feat: restart_claude_desktop() core logic (#9)

Platform-abstracted restart: macOS uses pkill -x Claude + open -a Claude,
Windows uses taskkill + relaunch via the Start-menu shortcut, Linux uses
pkill claude + a detached Popen relaunch. Not finding a running process is
not an error -- only a failed relaunch is reported as failure.

Also adds profile_targets_claude_desktop() to distinguish Claude Desktop
profiles (claude_desktop_config.json) from Claude Code profiles, used to
gate the restart button in the GUI.

bcc_core.py

@@ -29,6 +29,7 @@ import threading
 import time
 from dataclasses import dataclass
 from pathlib import Path
+from typing import NamedTuple
 from urllib.parse import urlparse
 
 CONFIG_FILENAME = "claude_desktop_config.json"
@@ -135,6 +136,17 @@ def profile_from_path(path: str | os.PathLike) -> Profile:
     return Profile(label=label, path=p, config_exists=p.is_file())
 
 
+def profile_targets_claude_desktop(profile: Profile) -> bool:
+    """
+    True when `profile` points at a Claude Desktop config
+    (claude_desktop_config.json), as opposed to Claude Code (~/.claude.json
+    or the legacy ~/.claude/settings.json). Used to gate Desktop-only actions
+    like "Restart Claude Desktop" so they never show up for a Claude Code
+    profile -- restarting the CLI makes no sense.
+    """
+    return Path(profile.path).name == CONFIG_FILENAME
+
+
 # --------------------------------------------------------------------------- #
 # Load / extract / apply
 # --------------------------------------------------------------------------- #
@@ -474,7 +486,7 @@ def _normalize_unicode(text: str, notes: list[str]) -> str:
     out = text
     for junk in _JUNK_CHARS:
         out = out.replace(junk, "")
-    out = out.replace(" ", " ")  # non-breaking space
+    out = out.replace("\xa0", " ")  # non-breaking space
     for smart, ascii_q in _QUOTE_MAP.items():
         out = out.replace(smart, ascii_q)
     if out != text:
@@ -1459,3 +1471,91 @@ def pin_command_path(data: dict, path: str | None = None) -> tuple[dict, str | N
                     out["args"] = args
                     return out, f"'{c}'  →  {resolved}"
     return data, None
+
+
+# --------------------------------------------------------------------------- #
+# Restart Claude Desktop (issue #9)
+#
+# Scoped strictly to Claude DESKTOP, the GUI app -- never Claude Code (the
+# CLI), which has no long-running process to bounce. Callers should gate this
+# behind profile_targets_claude_desktop() before offering it in the UI.
+# --------------------------------------------------------------------------- #
+class RestartResult(NamedTuple):
+    """Outcome of a restart_claude_desktop() attempt."""
+
+    success: bool
+    detail: str
+
+
+def _run_quiet(cmd: list[str]) -> None:
+    """Best-effort fire-and-forget command. Never raises: a nonzero exit (e.g.
+    pkill finding nothing to kill) is expected and not an error."""
+    with contextlib.suppress(OSError):
+        subprocess.run(cmd, capture_output=True)
+
+
+def _restart_claude_desktop_macos() -> RestartResult:
+    _run_quiet(["pkill", "-x", "Claude"])
+    try:
+        result = subprocess.run(["open", "-a", "Claude"], capture_output=True, text=True)
+    except OSError as e:
+        return RestartResult(False, f"Couldn't launch Claude Desktop: {e}")
+    if result.returncode != 0:
+        detail = (result.stderr or result.stdout or "").strip() or "'open -a Claude' failed"
+        return RestartResult(False, detail)
+    return RestartResult(True, "Claude Desktop restarted.")
+
+
+def _claude_windows_start_menu_shortcut() -> Path:
+    appdata = os.environ.get("APPDATA", str(Path.home()))
+    return Path(appdata) / "Microsoft" / "Windows" / "Start Menu" / "Programs" / "Claude.lnk"
+
+
+def _restart_claude_desktop_windows() -> RestartResult:
+    _run_quiet(["taskkill", "/IM", "Claude.exe", "/F"])
+    shortcut = _claude_windows_start_menu_shortcut()
+    try:
+        # `cmd /c start "" <target>` launches detached, the same as double-clicking
+        # the Start-menu shortcut, and returns immediately.
+        result = subprocess.run(
+            ["cmd", "/c", "start", "", str(shortcut)], capture_output=True, text=True
+        )
+    except OSError as e:
+        return RestartResult(False, f"Couldn't launch Claude Desktop: {e}")
+    if result.returncode != 0:
+        detail = (
+            result.stderr or result.stdout or ""
+        ).strip() or "failed to relaunch Claude Desktop"
+        return RestartResult(False, detail)
+    return RestartResult(True, "Claude Desktop restarted.")
+
+
+def _restart_claude_desktop_linux() -> RestartResult:
+    _run_quiet(["pkill", "claude"])
+    try:
+        # The Linux launcher is the app itself (no "open"-style helper), so it
+        # has to be started detached rather than waited on.
+        subprocess.Popen(
+            ["claude"],
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+            start_new_session=True,
+        )
+    except OSError as e:
+        return RestartResult(False, f"Couldn't launch Claude Desktop: {e}")
+    return RestartResult(True, "Claude Desktop restarted.")
+
+
+def restart_claude_desktop() -> RestartResult:
+    """
+    Kill and relaunch the Claude Desktop app so a freshly saved config takes
+    effect. The app not currently running is NOT a failure -- pkill/taskkill
+    exiting non-zero just means "nothing to kill", and we go straight to
+    relaunching. Only a failed relaunch is reported as success=False.
+    """
+    if sys.platform == "darwin":
+        return _restart_claude_desktop_macos()
+    if sys.platform.startswith("win"):
+        return _restart_claude_desktop_windows()
+    return _restart_claude_desktop_linux()