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UpdatedJuly 19, 2026 at 00:10

Customize smelt. Change theme/colors, rebind keys, add slash commands, register tools/plugins, toggle settings, write skills. Includes the full Lua API surface (signatures, descriptions) and pointers to the on-disk built-in source.

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SKILL.md

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This SKILL.md is very large, so SkillsMP previews the first section here. View on GitHub

Customizing smelt

Smelt is configured in Lua. Anything the user asks you to tweak (colors, keybinds, slash commands, settings, tools, plugins, skills) happens by editing Lua files under the user's config directory and reloading the runtime.

This skill gives you:

The core principle for how to respond
Where customization files live
Concrete recipes for the common asks
The full Lua API surface (every namespace, signature, and one-line description) so you can look up the exact function before you write the edit

Core principle: persist the change, don't punt to slash commands

When the user asks to change something, edit the config file so the change survives a restart. Do not answer with "use a slash command" for durable customization. Slash commands are runtime actions a user runs themselves; they don't update init.lua, so preference changes are lost on the next launch.

Your default workflow is:

Read the user's ~/.config/smelt/init.lua (create it if missing).
Edit in the specific Lua call that effects the change (e.g. smelt.theme.set("SmeltAccent", { fg = { ansi = 208 } })). Preserve every existing line.
Call smelt_reload so the edit takes effect now without waiting for the user to restart smelt.
Briefly tell the user what changed and where.

Mention runtime slash commands only for explicitly session-scoped choices such as /color.

When to use this skill

Load it whenever the user asks to persistently modify how smelt itself behaves:

"change the prompt color to X" / "switch theme to " / "make accents "
"rebind to " / "add a shortcut for X"
"add a /command that does X"
"set to X" / "turn on vim mode" / "disable thinking blocks"
"add an MCP server" / "register a provider" / "use OpenRouter"
"register a tool that "
"write a plugin that "
"write a skill that "

Do not load this skill for ordinary coding work in the user's project. Only load it when the target of the change is smelt's own config.

Where things live

User-editable

Smelt reads Lua from these locations, later sources overriding earlier:

Path	Purpose
Embedded in the binary	Built-in plugins, commands, colorschemes
`$XDG_CONFIG_HOME/smelt/` (default `~/.config/smelt/`)	Global user config
`<cwd>/.smelt/`	Project-local config (gated by `/trust`)

Inside each user dir, the layout is:

~/.config/smelt/
  init.lua                       -- main entry point, runs at startup
  plugins/*.lua                  -- extra Lua chunks loaded after init.lua
  commands/*.lua                 -- /command definitions
  completers/*.lua               -- prompt completers
  tools/*.lua                    -- agent tool registrations
  dialogs/*.lua                  -- custom dialogs
  colorschemes/<name>.lua        -- colorschemes (load via smelt.theme.use)
  skills/<name>/SKILL.md         -- skills (user-authored)
  AGENTS.md                      -- extra system-prompt content

Use ~/.config/smelt/ for changes that should apply everywhere. Use ./.smelt/ for changes that should only apply in the current project (run /trust once after creating it).

Read-only built-in source (for reference)

On every launch, smelt mirrors its embedded runtime/lua/smelt/ tree to:

$XDG_DATA_HOME/smelt/builtins/lua/smelt/

Default: ~/.local/share/smelt/builtins/lua/smelt/. The mirror is version-stamped, so an upgrade refreshes it. Treat this directory as read-only: edits there are wiped on the next launch after a smelt upgrade. Use it for reading examples. Write changes to ~/.config/smelt/ (or ./.smelt/).

What's inside that's useful when authoring custom Lua:

Path under `builtins/lua/smelt/`	What it gives you
`_meta/<module>.lua`	LuaCATS type stubs. Best place to look up exact signatures + field shapes.
`_meta/_types.lua`	Every class / alias used in `_meta/*.lua` (e.g. `smelt.theme.ThemeSpec`).
`commands/<name>.lua`	Worked `smelt.cmd.register` examples (e.g. `docs.lua`).
`colorschemes/<name>.lua`	Worked `ThemeSpec` tables. `default.lua` is the canonical reference.
`plugins/<name>.lua`	Bundled plugin patterns (e.g. background commands, plan mode).
`completers/<name>.lua`	Built-in completer patterns.
`dialogs/<name>.lua`	Built-in dialog patterns.

Reach for these before writing new Lua: copy the closest worked example, then adapt.

Reference docs

For deep details on a specific function (parameter shapes, return tables, opts records), read the LuaCATS type stubs under the builtins mirror:

$XDG_DATA_HOME/smelt/builtins/lua/smelt/_meta/

One file per namespace (cmd.lua, keymap.lua, theme.lua, etc.) plus _types.lua for shared classes/aliases referenced by signatures. The stubs use LuaCATS syntax (---@class, ---@field, ---@type fun(...)), which is dense but precise. The API index further down in this skill is a flattened summary of the same data.

Finding the config + builtins dirs from a shell

# config dir (where init.lua lives):
echo "${XDG_CONFIG_HOME:-$HOME/.config}/smelt"

# builtins dir (read-only worked examples):
echo "${XDG_DATA_HOME:-$HOME/.local/share}/smelt/builtins/lua/smelt"

If init.lua doesn't exist, create the directory and the file. The first-launch wizard does this normally, but you may be invoked when neither has happened yet.

Hot reload

Lua config edits are hot-reloaded automatically by default. The reload re-runs init.lua, all autoloaded plugins/commands/tools, and the user's plugins/. Persistent state (smelt.state, smelt.signal) survives across the cycle; module-local state in plugins is reset.

You (the agent) trigger the reload by calling the smelt_reload tool. Do this once, at the end of your turn after every set of edits to files under ~/.config/smelt/ or ./.smelt/. The tool schedules the reload to fire when the current turn completes, so it never cancels its own in-flight call. Multiple calls in the same turn collapse into one reload.

Do not silently flip smelt.settings.auto_reload in the user's config. It is enabled by default, but if the user disabled it, respect that choice.

For reference (don't recommend these unless the user asks):

How	Triggered by	When it fires
`smelt_reload` tool	You, the agent	At end of the current turn (the path you should use)
`/reload`	User typing	Immediately (blocks if agent is busy)
`F5`	User keypress	Immediately (blocks if agent is busy)
`auto_reload` setting	User setting	Lua-file changes, debounced and deferred until the agent is idle

Prompt inputs (AGENTS.md, SKILL.md, --system-prompt) and markdown custom-command registration stay manual via /reload. Existing markdown custom commands read their file body on each invocation, so body edits do not need reload.

