feat(updater): verifikasi SHA-256 sebelum mengganti AppImage; CI menerbitkan .sha256 + .zsync

- do_update: unduh → verifikasi checksum rilis → baru ganti berkas (mismatch = dibatalkan)
- workflow: hasilkan GAMEMAX-LCD-x86_64.AppImage.sha256 dan .zsync (zsyncmake), lampirkan ketiganya
- README: bagian Updates menjelaskan checksum + zsync (delta update opsional)
- versi 1.2.3

.github/workflows/release.yml

@@ -21,7 +21,7 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install -y --no-install-recommends \
-            libgl1 libegl1 libxkbcommon0 libdbus-1-3 libfuse2 fuse
+            libgl1 libegl1 libxkbcommon0 libdbus-1-3 libfuse2 fuse zsync
 
       - name: Set up uv
         uses: astral-sh/setup-uv@v5
@@ -38,6 +38,15 @@ jobs:
         run: |
           ./dist/GAMEMAX-LCD-x86_64.AppImage --selftest
 
+      - name: Checksum and zsync metadata
+        run: |
+          cd dist
+          sha256sum GAMEMAX-LCD-x86_64.AppImage > GAMEMAX-LCD-x86_64.AppImage.sha256
+          zsyncmake -u "https://github.com/${{ github.repository }}/releases/download/${{ github.ref_name }}/GAMEMAX-LCD-x86_64.AppImage" \
+            -o GAMEMAX-LCD-x86_64.AppImage.zsync GAMEMAX-LCD-x86_64.AppImage
+          cat GAMEMAX-LCD-x86_64.AppImage.sha256
+          ls -l
+
       - name: Publish release
         uses: softprops/action-gh-release@v2
         with:
@@ -58,5 +67,12 @@ jobs:
             Device access still needs the udev rule once:
             `sudo cp packaging/70-gamemax.rules /etc/udev/rules.d/ && sudo udevadm control --reload`
 
+            **Integrity:** verify the download with the published SHA-256, or use
+            `appimageupdatetool`/AppImageUpdate with the `.zsync` asset for delta updates.
+            The built-in updater (v1.2.3+) also verifies that checksum before replacing itself.
+
             Independent project, not affiliated with the vendor — see DISCLAIMER.md.
-          files: dist/GAMEMAX-LCD-x86_64.AppImage
+          files: |
+            dist/GAMEMAX-LCD-x86_64.AppImage
+            dist/GAMEMAX-LCD-x86_64.AppImage.sha256
+            dist/GAMEMAX-LCD-x86_64.AppImage.zsync

README.md

@@ -105,6 +105,7 @@ temperature source (Tctl vs Tccd).
 - **Plug and play**: the service waits for the device, streams while present and keeps
   waiting through unplug/replug; a udev rule grants access to the logged-in user
 - **Single instance**: launching the app again just raises the running window
+- **Self-update from GitHub Releases** (check + one-click update)
 - **Donate / GitHub buttons** in the app (window and tray menu)
 - **AppImage build** script (`packaging/build_appimage.sh`, PySide6 bundled)
 
