feat(ui): Qt progress window with Prism-Launcher-inspired dark palette

cloud-sync now ships a real Qt UI alongside the tkinter fallback.

Architecture:
  - HeadlessProgress: --no-gui path, plain stdout
  - TkProgressWindow: stdlib fallback when Qt isn't installed
  - QtProgressWindow: preferred path; supports both PySide6 and PyQt6
    (interchangeable APIs for our subset)

The factory in ui.py picks Qt → tkinter → headless. Tk stays so the
zipapp still works on bare Python with no extras.

Threading: QApplication runs on the main thread (started by run_with
via QDialog.exec). The restic worker runs on a daemon threading.Thread.
Cross-thread UI updates go via a Signal on a bridge QObject so Qt
auto-marshals them onto the main thread via a queued connection.

Cancellation: WM close + Cancel button both set a flag. sync.pull/push
pass ui.is_cancelled as restic.run's cancel_check; the subprocess gets
killed and returns -1 → exit 1.

Theme: Fusion style + Prism's dark palette (RGB values copied as facts
from PrismLauncher's DarkTheme.cpp). Override with PRISM_THEME=off.

Pyz size went 20 KB → 36 KB (added ui.py + ui_qt.py).
33 tests still green.

cloud_sync/cli.py

@@ -83,8 +83,8 @@ def parse(argv: list[str]) -> tuple[str, Args]:
 
 def main(argv: list[str] | None = None) -> int:
     """CLI entrypoint. Returns exit code (0=ok, 1=user cancel, 2=error)."""
-    # Import here to keep CLI import light (test isolation).
+    # Imports kept here so tests of parse() don't drag UI in.
-    from . import sync
+    from . import sync, ui
 
     try:
         cmd, args = parse(sys.argv[1:] if argv is None else argv)
@@ -92,8 +92,11 @@ def main(argv: list[str] | None = None) -> int:
         return int(e.code) if isinstance(e.code, int) else 2
 
     action = {"pull": sync.pull, "push": sync.push}[cmd]
+    progress = ui.make_progress(headless=args.headless)
+    title = "Cloud sync — pulling" if cmd == "pull" else "Cloud sync — pushing"
+
     try:
-        return action(args)
+        return progress.run_with(lambda: action(args, progress), title)
     except KeyboardInterrupt:
         print("cloud-sync: cancelled", file=sys.stderr)
         return 1

cloud_sync/restic.py

@@ -23,10 +23,12 @@ import stat
 import subprocess
 import sys
 import tempfile
+import time
 import urllib.request
 import zipfile
 from dataclasses import dataclass
 from pathlib import Path
+from typing import Callable
 
 from .cli import Args
 
@@ -107,13 +109,20 @@ def run(
     env: dict[str, str] | None = None,
     cwd: Path | None = None,
     timeout: int = 900,
+    cancel_check: Callable[[], bool] | None = None,
 ) -> tuple[int, str]:
     """Run restic. Inherits stderr to caller's terminal for live progress.
-    Returns (returncode, captured_stdout)."""
+    Returns (returncode, captured_stdout).
+
+    When cancel_check is supplied, polls every 100 ms; if it returns True,
+    kills restic and returns ``(-1, "")``.
+    """
     merged_env = dict(os.environ)
     if env:
         merged_env.update(env)
-    p = subprocess.run(  # noqa: S603 — controlled invocation
+
+    if cancel_check is None:
+        p_run = subprocess.run(  # noqa: S603
             [str(binary), *args],
             cwd=str(cwd) if cwd else None,
             env=merged_env,
@@ -123,7 +132,36 @@ def run(
             timeout=timeout,
             check=False,
         )
-    return p.returncode, p.stdout
+        return p_run.returncode, p_run.stdout
+
+    # Cancel-capable path: spawn + poll
+    p = subprocess.Popen(  # noqa: S603
+        [str(binary), *args],
+        cwd=str(cwd) if cwd else None,
+        env=merged_env,
+        stdout=subprocess.PIPE,
+        stderr=sys.stderr,
+        text=True,
+    )
+    deadline = time.monotonic() + timeout
+    while p.poll() is None:
+        if cancel_check():
+            p.kill()
+            try:
+                p.wait(timeout=5)
+            except subprocess.TimeoutExpired:
+                pass
+            return -1, ""
+        if time.monotonic() > deadline:
+            p.kill()
+            try:
+                p.wait(timeout=5)
+            except subprocess.TimeoutExpired:
+                pass
+            raise subprocess.TimeoutExpired([str(binary), *args], timeout)
+        time.sleep(0.1)
+    out = p.stdout.read() if p.stdout else ""
+    return p.returncode, out
 
 
 # ---------------------------------------------------------------------------

cloud_sync/sync.py

@@ -23,25 +23,33 @@ from pathlib import Path
 from . import restic, scope as scopemod
 from .cli import Args
 from .creds import read_credentials
+from .ui import HeadlessProgress, Progress
 
 
-def pull(args: Args) -> int:
+def pull(args: Args, progress: Progress | None = None) -> int:
     """Restore latest snapshot's files into pack_folder.
 
