feat: Add S3 support for artifacts

pyproject.toml

@@ -115,6 +115,7 @@ eval = [
 test = [
   # go/keep-sorted start
   "a2a-sdk>=0.3.0,<0.4.0",
+  "aioboto3>=15.5.0",                             # For S3 Artifact Service tests
   "anthropic>=0.43.0",                            # For anthropic model tests
   "crewai[tools];python_version>='3.10' and python_version<'3.12'",         # For CrewaiTool tests; chromadb/pypika fail on 3.12+
   "kubernetes>=29.0.0",                           # For GkeCodeExecutor
@@ -144,6 +145,7 @@ docs = [
 
 # Optional extensions
 extensions = [
+  "aioboto3>=15.5.0",                           # For S3 Artifact Service
   "anthropic>=0.43.0",                          # For anthropic model support
   "beautifulsoup4>=3.2.2",                      # For load_web_page tool.
   "crewai[tools];python_version>='3.10' and python_version<'3.12'",       # For CrewaiTool; chromadb/pypika fail on 3.12+

src/google/adk/artifacts/__init__.py

@@ -16,10 +16,12 @@
 from .file_artifact_service import FileArtifactService
 from .gcs_artifact_service import GcsArtifactService
 from .in_memory_artifact_service import InMemoryArtifactService
+from .s3_artifact_service import S3ArtifactService
 
 __all__ = [
     'BaseArtifactService',
     'FileArtifactService',
     'GcsArtifactService',
     'InMemoryArtifactService',
+    'S3ArtifactService',
 ]

src/google/adk/artifacts/file_artifact_service.py

@@ -106,7 +106,7 @@ def _resolve_scoped_artifact_path(
   pure_path = _to_posix_path(stripped)
 
   scope_root_resolved = scope_root.resolve(strict=False)
-  if pure_path.is_absolute():
+  if Path(stripped).is_absolute():
     raise ValueError(
         f"Absolute artifact filename {filename!r} is not permitted; "
         "provide a path relative to the storage scope."