Problem

The Dashboard Playground (/playground) fails to send chat messages. Requests to /api/router/v1/chat/completions return 404 page not found.

Root Cause

The dashboard backend proxies all /api/router/* requests to semantic-router:8080, but the semantic router's HTTP API doesn't expose /v1/chat/completions. This endpoint only exists through Envoy (port 8801) via the ext_proc pipeline.

Steps to Reproduce

1. Run docker compose up with the default configuration
2. Open http://localhost:8700/playground
3. Send any chat message
4. Observe: No response (request returns 404)

Evidence

Dashboard proxies to semantic-router:8080

$ curl -X POST http://localhost:8700/api/router/v1/chat/completions
-H "Content-Type: application/json"
-d '{"model":"MoM","messages":[{"role":"user","content":"hello"}]}'

404 page not found

But Envoy (port 8801) works correctly

$ curl -X POST http://localhost:8801/v1/chat/completions
-H "Content-Type: application/json"
-d '{"model":"MoM","messages":[{"role":"user","content":"hello"}]}'

{"id":"chatcmpl-...","choices":[...]} # ✅ Works### Expected Behavior
Chat messages should be routed through Envoy and return LLM responses.