examples(voice-agent): address review

- README: list Cartesia as TTS (OpenAI=LLM, Deepgram=STT), add CARTESIA_API_KEY,
  fix DEMO_SCRIPT link to DEMO_SCRIPT_METADATA.md.
- next.config: derive dir from import.meta.url (Node 18 compatible).
- agent.py: validate region from data channel against an allow-list; fix stale
  'upload.py' hint to 'seed_index.py'.
- seed_index.py: fail fast if Moss credentials are missing.
- RetrievalPanel: add type=button + aria-pressed on the region toggle.

Author: HarshaNalluru

moss-live-labs/examples/voice-agent/README.md

@@ -13,8 +13,8 @@ Browser (web/)  ⟷  LiveKit room  ⟷  agent.py (STT → LLM → TTS)  ⟷  Mos
 
 - A [Moss](https://moss.dev) account (project ID + key)
 - [LiveKit](https://livekit.io) running locally (`livekit-server --dev`)
-- [OpenAI](https://platform.openai.com) (LLM + text-to-speech) and
-  [Deepgram](https://deepgram.com) (speech-to-text) API keys
+- [OpenAI](https://platform.openai.com) (LLM), [Deepgram](https://deepgram.com)
+  (speech-to-text), and [Cartesia](https://cartesia.ai) (text-to-speech) API keys
 - Python 3.14+ (`uv`) and Node 18+ (`npm`) for the web UI
 
 ## Setup
@@ -25,7 +25,7 @@ cp .env.example .env          # fill in your Moss + provider keys
 python agent.py download-files
 ```
 
-`.env` keys: `MOSS_PROJECT_ID`, `MOSS_PROJECT_KEY`, `OPENAI_API_KEY`, `DEEPGRAM_API_KEY`.
+`.env` keys: `MOSS_PROJECT_ID`, `MOSS_PROJECT_KEY`, `OPENAI_API_KEY`, `DEEPGRAM_API_KEY`, `CARTESIA_API_KEY`.
 For local LiveKit, leave the `LIVEKIT_*` values as-is; for LiveKit Cloud, set them to your
 project's URL/key/secret and copy the same three into `web/.env.local`. The index name
 defaults to `demo-customer_faqs` (override with `MOSS_INDEX_NAME`).
@@ -67,7 +67,7 @@ On each user turn, `agent.py` queries Moss and publishes the results to the Live
 on the `moss.retrieval` data channel (`{query, docs:[{text, score}], took_ms}`). The web
 UI listens on that channel and renders them. The voice pipeline is otherwise untouched.
 
-See [`DEMO_SCRIPT.md`](./DEMO_SCRIPT.md) for a ready-to-record walkthrough.
+See [`DEMO_SCRIPT_METADATA.md`](./DEMO_SCRIPT_METADATA.md) for a ready-to-record walkthrough.
 
 ## Resources
 

moss-live-labs/examples/voice-agent/agent.py

@@ -28,7 +28,10 @@
 INDEX_NAME = os.getenv("MOSS_INDEX_NAME", "demo-customer_faqs")
 # This support line serves one region. Metadata filtering scopes retrieval to
 # region-specific policies + global ("all") docs. Set MOSS_REGION=EU to compare.
+ALLOWED_REGIONS = {"US", "EU"}
 REGION = os.getenv("MOSS_REGION", "US")
+if REGION not in ALLOWED_REGIONS:
+    REGION = "US"
 
 logging.basicConfig(level=logging.INFO)
 logger = logging.getLogger("moss-agent")
@@ -135,7 +138,7 @@ async def entrypoint(ctx: JobContext):
         logger.info(f"Successfully loaded index: {INDEX_NAME}")
     except Exception as e:
         logger.warning(f"Index not found or failed to load: {e}")
-        logger.warning("Moss queries will fail until the index is created. Run upload.py first.")
+        logger.warning("Moss queries will fail until the index is created. Run seed_index.py first.")
 
     # Create Session
     session = AgentSession(
@@ -163,9 +166,11 @@ def _on_data(pkt: rtc.DataPacket):
         if pkt.topic == "moss.region":
             try:
                 r = json.loads(bytes(pkt.data).decode("utf-8")).get("region")
-                if r:
+                if r in ALLOWED_REGIONS:
                     agent.region = r
                     logger.info(f"Region filter set to {r}")
+                else:
+                    logger.warning(f"Ignoring unknown region {r!r} (allowed: {sorted(ALLOWED_REGIONS)})")
             except Exception as e:
                 logger.warning(f"Bad region packet: {e}")
 

moss-live-labs/examples/voice-agent/seed_index.py

@@ -28,6 +28,11 @@
 
 
 async def main() -> None:
+    if not MOSS_PROJECT_ID or not MOSS_PROJECT_KEY:
+        raise SystemExit(
+            "Missing MOSS_PROJECT_ID / MOSS_PROJECT_KEY. Copy .env.example to .env and fill them in."
+        )
+
     faqs = json.loads(FAQS_PATH.read_text())
     docs = [
         DocumentInfo(

moss-live-labs/examples/voice-agent/web/components/RetrievalPanel.tsx

@@ -61,6 +61,8 @@ export function RetrievalPanel() {
           {REGIONS.map((r) => (
             <button
               key={r}
+              type="button"
+              aria-pressed={region === r}
               onClick={() => setRegion(r)}
               style={{
                 padding: "6px 18px",

moss-live-labs/examples/voice-agent/web/next.config.mjs

@@ -1,8 +1,14 @@
+import { dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+// Node 18 doesn't provide import.meta.dirname; derive it from import.meta.url.
+const rootDir = dirname(fileURLToPath(import.meta.url));
+
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   reactStrictMode: true,
   // This app lives in a monorepo with other lockfiles; pin the tracing root here.
-  outputFileTracingRoot: import.meta.dirname,
+  outputFileTracingRoot: rootDir,
 };
 
 export default nextConfig;