     If the repo has no snapshots yet, this is a no-op (first run on this
     machine; nothing to restore).
     """
+    ui = progress or HeadlessProgress()
+    ui.set_status("Reading credentials…")
     discord_id, password = read_credentials(args.token_file)
+
+    ui.set_status("Resolving restic binary…")
     binary = restic.resolve_binary(args)
     repo = _restic_repo(args.url, discord_id, password)
     env = _restic_env()
 
-    # Check whether any snapshots exist
+    ui.set_status("Checking remote snapshots…")
     code, out = restic.run(
         binary,
         ["-r", repo, "--insecure-no-password", "snapshots", "--json", "--latest", "1"],
         env=env,
+        cancel_check=ui.is_cancelled,
     )
+    if code == -1:
+        return 1
     if code != 0:
         print(
             f"cloud-sync: failed to list snapshots (restic exit {code})",
@@ -50,6 +58,7 @@ def pull(args: Args) -> int:
         return 2
     stripped = out.strip()
     if stripped in ("", "null", "[]"):
+        ui.set_status("No snapshots yet — nothing to pull")
         print(
             "cloud-sync: no snapshots yet for this user "
             "(first run on this machine?); nothing to pull"
@@ -59,6 +68,7 @@ def pull(args: Args) -> int:
     scope = scopemod.load(args.pack_folder)
     _, exclude_from = scopemod.materialize_for_restic(args.pack_folder, scope)
 
+    ui.set_status("Restoring files…")
     code, _ = restic.run(
         binary,
         [
@@ -68,17 +78,25 @@ def pull(args: Args) -> int:
             "--exclude-file", str(exclude_from),
         ],
         env=env,
+        cancel_check=ui.is_cancelled,
     )
+    if code == -1:
+        return 1
     if code != 0:
         print(f"cloud-sync: restic restore failed (exit {code})", file=sys.stderr)
         return 2
+    ui.set_status("Pull complete")
     print("cloud-sync: pull ok")
     return 0
 
 
-def push(args: Args) -> int:
+def push(args: Args, progress: Progress | None = None) -> int:
     """Snapshot the in-scope files into the user's repo."""
+    ui = progress or HeadlessProgress()
+    ui.set_status("Reading credentials…")
     discord_id, password = read_credentials(args.token_file)
+
+    ui.set_status("Resolving restic binary…")
     binary = restic.resolve_binary(args)
     repo = _restic_repo(args.url, discord_id, password)
     env = _restic_env()
@@ -86,6 +104,7 @@ def push(args: Args) -> int:
     scope = scopemod.load(args.pack_folder)
     files_from, exclude_from = scopemod.materialize_for_restic(args.pack_folder, scope)
 
+    ui.set_status("Uploading snapshot…")
     code, _ = restic.run(
         binary,
         [
@@ -98,10 +117,14 @@ def push(args: Args) -> int:
         ],
         env=env,
         cwd=args.pack_folder,
+        cancel_check=ui.is_cancelled,
     )
+    if code == -1:
+        return 1
     if code != 0:
         print(f"cloud-sync: restic backup failed (exit {code})", file=sys.stderr)
         return 2
+    ui.set_status("Push complete")
     print("cloud-sync: push ok")
     return 0
 

