docs: record remote main integration

.project-docs/40-domain/business-rules.md

@@ -21,8 +21,23 @@
   per project and assign its Skill to an Agent.
 - Production Marketplace trust fails closed while the official Ed25519 public key is
   absent. Test-only/integration keys and packaged unknown-key rejection are evidence,
-  not authority to activate production. Release B hosted Provider runtime remains
-  closed behind its separate Provider gate.
+  not authority to activate production. Generic `platform_hosted` client execution is
+  implemented, but production package trust and real Provider activation remain closed
+  until the official key and separate server pricing, credential, Admission, and
+  acceptance gates are ready.
+- A `platform_hosted` Skill or tool may enter only an installed, enabled, assigned,
+  trusted, compatible, policy-admitted parent Pi logical thread. Unknown, disabled, or
+  ineligible assignments stay inert; child workers receive no hosted Plugin projection.
+- A metered hosted mutation requires explicit client confirmation before resolve,
+  Admission, or charging. Works Square owns price, payer, Token Point policy, and receipt
+  state. Stable logical operation identity survives response loss and Main restart;
+  `submission_unknown` must not become a fresh request or be conflated with a billing
+  `pending_review` receipt.
+- Electron Main to fixed Works Square routes is the only hosted Plugin transport.
+  Packages, Renderer state, Pi arguments/results, logs, and saved project metadata must
+  not expose Provider credentials, URLs, credit balances, raw responses, or Provider job
+  IDs. Saving a hosted result must use bounded project-relative paths and the existing
+  project write lease.
 - 面向用户的 AI 编程新建流程必须在 `mini_game`、`mini_program`、`custom` 中选择；`ProjectType` 是产品类型，创建后不能通过 UI 或 Host API 修改，未传类型的兼容 API 调用按 `custom` 处理。
 - 新建小游戏和小程序会生成平台固定版本的受控 Vite 发布模板，并可使用项目配置中的单一“提交审核”入口；`custom` 和缺少类型字段的旧项目不提供一键发布。
 - `ProjectType` 不等于 `BuildPreset`：第一期两个可发布产品类型都映射到内部受控 Vite preset；本地 `projectType` 不是授权边界，Main-owned 安全打包、Host API 和服务端包体校验仍必须执行。