docs: align runtime-context contracts

packages/fs/fs-sandbox/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/fs/fs-sandbox/README.md
-README.md: bce22feac8b6b4a31abc0cbfddd39681ad437062
-README.zh.md: 0bb0190f5a0506f2d10f82a5f03370b977472aee
+README.md: d6070f4971e7531e929e659b6b5ed476a672dc5d
+README.zh.md: c051b240163f229f7fbc583939c9f4da5095e9aa

packages/fs/fs-sandbox/README.md

@@ -30,11 +30,11 @@ The policy owner contributes capability-neutral `sandbox:policy` context. Indire
 
 #### Token effect
 
-The current-policy clause adds a small fixed prefix while this backend is mounted; a denial adds the bounded marker and escalation hint to conversation history.
+The current-policy clause adds a small runtime-context message while this backend is mounted; a denial adds the bounded marker and escalation hint to conversation history.
 
 #### KV Cache effect
 
-A standing-policy change updates the owner-rendered request prefix; operation results remain append-only.
+A standing-policy change appends an owner-rendered superseding runtime-context snapshot after retained history; operation results remain append-only.
 
 ## Known Limitations and Deferred Work
 

packages/fs/fs-sandbox/README.zh.md

@@ -30,11 +30,11 @@
 
 #### Token 影响
 
-该后端挂载期间，当前策略条款会在前缀中增加少量固定内容；拒绝则会把有界标记和升级提示追加到对话历史。
+该后端挂载期间，当前策略条款会增加一条简短的运行时上下文消息；拒绝则会把有界标记和升级提示追加到对话历史。
 
 #### KV Cache 影响
 
-常驻策略发生变化时，归属方渲染的请求前缀会更新；操作结果保持仅追加。
+常驻策略发生变化时，会在保留的历史之后追加一份由归属方渲染、取代先前状态的运行时上下文快照；操作结果保持仅追加。
 
 ## 已知限制与暂缓事项