Recipes

Rebind a key

smelt.keymap.set(mode, chord, handler) -> Reg. Modes are "n" (normal), "i" (insert), "v" (visual), or "" (all). Chord syntax follows nvim conventions: <C-y>, <S-Tab>, <leader>x, etc.

-- In ~/.config/smelt/init.lua
smelt.keymap.set_leader("<space>")
smelt.keymap.set("n", "<leader>r", function()
  smelt.cmd.run("resume")
end)

<leader> expands when the binding is registered; existing bindings keep the leader value they were created with. The default leader is a single backslash (\\).

-- In ~/.config/smelt/init.lua
smelt.keymap.set("n", "<C-y>", function()
  local text = smelt.transcript.loaded_text_expensive()
  smelt.clipboard.write(text)
  smelt.notify.info("copied transcript")
end)

To remove a binding programmatically use smelt.keymap.unset(mode, chord). For permanent removal, just delete the registration line.

smelt.keymap.list() returns every currently-bound chord. Useful when the user asks "what's bound to X?".

Change the accent color

Edit ~/.config/smelt/init.lua and add (or update) a smelt.theme.set call for the relevant highlight group:

-- In ~/.config/smelt/init.lua
smelt.theme.set("SmeltAccent", { fg = { ansi = 208 }, bold = true })

smelt.theme.set(group, style) overrides one highlight group; the override persists across reloads because it lives in init.lua. Common group names: SmeltAccent (primary accent), Comment, SmeltDiffAddBg, SmeltDiffRemoveBg, SmeltSlug (task-slug pill), SmeltBar (prompt bars + statusline separator). Use smelt.theme.snapshot() to dump every currently-set group when the user needs to discover names.

If the user names a session-color preset ("ember", "coral", "rose", "gold", "ice", "sky", "blue", "lavender", "lilac", "mint", "sage", "silver"), set the relevant highlight group in init.lua with smelt.theme.set(...) so the preference survives a restart:

smelt.theme.set("SmeltAccent", { fg = { ansi = 208 } })

The runtime command /color <preset> is session-only and exists to distinguish parallel sessions. Use it only when the user explicitly asks for a current-session color.

Write a full colorscheme

Drop a Lua file at ~/.config/smelt/lua/smelt/colorschemes/<name>.lua that returns a ThemeSpec table:

return {
  groups = {
    SmeltAccent      = { fg = { ansi = 208 }, bold = true },
    Comment          = { fg = { ansi = 244 } },
    SmeltDiffAddBg   = { bg = { ansi = 22 } },
    -- string-valued entries reference another group in this spec:
    SmeltDiffAdd     = "SmeltAccent",
  },
}

Then load it: smelt.theme.use("<name>"). Read $XDG_DATA_HOME/smelt/builtins/lua/smelt/colorschemes/default.lua for the canonical worked example. Light/dark variants share the same file: gate by smelt.theme.is_light() if needed.

Add a /command

Drop a file at ~/.config/smelt/commands/<name>.lua (or inline in init.lua):

smelt.cmd.register("greet", function(arg)
  smelt.notify.info("hello " .. (arg or "world"))
end, {
  desc = "say hello",
  args = "[name]",      -- shown in /command help
  busy = "run",         -- run (default), reject, queue_request, or queue_command
  startup_ok = false,   -- runnable before init is complete (default false)
  hidden = false,       -- hide from completer + help (default false)
})

The handler receives the trailing argument string (or nil). Errors are surfaced as in-app notifications.

Worked example: read $XDG_DATA_HOME/smelt/builtins/lua/smelt/commands/docs.lua to see how /docs uses smelt.os.open_url, smelt.clipboard.write, and smelt.notify.info for a graceful clipboard fallback.

Toggle/set a setting

Write the assignment into ~/.config/smelt/init.lua. Assigning an unknown key or wrong type raises at the call site.

-- In ~/.config/smelt/init.lua
smelt.settings.vim = true
smelt.settings.auto_compact = true
smelt.settings.compact_threshold = 0.65
smelt.settings.show_tps = true

The full table of settings (key, type, default, description) is in the Settings section further down; use it to confirm a key exists and is spelled correctly before writing.

/settings and --set KEY=VALUE exist as runtime/CLI overrides but do not persist; always make the change in init.lua so it survives a restart.

Customize the status line

The status line is a pure-Lua module that ships as smelt.statusline. Register a named source via M.add(name, handler) and the renderer calls it each frame:

local sl = require("smelt.statusline")
sl.add("greeting", function()
  return { { text = "hi ", hl_group = "SmeltAccent" } }
end)

The handler returns a segment table or a list of them. Each segment is { text, hl_group?, style?, priority?, align_right?, truncatable?, separated? }. Remove a source with sl.remove(name). The canonical worked example lives at $XDG_DATA_HOME/smelt/builtins/lua/smelt/statusline.lua; its core source is what draws the built-in segments (vim mode, agent mode, tps, task label, etc.).

Pin startup defaults (model / mode / reasoning)

smelt.defaults.set({
  model = "openai/gpt-5.5",
  mode = "plan",
  reasoning_effort = "high",
})

CLI flags still win over this. Each field is optional.

Register a provider

smelt.provider.register("openai", {
  type = "openai",
  api_base = "https://api.openai.com/v1",
  api_key_env = "OPENAI_API_KEY",
  models = { "gpt-5.5", { name = "gpt-5-mini", temperature = 0.7 } },
})

type is one of openai-compatible, openai, codex, anthropic-compatible, anthropic, copilot. Re-registering the same name replaces the previous entry.

Register an MCP server

smelt.mcp.register("filesystem", {
  command = { "npx", "-y", "@modelcontextprotocol/server-filesystem", "/tmp" },
  env = { DEBUG = "true" },
  timeout = 30000,
  enabled = true,
})

MCP tool names get prefixed with the server name (filesystem_read_file) and default to ask-permission.

Register an agent tool

smelt.tools.register({
  name = "weather",
  description = "Look up the current weather for a city.",
  parameters = {
    type = "object",
    properties = {
      city = { type = "string", description = "City name" },
    },
    required = { "city" },
  },
  execute = function(args, ctx)
    local resp = smelt.http.get("https://wttr.in/" .. args.city .. "?format=3")
    return resp.body
  end,
  summary = function(args) return "weather: " .. args.city end,
  -- optional: approval_patterns, preflight, render, decide, override
})

Pass override = true to replace a built-in tool with the same name.