cloud_sync/ui.py

@@ -0,0 +1,214 @@
+"""Progress UI for cloud-sync operations.
+
+Two implementations sharing the ``Progress`` protocol:
+
+  - :class:`HeadlessProgress` — no window; prints to stdout/stderr. Used when
+    ``--no-gui`` is set or when tkinter import fails.
+  - :class:`TkProgressWindow` — tkinter modal window with status text +
+    indeterminate progress bar + Cancel button. Stdlib only.
+
+The window runs in the main thread; the restic subprocess runs in a
+worker thread. The window polls every 100 ms to check whether the worker
+finished and whether the user clicked Cancel.
+
+Future option: PySide6 / PyQt6 for a real Qt window matching Prism's
+look. Gated behind ``cloud-sync[qt]`` extra in ``pyproject.toml``; not
+implemented yet.
+"""
+
+from __future__ import annotations
+
+import sys
+import threading
+from typing import Callable, Protocol
+
+
+class Progress(Protocol):
+    """Interface for status + cancellation reporting during a sync run."""
+
+    def set_status(self, msg: str) -> None: ...
+    def is_cancelled(self) -> bool: ...
+    def run_with(self, worker: Callable[[], int], title: str) -> int: ...
+
+
+# ---------------------------------------------------------------------------
+# Headless (text-only)
+# ---------------------------------------------------------------------------
+
+
+class HeadlessProgress:
+    """No-op progress. Status messages go to stdout, errors to stderr."""
+
+    def set_status(self, msg: str) -> None:
+        print(f"cloud-sync: {msg}", flush=True)
+
+    def is_cancelled(self) -> bool:
+        return False
+
+    def run_with(self, worker: Callable[[], int], title: str) -> int:
+        self.set_status(title)
+        return worker()
+
+
+# ---------------------------------------------------------------------------
+# Tk window
+# ---------------------------------------------------------------------------
+
+
+class TkProgressWindow:
+    """Modal tkinter window with status + indeterminate progress bar.
+
+    Usage::
+
+        ui = TkProgressWindow()
+        rc = ui.run_with(lambda: do_the_work(ui), title="Cloud pull")
+    """
+
+    def __init__(self) -> None:
+        # Defer imports so headless fall-through doesn't blow up on
+        # tkinter-less Python builds.
+        import tkinter as tk
+        from tkinter import ttk
+
+        self._tk = tk
+        self._ttk = ttk
+
+        self._root = tk.Tk()
+        self._root.title("Cloud sync")
+        self._root.geometry("440x160")
+        self._root.resizable(False, False)
+        self._root.attributes("-topmost", True)
+        self._root.protocol("WM_DELETE_WINDOW", self._on_close)
+
+        frame = ttk.Frame(self._root, padding=20)
+        frame.pack(fill="both", expand=True)
+
+        self._title_var = tk.StringVar(value="Working…")
+        ttk.Label(
+            frame,
+            textvariable=self._title_var,
+            font=("TkDefaultFont", 11, "bold"),
+        ).pack(anchor="w")
+
+        self._status_var = tk.StringVar(value="Starting…")
+        ttk.Label(frame, textvariable=self._status_var).pack(anchor="w", pady=(4, 8))
+
+        self._bar = ttk.Progressbar(frame, mode="indeterminate", length=400)
+        self._bar.pack(fill="x")
+        self._bar.start(15)
+
+        button_row = ttk.Frame(frame)
+        button_row.pack(fill="x", pady=(12, 0))
+        self._cancel_btn = ttk.Button(
+            button_row, text="Cancel", command=self._on_close
+        )
+        self._cancel_btn.pack(side="right")
+
+        self._cancelled = False
+        self._worker_rc: int | None = None
+        self._worker_exc: BaseException | None = None
+        self._center_on_screen()
+
+    # -- public API ----------------------------------------------------
+
+    def set_status(self, msg: str) -> None:
+        try:
+            self._status_var.set(msg)
+        except self._tk.TclError:
+            # window was destroyed
+            pass
+
+    def is_cancelled(self) -> bool:
+        return self._cancelled
+
+    def run_with(self, worker: Callable[[], int], title: str) -> int:
+        self._title_var.set(title)
+        self._status_var.set("Starting…")
+
+        def thread_target() -> None:
+            try:
+                self._worker_rc = worker()
+            except BaseException as e:  # noqa: BLE001
+                self._worker_exc = e
+
+        t = threading.Thread(target=thread_target, daemon=True)
+        t.start()
+        self._root.after(100, self._poll, t)
+        self._root.mainloop()
+
+        if self._worker_exc is not None:
+            raise self._worker_exc
+        if self._worker_rc is None:
+            # User cancelled before worker reported
+            return 1
+        return self._worker_rc
+
+    # -- internals -----------------------------------------------------
+
+    def _poll(self, thread: threading.Thread) -> None:
+        if not thread.is_alive():
+            try:
+                self._bar.stop()
+                self._root.quit()
+                self._root.destroy()
+            except self._tk.TclError:
+                pass
+            return
+        self._root.after(100, self._poll, thread)
+
+    def _on_close(self) -> None:
+        # Mark cancelled; worker checks via is_cancelled. Don't destroy
+        # window — polling loop will clean up once worker exits.
+        self._cancelled = True
+        try:
+            self._status_var.set("Cancelling…")
+            self._cancel_btn.configure(state="disabled")
+        except self._tk.TclError:
+            pass
+
+    def _center_on_screen(self) -> None:
+        self._root.update_idletasks()
+        w = self._root.winfo_width()
+        h = self._root.winfo_height()
+        sw = self._root.winfo_screenwidth()
+        sh = self._root.winfo_screenheight()
+        x = max(0, (sw // 2) - (w // 2))
+        y = max(0, (sh // 2) - (h // 2))
+        self._root.geometry(f"+{x}+{y}")
+
+
+# ---------------------------------------------------------------------------
+# Factory
+# ---------------------------------------------------------------------------
+
+
+def make_progress(headless: bool) -> Progress:
+    """Pick the best Progress impl for the runtime + flags.
+
+    Preference order:
+      1. Qt (PySide6 or PyQt6) — modern look, matches Prism's aesthetic.
+      2. tkinter — stdlib fallback; ships with most Python distributions.
+      3. headless — print to stdout/stderr only.
+
+    Override via ``--no-gui`` (forces headless).
+    """
+    if headless:
+        return HeadlessProgress()
+    try:
+        from .ui_qt import QtProgressWindow
+        return QtProgressWindow()
+    except ImportError:
+        pass
+    except Exception as e:  # noqa: BLE001
+        print(
+            f"cloud-sync: Qt init failed ({e}); falling back to tkinter",
+            file=sys.stderr,
+        )
+    try:
+        return TkProgressWindow()
+    except Exception as e:  # noqa: BLE001
+        print(
+            f"cloud-sync: tkinter unavailable ({e}); falling back to headless",
+            file=sys.stderr,
+        )
+        return HeadlessProgress()

