fix(webui): keep schema defaults out of model presets

nanobot/webui/settings_api.py

@@ -280,7 +280,10 @@ def migrate_model_configurations(
     config_path: Path | None = None,
 ) -> dict[str, Any]:
     config = _load_settings_config(config_path)
-    if models.migrate_model_configurations(config):
+    if models.migrate_model_configurations(
+        config,
+        oauth_status=_oauth_provider_status,
+    ):
         _save_settings_config(config, config_path)
     return settings_payload(config_path=config_path)
 

nanobot/webui/settings_models.py

@@ -81,6 +81,7 @@ class ModelSettingsPayload(TypedDict):
     model_presets: list[dict[str, Any]]
     model_call_order: list[str]
     model_call_order_editable: bool
+    model_configuration_migratable: bool
     providers: list[dict[str, Any]]
 
 
@@ -925,6 +926,48 @@ def _model_call_order_state(config: Config) -> tuple[list[str], bool]:
     return order, True
 
 
+def _legacy_model_configuration_migratable(
+    config: Config,
+    oauth_status: OAuthStatusReader,
+) -> bool:
+    """Return whether the implicit default represents usable legacy configuration.
+
+    A pristine config still carries schema defaults for backwards compatibility.
+    Those defaults are not user configuration and must not be materialized as a
+    preset. Inline fallbacks, or a default whose matching provider is configured,
+    are evidence that there is real legacy state to preserve.
+    """
+    _, editable = _model_call_order_state(config)
+    if editable:
+        return False
+
+    defaults = config.agents.defaults
+    if defaults.fallback_models:
+        return True
+
+    provider_name = defaults.provider
+    if provider_name == "auto":
+        model_prefix = defaults.model.split("/", 1)[0] if "/" in defaults.model else ""
+        if model_prefix and resolve_settings_provider(config, model_prefix) is not None:
+            provider_name = model_prefix
+        else:
+            provider_name = (
+                config.get_provider_name(
+                    defaults.model,
+                    preset=config.resolve_default_preset(),
+                )
+                or ""
+            )
+    if not provider_name or provider_name == "auto":
+        return False
+
+    resolved_provider = resolve_settings_provider(config, provider_name)
+    if resolved_provider is None:
+        return False
+    spec, _, provider_config = resolved_provider
+    return provider_configured_for_settings(spec, provider_config, oauth_status)
+
+
 def _validate_configured_provider(
     config: Config,
     provider: str,
@@ -1073,6 +1116,10 @@ def model_settings_payload(
         "model_presets": model_presets,
         "model_call_order": model_call_order,
         "model_call_order_editable": model_call_order_editable,
+        "model_configuration_migratable": _legacy_model_configuration_migratable(
+            config,
+            oauth_status,
+        ),
         "providers": providers,
     }
 
@@ -1153,6 +1200,10 @@ def create_model_configuration(
         raise WebUISettingsError("configuration already exists", status=409)
     _validate_configured_provider(config, provider, oauth_status)
 
+    activate_as_primary = not config.model_presets and not _legacy_model_configuration_migratable(
+        config, oauth_status
+    )
+
     base = config.resolve_preset()
     max_tokens = _parse_positive_int(
         query_first_alias(query, "max_tokens", "maxTokens"),
@@ -1180,6 +1231,9 @@ def create_model_configuration(
         temperature=temperature if temperature is not None else base.temperature,
         reasoning_effort=reasoning_effort,
     )
+    if activate_as_primary:
+        config.agents.defaults.model_preset = name
+        config.agents.defaults.fallback_models = []
     return name
 
 
@@ -1299,8 +1353,18 @@ def update_model_call_order(config: Config, query: QueryParams) -> bool:
     return changed
 
 
-def migrate_model_configurations(config: Config) -> bool:
+def migrate_model_configurations(
+    config: Config,
+    *,
+    oauth_status: OAuthStatusReader,
+) -> bool:
     """Materialize legacy primary/inline model settings as named presets."""
+    _, editable = _model_call_order_state(config)
+    if editable:
+        return False
+    if not _legacy_model_configuration_migratable(config, oauth_status):
+        raise WebUISettingsError("there is no legacy model configuration to convert", status=409)
+
     defaults = config.agents.defaults
     primary = config.resolve_preset()
     created: list[str] = []

tests/webui/test_settings_api.py

@@ -287,6 +287,33 @@ def test_create_model_configuration_accepts_legacy_label_without_changing_call_o
     assert duplicate.value.status == 409
 
 
+def test_first_model_configuration_replaces_unused_schema_default(
+    tmp_path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    config_path = tmp_path / "config.json"
+    config = Config()
+    config.providers.openai.api_key = "sk-test"
+    save_config(config, config_path)
+    monkeypatch.setattr("nanobot.config.loader._current_config_path", config_path)
+
+    payload = create_model_configuration(
+        {
+            "name": ["openai"],
+            "provider": ["openai"],
+            "model": ["openai/gpt-4.1"],
+        }
+    )
+
+    assert payload["model_call_order"] == ["openai"]
+    assert payload["model_call_order_editable"] is True
+    assert payload["agent"]["model_preset"] == "openai"
+    saved = load_config(config_path)
+    assert saved.agents.defaults.model_preset == "openai"
+    assert saved.agents.defaults.fallback_models == []
+    assert saved.model_presets["openai"].model == "openai/gpt-4.1"
+
+
 def test_create_model_configuration_preserves_canonical_name(
     tmp_path,
     monkeypatch: pytest.MonkeyPatch,
@@ -337,7 +364,7 @@ def test_create_model_configuration_accepts_dynamic_custom_provider(
         }
     )
 
