fix(tools): enforce REPL execution permissions

[BunsDev]

Motivation

• The REPL tool previously executed model-supplied code (bash/python/node) without consulting the repository's permission handler, allowing a model or prompt-injection to run arbitrary local commands despite PermissionLevel::Execute metadata.
• Enforce the existing permission model so headless/default AutoPermissionHandler and interactive flows can deny or prompt before code execution.

Description

• Add an explicit permission check using ctx.check_permission(self.name(), &reason, false) before spawning or reusing a REPL session in crates/tools/src/repl_tool.rs.
• Validate requested interpreter language with interpreter_for(&language) and return an error for unsupported languages before prompting.
• Add a regression test in repl_tool.rs that uses a DenyPermissionHandler and asserts the tool returns a permission error and does not create a REPL session.
• Keep the change minimal and localized to crates/tools/src/repl_tool.rs and its unit tests to preserve existing architecture and behavior.

Testing

• Ran the new unit test: cargo test --package claurst-tools repl_tool::tests::execute_denies_without_repl_session_when_permission_denied -- --nocapture — passed.
• Ran package-level checks: cargo check --package claurst-tools — passed.
• Ran formatting check: rustfmt --edition 2021 --check src-rust/crates/tools/src/repl_tool.rs — passed.
• cargo check --workspace could not be completed in this environment due to missing system alsa pkg-config files required by alsa-sys (external system dependency), and cargo clippy --all-targets -D warnings is blocked by pre-existing clippy warnings in claurst-core unrelated to this patch.

---

Codex Task

[Copilot]

Pull request overview

This PR tightens the Rust REPL tool’s security model by ensuring code execution is gated by the repository’s permission handler, preventing model-supplied code from running without an explicit Execute permission decision.

Changes:

• Adds an explicit ctx.check_permission(...) gate before creating/reusing a REPL session.
• Validates the requested interpreter language early and errors out for unsupported languages before any permission prompt.
• Adds a regression test asserting permission denial prevents REPL session creation.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.