Permission rules

smelt.permissions.extend({
  default = { patterns = { bash = { allow = { "git log *", "git status *" } } } },
  apply   = { patterns = { bash = { allow = { "git commit *", "git push *" } } } },
  yolo    = { patterns = { mcp  = { allow = { "*" } } } },
})

Modes: default, plan, apply, yolo. Tool kinds include bash and mcp. For the full match-rule grammar, read $XDG_DATA_HOME/smelt/builtins/lua/smelt/_meta/permissions.lua or look up smelt.permissions in the API index further down.

Write a project-local skill

When the user wants the agent to know something only inside this project:

<project>/.smelt/skills/<name>/SKILL.md

With frontmatter:

---
name: my-skill
description: One-line summary the agent reads to decide whether to load.
---

# Skill body in markdown

Any reference content the agent should consult on demand.

Then run /trust once after creating .smelt/. The agent will see the skill in its # Skills listing and can load it via load_skill.

Bundled plugins

Bundled with smelt. Drop a file under ~/.config/smelt/plugins/ to add your own.

Autoloaded

Loaded on every launch unless opted out via smelt.builtins.disable({ plugins = { "<name>" } }) in early.lua.

Plugin	Summary
`smelt.plugins.banner`	Empty-state logo decoration + shutdown logo/resume-hint banner.
`smelt.plugins.compact`	Compaction plugin.
`smelt.plugins.debug_panel`	F3 debug panel.
`smelt.plugins.esc_chord`	Esc-Esc: cancel in-flight foreground/background work (`smelt.work.busy` tokens, e.g. /compact), or rewind to the previous turn when idle.
`smelt.plugins.goal`	Goal lifecycle plugin.
`smelt.plugins.perf_panel`	F12 perf panel.
`smelt.plugins.plan_mode`	Plan-mode plugin: registers the `plan` mode and `present_plan` tool.
`smelt.plugins.predict`	Input prediction plugin.
`smelt.plugins.process_control`	Ctrl-G: move a foreground bash command to the background registry.
`smelt.plugins.scroll_pills`	Scroll-pill overlays for transcript navigation: * Bottom pill - " ↓ jump to bottom " while scrolled off-tail; click re-pins to tail. * Top pill - first line of the nearest user message above the viewport; click reveals it with one row of gap so repeated clicks walk back.
`smelt.plugins.terminal_title`	Static terminal window/tab title.
`smelt.plugins.title`	Session title plugin.
`smelt.plugins.turn_notifications`	Optional terminal desktop notification when an agent turn ends.
`smelt.plugins.upgrade`	Autoupgrade plugin.
`smelt.plugins.version`	/version - surface the running smelt build identity as a notification.

Opt-in

Shipped but not autoloaded. Add require("smelt.plugins.<name>") to ~/.config/smelt/init.lua to enable.

Plugin	Summary
`smelt.plugins.inspect`	Optional plugin: `/inspect` opens a local web UI for browsing sessions, their history, and provider request/response audit data.
`smelt.plugins.lsp`	Optional LSP tool facade for agent code navigation.
`smelt.plugins.which_key`	Which-key style popup for pending global Lua keymaps.

Settings

Read or write via smelt.settings.<key> from init.lua. Run /reload after editing config to apply changes without restarting. Override from the CLI with --set KEY=VALUE. Assigning an unknown key or wrong type raises at the call site.

Key	Type	Default	Description
`vim`	`bool`	`false`	Vi keybindings in the prompt.
`system_clipboard`	`bool`	`true`	Sync prompt kills and yanks with the OS clipboard. Disable to keep `C-w`/`C-k`/`C-u`/`C-y` and vim `y`/`p` internal when OSC 52 clipboard writes are unreliable. Bracketed terminal paste still works.
`auto_compact`	`bool`	`true`	Auto-summarize when request context usage crosses `compact_threshold` (forced on in headless).
`auto_continue`	`"off"` \| `"goal"` \| `"always"`	`"goal"`	Idle auto-continue policy: `off` disables it, `goal` continues active auto goals, and `always` continues any idle session.
`show_tps`	`bool`	`true`	Tokens/sec in status bar.
`show_tokens`	`bool`	`true`	Context token count in status bar.
`show_cost`	`bool`	`true`	Session cost in status bar.
`show_prediction`	`bool`	`true`	Ghost-text input predictions in the prompt.
`show_tips`	`bool`	`true`	Curated discovery tips in the start banner and prompt chrome.
`file_icons`	`bool`	`false`	Show Nerd Font file-type icons before inline-code paths that point at existing files.
`file_icon_colors`	`bool`	`true`	Color inline-code file icons with nvim-web-devicons colors when `file_icons` is enabled.
`show_slug`	`bool`	`true`	Task-slug label in status bar.
`terminal_title`	`bool`	`true`	Keep the terminal window/tab title in sync with the current session title.
`restrict_to_workspace`	`bool`	`true`	Downgrade `Allow` to `Ask` for paths outside the workspace.
`redact_secrets`	`bool`	`false`	Scrub detected secrets from user input and tool results before they reach the LLM.
`auto_reload`	`bool`	`true`	Watch Lua config inputs (init.lua, plugins/, commands/, completers/, tools/, dialogs/, runtime overrides) and dispatch `/reload` when any of them changes. Prompt inputs such as AGENTS.md, SKILL.md, and `--system-prompt` stay manual via `/reload`.
`compact_threshold`	`number`	`0.8`	Fraction of the configured context window (0, 1] at which the bundled compact plugin auto-triggers before oversized requests.
`compact_keep_recent_groups`	`number`	`1`	Minimum number of trailing message groups kept verbatim after compaction. A group is a user message, a plain assistant message, or an assistant tool-use step together with its tool outputs.
`request_audit`	`"off"` \| `"summary"` \| `"full"`	`"summary"`	Request audit storage mode. `summary` keeps timing, token, cost, and size metadata only; `full` stores reconstructable provider payloads; `off` disables request audit writes.
`fast_mode`	`bool`	`false`	Request the provider's accelerated inference mode when supported.
`cache_ttl_long`	`bool`	`false`	Anthropic prompt cache TTL. `false` uses the 5-minute ephemeral TTL; `true` opts into the 1-hour TTL. Has no effect on non-Anthropic providers.
`web_search_provider`	`"duckduckgo"` \| `"brave"`	`"duckduckgo"`	Search provider used by the built-in `web_search` tool.
`brave_search_api_key_env`	string	`"BRAVE_SEARCH_API_KEY"`	Environment variable containing the Brave Search API key.
`worktree_root`	string	`".worktrees"`	Root directory for managed git worktrees. Relative paths are resolved inside the git root and contain worktrees directly; absolute paths are external roots and get a per-repository bucket. Supports leading `~`, `$VAR`, and `${VAR}` expansion; relative roots may not escape the repo.
`autoupgrade`	`"off"` \| `"notify"` \| `"auto"`	`"notify"`	Autoupgrade behavior. `"off"` skips checks; `"notify"` shows a pill when an update is available; `"auto"` installs in background on detection.
`autoupgrade_channel`	`"stable"` \| `"unstable"`	`"stable"`	Release channel autoupgrade tracks: `"stable"` (tagged releases, including prereleases) or `"unstable"` (`main` HEAD).
`autoupgrade_interval`	`number`	`3600`	Seconds between background autoupgrade checks. The upgrade plugin clamps to a 60-second minimum to avoid hammering GitHub.

