feat(memory): add SQLite memory service

Author: summerx96

contributing/samples/memory/README.md

@@ -0,0 +1,33 @@
+# Memory Sample
+
+This sample demonstrates memory usage with ADK. The included `main.py` uses
+in-memory services for simplicity. For persistent local memory, use SQLite.
+
+## Persistent Local Memory (SQLite)
+
+Programmatic usage:
+
+```python
+from google.adk.memory.sqlite_memory_service import SqliteMemoryService
+from google.adk.runners import Runner
+from google.adk.sessions.in_memory_session_service import InMemorySessionService
+
+memory_service = SqliteMemoryService(db_path="memory.db")
+runner = Runner(
+    app_name="my_app",
+    agent=agent.root_agent,
+    session_service=InMemorySessionService(),
+    memory_service=memory_service,
+)
+```
+
+CLI usage (supported for `adk web` and `adk api_server`):
+
+```bash
+adk web path/to/agents_dir --memory_service_uri=sqlite:///memory.db
+```
+
+Notes:
+- `sqlite:///memory.db` uses a relative path.
+- `sqlite:////abs/path/memory.db` uses an absolute path.
+- `adk run` currently ignores `--memory_service_uri`.

src/google/adk/cli/service_registry.py

@@ -317,8 +317,22 @@ def agentengine_memory_factory(uri: str, **kwargs):
     )
     return VertexAiMemoryBankService(**params)
 
+  def sqlite_memory_factory(uri: str, **kwargs):
+    from ..memory.sqlite_memory_service import SqliteMemoryService
+
+    parsed = urlparse(uri)
+    db_path = parsed.path
+    if not db_path:
+      db_path = ":memory:"
+    elif db_path.startswith("/"):
+      db_path = db_path[1:]
+    kwargs_copy = kwargs.copy()
+    kwargs_copy.pop("agents_dir", None)
+    return SqliteMemoryService(db_path=db_path, **kwargs_copy)
+
   registry.register_memory_service("rag", rag_memory_factory)
   registry.register_memory_service("agentengine", agentengine_memory_factory)
+  registry.register_memory_service("sqlite", sqlite_memory_factory)
 
 
 def _load_gcp_config(

src/google/adk/memory/__init__.py

@@ -15,13 +15,15 @@
 
 from .base_memory_service import BaseMemoryService
 from .in_memory_memory_service import InMemoryMemoryService
+from .sqlite_memory_service import SqliteMemoryService
 from .vertex_ai_memory_bank_service import VertexAiMemoryBankService
 
 logger = logging.getLogger('google_adk.' + __name__)
 
 __all__ = [
     'BaseMemoryService',
     'InMemoryMemoryService',
+    'SqliteMemoryService',
     'VertexAiMemoryBankService',
 ]