posit-dev / posit-dev/mcp-repl

Guard workspace-write against unsafe workspace roots

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Dominant language
Rust
Stars
70
Forks
5
PR merge metrics
No merged PRs in 30d

Description

Claude Desktop launches mcp servers from /. This is problematic with the default mcp-repl sandbox configuration of workspace-write, since it causes the sandbox to treat / as the workspace root and gives the repl process broad write permissions.

One possible solution: add guardrails to mcp-repl to reject / or ~ as workspace roots with workspace-write, and fall back to read-only when they are encountered. It might also make sense to fall back to read-only if there is not a .git directory in a project.

Source: https://github.com/posit-dev/mcp-repl/issues/28

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing how mcp-repl resolves workspace roots and applies the workspace-write sandbox configuration. Reproduce the Claude Desktop launch from /, then verify that unsafe roots are rejected or use read-only mode, and consider the stated .git condition as part of the acceptance criteria.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
security
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

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