Tier rule: Host vs UiHost

Two tiers exist:

Host: works everywhere, including headless (smelt -p '...').
UiHost: needs the TUI; calling these from a headless run raises.

If you're writing a plugin that might run headless (CI scripts, batch prompts), avoid UiHost calls or gate them on smelt.frontend.is_interactive(). The API index below labels every namespace with its tier.

Gotchas

Reg-returning registrations. smelt.keymap.set, smelt.cmd.register, smelt.tools.register, etc. return a Reg table with :remove(). Hold onto it if you want to unregister later; otherwise reload simply re-runs init.lua and re-registers.
Unknown setting/chord/mode keys raise. Better to fail loud than silently no-op. Check the recipes above for valid values.
Hot reload wipes the Lua context. Don't rely on module-local state surviving a /reload. Use smelt.state / smelt.signal for state that needs to persist.
.smelt/ requires trust. After creating or editing project config, the user must run /trust. The next reload after an edit fails until they do.
Don't hand-edit _meta/ stubs or docs/docs/reference/api/. Those are auto-generated by cargo xtask gen-lua-docs from the Rust side. The same is true for the API index region of this skill.
The builtins dir is read-only. Edits to $XDG_DATA_HOME/smelt/builtins/ are wiped on the next smelt upgrade. Make changes under ~/.config/smelt/ or ./.smelt/.
Preserve existing config when editing init.lua. Always Read the file first, then Edit the specific lines you're changing. Never overwrite the whole file from a template, you'll wipe the user's providers, MCP servers, permissions, and custom plugins. If init.lua doesn't exist, create a minimal one with only the lines the request needs.

Lua API surface

What follows is the auto-generated index of every public smelt.* function: namespace, tier, one-line summary, and signature for each function. For deep details (parameter shapes, return tables, type records), open the matching _meta/<stem>.lua stub under the builtins dir ($XDG_DATA_HOME/smelt/builtins/lua/smelt/_meta/).

Host tier

Available in every runtime, including headless mode.

`smelt.agent`

Agent-facing prompt customization for Lua plugins.

smelt.agent.add_system_prompt :: fun(text: string): smelt.Reg Append concise guidance to the system prompt while this Lua runtime is active.

`smelt.auth`

Authenticated provider helpers.

smelt.auth.managed_usage :: fun(provider: string): { summary: table?, limits: table[] }?, string? Fetch parsed managed-provider usage.
smelt.auth.request :: fun(provider: string, opts: { path: string, method: string?, body: string? }): { status: integer, body: string }?, string? Run an authenticated request against a provider-owned endpoint using smelt-managed credentials.

`smelt.builtins`

Opt out of bundled smelt.<dotted> modules.

smelt.builtins.disable :: fun(selector: smelt.builtins.Selector): integer Mark the bundled modules in selector as disabled.
smelt.builtins.enable :: fun(selector: smelt.builtins.Selector): integer Undo a prior disable for the bundled modules in selector.
smelt.builtins.is_disabled :: fun(module: string): boolean Return true if the dotted module name (e.g.
smelt.builtins.list :: fun(): table Return the sorted dotted module names that are currently disabled.

`smelt.cli`

Declare and read CLI flags from Lua.

smelt.cli.get :: fun(name: string): any Return the parsed value of the Lua-declared CLI flag name.
smelt.cli.list :: fun(): table Return the names of every Lua-declared CLI flag, in registration order.
smelt.cli.register_flag :: fun(opts: smelt.cli.RegisterFlagOpts): nil Register a CLI flag.

`smelt.clipboard`

Read and write the system clipboard.

smelt.clipboard.read :: fun(): string? Read the current clipboard contents as a string, or nil if empty/unavailable.
smelt.clipboard.write :: fun(text: string): nil Write text to the system clipboard.

`smelt.defaults`

Startup fallbacks for new sessions.

smelt.defaults.set :: fun(cfg: smelt.defaults.Config): nil Set startup defaults for fresh sessions.

`smelt.events`

Occurrence-oriented subscriptions over event-shaped signals such as turn_start, tool_start, and turn_complete.

smelt.events.emit :: fun(event: smelt.events.Name, payload: any): nil Publish payload for the event named event.
smelt.events.new :: fun(event: smelt.events.Name): nil Declare an event named event.
smelt.events.on :: fun(event: smelt.events.Name, handler: fun(value: any)): smelt.Reg Register handler(payload) for the event named event.

`smelt.files`

Workspace file search.

smelt.files.accept :: fun(item: table, opts: table?): boolean, string? Record a selected file result for recent-selection ranking.
smelt.files.rescan :: fun(opts: table?): boolean, string? Trigger an asynchronous full rescan for the current workspace or opts.cwd.
smelt.files.search :: fun(query: string, opts: table?): table Search workspace files.
smelt.files.status :: fun(opts: table?): table Return indexing status for the current workspace or opts.cwd: { root, initialized, files, scanned, scanning, watcher_ready, warmup_complete }.

`smelt.frontend`

Query which frontend is active (TUI vs headless).

smelt.frontend.is_interactive :: fun(): boolean Return true when the frontend supports interactive prompts (a TTY user is present).
smelt.frontend.kind :: fun(): string Return the active frontend kind (e.g.

