feat: retry con backoff su errori transitori + timeoutMs applicato

- gatewayRequest: max 3 retry su 429/5xx/timeout/errore rete, backoff esponenziale + jitter, rispetta Retry-After (cap 10s)
- AbortError (annullamento utente) propagato, mai ritentato
- timeoutMs dalla config usato come fallback quando pi non fornisce signal
- testato: 503→200, sempre-503 (4 tentativi), 429+Retry-After, rete giù, abort

extensions/index.ts

@@ -37,6 +37,14 @@ const CONFIG_DEFAULTS: MemoryConfig = {
 	timeoutMs: 30_000,
 };
 
+// Retry su errori transitori (429/5xx/timeout): backoff esponenziale + jitter
+const MAX_RETRIES = 3;
+const RETRY_BASE_MS = 500;
+
+function sleep(ms: number): Promise<void> {
+	return new Promise((r) => setTimeout(r, ms));
+}
+
 function loadConfig(): MemoryConfig {
 	try {
 		return { ...CONFIG_DEFAULTS, ...JSON.parse(fs.readFileSync(CONFIG_FILE, "utf8")) };
@@ -67,14 +75,41 @@ async function gatewayRequest(
 		"X-API-Key": cfg.apiKey,
 	};
 	if (idempotencyKey) headers["Idempotency-Key"] = idempotencyKey;
-	const res = await fetch(`${cfg.url}${route}`, {
-		method,
-		signal,
-		headers,
-		body: body ? JSON.stringify(body) : undefined,
-	});
-	const data = await res.json().catch(() => ({}));
-	return { ok: res.ok, status: res.status, data };
+
+	let lastError: unknown = null;
+	for (let attempt = 0; attempt <= MAX_RETRIES; attempt++) {
+		// timeout fallback: se pi non fornisce un signal, usa timeoutMs dalla config
+		const timeoutSignal = signal ?? AbortSignal.timeout(cfg.timeoutMs ?? 30_000);
+		try {
+			const res = await fetch(`${cfg.url}${route}`, {
+				method,
+				signal: timeoutSignal,
+				headers,
+				body: body ? JSON.stringify(body) : undefined,
+			});
+			const data = await res.json().catch(() => ({}));
+			// retry solo su errori transitori (429/5xx), rispettando Retry-After
+			if ((res.status === 429 || res.status >= 500) && attempt < MAX_RETRIES) {
+				const retryAfter = res.headers.get("retry-after");
+				const delay = retryAfter
+					? Math.min(Number(retryAfter) * 1000 || RETRY_BASE_MS, 10_000)
+					: RETRY_BASE_MS * 2 ** attempt + Math.random() * 200;
+				await sleep(delay);
+				continue;
+			}
+			return { ok: res.ok, status: res.status, data };
+		} catch (e) {
+			// annullamento utente: propaga, non ritentare
+			if (e instanceof Error && e.name === "AbortError") throw e;
+			// errore di rete/timeout: retry con backoff
+			lastError = e;
+			if (attempt < MAX_RETRIES) {
+				await sleep(RETRY_BASE_MS * 2 ** attempt + Math.random() * 200);
+				continue;
+			}
+		}
+	}
+	return { ok: false, status: 0, data: { error: "network_error", detail: String(lastError ?? "unknown") } };
 }
 
 // ---------------------------------------------------------------------------