versionless

request (pinned 2025-06-01)
  → up(change 2026-05-14) → up(...) → handler sees the CURRENT shape
  → handler returns the CURRENT shape
  → down(...) → down(change 2026-05-14) → response in 2025-06-01 shape

// src/versionless.ts
import { createVersionless } from "@versionless/core";

export const v = createVersionless({
  project: "my-api",
  scheme: "date",
  current: "2026-07-21",
  resolve: [
    { header: "x-api-version" },                    // explicit pin
    { apiKey: (key) => db.pinnedVersion(key) },     // per-key pinning, Stripe-style
    { default: "current" },                         // unpinned = latest
  ],
  // Optional: pass an apiKey to light up the hosted dashboard with live
  // adoption/sunset/drift telemetry. Without it: zero network calls.
});

// wire the adapter (Elysia shown; Hono/Express/tRPC in the adapters docs)
import { versionless } from "@versionless/adapter-elysia";
app.use(versionless(v));

// break the contract? register a change instead of forking the handler
v.change("2026-05-14", {
  describe: "user.name split into firstName/lastName",
  routes: ["GET /users/:id", "POST /users"],
  request:  { up:   ({ name, ...r }) => ({ ...r, ...splitName(name) }) },
  response: { down: ({ firstName, lastName, ...r }) => ({ ...r, name: `${firstName} ${lastName}` }) },
});