weichen
2c4ccc33c4
Why: Real project messages and retrieved material need a scoped observer and preflight decision contract before they can become governed project candidates.
Evidence: Registration denial test was RED before the implementation; go test ./... passed on Backend origin/main 2716b9e.
Impact: Add public X3 types and trusted single-provider registration; the production observer slot is deliberately not wired yet, so no project observation behavior is claimed.
Refs: TT-N03, TT-R01; approved work observation stage-five plan r1
Agent-System-Backend
对话系统后端：Go 模块化单体，默认构建为单二进制（go:embed 内嵌前端与嵌入式 SQLite 存储）。组合 Agent-Native / Agent-Squad / Agent-Intent 生态，依赖 agent-system-core 契约。
契约与架构见 Agent-System-Documents 设计方案与架构文档；开发规范见 development-guidelines（Dev 仓 development/guidelines）。本仓为 Agent-System 多仓组合的组成部分。