Repair Customer Import History

Problem/Feature Description

Customer success uses a nightly partner import to update customer profiles shown in the admin console. A recent partner change caused old import entries to be overwritten, and support can no longer tell which source file created a displayed value. The current code also makes it hard to know which fields are partner data, stored data, or admin-facing display data.

Rework the import module so historical imports remain explainable and the admin view can still be produced from the stored data. Keep the task focused on the import feature.

Output Specification

Produce a TypeScript project in the current directory. Include updated source files and focused tests covering the repaired import behavior.

Input Files

The following files are provided as inputs. Extract them before beginning.

=============== FILE: AGENTS.md ===============

Project Instructions

• Runtime validation uses Zod.
• Feature-owned code should stay under src/features/<feature>/.
• Tests use Vitest.
• Application modules use named exports.

=============== FILE: package.json =============== { "type": "module", "scripts": { "test": "vitest run", "typecheck": "tsc --noEmit" }, "dependencies": { "zod": "^3.23.8" }, "devDependencies": { "typescript": "^5.5.3", "vitest": "^2.0.4" } }

=============== FILE: tsconfig.json =============== { "compilerOptions": { "target": "ES2022", "module": "NodeNext", "moduleResolution": "NodeNext", "strict": true, "exactOptionalPropertyTypes": true, "noUncheckedIndexedAccess": true, "skipLibCheck": true }, "include": ["src/**/*.ts"] }

=============== FILE: src/features/customers/importCustomers.ts =============== export type Customer = { id: string | null; email: string | null; fullName: string | null; plan: string | null; source: string | null; importedAt: string | null; displayName: string | null; rowNumber: number | null; };

const customers: Customer[] = [];

export function importCustomers(sourceName: string, rows: unknown[]): Customer[] { rows.forEach((row, index) => { const data = row as any; const existing = customers.find((customer) => customer.email === data.email); const next: Customer = { id: existing?.id ?? String(index), email: data.email ?? null, fullName: data.name ?? data.full_name ?? null, plan: data.plan ?? null, source: sourceName, importedAt: new Date().toISOString(), displayName: data.name ?? data.email ?? null, rowNumber: index };

if (existing) {
  Object.assign(existing, next);
} else {
  customers.push(next);
}

});

return customers.map((customer) => ({ ...customer, displayName: customer.displayName || customer.email })); }

export function listCustomers(): Customer[] { return customers; }