feat: add circuit breaker to gateway runtime client

gateway/src/http/routes/twilio-connect-action-webhook.ts

@@ -1,6 +1,6 @@
 import type { GatewayConfig } from "../../config.js";
 import { getLogger } from "../../logger.js";
-import { forwardTwilioConnectActionWebhook } from "../../runtime/client.js";
+import { CircuitBreakerOpenError, forwardTwilioConnectActionWebhook } from "../../runtime/client.js";
 import { validateTwilioWebhookRequest } from "../../twilio/validate-webhook.js";
 
 const log = getLogger("twilio-connect-action-webhook");
@@ -20,6 +20,12 @@ export function createTwilioConnectActionWebhookHandler(config: GatewayConfig) {
         headers: runtimeResponse.headers,
       });
     } catch (err) {
+      if (err instanceof CircuitBreakerOpenError) {
+        return Response.json(
+          { error: "Service temporarily unavailable" },
+          { status: 503, headers: { "Retry-After": String(err.retryAfterSecs) } },
+        );
+      }
       log.error({ err }, "Failed to forward Twilio connect-action webhook to runtime");
       return Response.json({ error: "Internal server error" }, { status: 502 });
     }

gateway/src/http/routes/twilio-status-webhook.ts

@@ -1,6 +1,6 @@
 import type { GatewayConfig } from "../../config.js";
 import { getLogger } from "../../logger.js";
-import { forwardTwilioStatusWebhook } from "../../runtime/client.js";
+import { CircuitBreakerOpenError, forwardTwilioStatusWebhook } from "../../runtime/client.js";
 import { validateTwilioWebhookRequest } from "../../twilio/validate-webhook.js";
 
 const log = getLogger("twilio-status-webhook");
@@ -23,6 +23,12 @@ export function createTwilioStatusWebhookHandler(config: GatewayConfig) {
         headers: runtimeResponse.headers,
       });
     } catch (err) {
+      if (err instanceof CircuitBreakerOpenError) {
+        return Response.json(
+          { error: "Service temporarily unavailable" },
+          { status: 503, headers: { "Retry-After": String(err.retryAfterSecs) } },
+        );
+      }
       log.error({ err }, "Failed to forward Twilio status webhook to runtime");
       return Response.json({ error: "Internal server error" }, { status: 502 });
     }

gateway/src/http/routes/twilio-voice-webhook.ts

@@ -1,6 +1,6 @@
 import type { GatewayConfig } from "../../config.js";
 import { getLogger } from "../../logger.js";
-import { forwardTwilioVoiceWebhook } from "../../runtime/client.js";
+import { CircuitBreakerOpenError, forwardTwilioVoiceWebhook } from "../../runtime/client.js";
 import { resolveAssistant, resolveAssistantByPhoneNumber, isRejection } from "../../routing/resolve-assistant.js";
 import { validateTwilioWebhookRequest } from "../../twilio/validate-webhook.js";
 
@@ -69,6 +69,12 @@ export function createTwilioVoiceWebhookHandler(config: GatewayConfig) {
         headers: runtimeResponse.headers,
       });
     } catch (err) {
+      if (err instanceof CircuitBreakerOpenError) {
+        return Response.json(
+          { error: "Service temporarily unavailable" },
+          { status: 503, headers: { "Retry-After": String(err.retryAfterSecs) } },
+        );
+      }
       log.error({ err }, "Failed to forward Twilio voice webhook to runtime");
       return Response.json({ error: "Internal server error" }, { status: 502 });
     }

gateway/src/index.ts

@@ -17,6 +17,7 @@ import { createWhatsAppDeliverHandler } from "./http/routes/whatsapp-deliver.js"
 import { createOAuthCallbackHandler } from "./http/routes/oauth-callback.js";
 import { createPairingProxyHandler } from "./http/routes/pairing-proxy.js";
 import { getLogger, initLogger } from "./logger.js";
+import { CircuitBreakerOpenError } from "./runtime/client.js";
 import { buildSchema } from "./schema.js";
 import { callTelegramApi } from "./telegram/api.js";
 import { reconcileTelegramWebhook } from "./telegram/webhook-manager.js";
@@ -64,6 +65,12 @@ function main() {
     port: config.port,
     websocket: getRelayWebsocketHandlers(),
     error(err) {
+      if (err instanceof CircuitBreakerOpenError) {
+        return Response.json(
+          { error: "Service temporarily unavailable — runtime is unreachable" },
+          { status: 503, headers: { "Retry-After": String(err.retryAfterSecs) } },
+        );
+      }
       log.error({ err }, "Unhandled gateway error");
       return Response.json({ error: "Internal server error" }, { status: 500 });
     },