`smelt.fs`

Sync filesystem primitives.

smelt.fs.complete_path :: fun(dir: string, prefix: string, opts: table?): table?, string? List immediate filesystem completions under dir matching prefix.
smelt.fs.copy :: fun(from: string, to: string): integer?, string? Copy file from to to.
smelt.fs.exists :: fun(p: string): boolean Return true if a filesystem entry exists at p.
smelt.fs.file_info_async :: fun(path: string): table?, string? Return { is_file, len, mtime_ms } for path off the main thread, or (nil, err).
smelt.fs.glob :: fun(pattern: string, path: string?, opts: table?): string[]?, string? Find paths matching pattern under path (defaults to cwd).
smelt.fs.glob_async :: fun(pattern: string, path: string?, opts: table?): table?, string? Find paths matching pattern under path off the main thread.
smelt.fs.is_dir :: fun(p: string): boolean Return true if p exists and refers to a directory.
smelt.fs.is_file :: fun(p: string): boolean Return true if p exists and refers to a regular file.
smelt.fs.mkdir :: fun(p: string): boolean, string? Create directory p (parents must exist).
smelt.fs.mkdir_all :: fun(p: string): boolean, string? Create directory p along with any missing parent directories.
smelt.fs.mkdir_all_async :: fun(path: string): boolean, string? Create path and parents off the main thread.
smelt.fs.read :: fun(p: string): string?, string? Read p into a string.
smelt.fs.read_async :: fun(path: string): string?, string?, integer? Read path off the main thread.
smelt.fs.read_dir :: fun(p: string): string[]?, string? List the immediate entries of directory p.
smelt.fs.read_limited :: fun(p: string, max_bytes: integer): table?, string? Read at most max_bytes bytes from p.
smelt.fs.remove_dir :: fun(p: string): boolean, string? Delete the empty directory at p.
smelt.fs.remove_dir_all :: fun(p: string): boolean, string? Recursively delete the directory tree rooted at p.
smelt.fs.remove_file :: fun(p: string): boolean, string? Delete the file at p.
smelt.fs.rename :: fun(from: string, to: string): boolean, string? Rename or move from to to.
smelt.fs.size :: fun(p: string): integer?, string? Return the size of file p in bytes.
smelt.fs.watch :: fun(path: string, handler: fun(event: { kind: string, detail: string?, paths: string[] }), opts: table?): smelt.Reg Filesystem watcher.
smelt.fs.write :: fun(p: string, contents: string): boolean, string? Write contents to file p, creating it if necessary.
smelt.fs.write_async :: fun(path: string, contents: string): boolean, string?, integer? Write contents to path off the main thread.

`smelt.fs.file_state`

Cached file-state tracker used by tools to detect external modifications between reads and writes.

smelt.fs.file_state.get :: fun(p: string): any Look up the cached file-state entry for p.
smelt.fs.file_state.has :: fun(p: string): boolean Return true if the file-state cache has a recorded entry for p.
smelt.fs.file_state.mtime_ms :: fun(p: string): integer?, string? Return the modification time of p in milliseconds since the UNIX epoch.
smelt.fs.file_state.record_read :: fun(p: string, content: string, offset: integer, limit: integer): nil Record that p was read at byte range [offset, offset+limit) with content so subsequent staleness checks know what the agent has seen.
smelt.fs.file_state.record_read_with_mtime :: fun(p: string, content: string, offset: integer, limit: integer, mtime_ms: integer): nil Record that p was read with a caller-provided mtime in milliseconds, avoiding an extra stat call.
smelt.fs.file_state.record_write :: fun(p: string, content: string): nil Record that p was written with content so subsequent staleness checks see the latest state.
smelt.fs.file_state.staleness_error :: fun(p: string, noun: string?): string? Return an error message describing why the cached state of p is stale relative to disk, or nil if it is up to date.

`smelt.fuzzy`

Fuzzy-match scoring backed by neo_frizbee (SIMD Smith-Waterman).

smelt.fuzzy.rank :: fun(items: table, query: string): integer[] Rank items by fuzzy match against query.
smelt.fuzzy.score :: fun(text: string, query: string): integer? Fuzzy-match score for text against query.

`smelt.grep`

Ripgrep wrapper for searching files.

smelt.grep.run :: fun(pattern: string, path: string, opts: table?): { stdout: string, stderr: string, exit_code: integer, timed_out: boolean }?, string? Run ripgrep with pattern over path off the main thread.

`smelt.html`

HTML parsing: title extraction, link scraping, to_text, to_markdown, DDG results.

smelt.html.links :: fun(source: string, base: string?): string[] Extract all anchor href links from source.
smelt.html.parse_ddg_results :: fun(source: string): table Parse a DuckDuckGo HTML results page into rows of { title, link, description }.
smelt.html.title :: fun(source: string): string? Return the <title> text of source, or nil if no title element is present.
smelt.html.to_markdown :: fun(source: string, base: string?): table Convert source HTML to a { title, content, links } table where content is markdown.
smelt.html.to_text :: fun(source: string): string Strip HTML tags from source and return the visible text content.

`smelt.http`

Asynchronous HTTP get/post.

smelt.http.get :: fun(url: string, opts: table?): { status: integer, final_url: string, body: string, headers: table }?, string? Perform an HTTP GET against url.
smelt.http.post :: fun(url: string, body: string?, opts: table?): { status: integer, final_url: string, body: string, headers: table }?, string? Perform an HTTP POST against url with body bytes.
smelt.http.random_user_agent :: fun(): string Return a randomly selected User-Agent string from the built-in pool.

`smelt.http.cache`

Process-wide HTTP response cache.

smelt.http.cache.read :: fun(key: string): string? Look up a cached HTTP response by key.
smelt.http.cache.write :: fun(key: string, value: string): nil Store value in the HTTP response cache under key.

`smelt.image`

Image file detection and base64 data-URL loading.

smelt.image.data_url_from_bytes :: fun(bytes: string, mime: string): string Encode raw bytes as a base64 data: URL with the given mime type.
smelt.image.is_image_file :: fun(p: string): boolean Return true if p looks like an image file (matched by extension/sniffing).
smelt.image.label_from_path :: fun(p: string): string Return a display label for an image path.
smelt.image.mime_from_path :: fun(p: string): string Return the image MIME type inferred from p's extension.
smelt.image.read_as_data_url :: fun(p: string): string?, string? Read the image at p and encode it as a data: URL.
smelt.image.read_as_data_url_async :: fun(path: string): string?, string? Read and base64-encode an image off the main thread.

