feat: Add development mode with auto-reload (--dev flag)

src/google/adk/cli/cli.py

@@ -15,13 +15,18 @@
 from __future__ import annotations
 
 from datetime import datetime
+import os
 from pathlib import Path
+import threading
 from typing import Optional
 from typing import Union
 
 import click
 from google.genai import types
 from pydantic import BaseModel
+from watchdog.events import FileSystemEvent
+from watchdog.events import FileSystemEventHandler
+from watchdog.observers import Observer
 
 from ..agents.llm_agent import LlmAgent
 from ..apps.app import App
@@ -47,6 +52,35 @@ class InputFile(BaseModel):
   queries: list[str]
 
 
+class DevModeChangeHandler(FileSystemEventHandler):
+  """Handles file system events for development mode auto-reload."""
+
+  def __init__(self):
+    self.reload_needed = threading.Event()
+    self.last_modified_file = None
+
+  def _handle_event(self, event: FileSystemEvent):
+    """Handle file system events for .py and .yaml files."""
+    if event.is_directory:
+      return
+    if event.src_path.endswith(('.py', '.yaml')):
+      self.last_modified_file = event.src_path
+      self.reload_needed.set()
+
+  def on_modified(self, event: FileSystemEvent):
+    self._handle_event(event)
+
+  def on_created(self, event: FileSystemEvent):
+    self._handle_event(event)
+
+  def check_and_reset(self) -> tuple[bool, Optional[str]]:
+    """Check if reload is needed and reset the flag."""
+    if self.reload_needed.is_set():
+      self.reload_needed.clear()
+      return True, self.last_modified_file
+    return False, None
+
+
 async def run_input_file(
     app_name: str,
     user_id: str,
@@ -95,6 +129,9 @@ async def run_interactively(
     session: Session,
     session_service: BaseSessionService,
     credential_service: BaseCredentialService,
+    agent_loader: Optional[AgentLoader] = None,
+    agent_folder_name: Optional[str] = None,
+    change_handler: Optional[DevModeChangeHandler] = None,
 ) -> None:
   app = (
       root_agent_or_app
@@ -107,7 +144,44 @@ async def run_interactively(
       session_service=session_service,
       credential_service=credential_service,
   )
+
+  current_agent_or_app = root_agent_or_app
+
   while True:
+    # Check if we need to reload the agent in dev mode
+    if change_handler and agent_loader and agent_folder_name:
+      needs_reload, changed_file = change_handler.check_and_reset()
+      if needs_reload:
+        try:
+          click.secho(
+              f'\nDetected change in {changed_file}',
+              fg='yellow',
+          )
+          click.secho('Reloading agent...', fg='yellow')
+          # Remove from cache and reload
+          agent_loader.remove_agent_from_cache(agent_folder_name)
+          current_agent_or_app = agent_loader.load_agent(agent_folder_name)
+
+          # Update the app and runner with the new agent
+          app = (
+              current_agent_or_app
+              if isinstance(current_agent_or_app, App)
+              else App(name=session.app_name, root_agent=current_agent_or_app)
+          )
+          await runner.close()
+          runner = Runner(
+              app=app,
+              artifact_service=artifact_service,
+              session_service=session_service,
+              credential_service=credential_service,
+          )
+          click.secho('Agent reloaded successfully!\n', fg='green')
+        except Exception as e:
+          click.secho(
+              f'Error reloading agent: {e}\n',
+              fg='red',
+          )
+
     query = input('[user]: ')
     if not query or not query.strip():
       continue
@@ -137,6 +211,7 @@ async def run_cli(
     saved_session_file: Optional[str] = None,
     save_session: bool,
     session_id: Optional[str] = None,
+    dev_mode: bool = False,
     session_service_uri: Optional[str] = None,
     artifact_service_uri: Optional[str] = None,
 ) -> None:
@@ -153,6 +228,7 @@ async def run_cli(
       contains a previously saved session, exclusive with input_file.
     save_session: bool, whether to save the session on exit.
     session_id: Optional[str], the session ID to save the session to on exit.
+    dev_mode: bool, whether to enable development mode with auto-reload.
     session_service_uri: Optional[str], custom session service URI.
     artifact_service_uri: Optional[str], custom artifact service URI.
   """
@@ -174,9 +250,9 @@ async def run_cli(
 
   credential_service = InMemoryCredentialService()
   agents_dir = str(agent_parent_path)
-  agent_or_app = AgentLoader(agents_dir=agents_dir).load_agent(
-      agent_folder_name
-  )
+  agent_loader = AgentLoader(agents_dir=agents_dir)
+  agent_or_app = agent_loader.load_agent(agent_folder_name)
+
   session_app_name = (
       agent_or_app.name if isinstance(agent_or_app, App) else agent_folder_name
   )
@@ -194,53 +270,79 @@ def _print_event(event) -> None:
     author = event.author or 'system'
     click.echo(f'[{author}]: {"".join(text_parts)}')
 
