[salma2vec]

What and why

Closes #285

PiAgent.load_snapshot restores the workspace with _unpack, which extracts the archive into a staging directory and then iterates it. The archive of an empty workspace has no members, so tarfile.extractall never creates the staging directory, and staging.iterdir() raised FileNotFoundError. PUT /ext/snapshot therefore failed with HTTP 500 and the conversation was not installed for the target context. The A2A validator's snapshot step hits this, since it snapshots an agent that hasn't written to its workspace.

It's slightly worse than "nothing happens": _unpack removes the workspace's current contents before it iterates the staging directory. So a non-empty workspace restored from an empty snapshot ends up emptied anyway, while the request reports a failure.

The fix creates the staging directory before extracting (staging.mkdir() at the top of the try), so an empty archive restores as an empty workspace. That's the approach the issue suggests and the one the OpenHands agent (#281) uses. A failed extraction still leaves the workspace untouched (test_a_workspace_archive_that_fails_to_extract_changes_nothing), and the finally still removes the staging directory.

How it was tested

• New test_an_empty_workspace_archive_restores_an_empty_workspace: _pack an empty directory, _unpack it over a workspace holding one file, and expect an empty workspace. It fails on main with the FileNotFoundError from the issue and passes here.
• A by-hand check of the same case on main: FileNotFoundError is raised and the workspace's file is already gone. With this change the restore completes and leaves an empty workspace.
• pytest tst/unit/agents/pi: 41 passed (40 on main plus the new test).
• ruff check clean on both files.

Found and fixed with Claude Code. The runs above were executed locally.

🤖 Generated with Claude Code

Confidence Score: 5/5

This PR appears safe to merge.

Summary

Creates the staging directory before extracting a Pi workspace snapshot, so an empty archive restores successfully.

• Empty workspace snapshots restore as empty workspaces.

_{Reviews (1) · Last reviewed commit: "fix(pi): restore a snapshot of an empty ..." · Reviewed by Greptile}

[earakely-scale]

Thanks for making these fixes!