`smelt.json`

Encode/decode JSON for Lua plugins.

smelt.json.decode :: fun(text: string): any, string? Decode JSON into a Lua value.
smelt.json.encode :: fun(value: any, opts: table?): string Encode a Lua value as JSON.

`smelt.layout`

Declarative, width-independent content layout primitives for transcript/tool display.

smelt.layout.cap :: fun(child: any, opts: table): smelt.layout.Node Cap a child by rendered rows.
smelt.layout.code :: fun(content: string, opts: table?): smelt.layout.Node Syntax-highlighted code layout leaf.
smelt.layout.diff :: fun(opts: table): smelt.layout.Node Inline-diff render directive.
smelt.layout.elapsed :: fun(elapsed: any, opts: table?): smelt.layout.Node Dynamic elapsed-time text leaf.
smelt.layout.empty :: fun(): smelt.layout.Node Explicit zero-row layout node.
smelt.layout.file_view :: fun(opts: table): smelt.layout.Node Syntax-highlighted file-view render directive.
smelt.layout.gutter :: fun(child: any, opts: table?): smelt.layout.Node Render child with an explicit non-selectable gutter prefix on each emitted row.
smelt.layout.hbox :: fun(items: table): smelt.layout.Node Lay items out horizontally.
smelt.layout.line :: fun(spans: any, opts: table?): smelt.layout.Node Single styled line layout leaf.
smelt.layout.markdown :: fun(content: string, opts: table?): smelt.layout.Node Markdown layout leaf.
smelt.layout.panel :: fun(child: any, opts: table?): smelt.layout.Node Render child inside a full-width background panel.
smelt.layout.row_prefix :: fun(child: any, opts: table): smelt.layout.Node Apply row chrome to child after the child has produced rows.
smelt.layout.runs :: fun(lines: any, opts: table?): smelt.layout.Node Styled inline text layout leaf.
smelt.layout.separator :: fun(opts: table?): smelt.layout.Node Full-width horizontal separator.
smelt.layout.style :: fun(child: any, opts: table?): smelt.layout.Node Apply inherited style to a child layout.
smelt.layout.text :: fun(content: string, opts: table?): smelt.layout.Node Plain text layout leaf.
smelt.layout.vbox :: fun(items: table): smelt.layout.Node Stack items vertically into a single block layout.

`smelt.lifecycle`

Host-phase hooks keyed by event name.

smelt.lifecycle.guard :: fun(scopes: string|string[]|table?): smelt.lifecycle.Guard Create a guard whose :alive() flips false when any scoped epoch changes.
smelt.lifecycle.on :: fun(event: string, fn: function): smelt.Reg Queue fn(ctx) for the lifecycle event named event.
smelt.lifecycle.on_ready :: fun(fn: function): smelt.Reg Shorthand for lifecycle.on("ready", fn).
smelt.lifecycle.on_shutdown :: fun(fn: function): smelt.Reg Shorthand for lifecycle.on("shutdown", fn).

`smelt.log`

Structured JSONL log entries written to the engine log file.

smelt.log.error :: fun(event: string, data: any?): nil Write a JSONL log entry at Error level.
smelt.log.info :: fun(event: string, data: any?): nil Write a JSONL log entry at Info level.
smelt.log.warn :: fun(event: string, data: any?): nil Write a JSONL log entry at Warn level.

`smelt.lsp`

Generic stdio Language Server Protocol client.

smelt.lsp.configure :: fun(config: table): nil Configure available language servers.

`smelt.mcp`

Config-time MCP server registration.

smelt.mcp.list :: fun(): table Snapshot every declared MCP server.
smelt.mcp.register :: fun(name: string, cfg: smelt.mcp.Config): smelt.Reg Declare an MCP server named name.
smelt.mcp.status :: fun(name: string): string? Return the lifecycle status for server name: "disabled", "connecting", "connected", or "error".
smelt.mcp.tools :: fun(server: string?): table Snapshot every discovered MCP tool.

`smelt.messages`

Persistent message log with full bodies and tracebacks.

smelt.messages.append :: fun(kind: string, source: string, msg: string): nil Append a new message of kind ("error", "warn"/"warning", anything else falls back to "info") attributed to source with body msg.
smelt.messages.clear :: fun(): nil Drop every message from the log.
smelt.messages.count :: fun(): integer Return the total number of messages currently in the log.
smelt.messages.list :: fun(): table Return every persisted message as rows of { kind, source, summary, full, ts_ms }, ordered oldest-first.
smelt.messages.mark_read :: fun(): nil Mark every message in the log as read so unread_count returns 0 until new errors arrive.
smelt.messages.unread_count :: fun(): integer Return the number of unread error messages in the log.

`smelt.os`

Environment and system primitives: getenv, setenv, platform, cwd, pid, etc.

smelt.os.arch :: fun(): string Return the target CPU architecture as reported by std::env::consts::ARCH (e.g.
smelt.os.cwd :: fun(): string?, string? Return the current working directory as (path, nil), or (nil, err_string) on failure.
smelt.os.exe_path :: fun(): string?, string? Return the filesystem path to the running smelt binary as (path, nil) on success, or (nil, err_string) on failure.
smelt.os.getenv :: fun(name: string): string? Return the value of the environment variable name, or nil if it is not set.
smelt.os.home :: fun(): string? Return the user's home directory, or nil if it cannot be determined.
smelt.os.open_url :: fun(url: string): boolean, string? Open url in the system's default browser.
smelt.os.open_url_if_available :: fun(url: string): table Open url only when the host environment can auto-open a browser.
smelt.os.pid :: fun(): integer Return the OS process id of the running smelt instance.
smelt.os.platform :: fun(): string Return the target operating system as reported by std::env::consts::OS (e.g.
smelt.os.set_cwd :: fun(p: string): boolean, string? Change the process working directory to p.
smelt.os.setenv :: fun(name: string, value: string): nil Set the process environment variable name to value.
smelt.os.tempdir :: fun(): string Return the platform temporary directory path.
smelt.os.unsetenv :: fun(name: string): nil Remove the environment variable name from the process environment.

