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TypeScript best practices. Use when reading or editing any .ts or .tsx file.
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Create a researched, durable, approval-gated goal contract whose verification tools, repository-vault authentication, exact proof steps, rollout safety, and evidence lifecycle are ready before execution. Use when the user asks to set, create, refine, save, or verify a goal; asks whether an agent has everything needed to prove completion; wants a proof-driven alternative to a raw `/goal`; or explicitly invokes `$verify-goal`.
Relentlessly interview the user in dependency-aware batches to sharpen a plan, decision, design, idea, codebase change, or bug fix. Use when the user wants to get grilled, investigate a bug from a ticket or screenshots, pass unfinished grilling to a teammate, or pick it up from a PR. Begin each session by choosing native dialogs or one full text batch, then Sideshow or experimental Grill Visuals for live diagrams. In repositories, inspect current behavior, run a mandatory gap and blast-radius pass, and maintain durable decision docs as answers settle.
Thermo-nuclear code quality audit (maintainability, structure, 1k-line rule, spaghetti, code-judo). Invoked via Task after a parent gathers diff and file contents. Loads the rubric from the `thermo-nuclear-code-quality-review` skill in the cursor-team-kit plugin.
Validate your code changes through the no-mistakes pipeline - automated code review, tests, lint, docs, push, PR, and CI - before they reach upstream. Use when the user asks to run no-mistakes, gate or ship or validate their changes, push safely, asks you to do a task and then validate it, or invokes /no-mistakes.
Ask which skill or flow fits your situation. A router over the user-invoked skills in this repo.
Scan a codebase for deepening opportunities, present them as a visual HTML report, then grill through whichever one you pick.
| name | typescript-best-practices |
| description | TypeScript best practices. Use when reading or editing any .ts or .tsx file. |
Apply principle-type-system-discipline first; this skill grounds it in TypeScript syntax.
| Rule | Summary |
|---|---|
| Discriminated unions | Model variants with a kind literal discriminant so impossible states can't be represented. No optional-field bags. |
| Branded types | Brand primitives with & { readonly __brand: "X" } so they can't be mixed up. Validate once at creation. |
unknown over any | External data is unknown. any disables type checking everywhere it touches. |
No as casts | Every as is a runtime crash waiting. Cast only after validation. |
| Narrowing hierarchy | Discriminant switch > in operator > typeof/instanceof > user-defined type guard > as. |
| Type guards | Must verify the claim. A lying guard is worse than as because the bug hides behind a name that says it's safe. Name them isX or hasX. |
| Exhaustiveness | Inline const _exhaustive: never = x; in default arms so the compiler errors when a new variant is added. |
satisfies over as | Validates the value without widening literal types. |
| Boundary validation | Validate where data crosses in; trust types inside. Read brain/principles/boundary-discipline.md. |
| Schema-derived types | Reach for Pick/Omit/Parameters/ReturnType/Awaited/typeof before declaring a new interface. |
| Object args | Pass objects, not positional, so argument order is self-documenting. Skip on hot paths (per-frame render, tokenizers, parsers). |
| Real tests | Don't mock what you can run. Prefer the framework's real test primitives with leak/disposable checks, and verify UI in a running build. Mock only what you can't run locally. |
| Structured telemetry | Prefer structured logger diagnostics with enough context to debug from an id. No console.log in shipped code. |
Examples: references/patterns.md.
