feat: support invoke adk webserver app

(cherry picked from commit f392a4a0376477922ed49de94a64509bd186fbcd)

Author: innsd

agentkit/apps/agent_server_app/agent_server_app.py

@@ -15,6 +15,10 @@
 from typing import override
 
 import uvicorn
+import json
+from fastapi import Request
+from fastapi import HTTPException
+from fastapi.responses import StreamingResponse
 from google.adk.agents.base_agent import BaseAgent
 from google.adk.artifacts.in_memory_artifact_service import (
     InMemoryArtifactService,
@@ -30,6 +34,9 @@
 from google.adk.evaluation.local_eval_sets_manager import LocalEvalSetsManager
 from google.adk.memory.in_memory_memory_service import InMemoryMemoryService
 from google.adk.sessions.base_session_service import BaseSessionService
+from google.adk.agents.run_config import RunConfig, StreamingMode
+from google.adk.utils.context_utils import Aclosing
+from google.genai import types
 from veadk import Agent
 from veadk.memory.short_term_memory import ShortTermMemory
 
@@ -80,6 +87,89 @@ def __init__(
 
         self.app = self.server.get_fast_api_app()
 
+        async def _invoke_compat(request: Request):
+            # Extract headers (fallback keys supported)
+            headers = request.headers
+            user_id = (
+                headers.get("user_id") or headers.get("x-user-id") or "agentkit_user"
+            )
+            session_id = (
+                headers.get("session_id")
+                or headers.get("x-session-id")
+                or "agentkit_sample_session"
+            )
+
+            # Determine app_name from loader
+            app_names = self.server.agent_loader.list_agents()
+            if not app_names:
+                raise HTTPException(status_code=404, detail="No agents configured")
+            app_name = app_names[0]
+
+            # Parse payload and convert to ADK Content
+            try:
+                payload = await request.json()
+            except Exception:
+                payload = None
+
+            text = payload.get("prompt") if isinstance(payload, dict) else None
+            if text is None:
+                if payload is not None:
+                    try:
+                        text = json.dumps(payload, ensure_ascii=False)
+                    except Exception:
+                        text = ""
+                else:
+                    try:
+                        body_bytes = await request.body()
+                        text = body_bytes.decode("utf-8")
+                    except Exception:
+                        text = ""
+            content = types.UserContent(parts=[types.Part(text=text or "")])
+
+            # Ensure session exists
+            session = await self.server.session_service.get_session(
+                app_name=app_name, user_id=user_id, session_id=session_id
+            )
+            if not session:
+                await self.server.session_service.create_session(
+                    app_name=app_name, user_id=user_id, session_id=session_id
+                )
+
+            async def event_generator():
+                try:
+                    runner = await self.server.get_runner_async(app_name)
+                    async with Aclosing(
+                        runner.run_async(
+                            user_id=user_id,
+                            session_id=session_id,
+                            new_message=content,
+                            run_config=RunConfig(streaming_mode=StreamingMode.SSE),
+                        )
+                    ) as agen:
+                        async for event in agen:
+                            yield (
+                                "data: "
+                                + event.model_dump_json(
+                                    exclude_none=True, by_alias=True
+                                )
+                                + "\n\n"
+                            )
+                except Exception as e:
+                    yield f'data: {{"error": "{str(e)}"}}\n\n'
+
+            return StreamingResponse(
+                event_generator(),
+                media_type="text/event-stream",
+                headers={
+                    "Cache-Control": "no-cache",
+                    "Connection": "keep-alive",
+                    "X-Accel-Buffering": "no",
+                },
+            )
+
+        # Compatibility route for AgentKit CLI invoke
+        self.app.add_api_route("/invoke", _invoke_compat, methods=["POST"])
+
     def run(self, host: str, port: int = 8000) -> None:
         """Run the app with Uvicorn server."""
         uvicorn.run(self.app, host=host, port=port)