Lists multiple specific concrete actions and artifacts: keeping runtimes in sync, executable lookup, env construction, CLI session launch env, tooling status probes, and names specific files like 'claude-sdk-runtime.ts' and 'codex-sdk-runtime.ts'.

Clearly answers both 'what' (keep Claude and Codex provider runtimes in sync) and 'when' (explicit 'Use when' clause listing specific files and scenarios, plus a 'Trigger on phrases' clause with concrete keywords).

Excellent coverage of natural trigger terms including file paths, conceptual phrases ('provider runtime', 'claude adapter', 'codex adapter', 'sibling adapter'), environment variables ('PATH env', 'CLAUDE_CONFIG_DIR', 'CODEX_HOME'), and even Korean-language triggers for multilingual users.

Highly distinctive — targets a very specific niche of keeping two named provider runtimes in sync within the Stave project, referencing exact file paths and environment variables that are unlikely to overlap with other skills.

The skill is mostly efficient and well-targeted, but includes some sections that could be tightened — the introductory paragraph explaining why divergence is bad is unnecessary context for Claude, and the 'Common Failure Modes' section partially restates what the checklist already covers. The 'Use This Skill When' / 'Do Not Use When' sections are useful but slightly verbose.

The skill provides highly concrete, actionable guidance: specific file paths to check, a detailed checklist with precise grep targets and field names, exact verification commands (`bun run typecheck`), and a structured output format. This is an instruction-only skill that achieves full actionability without needing code examples.

The workflow is clearly sequenced through a numbered checklist (behavior parity → runtime options → event emission → CLI env → probe mismatch → SDK upgrade), followed by explicit verification steps that include both providers and real turn-start paths. The probe vs runtime mismatch section serves as a critical validation checkpoint, and the guardrails section provides clear feedback loops for error prevention.

The content is well-organized with clear sections and a reference table, and it cross-references sibling skills (`the-ipc-contract-audit`, `the-provider-router`, `the-terminal-surface-guard`). However, with no bundle files provided, the skill is a monolithic ~150-line document; the detailed checklist items and common failure modes could potentially be split into referenced files for better progressive disclosure. The reference to `docs/providers/codex-upgrade-checklist.md` is good but is the only external content reference.