fix(markdown): a rewritten assistant reply reseeds the session instead of resuming it

src/beaver_gateway/backends/claude_sdk.py

@@ -296,6 +296,7 @@ class ClaudeSdkBackend:
         system: str | None = None,  # noqa: ARG002 - the agent owns its prompt
         conversation_id: str | None = None,
         session_id: str | None = None,
+        reseed: bool = False,
         capture: TurnCapture | None = None,
         kind: str = "deep",
         pinned: bool = False,
@@ -315,7 +316,9 @@ class ClaudeSdkBackend:
         prior = history[:-1]
         key = conversation_id or fingerprint(prior)
         spec = _SessionSpec(kind=kind, pinned=pinned, tools=tools)
-        live = await self._acquire(key, session_id=session_id, history=prior, spec=spec)
+        live = await self._acquire(
+            key, session_id=session_id, history=prior, spec=spec, reseed=reseed
+        )
         message_id = f"msg_{uuid.uuid4().hex}"
         yield build_message_start(message_id=message_id, model=self._agent.model)
         turn = _Turn()
@@ -484,10 +487,13 @@ class ClaudeSdkBackend:
         session_id: str | None,
         history: list[dict[str, Any]],
         spec: _SessionSpec,
+        reseed: bool = False,
     ) -> Session:
         live = self._pool.get(key)
         if live is not None:
-            return live
+            if not reseed:
+                return live
+            await self._pool.close(key)
         resume = session_id
         if resume is not None:
             await self.repair_session(resume)