Solution to PowerShell on Windows in Letta Code

[waynemerry]

Letta Code git bash patch — what we did and why
───────────────────────────────
The Problem
On Windows, Letta Code's RunShellCommand tool defaults to PowerShell or cmd.exe when spawning shells. This caused several friction points on our dev setup:

• HEREDOC syntax (<< 'EOF') doesn't work in PowerShell/cmd
• Bare & operators aren't valid in PowerShell
• Unix path conventions (/c/Users/...) don't work in cmd
• Our Docker commands, pytest invocations, and git operations all assume a Unix-style shell
• We run Git Bash (MINGW64) as our primary terminal and wanted Letta Code to use it too
  ───────────────────────────────
  The Patch
  We patched letta.js directly at:
  C:\Users<USER>\AppData\Roaming\npm\node_modules@letta-ai\letta-code\letta.js
  Inside the windowsLaunchers() function, which controls what shell is tried first when executing a command on Windows, we added a GIT_BASH_PATH override block before the PowerShell fallback:
  // GIT_BASH_PATH patch
  const gitBash = process.env.GIT_BASH_PATH || "";
  if (gitBash) {
  pushUnique(launchers, seen, [gitBash, "-c", trimmed]);
  }
  The original code tried powershell.exe first, then pwsh, then cmd.exe. Our patch inserts Git Bash at position 0 of the launcher list when the GIT_BASH_PATH environment variable is set. If it's not set,
  behaviour is identical to stock — making the patch safely opt-in.
  then sets in his shell environment:
  GIT_BASH_PATH=C:\Program Files\Git\bin\bash.exe
  ───────────────────────────────
  Benefits in Letta Code Sessions
  Once the patch was applied, the improvement was immediate and substantial:

1. All Unix commands work natively — grep, ls, cp, rm, find, cat, wc, sed, awk all execute without Windows-specific workarounds
2. Docker commands work — docker exec, docker-compose run exactly as they would on Linux
3. Git commands work fully — git diff, git log, git status with full output, including pipes
4. Path conventions unified — /c/doc/Programming/... paths work, removing the friction of translating between Windows and Unix path formats
5. Parallel tool calls work reliably — the & operator for backgrounding is valid in bash; PowerShell's & has different semantics that caused issues
6. Script portability — management commands, pytest runs, and the rlm skill all use standard bash syntax that now executes without modification
7. PYTHONIOENCODING and other env var patterns — work as expected in bash; in cmd/PowerShell they require different syntax
   The patch is minimal, non-breaking (opt-in via env var), and survives the Letta Code session — though it needs to be reapplied after npm updates the @letta-ai/letta-code package. We've documented this
   in session memory so we remember to re-patch after upgrades.