refactor(agent): trim model preset runtime wiring

Co-authored-by: Cursor <cursoragent@cursor.com>

nanobot/agent/loop.py

@@ -289,11 +289,10 @@ class AgentLoop:
         tools_config: ToolsConfig | None = None,
         image_generation_provider_config: ProviderConfig | None = None,
         image_generation_provider_configs: dict[str, ProviderConfig] | None = None,
-        provider_snapshot_loader: Callable[[], ProviderSnapshot] | None = None,
+        provider_snapshot_loader: Callable[..., ProviderSnapshot] | None = None,
         provider_signature: tuple[object, ...] | None = None,
         model_presets: dict[str, ModelPresetConfig] | None = None,
         model_preset: str | None = None,
-        model_preset_snapshot_builder: Callable[[str], ProviderSnapshot] | None = None,
     ):
         from nanobot.config.schema import ToolsConfig
 
@@ -304,10 +303,7 @@ class AgentLoop:
         self.provider = provider
         self._provider_snapshot_loader = provider_snapshot_loader
         self._provider_signature = provider_signature
-        self._config_provider_signature = provider_signature
-        self._config_default_selection_signature = (
-            provider_signature[:2] if provider_signature is not None else None
-        )
+        self._default_selection_signature = provider_signature[:2] if provider_signature else None
         self.workspace = workspace
         self.model = model or provider.get_default_model()
         self.max_iterations = (
@@ -403,7 +399,6 @@ class AgentLoop:
             model=self.model,
         )
         self.model_presets: dict[str, ModelPresetConfig] = model_presets or {}
-        self._model_preset_snapshot_builder = model_preset_snapshot_builder
         self._active_preset: str | None = None
         if model_preset:
             self.set_model_preset(model_preset, notify=False)
@@ -435,9 +430,8 @@ class AgentLoop:
         resolved = config.resolve_preset()
         model = extra.pop("model", None) or resolved.model
         context_window_tokens = extra.pop("context_window_tokens", None) or resolved.context_window_tokens
-        model_preset_snapshot_builder = extra.pop("model_preset_snapshot_builder", None)
-        model_presets = dict(config.model_presets)
-        model_presets["default"] = config.resolve_default_preset()
+        provider_snapshot_loader = extra.pop("provider_snapshot_loader", None)
+        model_presets = {**config.model_presets, "default": config.resolve_default_preset()}
         return cls(
             bus=bus,
             provider=provider,
@@ -461,9 +455,8 @@ class AgentLoop:
             tools_config=config.tools,
             model_presets=model_presets,
             model_preset=defaults.model_preset,
-            model_preset_snapshot_builder=(
-                model_preset_snapshot_builder
-                or (lambda name: build_provider_snapshot(config, preset_name=name))
+            provider_snapshot_loader=provider_snapshot_loader or (
+                lambda preset_name=None: build_provider_snapshot(config, preset_name=preset_name)
             ),
             **extra,
         )
@@ -475,14 +468,8 @@ class AgentLoop:
     def _publish_runtime_model_updated(self, model_preset: str | None = None) -> None:
         """Notify WebUI clients that the effective runtime model changed."""
         self.bus.outbound.put_nowait(OutboundMessage(
-            channel="websocket",
-            chat_id="*",
-            content="",
-            metadata={
-                "_runtime_model_updated": True,
-                "model": self.model,
-                "model_preset": model_preset if model_preset is not None else self.model_preset,
-            },
+            channel="websocket", chat_id="*", content="",
+            metadata={"_runtime_model_updated": True, "model": self.model, "model_preset": model_preset if model_preset is not None else self.model_preset},
         ))
 
     def _apply_provider_snapshot(
@@ -517,36 +504,22 @@ class AgentLoop:
         except Exception:
             logger.exception("Failed to refresh provider config")
             return
-        if self._active_preset:
-            default_selection = snapshot.signature[:2]
-            if (
-                self._config_default_selection_signature is not None
-                and default_selection != self._config_default_selection_signature
-            ):
-                self._active_preset = None
-                self._config_provider_signature = snapshot.signature
-                self._config_default_selection_signature = default_selection
-                self._apply_provider_snapshot(snapshot)
-                return
-            self._config_provider_signature = snapshot.signature
-            self._config_default_selection_signature = default_selection
+        default_selection = snapshot.signature[:2]
+        if self._active_preset and self._default_selection_signature in (None, default_selection):
+            self._default_selection_signature = default_selection
             try:
                 snapshot = self._build_model_preset_snapshot(self._active_preset)
             except Exception:
                 logger.exception("Failed to refresh active model preset")
                 return
-            if snapshot.signature == self._provider_signature:
-                return
-            self._apply_provider_snapshot(snapshot)
-            return
+        else:
+            self._active_preset = None
+            self._default_selection_signature = default_selection
         if snapshot.signature == self._provider_signature:
             return
-        self._config_provider_signature = snapshot.signature
-        self._config_default_selection_signature = snapshot.signature[:2]
+        self._default_selection_signature = snapshot.signature[:2]
         self._apply_provider_snapshot(snapshot)
 
