Initial commit: Arb Pulse monolith with CI and optional Fly deploy.

Real-time BTC cross-exchange arbitrage detection (Kraken, Bybit, OKX, Binance)
with React dashboard, GitHub Actions CI, and documented Fly.io deploy workflow.

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/api.ts

@@ -0,0 +1,43 @@
+import type { StateSnapshot } from "./types";
+
+/**
+ * Subscribe to the live state stream over SSE. Uses a relative URL so it works
+ * behind the Vite dev proxy and same-origin in production. EventSource
+ * auto-reconnects on drop.
+ */
+export function subscribeState(
+  onSnapshot: (s: StateSnapshot) => void,
+  onStatus: (connected: boolean) => void,
+): () => void {
+  const source = new EventSource("/api/stream");
+
+  source.onopen = () => onStatus(true);
+  source.onerror = () => onStatus(false);
+  source.onmessage = (event) => {
+    try {
+      onSnapshot(JSON.parse(event.data) as StateSnapshot);
+    } catch {
+      /* ignore malformed frame */
+    }
+  };
+
+  return () => source.close();
+}
+
+async function post(path: string, body?: unknown): Promise<void> {
+  await fetch(`/api${path}`, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: body ? JSON.stringify(body) : undefined,
+  });
+}
+
+export const control = {
+  pause: () => post("/control/pause"),
+  resume: () => post("/control/resume"),
+  reset: () => post("/control/reset"),
+  setDemo: (enabled: boolean) => post("/control/demo", { enabled }),
+  setRecord: (enabled: boolean) => post("/control/record", { enabled }),
+  setThreshold: (pct: number) => post("/control/threshold", { pct }),
+  setMaxTrade: (btc: number) => post("/control/max-trade", { btc }),
+};