SWEn delivers production-ready implementations: type-safe APIs, test coverage, real artifacts in the codebase — not prototype code masquerading as ship-ready work.
as const narrowing, derived union types, a compile-time-checked job→persona mapping, and a single pricing function — all in 120 lines with zero runtime errors since ship.// ① Derived union type — adding a persona to HIRE_CATALOG // automatically extends this type. No manual maintenance. export type PersonaHireKey = keyof typeof PERSONA_HIRE_CATALOG; // ② Single source of truth for all personas + pricing export const PERSONA_HIRE_CATALOG = { huxley: { displayName: 'hUXley', role: 'AI UX / Brand Designer', jobPriceCents: 14900, fulltimePriceCents: 54900, }, pam: { displayName: 'PaM', role: 'AI Product Manager', jobPriceCents: 7900, fulltimePriceCents: 49900, }, // ... 16 more — all enforced by the Record<PersonaHireKey, ...> shape } as const; // ③ Narrows literals — no widening to string/number // ④ O(1) job→persona routing, built once at module load const PROTECTED_JOB_TO_PERSONA = new Map<string, PersonaHireKey>(); for (const bundle of Object.values(PERSONA_CAPABILITY_BUNDLES)) { for (const jobName of bundle.protectedJobs) { PROTECTED_JOB_TO_PERSONA.set(jobName, bundle.personaKey); } } // ⑤ Single pricing function — previously duplicated 6× export function getPersonaHireAmountCents( personaKey: PersonaHireKey, mode: 'job' | 'fulltime' ): number { const persona = PERSONA_HIRE_CATALOG[personaKey]; return mode === 'fulltime' ? persona.fulltimePriceCents : persona.jobPriceCents; }
PersonaHireKey is inferred from the catalog object, not handwritten. New persona = type automatically expanded. Forgetting to add it causes a compile error at the call site.as const narrowing — without this, jobPriceCents: 14900 would widen to number, losing literal type precision and making price comparisons impossible at the type layer.