diff --git a/apps/petrinaut-website/api/oembed.ts b/apps/petrinaut-website/api/oembed.ts
index d7630168b55..8f28b3c5a47 100644
--- a/apps/petrinaut-website/api/oembed.ts
+++ b/apps/petrinaut-website/api/oembed.ts
@@ -9,11 +9,11 @@ import {
   isExampleSlug,
   PETRINAUT_DEMO_ORIGIN,
   type ExampleSlug,
-} from "../src/examples/catalog-metadata";
+} from "../src/examples/catalog-metadata.js";
 import {
   canonicalSearchString,
   validateSharedExampleSearch,
-} from "../src/examples/example-search";
+} from "../src/examples/example-search.js";
 
 const DEFAULT_WIDTH = 800;
 const DEFAULT_HEIGHT = 450;
diff --git a/apps/petrinaut-website/api/tsconfig.json b/apps/petrinaut-website/api/tsconfig.json
new file mode 100644
index 00000000000..3114db80a74
--- /dev/null
+++ b/apps/petrinaut-website/api/tsconfig.json
@@ -0,0 +1,10 @@
+{
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "types": ["node"],
+    "verbatimModuleSyntax": true
+  },
+  "include": ["./**/*.ts"]
+}
diff --git a/apps/petrinaut-website/api/voice/config.ts b/apps/petrinaut-website/api/voice/config.ts
index c6239de88db..07651eef807 100644
--- a/apps/petrinaut-website/api/voice/config.ts
+++ b/apps/petrinaut-website/api/voice/config.ts
@@ -1,4 +1,4 @@
-import { createOpenAIVoiceConfigHandler } from "../../src/server/voice/openai-voice-config";
+import { createOpenAIVoiceConfigHandler } from "../../src/server/voice/openai-voice-config.js";
 
 declare const process: {
   env: Record<string, string | undefined>;
diff --git a/apps/petrinaut-website/api/voice/realtime-call.ts b/apps/petrinaut-website/api/voice/realtime-call.ts
index dd6dee68187..7f047f5dcc0 100644
--- a/apps/petrinaut-website/api/voice/realtime-call.ts
+++ b/apps/petrinaut-website/api/voice/realtime-call.ts
@@ -1,5 +1,5 @@
-import { createOpenAIRealtimeCallHandler } from "../../src/server/voice/openai-realtime-call";
-import { reportVoiceDiagnostic } from "../../src/voice-diagnostics";
+import { createOpenAIRealtimeCallHandler } from "../../src/server/voice/openai-realtime-call.js";
+import { reportVoiceDiagnostic } from "../../src/voice-diagnostics.js";
 
 declare const process: {
   env: Record<string, string | undefined>;
diff --git a/apps/petrinaut-website/package.json b/apps/petrinaut-website/package.json
index d90b45168e0..9c270d2c0b3 100644
--- a/apps/petrinaut-website/package.json
+++ b/apps/petrinaut-website/package.json
@@ -12,7 +12,7 @@
     "fix:eslint": "oxlint --fix --type-aware --report-unused-disable-directives-severity=error .",
     "generate:icons": "node scripts/generate-favicons.mjs",
     "lint:eslint": "oxlint --type-aware --report-unused-disable-directives-severity=error .",
-    "lint:tsc": "tsgo --noEmit",
+    "lint:tsc": "tsgo --noEmit && tsgo --noEmit --project api/tsconfig.json",
     "preview": "vite preview",
     "test:unit": "vitest run --passWithNoTests"
   },
@@ -42,6 +42,7 @@
     "@fast-check/vitest": "0.4.1",
     "@tanstack/router-generator": "1.167.32",
     "@tanstack/router-plugin": "1.168.34",
+    "@types/node": "22.18.13",
     "@types/react": "19.2.14",
     "@types/react-dom": "19.2.3",
     "@typescript/native-preview": "7.0.0-dev.20260511.1",
diff --git a/apps/petrinaut-website/src/server/voice/openai-realtime-call.ts b/apps/petrinaut-website/src/server/voice/openai-realtime-call.ts
index db8aac05f1b..ee8d0e394b3 100644
--- a/apps/petrinaut-website/src/server/voice/openai-realtime-call.ts
+++ b/apps/petrinaut-website/src/server/voice/openai-realtime-call.ts
@@ -2,13 +2,13 @@ import {
   voiceErrorMessage,
   type VoiceDiagnosticReporter,
   type VoiceErrorCode,
-} from "../../voice-diagnostics";
+} from "../../voice-diagnostics.js";
 import {
   createOpenAIRealtimeSession,
   getOpenAIVoiceAvailability,
   OPENAI_REALTIME_CONNECTION_TIMEOUT_MS,
-} from "./openai-voice-policy";
-import { createVoiceRequestDiagnostics } from "./voice-request-diagnostics";
+} from "./openai-voice-policy.js";
+import { createVoiceRequestDiagnostics } from "./voice-request-diagnostics.js";
 
 const OPENAI_REALTIME_CALLS_ENDPOINT =
   "https://api.openai.com/v1/realtime/calls";
diff --git a/apps/petrinaut-website/src/server/voice/openai-voice-config.ts b/apps/petrinaut-website/src/server/voice/openai-voice-config.ts
index f43ce99bc14..699002753df 100644
--- a/apps/petrinaut-website/src/server/voice/openai-voice-config.ts
+++ b/apps/petrinaut-website/src/server/voice/openai-voice-config.ts
@@ -1,4 +1,4 @@
-import { getOpenAIVoiceAvailability } from "./openai-voice-policy";
+import { getOpenAIVoiceAvailability } from "./openai-voice-policy.js";
 
 interface VoiceEnvironment {
   readonly OPENAI_VOICE_API_KEY?: string;
diff --git a/apps/petrinaut-website/src/server/voice/voice-request-diagnostics.ts b/apps/petrinaut-website/src/server/voice/voice-request-diagnostics.ts
index 0673aa2e170..72191f0d67e 100644
--- a/apps/petrinaut-website/src/server/voice/voice-request-diagnostics.ts
+++ b/apps/petrinaut-website/src/server/voice/voice-request-diagnostics.ts
@@ -8,7 +8,7 @@ import {
   type VoiceDiagnosticReporter,
   type VoiceErrorCode,
   type VoiceOperation,
-} from "../../voice-diagnostics";
+} from "../../voice-diagnostics.js";
 
 interface VoiceRequestDiagnosticDependencies {
   readonly createRequestId?: () => string;
diff --git a/apps/petrinaut-website/tsconfig.json b/apps/petrinaut-website/tsconfig.json
index 60cf1627251..422ea6b82f3 100644
--- a/apps/petrinaut-website/tsconfig.json
+++ b/apps/petrinaut-website/tsconfig.json
@@ -13,7 +13,8 @@
     "resolveJsonModule": true,
     "noEmit": true,
     "skipLibCheck": true,
-    "isolatedModules": true
+    "isolatedModules": true,
+    "types": []
   },
-  "include": ["api", "src", "router-codegen-config.ts"]
+  "include": ["src", "router-codegen-config.ts"]
 }
diff --git a/yarn.lock b/yarn.lock
index cc5c5c0c50e..14b46c4d473 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -955,6 +955,7 @@ __metadata:
     "@tanstack/react-router": "npm:1.170.31"
     "@tanstack/router-generator": "npm:1.167.32"
     "@tanstack/router-plugin": "npm:1.168.34"
+    "@types/node": "npm:22.18.13"
     "@types/react": "npm:19.2.14"
     "@types/react-dom": "npm:19.2.3"
     "@typescript/native-preview": "npm:7.0.0-dev.20260511.1"