Anthropic gates newer models on a minimum Claude Code client version. With
CLICurrentVersion pinned at 2.1.220, claude-fable-5-1 fails every request with
"Claude Code 2.1.220 does not support this model; version 2.1.251 or newer is
required", and the only fix is a release that bumps one constant.
Add SUB2API_CLAUDE_CLI_VERSION, mirroring what internal/pkg/xai already does
with XAI_GROK_CLI_VERSION. CLICurrentVersion remains the built-in pin; the new
CLIVersion() is what every consumer reads. With no env var set the resolved
value equals the pin, so existing deployments are unaffected.
The value is resolved once at package init rather than per call: the User-Agent
header and the request body's cc_version are written by different code paths for
the same request, and reading different values would make that request
contradict itself.
Validation is strict (three numeric segments, not below the pin) because
identity_service.go documents what a malformed version does once it reaches an
account's persistent fingerprint: sustained 429s without reset headers, 5s
fallback cooldown, pool collapse into a 503 storm, and no reset entry point.
Invalid values warn and fall back rather than being silently dropped.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0168uDMAj9anaJrnH8CeFze6
- bump impersonated CLI version 2.1.92 -> 2.1.161; derive User-Agent from
CLICurrentVersion so the two hardcoded copies can no longer drift apart
- fix x-stainless headers to real 2.1.161 values: package-version
0.70.0 -> 0.94.0, runtime-version v24.13.0 -> v24.3.0 (verified against
the installed Bun-compiled binary)
- expand the disguise-path system prompt from a 2-block identity skeleton
to a 3-block layout (billing + identity + tool-agnostic prose), matching
real CC's multi-block shape; cache breakpoint moved to the last static
block. Deliberately excludes # Doing tasks / # Using your tools /
# Executing actions to avoid polluting proxied-client behavior
- stabilize the synthesized metadata.user_id session_id across conversation
turns: derive it from (account + client discriminator + first user
message) instead of a per-turn content/body hash. Sticky-routing
GenerateSessionHash is intentionally left untouched; remove now-dead
hashBodyForSessionSeed
Tests: update the 3-block system assertions in gateway_prompt_test and
gateway_anthropic_apikey_passthrough_test; add a session_id cross-turn
stability test in gateway_oauth_metadata_test.
Align Claude Code mimicry constants with the latest real CLI traffic
(see Parrot's src/transform/cc_mimicry.py). Anthropic now uses the full
set of anthropic-beta tokens to decide whether a request counts as
"official Claude Code"; requests missing tokens that real CLI ships
today are demoted to third-party usage:
Third-party apps now draw from your extra usage, not your plan limits.
Changes:
- claude/constants.go: add new beta tokens (prompt-caching-scope,
effort, redact-thinking, context-management, extended-cache-ttl) and
expose FullClaudeCodeMimicryBetas() for the OAuth mimicry path.
- claude/constants.go: bump default User-Agent to claude-cli/2.1.92.
- identity_service.go: bump defaultFingerprint User-Agent accordingly.
No behavioral change for clients that already send a newer UA (fingerprint
merge still prefers the incoming value).
The existing regex only matched the old format where account_uuid is
empty (account__session_). Real Claude Code clients and newer sub2api
generated user_ids use account_{uuid}_session_ which was silently
skipped, causing the original metadata.user_id to leak to upstream
when User-Agent is rewritten by an intermediate gateway.
Closes#766
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
