feat: named server sets — save/apply the Active/Disabled split (#52)

Sets live in the config under _bccServerSets (bcc-owned, ignored by
Claude, travels with the file). Apply enables exactly the set's members
and parks the rest; vanished members are reported, not fatal. GUI row:
set combo + Apply + Save set… + delete.

Closes #52

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bcc.py

@@ -38,6 +38,7 @@ from PySide6.QtWidgets import (
     QGridLayout,
     QHBoxLayout,
     QHeaderView,
+    QInputDialog,
     QLabel,
     QLineEdit,
     QListWidget,
@@ -1692,6 +1693,30 @@ class MainWindow(QMainWindow):
         self.search_box.textChanged.connect(self._on_search_changed)
         v.addWidget(self.search_box)
 
+        # Named server sets (issue #52): apply a saved Active/Disabled split
+        # in one click. Sets live in the config file under _bccServerSets.
+        sets_row = QHBoxLayout()
+        sets_lbl = QLabel("Set")
+        sets_lbl.setObjectName("muted")
+        sets_row.addWidget(sets_lbl)
+        self.sets_combo = QComboBox()
+        self.sets_combo.setMinimumWidth(120)
+        sets_row.addWidget(self.sets_combo, 1)
+        self.apply_set_btn = QPushButton("Apply")
+        self.apply_set_btn.setToolTip("Enable exactly this set's servers; disable the rest")
+        self.apply_set_btn.clicked.connect(self._apply_selected_set)
+        sets_row.addWidget(self.apply_set_btn)
+        self.save_set_btn = QPushButton("Save set…")
+        self.save_set_btn.setToolTip("Save the current Active/Disabled split as a named set")
+        self.save_set_btn.clicked.connect(self._save_set)
+        sets_row.addWidget(self.save_set_btn)
+        self.del_set_btn = QPushButton("−")
+        self.del_set_btn.setToolTip("Delete the selected set")
+        self.del_set_btn.setMaximumWidth(32)
+        self.del_set_btn.clicked.connect(self._delete_set)
+        sets_row.addWidget(self.del_set_btn)
+        v.addLayout(sets_row)
+
         # Active and Disabled sections live in a vertical splitter so the user
         # can drag the divider instead of being stuck with a fixed-height
         # disabled list.
@@ -1892,6 +1917,7 @@ class MainWindow(QMainWindow):
         self._undo_stack.clear()
         self.undo_btn.setEnabled(False)
         self._health.clear()  # health results are per-profile; a fresh load invalidates them
+        self._refresh_sets_combo()  # sets are per-config; repopulate from the loaded file
         self._refresh_tables(select_index=0 if self.servers else -1)
         self._update_status(saved=False)
         if repaired:
@@ -1991,6 +2017,73 @@ class MainWindow(QMainWindow):
         cur = self._current_index()
         self._refresh_tables(select_index=cur if cur >= 0 else None)
 