-    # -- model_preset property --
-
     @property
     def model_preset(self) -> str | None:
         return self._active_preset
@@ -557,23 +530,14 @@ class AgentLoop:
 
     def _build_model_preset_snapshot(self, name: str) -> ProviderSnapshot:
         preset = self.model_presets[name]
-        if self._model_preset_snapshot_builder is not None:
-            return self._model_preset_snapshot_builder(name)
+        if self._provider_snapshot_loader is not None:
+            return self._provider_snapshot_loader(preset_name=name)
         self.provider.generation = preset.to_generation_settings()
         return ProviderSnapshot(
             provider=self.provider,
             model=preset.model,
             context_window_tokens=preset.context_window_tokens,
-            signature=(
-                "model_preset",
-                name,
-                preset.model,
-                preset.provider,
-                preset.max_tokens,
-                preset.context_window_tokens,
-                preset.temperature,
-                preset.reasoning_effort,
-            ),
+            signature=("model_preset", name, preset.model_dump_json()),
         )
 
     def set_model_preset(self, name: str | None, *, notify: bool = True) -> None:

nanobot/cli/commands.py

@@ -672,7 +672,6 @@ def _run_gateway(
             "aihubmix": config.providers.aihubmix,
         },
         provider_snapshot_loader=load_provider_snapshot,
-        model_preset_snapshot_builder=lambda name: load_provider_snapshot(preset_name=name),
         provider_signature=provider_snapshot.signature,
     )
 

tests/agent/test_self_model_preset.py

@@ -104,11 +104,11 @@ def test_model_preset_setter_replaces_provider_from_snapshot(tmp_path) -> None:
         model="base-model",
         context_window_tokens=1000,
         model_presets={"deep": preset},
-        model_preset_snapshot_builder=lambda _name: ProviderSnapshot(
+        provider_snapshot_loader=lambda preset_name=None: ProviderSnapshot(
             provider=new_provider,
             model=preset.model,
             context_window_tokens=preset.context_window_tokens,
-            signature=("deep", preset.model),
+            signature=(preset_name, preset.model),
         ),
     )
 
@@ -135,7 +135,7 @@ def test_model_preset_setter_failure_leaves_old_state(tmp_path) -> None:
         model="base-model",
         context_window_tokens=1000,
         model_presets={"fast": preset},
-        model_preset_snapshot_builder=lambda _name: (_ for _ in ()).throw(
+        provider_snapshot_loader=lambda preset_name=None: (_ for _ in ()).throw(
             RuntimeError("provider unavailable")
         ),
     )
@@ -173,10 +173,11 @@ def test_active_model_preset_survives_unchanged_config_refresh(tmp_path) -> None
         workspace=tmp_path,
         model="base-model",
         context_window_tokens=1000,
-        provider_snapshot_loader=lambda: default_snapshot,
         provider_signature=default_snapshot.signature,
         model_presets={"fast": ModelPresetConfig(model="openai/gpt-4.1")},
-        model_preset_snapshot_builder=lambda _name: fast_snapshot,
+        provider_snapshot_loader=lambda preset_name=None: (
+            fast_snapshot if preset_name == "fast" else default_snapshot
+        ),
     )
 
     loop.set_model_preset("fast")
@@ -209,10 +210,11 @@ def test_config_model_refresh_clears_active_model_preset(tmp_path) -> None:
         workspace=tmp_path,
         model="base-model",
         context_window_tokens=1000,
-        provider_snapshot_loader=lambda: webui_snapshot,
+        provider_snapshot_loader=lambda preset_name=None: (
+            fast_snapshot if preset_name == "fast" else webui_snapshot
+        ),
         provider_signature=("base-model", "auto", "openai", "sk-old"),
         model_presets={"fast": ModelPresetConfig(model="openai/gpt-4.1")},
-        model_preset_snapshot_builder=lambda _name: fast_snapshot,
     )
 
     loop.set_model_preset("fast")