customizing-commands

# Customizing Commands Use this as the command-specific entrypoint for local mod slash commands. For broader mod work, recipes live in `../creating-mods/references/commands.md`, `../creating-mods/references/architecture.md`, `../creating-mods/references/ui.md`, and `../creating-mods/references/plan-mode.md`. Mod files live in: ```text ${LETTA_CONFIG_DIR:-$HOME/.letta}/mods/ ``` Use a focused file name, e.g. `${LETTA_CONFIG_DIR:-$HOME/.letta}/mods/review.ts` or `${LETTA_CONFIG_DIR:-$HOME/.letta}/mods/commands.ts`. ## First decide whether a command is right | User wants | Build | | --- | --- | | `/foo` sends a prompt or shows local output | Mod command | | `/foo` starts a reusable agent workflow | Skill + thin mod command | | Agent/model should autonomously call the capability | Mod tool, not a command | | Command shows transient progress/results | Mod command + panel | | Command needs model output while the main agent is busy | `runWhenBusy: true` command + forked `ctx.conversation` | If the command is a reusable workflow like `/goal`, put the workflow instructions in a skill and keep the mod command as a small launcher/prompt. ## Workflow 1. Inspect `${LETTA_CONFIG_DIR:-$HOME/.letta}/mods/` for related command files. 2. Preserve unrelated mod code; create a focused new file if merging is messy. 3. Register with `letta.commands.register()` and guard with `letta.capabilities.commands`. 4. Return the unregister function, or a disposer that calls it plus any timer/panel cleanup. 5. Tell the user the exact file path changed and to run `/reload`. ## Default prompt command ```ts export default function activate(letta) { if (!letta.capabilities.commands) return; return letta.commands.register({ id: "review", description: "Review current git changes", args: "[focus]", run(ctx) { const focus = ctx.args.trim(); return { type: "prompt", content: focus ? `Review current git changes. Focus on ${focus}.` : "Review current git changes. Focus on correctness issues.", systemReminder: true, }; }, }); } ``` ## Command result types ```ts type ModCommandResult = | { type: "prompt"; content: string; systemReminder?: boolean } | { type: "output"; output: string; success?: boolean } | { type: "handled" }; ``` - `prompt`: sends content to the agent. Use for normal slash shortcuts. - `output`: prints local text and does not contact the agent. - `handled`: command handled its own side effects/UI; common for panel commands. ## Rules - Command IDs omit the slash: `id: "review"`, not `"/review"`. - Use lowercase slugs with letters, numbers, and hyphens. - Do not register built-in command IDs. - `runWhenBusy: true` commands must not return `prompt` while the main agent is busy; use scoped conversation helpers/panels and return `handled`. - `showInTranscript: false` commands should usually return `handled`, not `prompt`. - Do not import Letta Code app internals. - Do not do surprising side effects on startup; mods activate on app start and `/reload`. ## More recipes - Simple output command, panel command, busy-safe conversation command: `../creating-mods/references/commands.md` - Complex command architecture, state, cleanup: `../creating-mods/references/architecture.md` - Panel/status UI patterns: `../creating-mods/references/ui.md` - Worked plan-mode command/tool composition: `../creating-mods/references/plan-mode.md`