+    # --- named server sets (issue #52) ------------------------------------ #
+    def _refresh_sets_combo(self, select: str | None = None):
+        sets = core.list_server_sets(self.full_config)
+        self.sets_combo.blockSignals(True)
+        self.sets_combo.clear()
+        for name in sorted(sets):
+            self.sets_combo.addItem(name)
+        if select is not None:
+            idx = self.sets_combo.findText(select)
+            if idx >= 0:
+                self.sets_combo.setCurrentIndex(idx)
+        self.sets_combo.blockSignals(False)
+        has_sets = bool(sets)
+        self.apply_set_btn.setEnabled(has_sets)
+        self.del_set_btn.setEnabled(has_sets)
+
+    def _apply_selected_set(self):
+        name = self.sets_combo.currentText()
+        sets = core.list_server_sets(self.full_config)
+        if name not in sets:
+            return
+        self._push_undo()
+        missing = core.apply_server_set(self.servers, sets[name])
+        self._refresh_tables(select_index=self._current_index() if self.servers else None)
+        self._mark_dirty()
+        on = sum(1 for s in self.servers if s.enabled)
+        msg = f"Applied set “{name}”  ·  {on} enabled. Review and Save."
+        if missing:
+            msg += f"  ⚠ no longer in this config: {', '.join(missing)}"
+        self.status.setText(msg)
+
+    def _save_set(self):
+        name, ok = QInputDialog.getText(
+            self,
+            "Save server set",
+            "Set name (saves which servers are currently Active):",
+            text=self.sets_combo.currentText(),
+        )
+        name = name.strip()
+        if not ok or not name:
+            return
+        if name in core.list_server_sets(self.full_config) and (
+            QMessageBox.question(self, "Set exists", f"Replace set “{name}”?")
+            != QMessageBox.StandardButton.Yes
+        ):
+            return
+        members = core.save_server_set(self.full_config, name, self.servers)
+        self._refresh_sets_combo(select=name)
+        self._mark_dirty()  # the set is written on the next Save
+        self.status.setText(
+            f"Set “{name}” saved ({len(members)} server(s)). Press Save to write it."
+        )
+
+    def _delete_set(self):
+        name = self.sets_combo.currentText()
+        if not name:
+            return
+        if (
+            QMessageBox.question(self, "Delete set", f"Delete set “{name}”?")
+            != QMessageBox.StandardButton.Yes
+        ):
+            return
+        if core.delete_server_set(self.full_config, name):
+            self._refresh_sets_combo()
+            self._mark_dirty()
+            self.status.setText(f"Set “{name}” deleted. Press Save to write the change.")
+
     # --- test all (spawn-test every enabled local server) ---------------- #
     def _test_all_servers(self):
         targets = [s for s in self.servers if s.enabled and s.kind == "stdio"]

bcc_core.py

@@ -39,6 +39,12 @@ CONFIG_FILENAME = "claude_desktop_config.json"
 # we can toggle it back on without losing the definition.
 DISABLED_KEY = "_disabledMcpServers"
 
+# Named server sets: {set_name: [enabled server names]}. Same pattern as
+# DISABLED_KEY — a bcc-owned key Claude ignores, stored in the config file so
+# sets travel with it. Applying a set enables exactly the listed servers and
+# parks the rest under DISABLED_KEY.
+SETS_KEY = "_bccServerSets"
+
 BACKUP_DIRNAME = ".bcc_backups"
 MAX_BACKUPS = 15
 
@@ -409,6 +415,70 @@ def extract_servers(cfg: dict) -> list[ServerEntry]:
     return out
 
 
+# --------------------------------------------------------------------------- #
+# Named server sets (issue #52)
+# --------------------------------------------------------------------------- #
+def list_server_sets(cfg: dict) -> dict[str, list[str]]:
+    """
+    Return {set_name: [enabled server names]} from cfg's SETS_KEY.
+
+    Fail-soft: entries whose value isn't a list of strings (hand-edited or
+    corrupted) are skipped rather than raising, so one bad set never hides
+    the rest.
+    """
+    raw = cfg.get(SETS_KEY)
+    if not isinstance(raw, dict):
+        return {}
+    out: dict[str, list[str]] = {}
+    for name, members in raw.items():
+        if isinstance(members, list) and all(isinstance(m, str) for m in members):
+            out[str(name)] = list(members)
+    return out
+
+
+def save_server_set(cfg: dict, name: str, servers: list[ServerEntry]) -> list[str]:
+    """
+    Snapshot the current enabled-server names into cfg under SETS_KEY as
+    `name` (overwriting an existing set of that name). Returns the saved
+    member list. The caller decides when cfg reaches disk (normal Save flow).
+    """
+    members = [s.name for s in servers if s.enabled]
+    sets = cfg.get(SETS_KEY)
+    if not isinstance(sets, dict):
+        sets = {}
+        cfg[SETS_KEY] = sets
+    sets[name] = members
+    return members
+
+
+def delete_server_set(cfg: dict, name: str) -> bool:
+    """Remove set `name` from cfg. Drops SETS_KEY entirely when the last set
+    goes, so untouched configs don't grow an empty bcc key. Returns True if
+    something was deleted."""
+    sets = cfg.get(SETS_KEY)
+    if not isinstance(sets, dict) or name not in sets:
+        return False
+    del sets[name]
+    if not sets:
+        cfg.pop(SETS_KEY, None)
+    return True
+
+
+def apply_server_set(servers: list[ServerEntry], enabled_names: list[str]) -> list[str]:
+    """
+    Enable exactly the servers named in `enabled_names`; disable every other
+    entry (in place). Returns the set members that no longer exist in
+    `servers` — the caller surfaces those as a warning, and the rest of the
+    set still applies.
+    """
+    wanted = set(enabled_names)
+    present: set[str] = set()
+    for s in servers:
+        s.enabled = s.name in wanted
+        present.add(s.name)
+    return sorted(wanted - present)
+
+
 def resolve_name_collision(name: str, existing: set[str]) -> str:
     """
     Return a name guaranteed not to collide with `existing`.

