Core reference

createMswPanelController(options)

Creates a controller that tracks handlers, exposes snapshots, persists disabled state, and reapplies the enabled set through the supplied runtime.

interface CreateMswPanelControllerOptions {
  handlers?: readonly MswAnyHandler[];
  runtime: MswRuntimeController;
  storage?: MswPanelStorage | null;
  storageKey?: string;
  defaultEnabled?: boolean;
}

If handlers is omitted, the controller starts from runtime.listHandlers().

Persistence defaults — storage defaults to window.localStorage when available, and storageKey defaults to "msw-panel". Disabled handler state is therefore persisted across page reloads automatically with no extra configuration. Pass storage: null to opt out of persistence entirely.

Initial state default — defaultEnabled defaults to true. Set defaultEnabled: false to start with every handler disabled until the user enables the ones they want. Persisted user state still wins when present.

Controller interface

interface MswPanelController {
  getSnapshot(): MswPanelSnapshot;
  setAllEnabled(nextEnabled: boolean): void;
  setEnabled(id: string, nextEnabled: boolean): void;
  subscribe(listener: () => void): () => void;
  sync(): void;
  toggle(id: string): void;
}

Snapshot shape

type MswPanelHandlerKind = "graphql" | "http" | "unknown" | "websocket";

interface MswPanelHandlerSnapshot {
  id: string;
  enabled: boolean;
  kind: MswPanelHandlerKind;
  label: string;
  method: string | null;
  path: string | null;
}

interface MswPanelSnapshot {
  activeHandlers: number;
  disabledHandlers: number;
  handlers: MswPanelHandlerSnapshot[];
}

Behavior notes

• Disabled state is automatically persisted to localStorage under the key "msw-panel" and restored on the next page load. Pass storage: null to disable persistence.
• defaultEnabled only applies to handlers that do not already have persisted state.
• setAllEnabled() and setEnabled() are no-ops when nothing changes.
• sync() rebuilds records from the runtime and preserves enabled state where identities match.