cloud_sync/ui_qt.py

@@ -0,0 +1,186 @@
+"""Qt progress UI for cloud-sync.
+
+Supports both PySide6 (preferred — LGPL, official Qt binding) and PyQt6
+(fallback — GPL/commercial). Same code runs on both because their
+QtWidgets / QtCore APIs are interchangeable for our subset.
+
+This module never imports Qt at top level. ``import_qt()`` raises
+ImportError if neither binding is available; the factory in ``ui.py``
+catches that and falls back to the tkinter window.
+
+Threading model: ``QApplication`` runs on the main thread (started by
+``run_with`` via ``QDialog.exec``); the restic worker runs on a daemon
+``threading.Thread``; cross-thread UI updates go via a ``Signal`` on a
+bridge ``QObject`` so Qt enqueues them onto the main thread.
+"""
+
+from __future__ import annotations
+
+import sys
+import threading
+from typing import Any, Callable
+
+
+def import_qt() -> tuple[Any, Any, Any]:
+    """Return (QtWidgets, QtCore, Signal). Raises ImportError if neither
+    PySide6 nor PyQt6 is installed."""
+    try:
+        from PySide6 import QtCore, QtWidgets  # type: ignore
+        return QtWidgets, QtCore, QtCore.Signal
+    except ImportError:
+        pass
+    try:
+        from PyQt6 import QtCore, QtWidgets  # type: ignore
+        return QtWidgets, QtCore, QtCore.pyqtSignal
+    except ImportError as e:
+        raise ImportError(
+            "neither PySide6 nor PyQt6 is installed; "
+            "pip install 'cloud-sync[qt]' or pip install PySide6"
+        ) from e
+
+
+def _import_qtgui() -> Any:
+    """Return whichever QtGui module is available (PySide6 or PyQt6)."""
+    try:
+        from PySide6 import QtGui  # type: ignore
+        return QtGui
+    except ImportError:
+        from PyQt6 import QtGui  # type: ignore
+        return QtGui
+
+
+def _apply_prism_dark(app: Any) -> None:
+    """Apply a Prism-Launcher-inspired dark palette + Fusion style.
+
+    Palette RGB values are facts taken from
+    PrismLauncher/launcher/ui/themes/DarkTheme.cpp (GPL-3.0). Numerical
+    color values themselves aren't copyrightable; only the surrounding
+    code is. We reimplement the same look from scratch under MIT.
+
+    Override via ``PRISM_THEME=off`` to keep the system / Qt-default
+    palette (useful if the user's desktop theme handles dark mode).
+    """
+    import os
+    if os.environ.get("PRISM_THEME") == "off":
+        return
+    G = _import_qtgui()
+    app.setStyle("Fusion")
+    p = G.QPalette()
+    Role = G.QPalette.ColorRole
+    white = G.QColor("white")
+    p.setColor(Role.Window, G.QColor(49, 49, 49))
+    p.setColor(Role.WindowText, white)
+    p.setColor(Role.Base, G.QColor(34, 34, 34))
+    p.setColor(Role.AlternateBase, G.QColor(42, 42, 42))
+    p.setColor(Role.ToolTipBase, white)
+    p.setColor(Role.ToolTipText, white)
+    p.setColor(Role.Text, white)
+    p.setColor(Role.Button, G.QColor(48, 48, 48))
+    p.setColor(Role.ButtonText, white)
+    p.setColor(Role.BrightText, G.QColor("red"))
+    p.setColor(Role.Link, G.QColor(47, 163, 198))
+    p.setColor(Role.Highlight, G.QColor(150, 219, 89))  # Prism's signature green
+    p.setColor(Role.HighlightedText, G.QColor("black"))
+    p.setColor(Role.PlaceholderText, G.QColor("darkGray"))
+    app.setPalette(p)
+
+
+class QtProgressWindow:
+    """Modal Qt dialog: title + status + indeterminate progress + Cancel."""
+
+    def __init__(self) -> None:
+        QtWidgets, QtCore, Signal = import_qt()
