docs: record the forwarded-event surface and its face boundaries

Each owner package's README states which of its cordis events are forwarded and
that the declaration now lives in the client-safe ./types export. api/remotes
documents the allowlist as the single control point and the deliberate
both-faces listing of src/types.ts; development.md keeps the split-tsconfig rule
current.

packages/api/gateway/README.md

@@ -20,6 +20,8 @@ A cancellation-aware Remote method declares `signal: AbortSignal` as its final H
 
 Each call validates positional inputs, constructs the descriptor's exact named `args`, and sends it through `ctx.connection.rpc.call('/api', endpoint, ...)`. Generated cancellation-aware methods accept a final optional `AbortSignal`; the Client combines it with the contribution mount lifetime before calling Connection. The returned value is validated before reaching application code. Withdrawing a contribution removes its descriptors and methods together, aborts in-flight calls, and makes retained method handles reject.
 
+`ctx.remote.$on()` subscribes to one forwarded Host event. Its legal keys are exactly the Host assembly's forwarding selection, and the listener type is the owning package's own Cordis `Events` declaration, so no second signature can drift from it. Each subscription belongs to the calling fiber and disappears with it. Delivery is one-way and follows registration order; a listener that throws is logged and isolated from the remaining listeners, which never affects the frame pump. The delivery port is not part of the Remote contract: the Client half owning the Host frame sink emits the internal `remote/host-event` Cordis event, the Remote service is its only subscriber, and an event name nobody subscribes to is dropped, since the wire carries whatever the Host selected.
+
 Generated declaration merges provide the TypeScript API through the shared `TypeRTClientRemote` contract. The Client entry contains no Host Service or Host Cordis interface merge, and method lookup and invocation use ordinary objects and functions rather than a JavaScript Proxy.
 
 ## Model Experience
@@ -37,3 +39,4 @@ No direct effect; invoked business Services own any model-visible result.
 - Only strict generated contributions can mount on the Client face. SRC markers have no Client codec or type projection.
 - The package dispatches unary methods only. Incremental Session data uses a separate named-stream protocol over the same Connection.
 - Lookup resolvers are configured per key; an individual Remote parameter or endpoint cannot currently select a live-only policy under the same `agent`/`session` key.
+- Forwarded events reach `$on` exactly as the Host emitted them: no payload projection or redaction, no Scope-bound subscription, and no replay after a reconnect.

packages/api/gateway/README.zh.md

@@ -20,6 +20,8 @@ Connection 可用时，Host 入口会在 Connection 共享的 `/api` FetchHandle
 
 每次调用都会校验位置参数，构造与描述符完全匹配的具名 `args`，再通过 `ctx.connection.rpc.call('/api', endpoint, ...)` 发送。生成的支持取消的方法接受最后一个可选 `AbortSignal`；Client 会在调用 Connection 前将它与贡献项的挂载生命周期合并。返回值经过校验后才会交给应用代码。撤回贡献项会同时移除其描述符和方法、中止正在进行的调用，并使外部仍持有的方法句柄在调用时返回拒绝。
 
+`ctx.remote.$on()` 订阅一条被转发的 Host 事件。它的合法键恰好等于 Host 装配声明的转发选择，listener 类型就是事件所属包自己的 Cordis `Events` 声明，因此不存在会与之漂移的第二份签名。每个订阅归属发起调用的 fiber，并随该 fiber 一起消失。投递是单向的，并按注册顺序进行；抛错的 listener 会被记录并与其余 listener 隔离，绝不影响帧泵。投递口不属于 Remote 约定：持有 Host 帧 sink 的 Client 半发射内部 Cordis 事件 `remote/host-event`，Remote 服务是它唯一的订阅方，收到无人订阅的事件名即丢弃，因为 wire 上出现什么取决于 Host 的转发选择。
+
 生成的声明合并通过共享的 `TypeRTClientRemote` 约定提供 TypeScript API。Client 入口不包含 Host 服务或 Host Cordis 接口合并；方法查找和调用使用普通对象与函数，而不使用 JavaScript Proxy。
 
 ## 模型体验
@@ -37,3 +39,4 @@ Connection 可用时，Host 入口会在 Connection 共享的 `/api` FetchHandle
 - Client 侧只能挂载严格模式生成的贡献项。SRC 标记不具备 Client 编解码器或类型投影。
 - 该包只分发一元方法。增量会话数据通过同一个 Connection 上独立的具名流协议传输。
 - lookup resolver 按 key 配置；当前无法让单个 Remote 参数或 endpoint 在同一 `agent`/`session` key 下选择 live-only 策略。
+- 被转发的事件原样到达 `$on`：没有载荷投影或脱敏，不支持 Scope 化订阅，重连后也不重放。