-  if input_file:
-    session = await run_input_file(
-        app_name=session_app_name,
-        user_id=user_id,
-        agent_or_app=agent_or_app,
-        artifact_service=artifact_service,
-        session_service=session_service,
-        credential_service=credential_service,
-        input_path=input_file,
-    )
-  elif saved_session_file:
-    # Load the saved session from file
-    with open(saved_session_file, 'r', encoding='utf-8') as f:
-      loaded_session = Session.model_validate_json(f.read())
-
-    # Create a new session in the service, copying state from the file
-    session = await session_service.create_session(
-        app_name=session_app_name,
-        user_id=user_id,
-        state=loaded_session.state if loaded_session else None,
+  # Set up watchdog observer for dev mode
+  observer: Optional[Observer] = None
+  change_handler: Optional[DevModeChangeHandler] = None
+  if dev_mode:
+    agent_path = os.path.join(agent_parent_dir, agent_folder_name)
+    change_handler = DevModeChangeHandler()
+    observer = Observer()
+    observer.schedule(change_handler, agent_path, recursive=True)
+    observer.start()
+    click.secho(
+        'Auto-reload enabled - watching for file changes...',
+        fg='green',
     )
 
-    # Append events from the file to the new session and display them
-    if loaded_session:
-      for event in loaded_session.events:
-        await session_service.append_event(session, event)
-        _print_event(event)
-
-    await run_interactively(
-        agent_or_app,
-        artifact_service,
-        session,
-        session_service,
-        credential_service,
-    )
-  else:
-    session = await session_service.create_session(
-        app_name=session_app_name, user_id=user_id
-    )
-    click.echo(f'Running agent {agent_or_app.name}, type exit to exit.')
-    await run_interactively(
-        agent_or_app,
-        artifact_service,
-        session,
-        session_service,
-        credential_service,
-    )
+  try:
+    if input_file:
+      session = await run_input_file(
+          app_name=session_app_name,
+          user_id=user_id,
+          agent_or_app=agent_or_app,
+          artifact_service=artifact_service,
+          session_service=session_service,
+          credential_service=credential_service,
+          input_path=input_file,
+      )
+    elif saved_session_file:
+      # Load the saved session from file
+      with open(saved_session_file, 'r', encoding='utf-8') as f:
+        loaded_session = Session.model_validate_json(f.read())
+
+      # Create a new session in the service, copying state from the file
+      session = await session_service.create_session(
+          app_name=session_app_name,
+          user_id=user_id,
+          state=loaded_session.state if loaded_session else None,
+      )
+
+      # Append events from the file to the new session and display them
+      if loaded_session:
+        for event in loaded_session.events:
+          await session_service.append_event(session, event)
+          _print_event(event)
+
+      await run_interactively(
+          agent_or_app,
+          artifact_service,
+          session,
+          session_service,
+          credential_service,
+          agent_loader=agent_loader if dev_mode else None,
+          agent_folder_name=agent_folder_name if dev_mode else None,
+          change_handler=change_handler,
+      )
+    else:
+      session = await session_service.create_session(
+          app_name=session_app_name, user_id=user_id
+      )
+      click.echo(f'Running agent {agent_or_app.name}, type exit to exit.')
+      await run_interactively(
+          agent_or_app,
+          artifact_service,
+          session,
+          session_service,
+          credential_service,
+          agent_loader=agent_loader if dev_mode else None,
+          agent_folder_name=agent_folder_name if dev_mode else None,
+          change_handler=change_handler,
+      )
+  finally:
+    # Clean up observer
+    if observer:
+      observer.stop()
+      observer.join()
 
   if save_session:
     session_id = session_id or input('Session ID to save: ')

src/google/adk/cli/cli_eval.py

@@ -97,7 +97,15 @@ def parse_and_get_evals_to_run(
   eval_set_to_evals = {}
   for input_eval_set in evals_to_run_info:
     evals = []
-    if ":" not in input_eval_set:
+    # Check if the input is a file path that exists (e.g. C:\path\to\file.json)
+    if os.path.exists(input_eval_set):
+      eval_set = input_eval_set
+    # Check if it's a file path with cases (e.g. C:\path\to\file.json:case1,case2)
+    elif ":" in input_eval_set and os.path.exists(input_eval_set.rsplit(":", 1)[0]):
+      eval_set = input_eval_set.rsplit(":", 1)[0]
+      evals = input_eval_set.rsplit(":", 1)[1].split(",")
+      evals = [s for s in evals if s.strip()]
+    elif ":" not in input_eval_set:
       # We don't have any eval cases specified. This would be the case where the
       # the user wants to run all eval cases in the eval set.
       eval_set = input_eval_set