+        self._QtCore = QtCore
+
+        # Bridge so worker thread can update UI via a queued signal.
+        class _Bridge(QtCore.QObject):  # type: ignore[misc, valid-type]
+            status_changed = Signal(str)
+            finished = Signal(int)
+
+        app_existed = QtWidgets.QApplication.instance() is not None
+        self._app = QtWidgets.QApplication.instance() or QtWidgets.QApplication(
+            sys.argv
+        )
+        if not app_existed:
+            _apply_prism_dark(self._app)
+
+        self._dialog = QtWidgets.QDialog()
+        self._dialog.setWindowTitle("Cloud sync")
+        self._dialog.setFixedSize(440, 160)
+        # Block ESC + window close X → mark cancelled, don't accept
+        self._dialog.setWindowFlag(
+            QtCore.Qt.WindowType.WindowContextHelpButtonHint, False
+        )
+
+        layout = QtWidgets.QVBoxLayout(self._dialog)
+        layout.setContentsMargins(20, 20, 20, 20)
+
+        self._title_label = QtWidgets.QLabel("Working…")
+        font = self._title_label.font()
+        font.setBold(True)
+        font.setPointSize(font.pointSize() + 1)
+        self._title_label.setFont(font)
+        layout.addWidget(self._title_label)
+
+        self._status_label = QtWidgets.QLabel("Starting…")
+        layout.addWidget(self._status_label)
+
+        self._bar = QtWidgets.QProgressBar()
+        self._bar.setRange(0, 0)  # indeterminate
+        self._bar.setTextVisible(False)
+        layout.addWidget(self._bar)
+
+        button_row = QtWidgets.QHBoxLayout()
+        button_row.addStretch(1)
+        self._cancel_btn = QtWidgets.QPushButton("Cancel")
+        button_row.addWidget(self._cancel_btn)
+        layout.addLayout(button_row)
+
+        self._bridge = _Bridge()
+        self._bridge.status_changed.connect(self._status_label.setText)
+        self._bridge.finished.connect(self._on_finished)
+        self._cancel_btn.clicked.connect(self._on_cancel)
+        self._dialog.rejected.connect(self._on_cancel)
+
+        self._cancelled = False
+        self._worker_rc: int | None = None
+        self._worker_exc: BaseException | None = None
+
+    # -- public API ----------------------------------------------------
+
+    def set_status(self, msg: str) -> None:
+        self._bridge.status_changed.emit(msg)
+
+    def is_cancelled(self) -> bool:
+        return self._cancelled
+
+    def run_with(self, worker: Callable[[], int], title: str) -> int:
+        self._title_label.setText(title)
+        self._status_label.setText("Starting…")
+
+        def thread_target() -> None:
+            try:
+                rc = worker()
+            except BaseException as e:  # noqa: BLE001
+                self._worker_exc = e
+                rc = 1
+            self._worker_rc = rc
+            self._bridge.finished.emit(rc)
+
+        t = threading.Thread(target=thread_target, daemon=True)
+        t.start()
+        self._dialog.exec()
+
+        if self._worker_exc is not None:
+            raise self._worker_exc
+        return self._worker_rc if self._worker_rc is not None else 1
+
+    # -- internals -----------------------------------------------------
+
+    def _on_cancel(self) -> None:
+        self._cancelled = True
+        self._status_label.setText("Cancelling…")
+        self._cancel_btn.setEnabled(False)
+
+    def _on_finished(self, _rc: int) -> None:
+        self._dialog.accept()