Packages@downcity/cityCity

Common Patterns and Errors

Common City combinations in real cities, and how to reason about token, model, and service-related errors.

The three most common combinations

Pure AI city

  • @downcity/city
  • City exports from @downcity/city

AI city with minimal auth

  • @downcity/city
  • City exports from @downcity/city
  • @downcity/services

AI city with usage and payment

  • @downcity/city
  • City exports from @downcity/city
  • @downcity/services

Most common 401 / 403 causes

  • user_token was not sent
  • the token expired
  • the city_id does not match the token
  • the city has been paused

Most common 404 causes

  • the target service was never mounted into City
  • the Action path is wrong
  • you assumed a service was enabled, but forgot base.use(service())

Most common 422 causes

  • the AI call references a model that does not exist
  • the current model does not support the requested modality
  • the custom service input does not match what the Action expects

A simple debug order

  1. confirm whether the call is AI service, custom service, or service
  2. confirm whether the current phase is guest access or logged-in user access
  3. then compare city_id, user_token, service id, action id, and model id

Login and Token Flow

How guest User City, the accounts service, your own backend, user_token, and normal User City connect together.

Federation

The role of the Federation instance, runtime, router, and serve inside @downcity/city.

Table of Contents

The three most common combinationsPure AI cityAI city with minimal authAI city with usage and paymentMost common 401 / 403 causesMost common 404 causesMost common 422 causesA simple debug order