-    assert payload["agent"]["model_preset"] == "default"
+    assert payload["agent"]["model_preset"] == "tenant-model"
     assert payload["created_model_preset"] == "tenant-model"
     saved = load_config(config_path)
     assert saved.model_presets["tenant-model"].provider == DYNAMIC_PROVIDER_NAME
@@ -604,6 +631,7 @@ def test_migrate_model_configurations_preserves_legacy_chain(
     legacy_payload = settings_payload()
     assert legacy_payload["model_call_order"] == []
     assert legacy_payload["model_call_order_editable"] is False
+    assert legacy_payload["model_configuration_migratable"] is True
 
     payload = migrate_model_configurations()
 
@@ -621,6 +649,27 @@ def test_migrate_model_configurations_preserves_legacy_chain(
     assert set(load_config(config_path).model_presets) == {"gpt-4o", "claude-sonnet-4"}
 
 
+def test_schema_default_is_not_exposed_or_materialized_as_legacy_configuration(
+    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)
+
+    payload = settings_payload()
+
+    assert payload["model_configuration_migratable"] is False
+    assert payload["model_call_order_editable"] is False
+    with pytest.raises(WebUISettingsError) as error:
+        migrate_model_configurations()
+
+    assert error.value.status == 409
+    saved = load_config(config_path)
+    assert saved.agents.defaults.model_preset is None
+    assert saved.model_presets == {}
+
+
 def test_model_configuration_advanced_options_round_trip(
     tmp_path,
     monkeypatch: pytest.MonkeyPatch,
@@ -2288,7 +2337,7 @@ def test_create_model_configuration_accepts_configured_oauth_provider(
         }
     )
 
-    assert payload["agent"]["model_preset"] == "default"
+    assert payload["agent"]["model_preset"] == "codex"
     assert payload["created_model_preset"] == "codex"
     saved = load_config(config_path)
     assert saved.model_presets["codex"].provider == "openai_codex"
@@ -2376,7 +2425,7 @@ def test_create_model_configuration_accepts_azure_openai_aad_mode(
         }
     )
 
-    assert payload["agent"]["model_preset"] == "default"
+    assert payload["agent"]["model_preset"] == "azure-aad"
     assert payload["created_model_preset"] == "azure-aad"
     saved = load_config(config_path)
     assert saved.model_presets["azure-aad"].provider == "azure_openai"

tests/webui/test_settings_models.py

@@ -53,6 +53,7 @@ def test_model_domain_owns_dto_and_config_updates() -> None:
         "model_presets",
         "model_call_order",
         "model_call_order_editable",
+        "model_configuration_migratable",
         "providers",
     }
     assert payload["agent"]["model"] == "openai/gpt-5.4"

webui/src/components/settings/models/ModelsSettings.tsx

@@ -560,7 +560,8 @@ export function ModelsSettings({
           {tx("settings.models.presets", "Model presets")}
         </SettingsSectionTitle>
         <SettingsGroup>
-          {!settings.model_call_order_editable ? (
+          {!settings.model_call_order_editable &&
+          settings.model_configuration_migratable !== false ? (
             <div className="flex flex-col gap-4 px-4 py-4 sm:flex-row sm:items-center sm:justify-between sm:px-5">
               <div className="flex min-w-0 items-start gap-3">
                 <span className="grid h-9 w-9 shrink-0 place-items-center rounded-control bg-muted text-muted-foreground">

webui/src/lib/types.ts

@@ -595,6 +595,8 @@ export interface SettingsPayload {
   }>;
   model_call_order: string[];
   model_call_order_editable: boolean;
+  /** Whether an actual legacy model configuration is available to convert. */
+  model_configuration_migratable?: boolean;
   created_model_preset?: string;
   created_provider?: string;
   providers: Array<{

webui/src/tests/settings-models.test.tsx

@@ -690,6 +690,7 @@ describe("Settings models", () => {
       model_presets: [defaultPreset],
       model_call_order: [],
       model_call_order_editable: false,
+      model_configuration_migratable: true,
     };
     const fetchMock = vi.fn(async (input: RequestInfo | URL) => {
       const url = String(input);
@@ -725,6 +726,48 @@ describe("Settings models", () => {
     expect(screen.queryByText("Default")).not.toBeInTheDocument();
   });
 
+  it("starts fresh users with an empty preset list instead of legacy conversion", async () => {
+    const base = settingsPayload();
+    const freshPayload: SettingsPayload = {
+      ...base,
+      agent: {
+        ...base.agent,
+        model: "anthropic/claude-opus-4-5",
+        provider: "auto",
+        resolved_provider: null,
+        has_api_key: false,
+        model_preset: "default",
+      },
+      model_presets: [
+        {
+          ...base.model_presets[0],
+          name: "default",
+          label: "Default",
+          active: true,
+          is_default: true,
+          model: "anthropic/claude-opus-4-5",
+          provider: "auto",
+          resolved_provider: null,
+        },
+      ],
+      model_call_order: [],
+      model_call_order_editable: false,
+      model_configuration_migratable: false,
+      providers: [],
+    };
+    vi.stubGlobal("fetch", vi.fn(() => new Promise<Response>(() => {})));
+
+    renderSettingsView({ initialSection: "models", initialSettings: freshPayload });
+
+    expect(
+      await screen.findByRole("button", { name: "New model preset" }),
+    ).toBeInTheDocument();
+    expect(
+      screen.queryByRole("button", { name: "Convert to presets" }),
+    ).not.toBeInTheDocument();
+    expect(screen.queryByText("claude-opus-4-5")).not.toBeInTheDocument();
+  });
+
   it("does not expose the synthetic default configuration as a WebUI preset", async () => {
     const base = settingsPayload();
     const payload: SettingsPayload = {