Apply optional polish from PR #1 sidecar review

README.md

@@ -71,3 +71,9 @@ npm run dev
 npm test
 npm run typecheck
 ```
+
+The test suite covers the Resend seam with an injected fake `fetch`, so it never
+touches the network. Before cutting a release, run a manual smoke test against
+real Resend in staging: point `RESEND_API_KEY` + `RESEND_FROM` (or an inline
+`apiKey`/`from`) at a Resend test key and confirm `POST /ops/send-email` returns
+a real `email_...` id.

src/errors.ts

@@ -21,7 +21,7 @@ export class ValidationError extends ResendToolError {
   ) {
     super(`This request couldn't be processed: ${reason}`);
   }
-  protected extraFields() {
+  protected override extraFields() {
     return { field: this.field, reason: this.reason };
   }
 }
@@ -40,7 +40,7 @@ export class ProviderUnauthorizedError extends ResendToolError {
   constructor(public providerStatus: number) {
     super(`Resend rejected the configured credentials (HTTP ${providerStatus}).`);
   }
-  protected extraFields() {
+  protected override extraFields() {
     return { providerStatus: this.providerStatus };
   }
 }
@@ -51,7 +51,7 @@ export class ProviderRejectedError extends ResendToolError {
   constructor(public providerStatus: number) {
     super(`Resend rejected the email (HTTP ${providerStatus}).`);
   }
-  protected extraFields() {
+  protected override extraFields() {
     return { providerStatus: this.providerStatus };
   }
 }
@@ -78,7 +78,7 @@ export class UpstreamTimeoutError extends ResendToolError {
   constructor(public timeoutSeconds: number) {
     super(`The Resend request timed out after ${timeoutSeconds}s.`);
   }
-  protected extraFields() {
+  protected override extraFields() {
     return { timeoutSeconds: this.timeoutSeconds };
   }
 }

src/resend.ts

@@ -57,6 +57,9 @@ export async function sendEmail(
       payload = (await res.json()) as Record<string, unknown> | null;
     } catch {
       if (controller.signal.aborted) throw new Error('timed out mid-body');
+      // Non-JSON provider response. Downstream id-extraction maps this to
+      // upstream_unreachable; log the status (never the body) to aid debugging.
+      logger.warn('resend response body was not JSON', { status: res.status });
       payload = null;
     }
   } catch (err) {

tsconfig.json

@@ -15,6 +15,7 @@
     "sourceMap": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
+    "noImplicitOverride": true,
     "noFallthroughCasesInSwitch": true
   },
   "include": ["src/**/*.ts"],