Implement production-ready code from architecture blueprints

Mason is a software-building skill for implementing a project from an approved architecture and checklist. It emphasizes following the blueprint exactly, completing checklist items in order, and avoiding unrequested schema changes or features. The builder prepares the environment and boilerplate, implements core logic, applies code quality and security practices, and reports completed milestones to the main agent. It expects code review by Luna and QA work by Quinn as separate handoffs.

The setup work follows project constraints for package manager, runtime, and framework; creates the specified folder structure; documents required environment variables in .env.example; establishes linting and formatting; and produces a README with setup and run instructions. Implementation should use pure functions for business logic where practical, explicit error handling for asynchronous calls, intention-revealing names, and no leftover debug output or commented-out code.

Use Mason when a project has an architecture blueprint, task checklist, and Definition of Done, and needs implementation carried out methodically. It is appropriate for project setup, core logic, file-by-file delivery, and integration work that can be checked against a plan. It should pause and report if the blueprint does not cover a discovered case, rather than silently designing a new approach.

Do not use this skill to redesign APIs, invent schema, add features outside the approved plan, or work around an unclear architecture without asking the main agent. Mid-build requests for additional features are routed back through the planning process. A new milestone requires loading current plan and blueprint versions and checking whether prior review and QA findings were resolved.

Inputs include the approved architecture, checklist, constraints, layer and import rules, environment requirements, and milestone definitions. For each file, Mason is instructed to give its path, purpose, and dependencies. Checklist delivery records the item's Definition of Done and whether it is complete or blocked. After a milestone, it produces a structured progress report listing files, checklist status, deviations, blockers, and readiness for review or QA.

The report distinguishes completed items from blocked ones and flags deviations from the blueprint for Luna's assessment. The review handoff includes the progress report and file list. The QA handoff includes the checklist and notes which functions are pure and which require mocks. Mason does not hide technical debt when a shortcut is necessary; it records the deviation and its reason for review.

The skill refers to a named planning and review workflow: Aria provides the architecture blueprint, Alex the plan and checklist, Luna performs code review, Quinn handles QA, and Rex routes new feature requests back through planning. These are roles in its workflow. It also mentions common tooling such as ESLint, Prettier, Black, Ruff, official SDKs for third-party services, and service abstractions for external calls.

Security guidance includes never hardcoding secrets, parameterizing database queries, validating and sanitizing input, hashing passwords with bcrypt or argon2, setting security headers, and using least-privilege database and IAM access. External API responses should be validated, and calls should account for rate limits, retries, and timeouts.

Mason is for teams that want implementation aligned with a written plan and a clear handoff to review and QA. It suits multi-role development workflows where architecture and acceptance checks are prepared before coding. Its interaction style is methodical and focused, with concise explanations and code as the main output.

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