tests/test_core.py

@@ -769,6 +769,68 @@ def test_args_secret_warning_empty():
     assert c.args_secret_warning({"args": []}) is None
 
 
+# --------------------------------------------------------------------------- #
+# Named server sets (issue #52)
+# --------------------------------------------------------------------------- #
+def _three_servers():
+    return [
+        c.ServerEntry("alpha", {"command": "npx"}, True),
+        c.ServerEntry("beta", {"command": "uvx"}, True),
+        c.ServerEntry("gamma", {"url": "https://x.example/mcp"}, False),
+    ]
+
+
+def test_save_and_list_server_sets_roundtrip():
+    cfg: dict = {}
+    members = c.save_server_set(cfg, "webdev", _three_servers())
+    assert members == ["alpha", "beta"]  # only the enabled ones
+    assert c.list_server_sets(cfg) == {"webdev": ["alpha", "beta"]}
+
+
+def test_apply_server_set_enables_exactly_the_members():
+    servers = _three_servers()
+    missing = c.apply_server_set(servers, ["gamma"])
+    assert missing == []
+    assert [s.enabled for s in servers] == [False, False, True]
+
+
+def test_apply_server_set_reports_missing_members():
+    servers = _three_servers()
+    missing = c.apply_server_set(servers, ["alpha", "vanished", "gone"])
+    assert missing == ["gone", "vanished"]
+    assert [s.enabled for s in servers] == [True, False, False]  # rest still applied
+
+
+def test_delete_server_set_drops_empty_key():
+    cfg: dict = {}
+    c.save_server_set(cfg, "only", _three_servers())
+    assert c.delete_server_set(cfg, "only") is True
+    assert c.SETS_KEY not in cfg  # no empty bcc key left behind
+    assert c.delete_server_set(cfg, "only") is False
+
+
+def test_server_sets_survive_write_and_reload(tmp_path):
+    cfgpath = tmp_path / "cfg.json"
+    cfg = {"mcpServers": {"alpha": {"command": "npx"}}}
+    c.save_server_set(cfg, "webdev", [c.ServerEntry("alpha", {"command": "npx"}, True)])
+    c.write_config(cfgpath, cfg)
+    reloaded = c.load_config(cfgpath)
+    assert c.list_server_sets(reloaded) == {"webdev": ["alpha"]}
+
+
+def test_apply_servers_preserves_sets_key():
+    cfg: dict = {"mcpServers": {}}
+    c.save_server_set(cfg, "s", [c.ServerEntry("alpha", {"command": "npx"}, True)])
+    c.apply_servers(cfg, _three_servers())
+    assert c.SETS_KEY in cfg  # the server writer never touches sets
+
+
+def test_list_server_sets_skips_malformed_entries():
+    cfg = {c.SETS_KEY: {"good": ["a"], "bad-not-list": "a", "bad-items": ["a", 3]}}
+    assert c.list_server_sets(cfg) == {"good": ["a"]}
+    assert c.list_server_sets({c.SETS_KEY: "junk"}) == {}
+
+
 # --------------------------------------------------------------------------- #
 # resolve_name_collision (paste/import duplicate-name handling — issue #8)
 # --------------------------------------------------------------------------- #