What problem does it solve? Changing an existing codebase or system is risky when the current implementation is mistaken for the complete specification, unknowns get hidden, and work loses traceability across requirements, design, and testing. This Skill structures brownfield change work into explicit phases with evidence, gates, and human decision points so nothing proceeds on guesses. ## Core Features & Use Cases - Phase-based orchestration: Carry one upstream item through requirements, planning, design, manufacturing, testing, and closure while preserving traceability anchors and recording every unknown with impact, resolver, and owner. - Specification reconciliation and validation: Validate existing requirements for authority, freshness, and testability, then reconcile current specification, current behavior, and new requirements into an approved delta matrix before design. - File-edit integrity and testability gates: Enforce encoding/BOM/newline preservation, compare-and-swap revision checks, uncommitted-work classification, and a testability gate that generates only traceable test-case candidates. - Use Case: A team must modify a legacy service whose documentation is stale. Use this Skill to validate the existing requirement, reconcile it against observed behavior, plan the delta, implement with file-integrity checks, and produce a summary-first closure report with residual risks and handoffs. ## Quick Start Use $brownfield-workflow in the planning phase to define the impact scope and testability inputs for your upstream work item.
