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

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

@@ -0,0 +1,82 @@
+"""Agent runner descriptor."""
+from __future__ import annotations
+
+import typing
+import pydantic
+
+from langbot_plugin.api.entities.builtin.agent_runner.manifest import (
+    AgentRunnerCapabilities,
+    AgentRunnerPermissions,
+)
+
+
+class AgentRunnerDescriptor(pydantic.BaseModel):
+    """Descriptor for an agent runner.
+
+    Represents the discovered metadata for a runner, including
+    its identity, capabilities, permissions, and configuration schema.
+    """
+
+    id: str
+    """Unique runner ID: plugin:author/plugin_name/runner_name"""
+
+    source: typing.Literal['plugin']
+    """Runner source type"""
+
+    label: dict[str, str]
+    """Display labels keyed by locale (e.g., en_US, zh_Hans)"""
+
+    description: dict[str, str] | None = None
+    """Optional description keyed by locale"""
+
+    plugin_author: str
+    """Plugin author from manifest"""
+
+    plugin_name: str
+    """Plugin name from manifest"""
+
+    runner_name: str
+    """AgentRunner component name from manifest"""
+
+    plugin_version: str | None = None
+    """Optional plugin version"""
+
+    config_schema: list[dict[str, typing.Any]] = pydantic.Field(default_factory=list)
+    """Configuration schema using DynamicForm format"""
+
+    capabilities: AgentRunnerCapabilities = pydantic.Field(
+        default_factory=AgentRunnerCapabilities
+    )
+    """Runner capabilities: streaming, tool_calling, knowledge_retrieval, etc."""
+
+    permissions: AgentRunnerPermissions = pydantic.Field(
+        default_factory=AgentRunnerPermissions
+    )
+    """Requested LangBot resource permissions."""
+
+    raw_manifest: dict[str, typing.Any] = pydantic.Field(default_factory=dict)
+    """Original manifest for reference"""
+
+    model_config = pydantic.ConfigDict(
+        extra='allow',
+    )
+
+    def get_plugin_id(self) -> str:
+        """Return plugin identifier as author/name."""
+        return f'{self.plugin_author}/{self.plugin_name}'
+
+    def supports_streaming(self) -> bool:
+        """Check if runner supports streaming output."""
+        return self.capabilities.streaming
+
+    def supports_tool_calling(self) -> bool:
+        """Check if runner supports tool calling."""
+        return self.capabilities.tool_calling
+
+    def supports_knowledge_retrieval(self) -> bool:
+        """Check if runner supports knowledge retrieval."""
+        return self.capabilities.knowledge_retrieval
+
+    def supports_steering(self) -> bool:
+        """Check if runner supports run steering/follow-up input."""
+        return bool(getattr(self.capabilities, 'steering', False))