Add Letta Code as a supported host

[Keziake]

Summary

Request to add Letta Code as a supported host in gstack's declarative host config system.

Letta Code is an AI coding agent by Letta Corporation — the team behind the open-source Letta framework for stateful LLM agents. It runs as a CLI (letta)
installed via npm install -g @letta-ai/letta-code and shares a similar skill format to Claude Code (markdown SKILL.md files with YAML frontmatter).

Why

Letta Code is gaining traction as a coding agent with unique capabilities:

• Persistent memory — agents retain context across sessions via MemFS (git-backed memory filesystem)
• Skills system — SKILL.md files with name and description frontmatter, discovered and loaded on demand
• Mods — TypeScript mods at ~/.letta/mods/ that extend the harness with tools, commands, events, panels, and providers
• Subagents — agents can spawn specialized subagents for parallel work
• Hooks — PreToolUse, Stop, and other lifecycle hooks for safety and automation
• Crons — self-invocation for time-based task scheduling

Adding Letta Code as a host would let gstack's 23+ specialist skills (office-hours, plan-ceo-review, review, qa, ship, etc.) work with Letta Code, expanding gstack's reach to another AI
coding agent.

Proposed Host Config

Based on docs/ADDING_A_HOST.md, here's a starting point for hosts/letta.ts:

import type { HostConfig } from '../scripts/host-config';

const letta: HostConfig = {
  name: 'letta',
  displayName: 'Letta Code',
  cliCommand: 'letta',
  cliAliases: ['letta-code'],

  globalRoot: '.letta/skills/gstack',
  localSkillRoot: '.letta/skills/gstack',
  hostSubdir: '.letta',
  usesEnvVars: true,

  frontmatter: {
    mode: 'allowlist',
    keepFields: ['name', 'description'],
    descriptionLimit: null,
  },

  generation: {
    generateMetadata: false,
    skipSkills: ['codex'],
  },

  pathRewrites: [
    { from: '~/.claude/skills/gstack', to: '~/.letta/skills/gstack' },
    { from: '.claude/skills/gstack', to: '.letta/skills/gstack' },
    { from: '.claude/skills', to: '.letta/skills' },
  ],

  runtimeRoot: {
    globalSymlinks: ['bin', 'browse/dist', 'browse/bin', 'gstack-upgrade', 'ETHOS.md'],
    globalFiles: { 'review': ['checklist.md', 'TODOS-format.md'] },
  },

  install: {
    prefixable: false,
    linkingStrategy: 'symlink-generated',
  },

  learningsMode: 'basic',
};

export default letta;

Letta Code specifics

│ Item             │ Value                                                                    │
├──────────────────┼──────────────────────────────────────────────────────────────────────────┤
│ CLI binary       │ `letta` (installed via `npm install -g @letta-ai/letta-code`)            │
│ Skills directory │ `~/.letta/skills/` (env-level, shared across agents)                     │
│ Skill format     │ `SKILL.md` with YAML frontmatter (`name`, `description`)                 │
│ Project config   │ `AGENTS.md` (equivalent of `CLAUDE.md`)                                  │
│ Docs             │ [docs.letta.com/letta-code](https://docs.letta.com/letta-code/index.md)  │
│ GitHub           │ [github.com/letta-ai/letta-code](https://github.com/letta-ai/letta-code) │

Skill format compatibility

Letta Code's SKILL.md format is nearly identical to Claude Code's:

---
name: skill-name
description: When to use this skill
---

# Skill content...

The frontmatter uses name and description — the same fields gstack's allowlist mode already keeps. No frontmatter transformation should be needed beyond the standard allowlist.

Tool name mapping

Letta Code's built-in tools use similar names to Claude Code:

│ Claude Code │ Letta Code    │
├─────────────┼───────────────┤
│ Bash        │ Bash          │
│ Read        │ Read          │
│ Write       │ Write         │
│ Edit        │ Edit          │
│ Glob        │ Glob          │
│ Grep        │ Grep          │
│ WebSearch   │ web_search    │
│ WebFetch    │ fetch_webpage │

Most tool references in gstack skills should work as-is or with minimal rewrites.

Checklist

- [ ] Create hosts/letta.ts with the config above
- [ ] Register in hosts/index.ts
- [ ] Add .letta/ to .gitignore
- [ ] Run bun run gen:skill-docs --host letta and verify output
- [ ] Verify no .claude/skills path leakage in generated docs
- [ ] Run bun test test/gen-skill-docs.test.ts and bun test test/host-config.test.ts
- [ ] Update README.md with Letta Code install instructions
- [ ] Add --host letta to the setup table

Install command (for README)

git clone --single-branch --depth 1 https://github.com/garrytan/gstack.git ~/gstack
cd ~/gstack && ./setup --host letta

Or from within Claude Code with gstack already installed:

Install gstack for Letta Code: run `cd ~/.claude/skills/gstack && ./setup --host letta`

Context

I'm a Letta Code user and would love to use gstack's workflow skills (especially /office-hours, /review, /qa, and /ship) with Letta Code. Happy to help test or contribute a PR if
there's interest.