any-hub/specs/005-proxy-module-delegation/contracts

Contracts: Proxy Module Delegation

No external API surface changes are introduced by this feature. The core contract is the module handler interface used by the Proxy Dispatcher:

• Handler Contract (conceptual): Handle(ctx, route) processes requests for a given route/module, applies module-defined caching/rewrite, and returns structured logs with module_key, hub, domain, cache_hit, upstream_status, request_id.
• Registration Contract: Modules must register both metadata and handler; missing handlers must fail fast at startup.

If future external endpoints are added, document them here with request/response schemas.

Error Behaviors

• module_handler_missing: Forwarder无法找到给定 module_key 的 handler 时返回 500 {"error":"module_handler_missing"}，并记录 hub/domain/module_key/rollout_flag 等日志字段，便于排查配置缺失或注册遗漏。
• module_handler_panic: Module handler panic 被捕获后返回 500 {"error":"module_handler_panic"}，同时输出结构化日志 error=module_handler_panic，防止进程崩溃并提供观测。