fully supported until this issue is implemented.
• Do not route Claude Platform on AWS through first-party Anthropic OAuth/API-key auth.
• Do not infer Claude Platform on AWS from AWS_PROFILE or AWS_REGION alone. The explicit signal should be ANTHROPIC_AWS_WORKSPACE_ID.

Required implementation approach

Please implement the architectural option, not the quick transport-only patch.

Add a first-class internal runtime backend identity for Claude Platform on AWS, for example claude-platform-aws, and audit all places that currently treat firstParty as both model-ID format and auth/endpoint transport.

Important distinction:

• Claude Platform on AWS uses first-party Anthropic model IDs, not Bedrock model IDs.
• But it does not use first-party Anthropic auth or endpoint behavior.

Expected changes

• Add explicit backend/provider handling for claude-platform-aws without breaking existing bedrock, vertex, foundry, first-party Anthropic, Codex, Gemini, or OpenCode paths.
• Use the official @anthropic-ai/aws-sdk / AnthropicAws client only after checking the current stable package version and compatibility.
• Keep Bedrock priority higher when both CLAUDE_CODE_USE_BEDROCK and ANTHROPIC_AWS_WORKSPACE_ID are present.
• Require ANTHROPIC_AWS_WORKSPACE_ID as the explicit signal for Claude Platform on AWS.
• Require AWS_REGION or AWS_DEFAULT_REGION; show a clear non-ready status when missing.
• Support AWS SigV4 through the standard AWS credential chain, including AWS SSO and named profiles.
• Respect existing awsAuthRefresh behavior where appropriate, such as aws sso login --profile cc.
• Support ANTHROPIC_AWS_API_KEY as the alternate auth path.
• Ensure runtime status/preflight does not show Connect Anthropic for Claude Platform on AWS.
• Ensure runtime status only becomes ready when the actual request transport is wired and validated.
• Ensure first-party Anthropic OAuth/API key headers are not mixed into Claude Platform on AWS requests.
• Audit model catalog, model availability, beta/tool capability checks, settings sync, auth checks, telemetry/provider labels, and any getAPIProvider() === 'firstParty' branches.
• Keep host-managed env filtering scoped: allow Claude Platform on AWS env only for Anthropic/Claude Platform launches, not Codex/Gemini routing.

Tests to add

• Bedrock remains selected when CLAUDE_CODE_USE_BEDROCK=1 and ANTHROPIC_AWS_WORKSPACE_ID are both present.
• AWS_PROFILE and AWS_REGION alone do not select Claude Platform on AWS.
• ANTHROPIC_AWS_WORKSPACE_ID selects Claude Platform on AWS only for Anthropic-compatible launches.
• Codex/Gemini launches are not redirected by Claude Platform on AWS env vars.
• Missing region produces a non-ready status with a clear message.
• Runtime status does not offer Connect Anthropic for Claude Platform on AWS.
• Request client uses AnthropicAws for Claude Platform on AWS and does not include first-party Anthropic OAuth/API-key auth headers.
• AWS SSO/profile flow works with existing awsAuthRefresh assumptions.
• ANTHROPIC_AWS_API_KEY path is covered separately from SigV4.
• Model IDs remain first-party format and do not use Bedrock prefixes.

Non-goals

• Do not change the existing Bedrock implementation except where tests are needed to prove priority and non-regression.
• Do not use AWS_PROFILE or AWS_REGION as a backend selection signal by themselves.
• Do not silently mark Claude Platform on AWS as authenticated/ready before real request transport support exists.

Risk notes

This should not be implemented as a small one-off branch in the API client only. The risky part is that many existing checks use firstParty to mean both model ID format and first-party Anthropic auth/endpoint behavior. Claude Platform on AWS shares the model ID format, but not the auth/endpoint behavior.

Preferred reliability target: implement this as the larger architectural pass with focused tests across runtime status, env filtering, provider selection, auth, and request client behavior.