fix(state): include finish_reason in conversation replay

SELECT in get_messages_as_conversation() was missing finish_reason, so
assistant messages round-tripped through replay (including /branch copies)
silently dropped the provider's stop signal. Adds it to the SELECT, restores
it on assistant rows, and locks it in with a round-trip test.

hermes_state.py

@@ -1464,8 +1464,8 @@ class SessionDB:
             placeholders = ",".join("?" for _ in session_ids)
             rows = self._conn.execute(
                 "SELECT role, content, tool_call_id, tool_calls, tool_name, "
-                "reasoning, reasoning_content, reasoning_details, codex_reasoning_items, "
-                "codex_message_items "
+                "finish_reason, reasoning, reasoning_content, reasoning_details, "
+                "codex_reasoning_items, codex_message_items "
                 f"FROM messages WHERE session_id IN ({placeholders}) ORDER BY timestamp, id",
                 tuple(session_ids),
             ).fetchall()
@@ -1490,6 +1490,8 @@ class SessionDB:
             # that replay reasoning (OpenRouter, OpenAI, Nous) receive
             # coherent multi-turn reasoning context.
             if row["role"] == "assistant":
+                if row["finish_reason"]:
+                    msg["finish_reason"] = row["finish_reason"]
                 if row["reasoning"]:
                     msg["reasoning"] = row["reasoning"]
                 if row["reasoning_content"] is not None:

tests/test_hermes_state.py

@@ -399,6 +399,27 @@ class TestMessageStorage:
         assert msg["reasoning"] == "Thinking about what to say"
         assert msg["reasoning_details"] == details
 
+    def test_finish_reason_restored_by_get_messages_as_conversation(self, db):
+        """finish_reason on assistant messages must survive conversation replay.
+
+        Without this, /branch copies and other transcript round-trips silently
+        drop the provider's stop signal.
+        """
+        db.create_session(session_id="s1", source="cli")
+        db.append_message(
+            "s1",
+            role="assistant",
+            content="Done",
+            finish_reason="tool_calls",
+        )
+        db.append_message("s1", role="user", content="next")
+
+        conv = db.get_messages_as_conversation("s1")
+        assert conv[0]["role"] == "assistant"
+        assert conv[0]["finish_reason"] == "tool_calls"
+        # Non-assistant rows should not have a finish_reason key added.
+        assert "finish_reason" not in conv[1]
+
     def test_reasoning_content_persisted_and_restored(self, db):
         """reasoning_content must survive session replay as its own field."""
         db.create_session(session_id="s1", source="cli")