`smelt.parse`

Pure parsers: frontmatter extraction from markdown documents.

smelt.parse.frontmatter :: fun(content: string): any, string Split ----delimited YAML frontmatter from a markdown document.
smelt.parse.json :: fun(content: string): any Parse a JSON document into a Lua value.

`smelt.path`

Pure path arithmetic: normalize, join, relative, expand, display, etc.

smelt.path.basename :: fun(p: string): string? Return the final component (file name) of p, or nil if p ends in ...
smelt.path.canonical :: fun(p: string): string?, string? Resolve p to its canonical absolute form (following symlinks).
smelt.path.commands_dir :: fun(): string Return the absolute path to the slash-commands directory under the user config root.
smelt.path.config_dir :: fun(): string Return the absolute path to smelt's user config directory.
smelt.path.display :: fun(p: string): string Return a user-friendly rendering of p for UI display (e.g. with the home dir abbreviated to ~).
smelt.path.display_streaming :: fun(p: string): string Return a user-friendly rendering of a possibly partial path for streaming tool summaries.
smelt.path.expand :: fun(p: string): string Expand config-path syntax in p: leading ~, $VAR, and ${VAR}.
smelt.path.extension :: fun(p: string): string? Return the file extension of p (without the leading dot), or nil if there is none.
smelt.path.is_absolute :: fun(p: string): boolean Return true if p is an absolute path on the current platform.
smelt.path.join :: fun(...: string): string Join the variadic parts into a single path using the platform separator.
smelt.path.normalize :: fun(p: string): string Normalize p by collapsing redundant ., .., and separator components without touching the filesystem.
smelt.path.parent :: fun(p: string): string? Return the parent directory of p, or nil if p has no parent component.
smelt.path.relative :: fun(base: string, target: string): string Return the path of target expressed relative to base.

`smelt.perf`

Lightweight scope timers that feed smelt.metrics.perf_snapshot.

smelt.perf.time :: fun(label: string, fn: fun(): any): any Run fn() and record its elapsed time under label.

`smelt.process`

Run, spawn, list, and kill processes against the ProcessRegistry. spawned processes are non-blocking; run processes wait for completion.

smelt.process.detach_foreground :: fun(): boolean Move the most recently started foreground streaming process to the background process registry.
smelt.process.get_default_shell :: fun(): any Return the current default shell as { program, args }, or nil when the built-in sh -c default is in effect.
smelt.process.kill :: fun(id: string): nil Stop the registered process with id.
smelt.process.list :: fun(): table Return the registry of running processes as rows of { id, pid?, command, elapsed_secs }.
smelt.process.output :: fun(id: string): table Return the buffered output snapshot for registered process id without draining it.
smelt.process.read_output :: fun(id: string): table Drain buffered output from the registered process id.
smelt.process.run :: fun(cmd: string, args: string[]?, opts: table?): { stdout: string, stderr: string, exit_code: integer, timed_out: boolean }?, string? Run cmd with args off the main thread.
smelt.process.run_streaming :: fun(task_id: integer, call_id: string, command: string, timeout_ms: integer, background_on_timeout: boolean): nil Run command with a timeout_ms deadline, streaming each output line into the live tool call call_id and resolving task task_id with { content, is_error, timed_out, background_id? } (or { __cancelled = true } if cancelled).
smelt.process.set_default_shell :: fun(opts: table?): nil Override the wrapping shell used by spawn_bg and run_streaming for string-form commands.
smelt.process.spawn_bg :: fun(command: string): string Spawn command as a background child registered with the process registry.
smelt.process.stop :: fun(id: string): { text: string }?, string? Stop a registered background process and return its buffered output.

`smelt.provider`

List built-in model providers and register custom ones.

smelt.provider.has_real_rows :: fun(rows: table[]?): boolean Return true when the row list contains at least one non-synthetic row.
smelt.provider.is_loading :: fun(result: table?): boolean Return true when a provider or normalized result is still loading.
smelt.provider.item_key :: fun(item: table?): string? Return the stable identity key used to preserve selection across provider refreshes.
smelt.provider.list :: fun(): table Return every registered provider as an array of tables.
smelt.provider.middleware :: fun(mw: table): smelt.Reg Register provider middleware.
smelt.provider.normalize :: fun(result: table[]|table?, opts?: { show_message?: boolean, loading_message?: string }): smelt.provider.NormalizedResult Normalize a provider result or plain row list into renderable rows plus loading state.
smelt.provider.register :: fun(name: string, cfg: smelt.provider.Config): smelt.Reg Declare a provider named name.
smelt.provider.synthetic_only :: fun(rows: table[]?): boolean Return true when the row list is exactly one synthetic status/message row.

`smelt.reg`

Helpers for constructing Reg handles.

smelt.reg.compose :: fun(...: smelt.Reg?): smelt.Reg Combine variadic Regs into one.
smelt.reg.new :: fun(undo: fun()): smelt.Reg Wrap undo as a Reg.

`smelt.remember`

Per-key opt-in to last-used recall on launch.

smelt.remember.set :: fun(cfg: smelt.remember.Config): nil Set which startup choices are remembered across launches.

`smelt.shell`

Shell command splitting and interactive/background-operator validators.

smelt.shell.check_background_op :: fun(command: string): string? Return a user-facing error message if command uses the shell & background operator, or nil otherwise.
smelt.shell.check_interactive :: fun(command: string): string? Return a user-facing error message if command would invoke an interactive program (editor, REPL, pager, git -i, etc.), or nil if it is safe to run non-interactively.
smelt.shell.extract_paths :: fun(command: string): string[] Extract filesystem paths referenced by command for workspace permission checks.
smelt.shell.has_output_redirection :: fun(command: string): boolean Return true when command contains shell output redirection such as > or >>.
smelt.shell.split :: fun(command: string): string[] Split command into the sequence of subcommands separated by shell operators (;, &&, ||, |).
smelt.shell.split_with_ops :: fun(command: string): table Split command into subcommands and pair each with the operator that followed it.

`smelt.signal`

Named reactive values.

smelt.signal.get :: fun(name: smelt.signal.Name): any Return the current value of signal name, or nil when the signal is not declared.
smelt.signal.glob :: fun(pattern: string, handler: fun(arg1: string, arg2: any, arg3: any)): smelt.Reg Register handler(name, value, previous) for every signal whose name matches pattern (glob syntax).
smelt.signal.new :: fun(name: smelt.signal.Name, initial: any): nil Declare a signal named name with initial as its starting value.
smelt.signal.set :: fun(name: smelt.signal.Name, value: any): nil Publish value for signal name.
smelt.signal.subscribe :: fun(name: smelt.signal.Name, handler: fun(arg1: any, arg2: any)): smelt.Reg Register handler(value, previous) for signal name.

