feat(webui): add model settings runtime refresh

tests/agent/test_runtime_refresh.py

@@ -0,0 +1,49 @@
+from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+from nanobot.agent.loop import AgentLoop
+from nanobot.agent.runtime import AgentRuntime
+from nanobot.bus.queue import MessageBus
+
+
+def _provider(default_model: str, max_tokens: int = 123) -> MagicMock:
+    provider = MagicMock()
+    provider.get_default_model.return_value = default_model
+    provider.generation = SimpleNamespace(max_tokens=max_tokens)
+    return provider
+
+
+def test_runtime_refresh_updates_loop_dependents(tmp_path: Path) -> None:
+    old_provider = _provider("old-model")
+    new_provider = _provider("new-model", max_tokens=456)
+    loop = AgentLoop(
+        bus=MessageBus(),
+        provider=old_provider,
+        workspace=tmp_path,
+        model="old-model",
+        context_window_tokens=1000,
+        runtime_loader=lambda: AgentRuntime(
+            provider=new_provider,
+            model="new-model",
+            context_window_tokens=2000,
+            signature=("new-model",),
+        ),
+    )
+
+    loop._refresh_runtime()
+
+    assert loop.provider is new_provider
+    assert loop.model == "new-model"
+    assert loop.context_window_tokens == 2000
+    assert loop.runner.provider is new_provider
+    assert loop.subagents.provider is new_provider
+    assert loop.subagents.model == "new-model"
+    assert loop.subagents.runner.provider is new_provider
+    assert loop.consolidator.provider is new_provider
+    assert loop.consolidator.model == "new-model"
+    assert loop.consolidator.context_window_tokens == 2000
+    assert loop.consolidator.max_completion_tokens == 456
+    assert loop.dream.provider is new_provider
+    assert loop.dream.model == "new-model"
+    assert loop.dream._runner.provider is new_provider