Why

Agent logs show repeated attach_file failures when the model tries to attach screenshots generated in a previous session directory. The tool currently rejects all paths outside the current session, forcing awkward manual copy steps.

What changed

• Keep strict default-deny behavior for arbitrary filesystem paths.
• Allow attach_file to import files from sibling Netclaw session roots (.../sessions/* and .../netclaw-sessions/*) by copying them into the current session's attachments/ folder first.
• Continue rejecting paths outside recognized Netclaw session roots and reject symlink escapes.
• Update tool description text so agents understand cross-session handoff behavior.
• Add tests for:
  • sibling-session copy-and-attach success
  • symlink escape from sibling session rejection

Validation

• dotnet test --filter FullyQualifiedName~AttachFileToolTests
• dotnet test --filter FullyQualifiedName~SlackFileFlowIntegrationTests
• dotnet test --nologo
• dotnet slopwatch analyze

Observed regression evidence

From sys76-3 daemon logs:

• Error: File path must be within the session directory ... for attach_file calls that referenced prior session screenshot paths.
• Follow-up calls succeeded only after explicitly copying the same files into the current session directory.