fix(artifacts): Support nested API names

[spectaclehong]

Please ensure you have read the contribution guide before creating a pull request.

Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Fixes: Artifact API cannot load artifacts with path separators in names #6050

Problem:

Artifact services can save and list logical artifact names containing /, such as reports/summary.txt. The REST API also accepts these names through POST /artifacts because the filename is provided in the request body.

However, read/version/metadata/delete routes treated artifact_name as a single path segment. That made nested artifact names visible in the list endpoint but unreachable through the path-based endpoints.

Solution:

Update artifact read/version/metadata/delete routes to use FastAPI's {artifact_name:path} converter so nested logical artifact names can round-trip through the REST API.

Because {artifact_name:path} is catch-all, the version-specific routes are registered before the general artifact load route. No response schema changes are intended: endpoints that returned types.Part still return types.Part, and metadata endpoints still return ArtifactVersion / list[ArtifactVersion].

Also update artifact URI parsing so artifact references can resolve nested filenames such as folder/file.txt.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Targeted artifact API tests pass locally:

uv run pytest tests/unittests/cli/test_fast_api.py -k artifact -q

Result:

9 passed, 72 deselected

Artifact service and URI tests pass locally:

uv run pytest tests/unittests/artifacts/test_artifact_util.py tests/unittests/artifacts/test_artifact_service.py -q

Result:

77 passed

Python 3.10 tox unit suite passes locally:

uv tool run --from tox --with tox-uv tox -e py310

Result:

7045 passed, 21 skipped, 31 xfailed, 9 xpassed

Pre-commit hooks pass for changed files:

uv run pre-commit run --files src/google/adk/cli/api_server.py src/google/adk/artifacts/artifact_util.py tests/unittests/cli/test_fast_api.py tests/unittests/artifacts/test_artifact_util.py tests/unittests/artifacts/test_artifact_service.py

Manual End-to-End (E2E) Tests:

Validated a local REST API round-trip using the ADK API server route stack with InMemoryArtifactService:

• save reports/summary.txt
• list artifacts
• load with raw slash path
• load with encoded slash path
• list versions
• load version 0
• load version metadata
• delete with encoded slash path

All requests returned 200.

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

No dependent changes are required.

[rohityan]

Hi @spectaclehong , Thank you for your contribution! We appreciate you taking the time to submit this pull request. Your PR has been received by the team and is currently under review. We will provide feedback as soon as we have an update to share.

[rohityan]

Hi @GWeale , can you please review this.

[adk-bot]

Thank you @spectaclehong for your contribution! 🎉

Your changes have been successfully imported and merged via Copybara in commit b99546b.

Closing this PR as the changes are now in the main branch.