feat(crypto): boot-generated key + AES-256-GCM sealed values

server/test/crypto.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, test } from "bun:test";
+import { mkdtempSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { decrypt, encrypt, loadOrCreateKey, mask } from "../src/lib/crypto";
+
+describe("crypto", () => {
+  test("key is created once and reused", () => {
+    const dir = mkdtempSync(join(tmpdir(), "helios-"));
+    const a = loadOrCreateKey(dir);
+    const b = loadOrCreateKey(dir);
+    expect(a.length).toBe(32);
+    expect(a.equals(b)).toBe(true);
+  });
+
+  test("encrypt/decrypt round-trip; ciphertexts differ per call", () => {
+    const key = loadOrCreateKey(mkdtempSync(join(tmpdir(), "helios-")));
+    const sealed = encrypt(key, "sk-or-v1-secret");
+    expect(sealed.startsWith("enc:")).toBe(true);
+    expect(decrypt(key, sealed)).toBe("sk-or-v1-secret");
+    expect(encrypt(key, "sk-or-v1-secret")).not.toBe(sealed);
+  });
+
+  test("tampering fails closed", () => {
+    const key = loadOrCreateKey(mkdtempSync(join(tmpdir(), "helios-")));
+    const sealed = encrypt(key, "x");
+    const bad = sealed.slice(0, -2) + (sealed.endsWith("A") ? "BB" : "AA");
+    expect(() => decrypt(key, bad)).toThrow();
+  });
+
+  test("mask keeps only tail", () => {
+    expect(mask("sk-or-v1-abcdef")).toBe("…cdef");
+    expect(mask("abc")).toBe("…");
+  });
+});