Start Gyre from an icon: launch / quit / install-desktop

- python3 -m sandtable install-desktop puts a Gyre icon in the app grid and on
  the desktop (freedesktop .desktop entry with a "Quit Gyre" action).
- The icon runs `launch`: starts the web page in the background (no terminal,
  own session, log in .cache/server.log) if it isn't running, then opens it.
  A dialog shows the reason if it can't start.
- Quit link on the page (local computer only) and `quit`: stop any design,
  motors off, close the page.
- Gyre icon (sandtable/static/gyre.svg), also the page's tab icon.
- Simulator takes several lines per tick, so streaming tests aren't slowed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

software/sandtable/launcher.py

@@ -0,0 +1,112 @@
+"""Start Gyre from a desktop icon: run the web page in the background (no terminal window) and
+open it in the browser. Used by the Gyre icon (`install-desktop` puts it in the app grid and on
+the desktop):
+    python3 -m sandtable launch     start if needed, then open the page
+    python3 -m sandtable quit       stop any design, motors off, close Gyre
+"""
+import json
+import os
+import shutil
+import subprocess
+import sys
+import time
+import urllib.request
+import webbrowser
+
+SOFTWARE = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+ICON = os.path.join(SOFTWARE, 'sandtable', 'static', 'gyre.svg')
+LOG = os.path.join(SOFTWARE, '.cache', 'server.log')
+
+
+def status(port):
+    """The running Gyre page's status, or None if nothing (or something else) answers."""
+    try:
+        with urllib.request.urlopen(f'http://127.0.0.1:{port}/api/status', timeout=1.5) as r:
+            d = json.load(r)
+        return d if 'machine' in d else None
+    except Exception:
+        return None
+
+
+def say(title, msg, error=False):
+    """Tell the person at the desktop: a dialog if possible, else a notification."""
+    print(f'{title}: {msg}', flush=True)
+    if shutil.which('zenity'):
+        subprocess.run(['zenity', '--error' if error else '--info', '--title', title, '--width', '420',
+                        '--text', msg], stderr=subprocess.DEVNULL)
+    elif shutil.which('notify-send'):
+        subprocess.run(['notify-send', '-a', 'Gyre', title, msg])
+
+
+def launch(port=8765):
+    if status(port) is None:
+        os.makedirs(os.path.dirname(LOG), exist_ok=True)
+        log = open(LOG, 'a')
+        log.write(time.strftime('\n=== %Y-%m-%d %H:%M:%S starting from the Gyre icon\n'))
+        log.flush()
+        subprocess.Popen([sys.executable, '-m', 'sandtable', 'web', '--no-browser', '--http-port', str(port)],
+                         cwd=SOFTWARE, stdout=log, stderr=subprocess.STDOUT, stdin=subprocess.DEVNULL,
+                         start_new_session=True)        # keeps running after this launcher exits
+        t_end = time.time() + 25
+        while time.time() < t_end and status(port) is None:
+            time.sleep(0.4)
+        if status(port) is None:
+            with open(LOG) as f:
+                tail = ''.join(f.readlines()[-12:])
+            say('Gyre could not start', f'The page did not come up. The last lines of its log:\n\n{tail}', error=True)
+            return 1
+    webbrowser.open(f'http://127.0.0.1:{port}/')
+    return 0
+
+
+def quit_gyre(port=8765):
+    try:
+        req = urllib.request.Request(f'http://127.0.0.1:{port}/api/quit', data=b'{}', method='POST',
+                                     headers={'Content-Type': 'application/json'})
+        with urllib.request.urlopen(req, timeout=40) as r:
+            ok = json.load(r).get('ok')
+    except Exception:
+        ok = False
+    if not ok:
+        say('Gyre', 'Gyre is not running.')
+    return 0
+
+
+def install_desktop():
+    """Put a Gyre icon in the app grid and on the desktop (Linux desktops that follow the
+    freedesktop.org standard: GNOME, KDE, Cinnamon, Xfce...)."""
+    entry = f"""[Desktop Entry]
+Type=Application
+Name=Gyre
+GenericName=Sand art table
+Comment=Draw designs on the Gyre sand table
+Exec={sys.executable} -m sandtable launch
+Path={SOFTWARE}
+Icon={ICON}
+Terminal=false
+Categories=Utility;
+StartupNotify=false
+Actions=quit;
+
+[Desktop Action quit]
+Name=Quit Gyre
+Exec={sys.executable} -m sandtable quit
+"""
+    apps = os.path.expanduser('~/.local/share/applications')
+    os.makedirs(apps, exist_ok=True)
+    places = [os.path.join(apps, 'gyre.desktop')]
+    desktop = subprocess.run(['xdg-user-dir', 'DESKTOP'], capture_output=True, text=True).stdout.strip() \
+        if shutil.which('xdg-user-dir') else os.path.expanduser('~/Desktop')
+    if desktop and os.path.isdir(desktop) and desktop != os.path.expanduser('~'):
+        places.append(os.path.join(desktop, 'Gyre.desktop'))
+    for p in places:
+        with open(p, 'w') as f:
+            f.write(entry)
+        os.chmod(p, 0o755)
+        if shutil.which('gio'):                         # GNOME: allow launching from the desktop
+            subprocess.run(['gio', 'set', p, 'metadata::trusted', 'true'], stderr=subprocess.DEVNULL)
+    if shutil.which('update-desktop-database'):
+        subprocess.run(['update-desktop-database', apps], stderr=subprocess.DEVNULL)
+    for p in places:
+        print('  wrote', p)
+    return places