Anthropic tightened OAuth validation between 2026-04-14 and 2026-04-22.
Requests are now classified as third-party and routed to extra-usage
credits (or rejected with 'Third-party apps now draw from your extra
usage, not your plan limits') unless the fingerprint matches real
Claude Code. Ports the two upstream opencode-claude-auth fixes that
address this:
- PR #191 (merged, v1.4.10): PascalCase `mcp_` tool names. Hermes
prefixes tools with lowercase `mcp_bash`; the validator now flags
that as non-Claude-Code. Real CC uses `mcp_Bash` / `mcp_Read` /
`mcp_Background_output`. Adds a request-side rewrite hook plus a
response-side unhook that lowercases the first char after hermes
strips the prefix, so the tool dispatcher continues to receive the
original lowercase names.
- PR #207 (open, attempted fix for Claude Code 2.1.112): updates the
billing fingerprint. Changes the `cc_entrypoint` in the signed
billing header from `cli` to `sdk-cli`, adds the
`advisor-tool-2026-03-01` beta flag, injects the Stainless SDK
headers that real CC sends (`x-stainless-*`) plus
`anthropic-dangerous-direct-browser-access: true`, and appends
`?beta=true` to the /v1/messages query string. All non-body signals
ride the Anthropic Python SDK's per-request `extra_headers` and
`extra_query` kwargs so we don't need to rewrap the HTTP client.
Other changes:
- Bump __version__ to 1.1.0 and document the rationale above in the
module docstring.
- Extend `_EXTRA_OAUTH_BETAS` so both prompt-caching and advisor-tool
betas are appended to hermes's `_OAUTH_ONLY_BETAS` list.
- 10 new unit tests covering PascalCase rewrite (request + response),
sdk-cli entrypoint, Stainless headers, extra_query=beta:true, and
preservation of pre-existing extra_headers.
Smoke-tested on Linux with hermes-agent v0.10.0 against claude-sonnet-4-6,
claude-opus-4-6, and claude-opus-4-7 \u2014 all return 200 and complete
responses with the new patch loaded. Billing-tier routing (plan vs
extra-usage) cannot be verified from the client side; this tracks the
best-known upstream bypass as of 2026-04-22 but Anthropic may tighten
validation again at any time.
Refs: #6
Upstream: https://github.com/griffinmartin/opencode-claude-auth/pull/191
Upstream: https://github.com/griffinmartin/opencode-claude-auth/pull/207
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