fix(session): load pre-react-loop persisted sessions

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: 95b2ec9a4c111e5c44d31e36b37f1a574776edef
-README.zh.md: f3ef4ffeb11b44d1bcfb76722f93c162b71415fd
+README.md: bad0cc33d6ffec6e9b8abbc86cf3a0c79fd23b74
+README.zh.md: e1bd5e6f448fb31e38642dc3df1e1ccf5977ef9d

packages/core/session/README.md

@@ -77,7 +77,7 @@ Merge-extensible via `SessionEventMap` — a plugin declaration-merges its own t
 
 Also defines `TurnEndReasonMap`, the merge-extensible `kind`-tagged sum type for turn endings. `turn/start` carries only the turn number; the following entered `user/message` batch records its input, while `llm/retry` records request recovery.
 
-An interrupted live turn ends with `{ kind: 'aborted', reason: AgentCancelCause }`, preserving the typed cancellation cause in the durable transcript. A turn failure carries `{ kind: 'error', error }`; crash recovery alone synthesizes `{ kind: 'interrupted' }`.
+An interrupted live turn ends with `{ kind: 'aborted', reason: AgentCancelCause }`, preserving the typed cancellation cause in the durable transcript. Persistence imports the coarse aborted outcome from the supported older format as `{ kind: 'aborted', reason: { kind: 'legacy' } }`, because that record did not retain its caller. A turn failure carries `{ kind: 'error', error }`; crash recovery alone synthesizes `{ kind: 'interrupted' }`.
 
 Every `SessionEvent` carries two optional top-level fields (structural metadata):
 
@@ -91,7 +91,7 @@ Every `SessionEvent` carries two optional top-level fields (structural metadata)
 ### Extension points
 
 - Persistence plugins: subscribe to `session/event` (write-behind) and drain on `session/flush` (awaited) and fiber dispose. A durable backend reads the log and reloads it into a live session; the metadata seam (`SessionHeader`, `session.header`) is what such a backend stores beside the log.
-- Replay/fork: `create(id, { seed })` validates and freezes a contiguous current-format log and rebuilds its surface; request headers require provider/model, assistant messages require provider/model provenance, and a coarse aborted outcome must contain only `{ kind: 'aborted' }` (legacy reason-bearing records are rejected). `fork(source, boundary?, childSessionId?)` selects a completed-turn prefix and records lineage.
+- Replay/fork: `create(id, { seed })` validates and freezes a contiguous current-format log and rebuilds its surface; request headers require provider/model, and assistant messages require provider/model provenance. Persistence owns read compatibility before constructing this current-format seed. `fork(source, boundary?, childSessionId?)` selects a completed-turn prefix and records lineage.
 - Compaction: `dsh-compact-basic` appends a `user/message` replacement for summary checkpoints, while `dsh-compact-tool-result-prune` appends a content-only `tool/result` replacement. Tool-pairing boundary policy and its cache belong to the [`dsh-compact` seam](../../compact/compact/README.md), while this package owns ordered surface membership, replacement validation, and `replaceGeneration`.
 
 ## Model Experience

packages/core/session/README.zh.md

@@ -77,7 +77,7 @@
 
 此包还定义 `TurnEndReasonMap`，即用于轮次结束、可合并扩展且以 `kind` 为标签的和类型。`turn/start` 只携带轮次编号；之后进入步骤的 `user/message` 批次记录其输入，`llm/retry` 则记录请求恢复。
 
-被中断的实时轮次以 `{ kind: 'aborted', reason: AgentCancelCause }` 结束，在持久 transcript（文本记录）中保留类型化取消原因。轮次失败携带 `{ kind: 'error', error }`；只有崩溃恢复会合成 `{ kind: 'interrupted' }`。
+被中断的实时轮次以 `{ kind: 'aborted', reason: AgentCancelCause }` 结束，在持久 transcript（文本记录）中保留类型化取消原因。持久化会将受支持旧格式中的粗粒度中止结果导入为 `{ kind: 'aborted', reason: { kind: 'legacy' } }`，因为该记录没有保留调用方。轮次失败携带 `{ kind: 'error', error }`；只有崩溃恢复会合成 `{ kind: 'interrupted' }`。
 
 每个 `SessionEvent` 都有两个可选顶层字段（结构元数据）：
 
@@ -91,7 +91,7 @@
 ### 扩展点
 
 - 持久化插件：订阅 `session/event`（延后写入），并在 `session/flush`（受等待）及 fiber dispose（资源释放）时排空。持久后端读取日志并重新加载到实时会话；这类后端会把元数据 seam（`SessionHeader`、`session.header`）与日志一同存储。
-- 回放／fork：`create(id, { seed })` 校验并冻结连续的当前格式日志，再重建 surface；请求头必须包含提供方／模型，assistant 消息必须包含提供方／模型溯源信息，而粗粒度中止结果必须只含 `{ kind: 'aborted' }`（带旧版原因的记录会被拒绝）。`fork(source, boundary?, childSessionId?)` 选择已完成轮次前缀并记录谱系。
+- 回放／fork：`create(id, { seed })` 校验并冻结连续的当前格式日志，再重建 surface；请求头必须包含提供方／模型，assistant 消息必须包含提供方／模型溯源信息。持久化层在构造该当前格式 seed 前负责读取兼容性处理。`fork(source, boundary?, childSessionId?)` 选择已完成轮次前缀并记录谱系。
 - 压缩：`dsh-compact-basic` 为摘要检查点追加一个替换用 `user/message`，而 `dsh-compact-tool-result-prune` 追加仅修改内容的 `tool/result` 替换。工具配对边界策略及其缓存归 [`dsh-compact` seam](../../compact/compact/README.md) 所有；此包拥有有序 surface 成员关系、替换校验与 `replaceGeneration`。
 
 ## 模型体验

packages/core/session/src/types.ts

@@ -100,13 +100,16 @@ export type AgentCancelCause =
   | { readonly kind: 'hook'; readonly reason: string }
   | { readonly kind: 'disposed' }
 
+/** Durable cancellation cause, including imports whose original coarse record carried no cause. */
+export type TurnEndCancelCause = AgentCancelCause | { readonly kind: 'legacy' }
+
 /**
  * Why a turn ended. Merge-extensible sum type.
  */
 export interface TurnEndReasonMap {
   completed: { kind: 'completed' }
   /** A cancellation request interrupted the live turn. */
-  aborted: { kind: 'aborted'; reason: AgentCancelCause }
+  aborted: { kind: 'aborted'; reason: TurnEndCancelCause }
 
   blocked: { kind: 'blocked' }
   /**