feat(webui): add context window setting

tests/agent/test_runtime_refresh.py

@@ -4,7 +4,10 @@ from unittest.mock import MagicMock
 
 from nanobot.agent.loop import AgentLoop
 from nanobot.bus.queue import MessageBus
-from nanobot.providers.factory import ProviderSnapshot
+from nanobot.config.loader import save_config
+from nanobot.config.schema import Config
+from nanobot.providers.factory import ProviderSnapshot, load_provider_snapshot
+from nanobot.webui.settings_api import update_agent_settings
 
 
 def _provider(default_model: str, max_tokens: int = 123) -> MagicMock:
@@ -72,3 +75,30 @@ def test_llm_runtime_refreshes_provider_snapshot(tmp_path: Path) -> None:
     assert runtime.model == "new-model"
     assert loop.provider is new_provider
     assert loop.runner.provider is new_provider
+
+
+def test_settings_context_window_refreshes_runtime_state(
+    tmp_path: Path,
+    monkeypatch,
+) -> None:
+    config_path = tmp_path / "config.json"
+    config = Config()
+    config.agents.defaults.workspace = str(tmp_path / "workspace")
+    config.agents.defaults.model = "openai/gpt-4o"
+    config.agents.defaults.provider = "openai"
+    config.agents.defaults.context_window_tokens = 65_536
+    config.providers.openai.api_key = "sk-test"
+    save_config(config, config_path)
+    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
+
+    def loader(*, preset_name: str | None = None) -> ProviderSnapshot:
+        return load_provider_snapshot(config_path, preset_name=preset_name)
+
+    loop = AgentLoop.from_config(config, provider_snapshot_loader=loader)
+
+    payload = update_agent_settings({"context_window_tokens": ["262144"]})
+    loop._refresh_provider_snapshot()
+
+    assert payload["requires_restart"] is False
+    assert loop.context_window_tokens == 262_144
+    assert loop.consolidator.context_window_tokens == 262_144

tests/webui/test_settings_api.py

@@ -11,6 +11,7 @@ from nanobot.webui.settings_api import (
     _oauth_provider_status,
     create_model_configuration,
     settings_payload,
+    update_agent_settings,
     update_model_configuration,
     update_network_safety_settings,
 )
@@ -119,6 +120,60 @@ def test_update_model_configuration_edits_named_preset_and_selects(
     assert saved.model_presets["codex"].model == "openai-codex/gpt-5.5"
 
 
+def test_update_agent_settings_accepts_context_window_options(
+    tmp_path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    config_path = tmp_path / "config.json"
+    config = Config()
+    save_config(config, config_path)
+    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
+
+    payload = update_agent_settings({"context_window_tokens": ["262144"]})
+
+    assert payload["agent"]["context_window_tokens"] == 262144
+    saved = load_config(config_path)
+    assert saved.agents.defaults.context_window_tokens == 262144
+
+
+def test_update_model_configuration_accepts_context_window_options(
+    tmp_path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    config_path = tmp_path / "config.json"
+    config = Config()
+    config.model_presets["codex"] = ModelPresetConfig(
+        label="Codex",
+        provider="openai",
+        model="openai/gpt-4.1",
+    )
+    save_config(config, config_path)
+    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
+
+    payload = update_model_configuration(
+        {
+            "name": ["codex"],
+            "context_window_tokens": ["262144"],
+        }
+    )
+
+    assert payload["agent"]["context_window_tokens"] == 262144
+    saved = load_config(config_path)
+    assert saved.model_presets["codex"].context_window_tokens == 262144
+
+
+def test_update_context_window_rejects_unknown_values(
+    tmp_path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    config_path = tmp_path / "config.json"
+    save_config(Config(), config_path)
+    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
+
+    with pytest.raises(WebUISettingsError, match="context_window_tokens must be 65536 or 262144"):
+        update_agent_settings({"context_window_tokens": ["128000"]})
+
+
 def test_update_model_configuration_rejects_default_preset(
     tmp_path,
     monkeypatch: pytest.MonkeyPatch,