fix(persistence): tighten crash repair and dispose semantics

packages/session/src/index.ts

@@ -30,7 +30,7 @@ declare module 'cordis' {
     /**
      * Awaited durability checkpoint. The agent loop awaits
      * `ctx.parallel('session/flush', session)` at every turn end; persistence
-     * plugins (JSONL, sqlite — TODO, future phase) drain their write-behind
+     * plugins (JSONL, SQLite) drain their write-behind
      * buffers here and on fiber dispose.
      */
     'session/flush'(session: Session): Promise<void> | void

packages/session/src/repair.ts

@@ -27,9 +27,10 @@
  * — which every provider rejects as an invalid transcript on the next request.
  * Synthesizing an error result per orphaned call keeps resume safe.
  *
- * This module computes those synthetic closers from an event list; the backend
- * returns them inline from `load` (so the reconstructed session is balanced and
- * immediately usable) and persists them on the first post-load `append`.
+ * This module computes those synthetic closers from an event list; backends
+ * return them inline from `load` (so the reconstructed session is balanced and
+ * immediately usable) and persist them during that mutating load before any
+ * later append continues the log.
  *
  * @module @deepseek-ai/dsh-session/repair
  */