@@ -208,6 +209,27 @@ docs/        reverse-engineering.md — full analysis (Indonesian)
 assets/      previews and icon
 ```
 
+## Updates
+
+The app keeps itself current from GitHub Releases:
+
+- On start (when running from an AppImage) and from the **Periksa pembaruan** button or the
+  tray menu, it asks the GitHub API for the latest release and compares it with its version.
+- When a newer release exists, a **Perbarui ke vX.Y.Z** button appears. One click downloads
+  the release asset, replaces the running AppImage atomically, refreshes the sender from the
+  new bundle and restarts the service. Restart the app to use the new version.
+- The download is verified against the release's published **SHA-256** before the AppImage is
+  replaced; a mismatch aborts the update. Older releases without a checksum are updated with a
+  warning in the log.
+- Nothing is downloaded without that click, and no other files are touched.
+
+Each release publishes three assets: the AppImage, its `.sha256`, and a `.zsync` file for
+`appimageupdatetool` / AppImageUpdate (delta updates). The zsync file is optional — the
+built-in updater does not need it.
+
+If the check fails (offline, proxy), the message appears in the app log. `GAMEMAX_DEBUG=1`
+also mirrors the log to stdout for headless runs.
+
 ## Support
 
 If this project is useful to you:

src/gamemax_gui.py

@@ -8,6 +8,7 @@ mengendalikannya dan memakai gamemax_report.py sebagai pengirim.
     gamemax_gui.py --tray-only  # tanpa jendela
     gamemax_gui.py --selftest   # uji muat tanpa tampilan (untuk build AppImage)
 """
+import hashlib
 import json
 import math
 import os
@@ -30,7 +31,7 @@ from PySide6.QtWidgets import (
 )
 from PySide6.QtNetwork import QLocalServer, QLocalSocket
 
-APP_VERSION = "1.2.1"
+APP_VERSION = "1.2.3"
 REPO = "oxpoe/Gamemax-linux-apps"
 RELEASES_API = f"https://api.github.com/repos/{REPO}/releases/latest"
 UPDATE_ASSET = "GAMEMAX-LCD-x86_64.AppImage"
@@ -96,6 +97,19 @@ def ensure_ca_bundle():
             return
 
 
+def verify_sha256(path, sha_url):
+    """True/False bila berkas checksum tersedia, None bila rilis tidak menyediakannya."""
+    try:
+        with urllib.request.urlopen(sha_url, timeout=10) as resp:
+            expected = resp.read().decode().split()[0].strip().lower()
+    except Exception:  # noqa: BLE001
+        return None
+    if len(expected) != 64:
+        return None
+    actual = hashlib.sha256(open(path, "rb").read()).hexdigest()
+    return actual == expected
+
+
 def latest_release():
     """(tag, url aset) dari rilis terbaru GitHub — dipanggil dari thread pekerja."""
     ensure_ca_bundle()
@@ -503,6 +517,10 @@ class Window(QWidget):
         ensure_ca_bundle()
         tmp = target + ".new"
         urllib.request.urlretrieve(url, tmp)
+        checked = verify_sha256(tmp, url + ".sha256")
+        if checked is False:
+            os.unlink(tmp)
+            raise RuntimeError("checksum SHA-256 tidak cocok — unduhan dibatalkan")
         os.chmod(tmp, 0o755)
         os.replace(tmp, target)                      # ganti berkas secara atomik
         # sender di layanan juga diambil dari bundel baru
@@ -514,7 +532,11 @@ class Window(QWidget):
                 os.makedirs(INSTALL_DIR, exist_ok=True)
                 shutil.copyfile(sender, os.path.join(INSTALL_DIR, "gamemax_report.py"))
                 systemctl("restart", SERVICE)
-        return f"diperbarui ke {tag} — tutup jendela ini lalu buka lagi untuk memakai versi baru"
+        note = "" if checked is None else " (checksum SHA-256 terverifikasi)"
+        if checked is None:
+            note = " (rilis ini tidak menyertakan checksum)"
+        return (f"diperbarui ke {tag}{note} — tutup jendela ini lalu buka lagi "
+                "untuk memakai versi baru")
 
     # -------------------------------------------------------------- tugas latar
     def start_task(self, label, fn):
@@ -685,6 +707,8 @@ class Window(QWidget):
 
     def log(self, text):
         self.logview.appendPlainText(text)
+        if os.environ.get("GAMEMAX_DEBUG"):
+            print(text, flush=True)
 
     def warn_once(self, text):
         if getattr(self, "_warned", None) != text:
@@ -896,8 +920,8 @@ def _main():
                  ("periksa pembaruan", w.do_check_update))
         for name, fn in steps:
             try:
-                fn()
+                out = fn()
-                print(f"[ OK ] {name}")
+                print(f"[ OK ] {name}" + (f" — {out}" if isinstance(out, str) and out else ""))
             except Exception as exc:  # noqa: BLE001
                 print(f"[GAGAL] {name}: {exc}")
         # jalur asinkron yang dipakai tombol: centang layar kosong + simpan