huskies: merge 770

frontend/src/api/rpc.ts

@@ -0,0 +1,107 @@
+/**
+ * Lightweight read-RPC client over the `/ws` WebSocket.
+ *
+ * Opens a short-lived WebSocket, sends an `rpc_request` frame, waits for the
+ * matching `rpc_response`, then closes the connection.
+ */
+
+let correlationCounter = 0;
+
+function nextCorrelationId(): string {
+	return `rpc-${Date.now()}-${++correlationCounter}`;
+}
+
+/**
+ * Build the WebSocket URL for the `/ws` endpoint, deriving the protocol
+ * (ws/wss) and host from the current page location.
+ */
+function buildWsUrl(): string {
+	const proto = window.location.protocol === "https:" ? "wss:" : "ws:";
+	return `${proto}//${window.location.host}/ws`;
+}
+
+export interface RpcResponse<T = unknown> {
+	ok: boolean;
+	result?: T;
+	error?: string;
+	code?: string;
+}
+
+/**
+ * Send a read-RPC request over a temporary WebSocket connection and return
+ * the result.  Rejects if the server responds with `ok: false` or if the
+ * connection times out.
+ */
+export function rpcCall<T = unknown>(
+	method: string,
+	params: Record<string, unknown> = {},
+	timeoutMs = 5000,
+): Promise<T> {
+	return new Promise<T>((resolve, reject) => {
+		const correlationId = nextCorrelationId();
+		const ws = new WebSocket(buildWsUrl());
+		let settled = false;
+
+		const timer = setTimeout(() => {
+			if (!settled) {
+				settled = true;
+				ws.close();
+				reject(new Error(`RPC timeout for ${method}`));
+			}
+		}, timeoutMs);
+
+		ws.onopen = () => {
+			ws.send(
+				JSON.stringify({
+					kind: "rpc_request",
+					version: 1,
+					correlation_id: correlationId,
+					ttl_ms: timeoutMs,
+					method,
+					params,
+				}),
+			);
+		};
+
+		ws.onmessage = (event) => {
+			try {
+				const data = JSON.parse(event.data);
+				// Only process rpc_response frames matching our correlation ID.
+				if (
+					data.kind === "rpc_response" &&
+					data.correlation_id === correlationId
+				) {
+					settled = true;
+					clearTimeout(timer);
+					ws.close();
+					if (data.ok) {
+						resolve(data.result as T);
+					} else {
+						reject(
+							new Error(data.error || `RPC error: ${data.code || "UNKNOWN"}`),
+						);
+					}
+				}
+				// Ignore other messages (pipeline_state, onboarding_status, etc.)
+			} catch {
+				// Ignore non-JSON or unparseable messages
+			}
+		};
+
+		ws.onerror = () => {
+			if (!settled) {
+				settled = true;
+				clearTimeout(timer);
+				reject(new Error(`WebSocket error during RPC call to ${method}`));
+			}
+		};
+
+		ws.onclose = () => {
+			if (!settled) {
+				settled = true;
+				clearTimeout(timer);
+				reject(new Error(`WebSocket closed before RPC response for ${method}`));
+			}
+		};
+	});
+}