What problem does it solve? AI-generated code often papers over root causes, swallows errors silently, and drifts from specifications. This Skill anchors every code edit to a standing set of engineering rules so changes stay correct, typed, and reviewable across long sessions. ## Core Features & Use Cases - Always-On Principles: Root-cause-only fixes, no silent failures, boundary validation, strong typing without escape hatches, and mandatory halts on spec/code discrepancies. - By-Moment Reference: Twelve operational rules covering read-first context acquisition, version-aware API stability, concurrent testing strategy, atomic git commits, and plan tracking. - Uncertainty Governance: Numeric uncertainty thresholds (0.0 / 0.1-0.3 / >0.3) that dictate when to proceed, clarify, or halt, plus a failure-recovery protocol. - Use Case: When asked to refactor a Go module, the agent first reads surrounding code and tests, validates inputs at boundaries, writes tests concurrently with the fix, and stops to ask before any breaking API change on a post-1.0 project. ## Quick Start Apply the engineering rules while refactoring this function to handle errors explicitly and add concurrent tests.