// lib/migration-runner.ts
interface Migration { version: number; name: string; up: (s: any) => Promise<void>; }

const KEY = "__schema";
const LATEST = 3;

class Runner {
  migrations: Migration[] = [];
  register(m: Migration) { this.migrations.push(m); this.migrations.sort((a, b) => a.version - b.version); }

  async getVersion(): Promise<number> {
    const r = await chrome.storage.local.get(KEY);
    return r[KEY]?.v ?? 0;
  }

  async run() {
    const current = await this.getVersion();
    if (current >= LATEST) return { ok: true, errs: [] };
    const errs: string[] = [];
    for (const m of this.migrations) {
      if (m.version > current) {
        try { await this.backup(); await m.up(chrome.storage.local); await this.setVer(m.version); }
        catch (e) { errs.push(`${m.name}: ${e}`); await this.rollback(); break; }
      }
    }
    return { ok: errs.length === 0, errs };
  }

  private async backup() {
    const d = await chrome.storage.local.get(null);
    await chrome.storage.local.set({ __backup: { d, t: Date.now() } });
  }
  private async setVer(v: number) { await chrome.storage.local.set({ [KEY]: { v, migrated: Date.now() } }); }
  private async rollback() {
    const b = await chrome.storage.local.get("__backup");
    if (b.__backup?.d) await chrome.storage.local.set(b.__backup.d);
  }
}
export const runner = new Runner();

// migrations.ts
import { runner } from "./lib/migration-runner";

runner.register({ version: 1, name: "rename-prefs",
  up: async (s) => {
    const r = await s.get("preferences");
    if (r.preferences) { await s.set({ settings: r.preferences }); await s.remove("preferences"); }
  },
});

runner.register({ version: 2, name: "restructure",
  up: async (s) => {
    const r = await s.get("userData");
    if (r.userData) await s.set({ userData: { profile: r.userData, created: Date.now() } });
  },
});

// background.ts
import { runner } from "./lib/migration-runner";
import "./migrations";

chrome.runtime.onInstalled.addListener(async (details) => {
  if (details.reason === "update") {
    const r = await runner.run();
    r.ok ? console.log("Migrated") : console.error(r.errs);
  }
  await registerEphemeralState(); // alarms, context menus
});

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