feat!: Introduction of ADK folder for local session and artifact storage

Default CLI session storage to SQLite instead of in-memory

Previously, adk run and adk web used in-memory session storage by default, causing sessions to be lost on restart. Now sessions persist to .adk/session.db automatically. To use in-memory storage, pass --session-service-uri memory://

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 838975328

src/google/adk/cli/cli.py

@@ -26,12 +26,10 @@ from pydantic import BaseModel
 from ..agents.llm_agent import LlmAgent
 from ..apps.app import App
 from ..artifacts.base_artifact_service import BaseArtifactService
-from ..artifacts.in_memory_artifact_service import InMemoryArtifactService
 from ..auth.credential_service.base_credential_service import BaseCredentialService
 from ..auth.credential_service.in_memory_credential_service import InMemoryCredentialService
 from ..runners import Runner
 from ..sessions.base_session_service import BaseSessionService
-from ..sessions.in_memory_session_service import InMemorySessionService
 from ..sessions.session import Session
 from ..utils.context_utils import Aclosing
 from ..utils.env_utils import is_env_enabled
@@ -162,8 +160,9 @@ async def run_cli(
   user_id = 'test_user'
 
   # Create session and artifact services using factory functions
+  # Sessions persist under <agents_dir>/<agent>/.adk/session.db by default.
   session_service = create_session_service_from_options(
-      base_dir=agent_root,
+      base_dir=agent_parent_path,
       session_service_uri=session_service_uri,
   )
 

src/google/adk/cli/utils/local_storage.py

@@ -57,6 +57,32 @@ def create_local_database_session_service(
   return SqliteSessionService(db_path=str(session_db_path))
 
 
+def create_local_session_service(
+    *,
+    base_dir: Path | str,
+    per_agent: bool = False,
+) -> BaseSessionService:
+  """Creates a local SQLite-backed session service.
+
+  Args:
+    base_dir: The base directory for the agent(s).
+    per_agent: If True, creates a PerAgentDatabaseSessionService that stores
+      sessions in each agent's .adk folder. If False, creates a single
+      SqliteSessionService at base_dir/.adk/session.db.
+
+  Returns:
+    A BaseSessionService instance backed by SQLite.
+  """
+  if per_agent:
+    logger.info(
+        "Using per-agent session storage rooted at %s",
+        base_dir,
+    )
+    return PerAgentDatabaseSessionService(agents_root=base_dir)
+
+  return create_local_database_session_service(base_dir=base_dir)
+
+
 def create_local_artifact_service(
     *, base_dir: Path | str
 ) -> BaseArtifactService:

src/google/adk/cli/utils/service_factory.py

@@ -23,6 +23,7 @@ from ...memory.base_memory_service import BaseMemoryService
 from ...sessions.base_session_service import BaseSessionService
 from ..service_registry import get_service_registry
 from .local_storage import create_local_artifact_service
+from .local_storage import create_local_session_service
 
 logger = logging.getLogger("google_adk." + __name__)
 
@@ -62,10 +63,8 @@ def create_session_service_from_options(
     )
     return DatabaseSessionService(db_url=session_service_uri, **fallback_kwargs)
 
-  logger.info("Using in-memory session service")
-  from ...sessions.in_memory_session_service import InMemorySessionService
-
-  return InMemorySessionService()
+  # Default to per-agent local SQLite storage in <agents_root>/<agent>/.adk/.
+  return create_local_session_service(base_dir=base_path, per_agent=True)
 
 
 def create_memory_service_from_options(

tests/unittests/cli/utils/test_service_factory.py

@@ -19,10 +19,10 @@ from __future__ import annotations
 from pathlib import Path
 from unittest.mock import Mock
 
+from google.adk.cli.utils.local_storage import PerAgentDatabaseSessionService
 import google.adk.cli.utils.service_factory as service_factory
 from google.adk.memory.in_memory_memory_service import InMemoryMemoryService
 from google.adk.sessions.database_session_service import DatabaseSessionService
-from google.adk.sessions.in_memory_session_service import InMemorySessionService
 import pytest
 
 
@@ -44,12 +44,20 @@ def test_create_session_service_uses_registry(tmp_path: Path, monkeypatch):
   )
 
 
-def test_create_session_service_defaults_to_memory(tmp_path: Path):
+@pytest.mark.asyncio
+async def test_create_session_service_defaults_to_per_agent_sqlite(
+    tmp_path: Path,
+) -> None:
+  agent_dir = tmp_path / "agent_a"
+  agent_dir.mkdir()
   service = service_factory.create_session_service_from_options(
       base_dir=tmp_path,
   )
 
-  assert isinstance(service, InMemorySessionService)
+  assert isinstance(service, PerAgentDatabaseSessionService)
+  session = await service.create_session(app_name="agent_a", user_id="user")
+  assert session.app_name == "agent_a"
+  assert (agent_dir / ".adk" / "session.db").exists()
 
 
 def test_create_session_service_fallbacks_to_database(