Drop has_cloud_model_request_mark from shared.py::__all__. Its only caller is is_cloud_model_not_found in the same module, and the repo has no star-imports from providers.shared, so exporting it added dead public surface without a consumer. Keep the chain-wide model-request marker, but document why it marks every exception in the chain: OpenHands _unwrap_provider_exception classifies __cause__ or __context__, so a mark on only the caught wrapper could be discarded before classification. Correct docs/design/openapi-client-contract.md for the RUNTIME_REASON_CODES line shift introduced by this branch. Validation record: the full make ci gate passed on the preceding tree with 15193 passed, 17 skipped, and Rust checks included. The two failures recorded in 270a13d11's message were subsequently attributed to an intermittent full-suite isolation issue with no causal path to this diff; those tests depend on observer-bundle temp-root hashing and speakers temp-journal route state, neither of which this branch touches. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>