Streamlit Application Documentation

Documentation for the OCapistaine Streamlit application, deployed on Render and proxied through Vaettir.

Quick Start

If your Streamlit app shows "You need to enable JavaScript" or has WebSocket errors:

Quick Fix Guide - Fix 403 errors in 5 minutes

Deployment

Production:
  User → ocapistaine.vaettir.locki.io → Vaettir Nginx → Render

Development:
  User → ocapistaine-dev.vaettir.locki.io → Vaettir Nginx → ngrok → localhost

Access Points

Environment	URL	Backend
Production	https://ocapistaine.vaettir.locki.io	Render
Development	https://ocapistaine-dev.vaettir.locki.io	ngrok → local
Local only	http://localhost:8502	Direct

Guides

• Streamlit Setup - Full configuration guide (Render + ngrok)
• CORS Strategy - How CORS is handled per environment

Key Concepts

• CORS Configuration: Static on Render (render.yaml), dynamic for dev (set_streamlit_env.py)
• WebSocket Support: Required for Streamlit real-time updates, handled by Vaettir nginx proxy
• Session Management: Streamlit's built-in session state

Common Issues

App Shows JavaScript Required

Problem: Streamlit blocking proxy domain Solution: Check STREAMLIT_SERVER_ALLOWED_ORIGINS includes the proxy domain Guide: STREAMLIT_QUICKSTART.md

WebSocket 403 Forbidden

Problem: CORS blocking WebSocket connections Solution: Add the requesting origin to allowed origins Guide: STREAMLIT_SETUP.md

App Disconnected (Production)

Problem: Render instance cold start or crash Solution: Wait 30-60s for cold start, check Render dashboard for errors

App Disconnected (Development)

Problem: ngrok tunnel stopped or local app crashed Solution: Restart ngrok and local Streamlit process

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