Pass workspace directory to MCP servers

Summary

The Codex VS Code extension spawns MCP servers from the VS Code installation directory instead of the workspace directory. This fundamentally breaks semantic code analysis tools like Serena that rely on correct working directory to index and analyze codebases.

Impact

Serena provides symbolic code operations that are essential for large codebase work:

• find_symbol / find_referencing_symbols - call graph traversal
• replace_symbol_body - precise symbol-level edits
• get_symbols_overview - fast structural understanding

Without correct cwd, these tools cannot auto-detect the project, forcing users to manually activate projects every session. This defeats the purpose of semantic tooling.

Current State

| Client | MCP Server cwd | Works? |
|--------|---------------|--------|
| Codex CLI | Project directory | ✅ |
| Codex VS Code (Remote: WSL) | /mnt/c/.../Microsoft VS Code | ❌ |

Proposed Fix

When spawning MCP servers, pass cwd: ${workspaceFolder} (or the active workspace root). This is a one-line fix that would unblock all path-dependent MCP tools.

Workarounds Attempted

1. --project-from-cwd flag in Serena - fails because cwd is wrong
2. Manual activate_project each session - works but error-prone
3. Wrapper scripts - cannot access workspace info at spawn time
4. CODEX_WORKSPACE_ROOT env var - only available at tool-call time, not spawn time

I've also filed a feature request on Serena to use CODEX_WORKSPACE_ROOT at tool-call time (oraios/serena#970), but the proper fix should be in the VS Code extension.

Related Issues

• #7281 - WSL2 Remote spawns MCP with wrong cwd (my previous report)
• #4222 - MCP servers not launched in workspace folder
• #5387 - Related duplicate

Environment

• Codex VS Code extension: v0.4.67
• Platform: WSL2 Ubuntu on Windows 11
• VS Code: Remote - WSL