build

name	build
description	Use when implementing any non-trivial feature, change, or fix — "build me X", "add this feature", "implement this", "make this work", "can you create". Covers new functionality, meaningful changes to existing code, and anything where quality matters. Not for a one-line diff — just do that.

MasterMind — Build

The single "do it the genius way, end to end" workflow. It runs the loop from ~/.mastermind/engineering/core/agent-loop.md, pulling in the specialist agents and the field pack at each phase. Task: $ARGUMENTS.

Scale effort to the task (~/.mastermind/engineering/core/principles.md): a trivial change skips straight to implement+verify; a foundation gets the full loop. Don't perform ceremony the task doesn't warrant.

The loop

1. Understand — restate the real problem and its scope/lifespan; do the asked task and nothing more (~/.mastermind/engineering/core/rigor.md → Stay in scope). Read the relevant existing code and conventions first (delegate wide reading to a subagent to protect context); learn the stack if unfamiliar (~/.mastermind/engineering/core/agent-loop.md → Learn the stack first). Match the codebase.

2. Design (non-trivial only) — invoke the architect agent to produce the blueprint: module/component boundaries + interfaces, state model, data flow, key types, edge-case list. For a multi-file or unfamiliar change, write the design/spec down before coding. Skip for a clear one-file fix.

3. Decide the stack — apply the active field's stack-defaults.md. Choose the simplest thing that fully works; deviate only for a stated reason. Consult mentors.md if a call is contested.

Plan-first gate (opt-in, off by default). If the project's plan-first preference is on (.mastermind/prefs.md: plan-first: on) — or the user asks to "plan first" — do not start editing yet. Present a concise plan from steps 1–3: the goal, the approach, the files you'll touch, the steps, and any risk/decision worth a look.

The bar: clear enough for an enthusiastic junior engineer with poor taste, no judgement, no project context, and an aversion to testing to follow without asking you anything. That means exact file paths, not "the auth module"; bite-sized steps, not "implement the feature"; and a stated way to tell each step worked. If a step needs you to already know something the plan doesn't say, it isn't written yet. Then stop and wait for the user's go-ahead (this overrides the usual "decide and do" for this project — they opted in). If they adjust it, fold that in and re-show. On approval, announce 🧠 MasterMind ▸ implementing the plan with └ build · implement → verify → review beneath it, then proceed to step 4. Skip the gate entirely for a trivial one-liner (match effort to stakes) — it's for changes worth reviewing first.

4. Implement to rigor (~/.mastermind/engineering/core/rigor.md) — build against the design. Handle the unhappy paths (null/empty/loading/error/zero/one/many/offline/unauthorized/malformed). Types honest, no lazy placeholders, no dead code. Single-purpose units. Style like the surrounding code.

5. Verify — close the loop (~/.mastermind/engineering/core/agent-loop.md; the qa skill) — prove it works by driving the real thing: typecheck + lint + build, run the project's existing tests, and for UI exercise the actual flow / screenshot. Show the evidence; never assert success. If you can't verify it, it isn't done. Fix root causes. Don't add tests or a test framework unprompted — once it works, offer: "Built and verified — want me to add tests / do this test-first?"

6. Adversarial review — invoke the code-reviewer agent on the diff in a fresh context. Fix real must-fix findings (correctness/security/a11y); treat gap-hunting nits as optional to avoid over-engineering. Re-verify after fixes.

7. Capture & report — run the levelup skill (capture) to fold any durable lesson or correction into the active field's lessons.md. Report honestly in a few lines: what shipped, the evidence it works, and anything deferred. Commit / open a PR only if asked. If the project's cycle-report preference is on (.mastermind/prefs.md: markdown/html, or ask → offer once), also run the report skill to write a durable file — default is off, so most cycles just get this in-chat verdict. Skip it entirely for a one-line change.

Non-negotiables

Correctness, security, accessibility are never traded for speed. Speed is the reward for rigor. If an approach is wrong or unsafe, say so once with the better option (~/.mastermind/engineering/core/rigor.md refuse-list), then proceed.