fix(dotnet-reversing): install deps under home now the workspace mount is gone

[monoxgas]

Found while reviewing dreadnode-tiger#2400 (ENG-8273, remove E2B workspace mount).

What was wrong

dotnet_agent/bootstrap.py picked its dependency directory by probing /home/user/workspace:

if SANDBOX_WORKSPACE.is_mount():
    return SANDBOX_WORKSPACE / ".dreadnode" / "deps"
if (SANDBOX_WORKSPACE / ".dreadnode").exists() or os.environ.get("DREADNODE_SANDBOX"):
    return SANDBOX_WORKSPACE / ".dreadnode" / "deps"
return LOCAL_FALLBACK

With the platform's object-storage FUSE mount removed, every one of those branches is dead:

• is_mount() is now always false — the workspace is an ordinary local directory.
• DREADNODE_SANDBOX is set nowhere in the platform (no hits across the API, the SDK, or the deployment config).
• A fresh sandbox has no /home/user/workspace/.dreadnode, and nothing creates one now that deps resolve to the fallback.

So the probe already resolved to ~/.dreadnode/deps in every environment. This installs there directly and deletes the dead branch.

The false claims

Two comments told the agent something that is no longer true, in a file the agent reads:

• "Dependencies are installed to the workspace directory so they persist across sandbox restarts."
• "/home/user/workspace is S3-mounted and survives sandbox recreation."

Both are corrected. The behavioural consequence — .NET and ILSpy are re-downloaded on a new sandbox rather than reused from object storage — is inherent to the mount removal, not to this change; this only stops the code and its documentation from claiming otherwise.

Verification

No behaviour change in any reachable environment: the fallback branch is what already ran. ruff check --select F401,F821 clean (os is still used for the DOTNET_ROOT/PATH exports).

🤖 Generated with Claude Code

https://claude.ai/code/session_01GDDm7JrA7K5N1CLeWnFdyr