[shuv1337]

Summary

Fix the Claude subscription plugin advertising claude-cli/2.1.280, which Anthropic rejects for Fable 5.2 (minimum 2.1.290), even when a newer Claude Code is installed.

• Resolve claude --version lazily, directly through execFile (no shell), once per process; share the in-flight promise across concurrent OAuth/inference requests.
• Bound detection to 1.5 seconds and 1 KiB stdout, kill timed-out processes, and fall back silently on missing/failing/malformed/older installs to verified CLI 2.1.319.
• Use the same resolved user-agent for OAuth exchange/refresh and subscription inference. Ordinary API-key requests do not trigger detection.
• Keep x-app: cli, the system identity and dated beta feature IDs unchanged: they are not CLI version numbers. There is no plugin model allowlist; regression tests cover Fable 5.2 and Opus 5.5 model IDs and caller beta flags surviving shaping.
• Document the fallback floor and process cache (restart the server after upgrading Claude Code). No package version/release changes. No feature flag needed: this is a compatibility fix.

Changed files

All changes are confined to packages/claude-plugin/:

• src/identity.ts: detection, version floor and shared cache (new).
• src/oauth.ts: use the shared asynchronous identity for token requests.
• src/wire.ts: resolve the same identity for inference headers.
• src/hooks.ts: await headers and recheck cancellation before rewriting the request.
• test/identity.test.ts: detection parsing, newer/older versions, fallback failures, lazy/concurrent caching and minimum-version guard (new).
• test/oauth.test.ts, test/wire.test.ts: shared-identity assertions.
• test/hooks.test.ts: new-model and beta passthrough assertions.
• README.md: detection behavior and maintenance notes.

Validation

• bun test in packages/claude-plugin: 43 passed.
• bun test --only-failures --rerun-each 10 --randomize: 430 passed, seed 2900260791.
• bun typecheck in packages/claude-plugin: passed (package script uses tsc --noEmit).
• Root bun run check: passed, 37/37 typecheck tasks; lint reported existing warnings and zero errors.
• bun run prettier --check packages/claude-plugin and git diff --check: passed.
• Direct runtime checks: Node with installed Claude Code 2.1.319 and Bun with an empty executable search path both resolve the expected identity.
• OPENCODE_CHANNEL=integration-v2 OPENCODE_TARGET=linux-x64 bun run --cwd packages/cli build: passed. Host-target restriction only; no release or installation.

Live smoke test: blocked before provider request

Ran the built CLI with --standalone, anthropic/claude-fable-5-2, an archived, explicitly titled session, and a one-step agent denying every tool. Prompt: Reply with exactly OK. Do not use tools.

The run exited 1 with provider.no-route: Model unavailable: anthropic/claude-fable-5-2 before any Anthropic inference request. Follow-up --standalone auth list returned No authenticated integrations; --standalone models listed only Morph/Yeta models. This host's shuvcode does not have an active Claude subscription connection. No credential import/rotation or live server replacement was attempted. End-to-end Anthropic acceptance and subscription billing eligibility remain unverified.

Release

Do not merge/release from this task. Intended for the orchestrator's later integration-v2 release together with the upstream sync.

Visual

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