Add fleet groups, agent screenshots, deploy guards, and Crucible polish.

server/web/src/context/MatrixRainContext.tsx

@@ -0,0 +1,28 @@
+import { createContext, useContext, useMemo, useState, type ReactNode } from 'react';
+
+export type MatrixRainContextValue = {
+  /** True when Crucible has exactly one online node selected for remote ops. */
+  crucibleFocus: boolean;
+  setCrucibleFocus: (active: boolean) => void;
+};
+
+const MatrixRainContext = createContext<MatrixRainContextValue | null>(null);
+
+export function MatrixRainProvider({ children }: { children: ReactNode }) {
+  const [crucibleFocus, setCrucibleFocus] = useState(false);
+  const value = useMemo(
+    () => ({ crucibleFocus, setCrucibleFocus }),
+    [crucibleFocus]
+  );
+  return (
+    <MatrixRainContext.Provider value={value}>{children}</MatrixRainContext.Provider>
+  );
+}
+
+export function useMatrixRain(): MatrixRainContextValue {
+  const ctx = useContext(MatrixRainContext);
+  if (!ctx) {
+    return { crucibleFocus: false, setCrucibleFocus: () => {} };
+  }
+  return ctx;
+}