feat: detect MSIX-virtualized Claude config path + warn (#7)

bcc_core.py

@@ -191,6 +191,97 @@ def app_support_base() -> Path:
     return Path(os.environ.get("XDG_CONFIG_HOME", Path.home() / ".config"))
 
 
+def msix_config_paths(localappdata: str | os.PathLike | None = None) -> list[Path]:
+    """
+    Find MSIX/Store-packaged Claude Desktop configs.
+
+    When Claude Desktop is installed from the Microsoft Store (MSIX), Windows
+    virtualizes its filesystem writes to a per-package folder under
+    `%LOCALAPPDATA%\\Packages\\<PackageFamilyName>\\LocalCache\\Roaming\\Claude\\`
+    instead of the normal `%APPDATA%\\Claude\\`. A user (or BCC) editing the
+    plain %APPDATA% path can end up changing a file the running app never
+    reads -- see anthropics/claude-code issues #26073, #29100, #38830.
+
+    Globs `<localappdata>/Packages/*Claude*/LocalCache/Roaming/Claude/
+    claude_desktop_config.json` and returns every match that actually exists,
+    sorted for determinism. `localappdata` defaults to the %LOCALAPPDATA% env
+    var (falling back to the usual Windows path) but is accepted as a
+    parameter so this is unit-testable with tmp_path on any platform.
+
+    This function itself is platform-independent (it just globs whatever
+    directory it's given); callers that care about the *current* machine
+    should gate on sys.platform -- see `detect_msix_claude`.
+    """
+    base = (
+        Path(localappdata)
+        if localappdata is not None
+        else Path(os.environ.get("LOCALAPPDATA", str(Path.home() / "AppData" / "Local")))
+    )
+    packages = base / "Packages"
+    if not packages.is_dir():
+        return []
+    out: list[Path] = []
+    for pkg_dir in sorted(packages.glob("*Claude*")):
+        cfg = pkg_dir / "LocalCache" / "Roaming" / "Claude" / CONFIG_FILENAME
+        if cfg.is_file():
+            out.append(cfg)
+    return out
+
+
+def detect_msix_claude(
+    appdata: str | os.PathLike | None = None,
+    localappdata: str | os.PathLike | None = None,
+) -> Path | None:
+    """
+    Best-effort detection of an MSIX-virtualized Claude Desktop install.
+
+    Returns the first virtualized `claude_desktop_config.json` found (see
+    `msix_config_paths`), or None when not running on Windows, no matching
+    package folder exists, or a package folder exists but has no config file
+    written yet. The sys.platform gate makes this a safe no-op to call
+    unconditionally from discovery/diagnostics code on macOS/Linux.
+
+    `appdata`/`localappdata` are threaded through (rather than read straight
+    from os.environ) purely so the whole detection path is unit-testable via
+    tmp_path + monkeypatch without mutating real env vars.
+    """
+    if not sys.platform.startswith("win"):
+        return None
+    hits = msix_config_paths(localappdata)
+    return hits[0] if hits else None
+
+
+def msix_warning_text(
+    appdata: str | os.PathLike | None = None,
+    localappdata: str | os.PathLike | None = None,
+) -> str | None:
+    """
+    A one-line, paste-safe warning for the diagnostics/status surface when
+    Claude Desktop looks like an MSIX/Store install whose real config lives
+    somewhere other than the plain %APPDATA%\\Claude\\ path. Returns None
+    when nothing was detected (including on non-Windows platforms) or when
+    the virtualized path and the plain path happen to coincide -- i.e. there
+    is nothing surprising to warn about. Contains only filesystem paths, no
+    env values or secrets.
+    """
+    real = detect_msix_claude(appdata, localappdata)
+    if real is None:
+        return None
+    plain_base = (
+        Path(appdata)
+        if appdata is not None
+        else Path(os.environ.get("APPDATA", str(Path.home() / "AppData" / "Roaming")))
+    )
+    plain_cfg = plain_base / "Claude" / CONFIG_FILENAME
+    if plain_cfg == real:
+        return None
+    return (
+        "Claude Desktop looks like it's installed from the Microsoft Store (MSIX). "
+        f"Windows virtualizes its config, so edits to {plain_cfg} may be silently "
+        f"ignored by the running app. The real config is at: {real}"
+    )
+
+
 def discover_profiles() -> list[Profile]:
     """
     Find every `Claude*` data directory in the platform's app-support base
@@ -198,6 +289,11 @@ def discover_profiles() -> list[Profile]:
 
     Claude Desktop: scans the platform app-support folder for any `Claude*`
     directory (catches `Claude`, `Claude-Work`, etc.).
+    Windows/MSIX: if Claude Desktop was installed from the Microsoft Store,
+    its real config lives in a virtualized per-package folder rather than the
+    plain %APPDATA%\\Claude\\ path above (see `detect_msix_claude`); when
+    that's detected, it's surfaced here as its own profile so the user can
+    edit the file the app actually reads.
     Claude Code: user-scope MCP servers live in ~/.claude.json (that's what
     `claude mcp add` writes; project scope is a per-repo .mcp.json, which can
     be opened via 'Add config…'). NOT ~/.claude/settings.json — that file is
@@ -213,6 +309,12 @@ def discover_profiles() -> list[Profile]:
                 cfg = d / CONFIG_FILENAME
                 out.append(Profile(label=d.name, path=cfg, config_exists=cfg.is_file()))
 
+    msix_cfg = detect_msix_claude()
+    if msix_cfg is not None and str(msix_cfg) not in {str(p.path) for p in out}:
+        out.append(
+            Profile(label="Claude (Microsoft Store / MSIX)", path=msix_cfg, config_exists=True)
+        )
+
     home = Path.home()
     cc_cfg = home / ".claude.json"
     out.append(Profile(label="Claude Code", path=cc_cfg, config_exists=cc_cfg.is_file()))