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updater

import { updater } from "@tynd/core/client";

Auto-update checker + signed binary downloader. Verifies Ed25519 signatures over the raw downloaded bytes.

check(opts): Promise<UpdateInfo | null>

Fetch the manifest and return metadata if a newer version is available.

interface UpdaterCheckOptions {
  endpoint:       string;   // URL of the update.json manifest
  currentVersion: string;   // semver
}
 
interface UpdateInfo {
  version:   string;
  notes:     string | null;
  pubDate:   string | null;     // ISO-8601 if the manifest has one
  url:       string;
  signature: string;             // base64 Ed25519
  platform:  string;             // e.g. "windows-x86_64"
}
 
const info = await updater.check({
  endpoint: "https://releases.example.com/update.json",
  currentVersion: "1.0.0",
});
 
if (info) console.log(`Update available: ${info.version}`);

Returns null when already up to date.

downloadAndVerify(opts): Promise<UpdaterDownloadResult>

Streams the artifact to a temp file while hashing, then verifies the Ed25519 signature over the full downloaded bytes.

interface UpdaterDownloadOptions {
  url:         string;
  signature:   string;   // base64 Ed25519
  pubKey:      string;   // raw 32-byte Ed25519 pubkey, base64
  progressId?: string;   // scopes onProgress events to this download
}
 
interface UpdaterDownloadResult {
  path: string;
  size: number;
}
 
const off = updater.onProgress(({ phase, loaded, total }) => {
  console.log(`${phase}: ${loaded}/${total ?? "?"}`);
});
 
const { path, size } = await updater.downloadAndVerify({
  url:       info.url,
  signature: info.signature,
  pubKey:    UPDATER_PUB_KEY,
  progressId: "update-download",
});
 
off();

Rejects with a signature check failed error if verification fails.

onProgress(fn): () => void

Fires during download + verification. Throttled ~50 ms.

interface UpdaterProgress {
  id?:    string;
  phase:  "download" | "verified";
  loaded: number;
  total:  number | null;
}
 
const off = updater.onProgress((p) => {
  console.log(p.phase, p.loaded, p.total);
});

install(opts): Promise<UpdaterInstallResult>

Swaps the downloaded binary for the running one and optionally relaunches.

interface UpdaterInstallOptions {
  path:      string;
  relaunch?: boolean;   // defaults to true
}
 
interface UpdaterInstallResult {
  installed: boolean;
  path:      string;   // final on-disk path of the running binary
  relaunch:  boolean;
}
 
const result = await updater.install({ path, relaunch: true });

Platform semantics

  • Windows — delegates to a short cmd script (timeout /t 2 /nobreak > nul & move /y <new> <current> & start ""). Lets the current .exe unlock, then swaps + relaunches.
  • Linux (AppImage + any single-file binary) — fs::rename + chmod +x + spawn + exit. Linux keeps the old inode mapped while the exe is live.
  • macOS — not yet implemented. .app bundles are directories; callers manage the swap manually using the returned path.

Returns just before the current process exits. Don’t rely on any state after install resolves.

Manifest format (Tauri-compatible)

{
  "version":  "1.2.3",
  "notes":    "Bug fixes & perf.",
  "pub_date": "2026-04-19T12:00:00Z",
  "platforms": {
    "windows-x86_64": {
      "url":       "https://.../MyApp-1.2.3-setup.exe",
      "signature": "<base64 Ed25519>"
    },
    "darwin-aarch64": {
      "url":       "https://.../MyApp-1.2.3.dmg",
      "signature": "<base64 Ed25519>"
    },
    "linux-x86_64": {
      "url":       "https://.../MyApp-1.2.3.AppImage",
      "signature": "<base64 Ed25519>"
    }
  }
}

Platform key: <os>-<arch>, where os ∈ { windows | darwin | linux } (macos → darwin for GitHub Releases / Tauri parity) and arch ∈ { x86_64 | aarch64 }.

Trust model

  • Manifest served plain HTTPS (no meta-signature).
  • Each platform entry carries an Ed25519 signature over the raw artifact bytes.
  • Public key is baked into the app — a compromised manifest server can only redirect to a URL whose bytes still verify against the local pubkey.

Signing workflow

tynd keygen --out release/updater
tynd sign release/MyApp-1.2.3-setup.exe \
  --key release/updater.key \
  --out release/MyApp-1.2.3-setup.exe.sig

Bake the pubkey into your app source:

src/updater-key.ts
export const UPDATER_PUB_KEY = "cFpG...RVDv/RQ=";

Not yet handled

  • macOS .app swap (extract from .dmg / .tar.gz).
  • Periodic auto-check — roll your own setInterval.
  • Delta updates (binary diff).
  • Rollback on failure.

See the Auto-Updates guide.

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