feat(agent-runner): add plugin runner host integration

src/langbot/pkg/agent/runner/default_config.py

@@ -0,0 +1,72 @@
+"""Default AgentRunner binding configuration helpers."""
+
+from __future__ import annotations
+
+import sqlalchemy
+
+from ...core import app
+from ...entity.persistence import pipeline as persistence_pipeline
+from . import config_schema
+from .config_migration import ConfigMigration
+
+
+class AgentRunnerDefaultConfigService:
+    """Apply AgentRunner schema-defined defaults to host binding config."""
+
+    ap: app.Application
+
+    def __init__(self, ap: app.Application) -> None:
+        self.ap = ap
+
+    async def _get_runner_descriptor(self, runner_id: str):
+        registry = getattr(self.ap, 'agent_runner_registry', None)
+        if registry is None:
+            return None
+        try:
+            return await registry.get(runner_id, bound_plugins=None)
+        except Exception as e:
+            logger = getattr(self.ap, 'logger', None)
+            if logger:
+                logger.warning(f'Failed to load AgentRunner descriptor while setting default model: {e}')
+            return None
+
+    async def auto_set_default_pipeline_llm_model(self, model_uuid: str) -> bool:
+        """Set model_uuid into the default pipeline runner config when the selector is empty."""
+        result = await self.ap.persistence_mgr.execute_async(
+            sqlalchemy.select(persistence_pipeline.LegacyPipeline).where(
+                persistence_pipeline.LegacyPipeline.is_default == True
+            )
+        )
+        pipeline = result.first()
+        if pipeline is None:
+            return False
+
+        return await self.set_pipeline_llm_model_if_empty(pipeline, model_uuid)
+
+    async def set_pipeline_llm_model_if_empty(
+        self,
+        pipeline: persistence_pipeline.LegacyPipeline,
+        model_uuid: str,
+    ) -> bool:
+        """Set model_uuid into a pipeline's schema-defined LLM selector if it is empty."""
+        pipeline_config = pipeline.config
+        if not isinstance(pipeline_config, dict):
+            return False
+
+        runner_id = ConfigMigration.resolve_runner_id(pipeline_config)
+        if not runner_id:
+            return False
+
+        descriptor = await self._get_runner_descriptor(runner_id)
+        if descriptor is None:
+            return False
+
+        ai_config = pipeline_config.setdefault('ai', {})
+        runner_configs = ai_config.setdefault('runner_config', {})
+        runner_config = runner_configs.setdefault(runner_id, {})
+
+        if not config_schema.set_empty_llm_model_selection(descriptor, runner_config, model_uuid):
+            return False
+
+        await self.ap.pipeline_service.update_pipeline(pipeline.uuid, {'config': pipeline_config})
+        return True