## Summary
- Both JS and Python SDKs now validate that the configured E2B API key
matches `e2b_` followed by 40 hex characters (mirroring the server-side
check in
[`infra/.../keys/key.go`](https://github.com/e2b-dev/infra/blob/main/packages/shared/pkg/keys/key.go#L66))
and throw `AuthenticationError` / `AuthenticationException` with an
example token (`e2b_0000…`) and a link to the API Keys dashboard tab.
- Validation runs inside `ApiClient` / `ApiClient.__init__` whenever an
API key is present, so callers get immediate, actionable feedback
instead of a generic 401 from the server.
- Added unit tests (`validateApiKey.test.ts`,
`test_validate_api_key.py`) and updated existing fixtures that used
placeholder keys like `'test-key'` / `'base-api-key'` to use the valid
format.
## Test plan
- [x] `pnpm run format`, `pnpm run lint`, `pnpm run typecheck`
- [x] `pnpm exec vitest run tests/api/validateApiKey.test.ts
tests/api/handleApiError.test.ts tests/sandbox/abortSignal.test.ts
tests/template/abortSignal.test.ts
tests/sandbox/configPropagation.test.ts tests/connectionConfig.test.ts`
- [x] `poetry run pytest tests/test_validate_api_key.py
tests/test_api_client_transport.py
tests/sync/sandbox_sync/test_config_propagation.py
tests/async/sandbox_async/test_config_propagation.py
tests/test_connection_config.py`
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
Mish Ushakov
4a4bb36839