refactor(llm): simplify live request telemetry (round 2)

packages/host/apiproxy/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/host/apiproxy/README.md
-README.md: d3d1711242f71832f63eb570242fdf9e149cc988
-README.zh.md: 4e52058c1795ea23a9ca8ed46b8890c85f129eb4
+README.md: 263cb2f661e2f5b91cc4885ac99fe3afe61bbfbc
+README.zh.md: 400031b7d6d668d6ec7d2922b8a6abb855fe5b7b

packages/host/apiproxy/README.md

@@ -22,7 +22,7 @@ Workspace and Session lists are separate reconnect baselines. `workspace.create`
 
 `session.history` pages on message boundaries, and its tail page (no `beforeSeq`) carries session-level projections the page window cannot supply: the in-flight partial's chunk events; `todos`, the latest `todo/write` whole-list projection; and `metrics`, full-log usage deduplicated by `(turn, step)` plus current token-meter pressure. Older pages omit the session-level projections. Live `session/metrics` mux frames carry monotonic log/projection revisions, so clients reject stale frames and preserve the counters while prepending older pages. Cache reads and writes remain disjoint buckets; the cache-hit denominator is uncached input plus cache reads.
 
-Context capacity uses a distinct transient `session/model-request` mux frame emitted from the contained Agent notification after an actual request reaches dispatch. It carries turn, step, final provider/model, and optional capacity only to mux connections already open at that instant. `session.history`, mux subscription baselines, reconnects, and session restore never query or replay prior capacity; a frame without capacity explicitly clears the earlier connection-local value.
+Context capacity uses a distinct transient `session/model-request` mux frame emitted from the contained Agent notification after an observed request attempt returns its outer stream handle. This boundary does not prove provider I/O began. The frame carries turn, step, final provider/model, and optional capacity only to mux connections already open at that instant. `session.history`, mux subscription baselines, reconnects, and session restore never query or replay prior capacity; a frame without capacity explicitly clears the earlier connection-local value.
 
 The `command.*` and `skill.*` domains expose the host command registry and skill catalog to clients. Every method addresses one session's agent by `sessionId` (a served session always has an Agent; `command.*` resumes cold sessions through the same path as `session.*`, while `skill.list` resolves the project root from the session header without touching the Agent registry). `command.execute` runs a slash-command line host-side and returns a detached result; the carrier's request signal cancels the running handler. `host/commands-changed` is the catalog invalidation frame: clients refetch `command.list` instead of diffing.
 

packages/host/apiproxy/README.zh.md

@@ -22,7 +22,7 @@ Workspace 列表与 Session 列表是相互独立的重连基线。`workspace.cr
 
 `session.history` 按消息边界分页，其尾页（不带 `beforeSeq`）携带页窗口本身无法提供的会话级投影：进行中局部消息的分片事件；`todos`，即最后一次 `todo/write` 的整表投影；以及 `metrics`，即按 `(turn, step)` 去重的完整日志用量与当前 token 计量压力。较早的页面省略会话级投影。实时 `session/metrics` mux 帧携带单调递增的日志修订号与投影修订号，因此客户端会拒绝陈旧帧，并在向前加载较早页面时保留计数器。缓存读取与缓存写入保持为彼此独立的计数项；缓存命中率的分母是未缓存输入加缓存读取。
 
-上下文容量使用独立的临时 `session/model-request` mux 帧；实际请求到达分派点后，该帧由失败会被收容的 Agent 通知发出。该帧携带轮次、步骤、最终提供方／模型与可选容量，且只发送给当时已经打开的 mux 连接。`session.history`、mux 订阅基线、重连和会话恢复绝不会查询或回放先前的容量；不带容量的帧会显式清除较早的连接本地值。
+上下文容量使用独立的临时 `session/model-request` mux 帧；观察到的请求尝试返回外层流句柄后，该帧由失败会被收容的 Agent 通知发出。这个边界不能证明提供方 I/O 已开始。该帧携带轮次、步骤、最终提供方／模型与可选容量，且只发送给当时已经打开的 mux 连接。`session.history`、mux 订阅基线、重连和会话恢复绝不会查询或回放先前的容量；不带容量的帧会显式清除较早的连接本地值。
 
 `command.*` 与 `skill.*` 领域向客户端暴露宿主命令注册表和技能目录。每个方法都通过 `sessionId` 寻址一个会话的 Agent（被服务的会话必有 Agent；`command.*` 经由与 `session.*` 相同的路径恢复冷会话，而 `skill.list` 从会话头解析项目根目录，不触碰 Agent 注册表）。`command.execute` 在宿主侧运行一条斜杠命令行并返回脱耦结果；载体的请求信号可取消正在运行的处理器。`host/commands-changed` 是目录失效帧：客户端重新拉取 `command.list` 而不是做差分。
 

packages/host/apiproxy/src/api/events.ts

@@ -60,11 +60,11 @@ export type MuxFrame =
   | { type: 'session/subscribed'; sessionId: SessionId; lastSeq: number }
   | { type: 'session/metrics'; sessionId: SessionId; metrics: SessionMetrics }
   /**
-   * One model request observed by this already-open mux connection after its
-   * final route and stream handle were resolved. This frame is transient: mux
-   * baselines, reconnects, and session history never replay it. An absent
-   * `contextWindow` explicitly clears a capacity observed from an earlier
-   * request on the same connection.
+   * One request attempt observed by this already-open mux connection after its
+   * final route and outer `llm/stream` handle were obtained. This does not prove
+   * provider I/O began. The frame is transient: mux baselines, reconnects, and
+   * session history never replay it. An absent `contextWindow` explicitly clears
+   * a capacity observed from an earlier request on the same connection.
    */
   | {
     type: 'session/model-request'