From 90970d85f2360bf0060db49f92bccba6830aeb0f Mon Sep 17 00:00:00 2001
From: kshitijk4poor <82637225+kshitijk4poor@users.noreply.github.com>
Date: Fri, 11 Sep 2026 12:25:46 +0530
Subject: [PATCH] fix(gateway): a repeated /model --once keeps the earliest
 restore target
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`/model X --once` then `/model Y --once` before any turn replaced the
pending snapshot with one taken while X was live, so slot cleanup restored
X and made the first temporary model permanent (ehz0ah, review on #106966).
setdefault keeps the snapshot from the first command — the user's standing
override — as the restore target. One producer-driven regression test.
---
 gateway/slash_commands_model.py                |  6 ++++--
 tests/gateway/test_model_switch_persistence.py | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/gateway/slash_commands_model.py b/gateway/slash_commands_model.py
index 82bb31ab41..875707a874 100644
--- a/gateway/slash_commands_model.py
+++ b/gateway/slash_commands_model.py
@@ -269,8 +269,10 @@ class GatewayModelCommandsMixin:
         if one_turn:
             if not hasattr(self, "_pending_one_turn_model_restores"):
                 self._pending_one_turn_model_restores = {}
-            self._pending_one_turn_model_restores[ctx.session_key] = dict(
-                ctx.restore_snapshot or {"had_override": False, "override": None}
+            # A repeated --once before the turn runs must keep the EARLIEST snapshot: the later
+            # command's snapshot is the first temporary model, not the user's standing override.
+            self._pending_one_turn_model_restores.setdefault(
+                ctx.session_key, dict(ctx.restore_snapshot or {"had_override": False, "override": None}),
             )
         elif not picker and hasattr(self, "_pending_one_turn_model_restores"):
             self._pending_one_turn_model_restores.pop(ctx.session_key, None)
diff --git a/tests/gateway/test_model_switch_persistence.py b/tests/gateway/test_model_switch_persistence.py
index a668518a3e..79f2b7b695 100644
--- a/tests/gateway/test_model_switch_persistence.py
+++ b/tests/gateway/test_model_switch_persistence.py
@@ -282,3 +282,19 @@ class TestOneTurnNeverPersisted:
         # ...but NEVER written through to the persistent session store.
         runner.async_session_store.set_model_override.assert_not_awaited()
 
+    @pytest.mark.asyncio
+    async def test_repeated_once_keeps_the_earliest_restore_target(self, tmp_path, monkeypatch):
+        """`/model X --once` then `/model Y --once` before any turn: the pending snapshot must still
+        be the user's standing override (none here), not X — otherwise slot cleanup would make the
+        first temporary model permanent."""
+        runner = self._runner_with_store(tmp_path, monkeypatch)
+        sk = build_session_key(_make_source())
+
+        await runner._handle_model_command(self._event("/model gpt-5.5 --once"))
+        assert runner._session_model_overrides[sk]["model"] == "gpt-5.5"
+        await runner._handle_model_command(self._event("/model gpt-5.5 --once"))
+
+        # The second producer call snapshotted the live gpt-5.5 override; the pending restore
+        # must still be the ORIGINAL "no override" state.
+        assert runner._pending_one_turn_model_restores[sk]["had_override"] is False
+