CodeStable is a framework for AI coding assistants (Claude Code, Codex CLI) that provides a set of 'skills' — thin harnesses that guide AI agents through software development tasks such as feature implementation, bug fixing, refactoring, epic decomposition, code review, and lesson management. The system emphasizes risk-based assurance, evidence-driven decisions, and minimal project memory, with a core philosophy of 'thin harness, thick context'. It is distributed as plugins for both Claude Code and Codex CLI, and includes a meta-skill (eval-cs-skill) for authoring, evaluating, optimizing, and releasing skills. The repository contains extensive experiment infrastructure with 15+ structured experiments covering routing accuracy, end-to-end outcomes, planted-defect recall, and learning transfer across multiple models. It features a sophisticated evaluation pipeline with deterministic oracles, hidden tests, regression tests, and checkpointed resume. The codebase demonstrates high craftsmanship with clean abstractions, strict validation, and cognitive honesty tagging (measured/soft/underpowered). Key architectural patterns include the thin skill pattern (compact SKILL.md with progressive disclosure via references), adapter pattern for AI model execution (Claude Code, Codex CLI, API, mock), deterministic seed building for reproducible experiments, and a risk-to-assurance mapping used generically by all task skills. The project has 8 ADRs documenting design decisions and a v1-to-v2 migration path that reduced 32 skills to 8. While the codebase is well-maintained and actively developed, some experiments are marked underpowered and the learning transfer epic was cancelled without completing primary hypotheses. The evaluation system is complex and tightly coupled to specific model names and macOS sandbox profiles, which may limit portability.