docs: address prose review findings

packages/core/session/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/core/session/README.md
-README.md: 04d3cec7e431f5f265d52851eae59600536ce5b7
-README.zh.md: e9529b3c91c8d2413c64b4e344af83b6ebe698de
+README.md: 09e027c82fe1a81d97b3e70d95231ccc553e3ed1
+README.zh.md: 3fdd1e68b18f5ce4b3846ca0d2376b968a0754e3

packages/core/session/README.md

@@ -68,7 +68,7 @@ A `user/message` stores the complete `UserMessage` directly, including the ident
 
 ### Session event vocabulary (`types.ts`)
 
-The generated [persistence log event catalog](../../../docs/persistence-catalog.md) enumerates each append-only event type with its payload, surface badge, cited source-event seqs, and declaration site. Token accounting reads per-step `assistant/chunk { type: 'usage' }` records and treats `assistant/message.usage` as the committed-step fallback when no usage chunk exists; failed model-request attempts have no assistant message. Each `assistant/message` records the provider, model, and optional replay state.
+The generated [persistence log event catalog](../../../docs/persistence-catalog.md) enumerates each append-only event type with its payload, surface badge, and declaration site. Token accounting reads per-step `assistant/chunk { type: 'usage' }` records and treats `assistant/message.usage` as the committed-step fallback when no usage chunk exists; failed model-request attempts have no assistant message. Each `assistant/message` records the provider, model, and optional replay state.
 
 Merge-extensible via `SessionEventMap` — a plugin declaration-merges its own types (the compaction seam's `compact/*`, bounded recovery's non-surface `llm/retry`, the hook bridges' `hook/*`); merged members appear in the same catalog. A plugin owns the relational invariant for its merged events, including whether a log-only event may appear between turns. A producer that requires durability appends through `Session` and then awaits `ctx.sessions.flush(session)` without fabricating an execution turn.
 

packages/core/session/README.zh.md

@@ -68,7 +68,7 @@
 
 ### 会话事件词汇（`types.ts`）
 
-生成的[持久化日志事件目录](../../../docs/persistence-catalog.md)逐成员列举仅追加日志的事件类型、载荷、surface 标记、被引用的源事件 seq 与声明位置。Token 记账读取每个步骤的 `assistant/chunk { type: 'usage' }` 记录；如果没有用量分片，则将 `assistant/message.usage` 作为已提交步骤的后备。失败的模型请求尝试没有 assistant 消息。每条 `assistant/message` 都会记录提供方、模型和可选回放状态。
+生成的[持久化日志事件目录](../../../docs/persistence-catalog.md)逐成员列举仅追加日志的事件类型、载荷、surface 标记与声明位置。Token 记账读取每个步骤的 `assistant/chunk { type: 'usage' }` 记录；如果没有用量分片，则将 `assistant/message.usage` 作为已提交步骤的后备。失败的模型请求尝试没有 assistant 消息。每条 `assistant/message` 都会记录提供方、模型和可选回放状态。
 
 `SessionEventMap` 可通过合并扩展：插件使用声明合并添加自身类型（压缩 seam 的 `compact/*`、有界恢复的非 surface `llm/retry`、hook（钩子）桥接层的 `hook/*`）；合并成员会出现在同一目录中。插件拥有其合并事件的关系不变量，包括是否允许纯日志事件出现在轮次之间。需要持久性的生产方通过 `Session` 追加，再等待 `ctx.sessions.flush(session)`，无需虚构一个执行轮次。
 

packages/core/session/src/types.ts

@@ -352,9 +352,9 @@ export interface SurfaceIntent {
   surfaceOp: SurfaceOp
   /**
    * Complete set of known source-event seqs. `assistant/message` may use a
-   * present empty array for a known empty provider stream; omission means its
-   * source stream was not recorded. Other surface events require a non-empty set
-   * when this field is present.
+   * present empty array for a known empty provider stream; when the field is
+   * absent, the event does not record which earlier events produced the message.
+   * Other surface events require a non-empty set when this field is present.
    */
   sourceEventSeqs?: number[]
 }
@@ -386,7 +386,8 @@ export type SessionEvent<T extends SessionEventType = SessionEventType> = {
      * (e.g. the `assistant/chunk` seqs that built an `assistant/message`,
      * or the surface nodes shadowed by a compaction replace node). An
      * `assistant/message` may carry a present empty array for a known empty
-     * provider stream; omission means the source stream was not recorded.
+     * provider stream; when the field is absent, the event does not record which
+     * earlier events produced the message.
      */
     sourceEventSeqs?: number[]
     /** How this event entered the surface; absent for non-surface events. */