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

tests/test_routing.py

@@ -228,3 +228,30 @@ async def test_anthropic_turns_become_one_deep_conversation(stack: Stack) -> Non
             headers=AUTH,
         )
         assert r.status_code == 400 and "runs on 'd'" in r.json()["detail"]
+
+
+async def test_markdown_edited_reply_reseeds_the_session(stack: Stack) -> None:
+    async with stack.client(stack.markdown) as c:
+        r = await c.post(
+            "/chat",
+            json={"filename": "e.md", "agent": "d", "content": "### User:\n\nanimal\n"},
+            headers=AUTH,
+        )
+        assert r.status_code == 200, r.text
+        content = r.json()["new_content"]
+        assert "ok:animal" in content and len(ScriptedClient.instances) == 1
+        edited = content.replace("ok:animal", "penguin") + "\nwhich one?\n"
+        r = await c.post(
+            "/chat",
+            json={"filename": "e.md", "agent": "d", "content": edited},
+            headers=AUTH,
+        )
+        assert r.status_code == 200, r.text
+        assert len(ScriptedClient.instances) == 2
+        first, second = ScriptedClient.instances
+        assert not first.connected and second.prompts == ["which one?"]
+        assert second.options.resume not in (None, first.session_id)
+        assert "penguin" in repr(vars(stack.world.store))
+        async with stack.world.db.session() as session:
+            stored = await load_messages(session, conversation_id=1)
+        assert stored[1]["content"] == [{"type": "text", "text": "penguin"}]