`smelt.skills`

List and load skill content from the SkillLoader populated at startup.

smelt.skills.content :: fun(name: string): string?, string? Load the skill named name and return (content, nil) on success or (nil, err_string) if the skill is missing or failed to load.
smelt.skills.info :: fun(): table Return every discovered skill as { name, description, source, location, shadowed } rows sorted by name.
smelt.skills.list :: fun(): table Return the names of every skill discovered by the loader as a Lua array.

`smelt.state`

Per-plugin state.

smelt.state.get :: fun(name?: string): table Return an ephemeral state table.
smelt.state.persistent :: fun(name: string, opts: { debounce_ms: integer? }?): table

`smelt.task`

Yield-then-resume coroutine bridge: alloc and resume external tasks.

smelt.task.all :: fun(...: fun(): any): any[] Run fns concurrently; wait for all to finish.
smelt.task.alloc :: fun(): integer Allocate and return a fresh external task id used to pair a yielded coroutine with a later task.resume call.
smelt.task.external :: fun(start: fun(id: integer)): any Allocate an external task id, invoke start(id) to kick off whatever will eventually call smelt.task.resume(id, value) (or resolve through the Rust resume sink), and park until that resolution arrives.
smelt.task.is_cancelled :: fun(err: any): boolean Check whether an error value represents a task or engine-ask cancellation.
smelt.task.race :: fun(...: fun(): any): integer, any Run fns concurrently; first to return wins.
smelt.task.resume :: fun(id: integer, value: any): nil Resume the yielded task id with value.
smelt.task.timeout :: fun(ms: integer, fn: fun(): any): any, string? Run fn with an ms-millisecond deadline.
smelt.task.wait :: fun(id: integer, opts?: table): any Park the running task until smelt.task.resume(id, value) fires.

`smelt.tick`

Reload-safe periodic work.

smelt.tick.every :: fun(secs: integer, fn: fun()): smelt.Reg Reload-safe periodic work.

`smelt.time`

Wall-clock time parsing and formatting.

smelt.time.format :: fun(timestamp: integer, format: string): string? Format Unix seconds in the user's local time zone with a strftime-style format string.
smelt.time.format_utc :: fun(timestamp: integer, format: string): string? Format Unix seconds in UTC with a strftime-style format string.
smelt.time.now :: fun(): integer Return the current Unix timestamp in seconds.
smelt.time.now_ms :: fun(): integer Return the current Unix timestamp in milliseconds.
smelt.time.parse_iso8601 :: fun(timestamp: string): integer? Parse an ISO-8601 / RFC3339 timestamp and return Unix seconds, not milliseconds, or nil when the input is invalid.

`smelt.timer`

One-shot and recurring timer callbacks.

smelt.timer.every :: fun(ms: integer, handler: fun()): smelt.Reg Schedule handler to fire repeatedly every ms milliseconds.
smelt.timer.set :: fun(ms: integer, handler: fun()): smelt.Reg Schedule handler to run once after ms milliseconds.

`smelt.tools`

smelt.tools.call :: fun(name: string, args: table?, parent_call_id: string?): { content: string, is_error: boolean?, metadata: table? } Call another tool from within execute.
smelt.tools.default_summary :: fun(args: table?): string Best-effort one-liner summary of a tool call's arguments.
smelt.tools.list :: fun(): table Return the names of every registered plugin tool, sorted.
smelt.tools.middleware :: fun(name: string, mw: table): smelt.Reg Register middleware for tool name.
smelt.tools.patch :: fun(name: string, patch: table): smelt.Reg Patch metadata for an already-registered tool without replacing its handler.
smelt.tools.path_summary :: fun(path: string, ctx?: { final: boolean }, opts?: { prefix: string?, suffix: string? }): string Format a path for a tool summary.
smelt.tools.register :: fun(def: smelt.tools.ToolDef): smelt.Reg Register a plugin tool.
smelt.tools.resolve :: fun(request_id: integer, call_id: string, result: table): nil Resolve the pending tool call call_id from request request_id with { content, is_error, metadata? }.
smelt.tools.unregister :: fun(name: string): boolean Unregister a previously-registered tool by name.

`smelt.transcript.defaults`

Bundled default transcript renderers.

smelt.transcript.defaults.child_failed :: fun(child: smelt.transcript.Block): boolean True when a grouped child represents a failed or denied tool result.
smelt.transcript.defaults.group_children :: fun(group: smelt.transcript.Group): smelt.transcript.Block[] Return child snapshots for a transcript group snapshot.
smelt.transcript.defaults.group_failure_counts :: fun(group: smelt.transcript.Group): integer, integer Count failed and denied tool children in a transcript group snapshot.
smelt.transcript.defaults.render :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render any semantic transcript block with the bundled default policy.
smelt.transcript.defaults.render_assistant :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render assistant text.
smelt.transcript.defaults.render_code :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a code block with syntax highlighting.
smelt.transcript.defaults.render_compacted :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compacted-history marker.
smelt.transcript.defaults.render_compaction_preview :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render an in-flight compaction summary preview.
smelt.transcript.defaults.render_exec :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render an exec block.
smelt.transcript.defaults.render_group_child_list :: fun(group: smelt.transcript.Group, ctx: smelt.transcript.Context, opts: table?): smelt.layout.Node Render a compact ordered child list for collapsed group nodes.
smelt.transcript.defaults.render_group_children :: fun(group: smelt.transcript.Group, ctx: smelt.transcript.Context): smelt.layout.Node Render all group children through the bundled default block renderer.
smelt.transcript.defaults.render_llm_markdown :: fun(content: string?, opts: table?): smelt.layout.Node Render LLM-authored Markdown with the shared transcript Markdown path.
smelt.transcript.defaults.render_llm_markdown_tail :: fun(content: string?, ctx: smelt.transcript.Context?, opts: table?): smelt.layout.Node Render capped LLM-authored Markdown for tool bodies and other long outputs.
smelt.transcript.defaults.render_mode :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a mode note.
smelt.transcript.defaults.render_process_status :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a process-status note.
smelt.transcript.defaults.render_thinking :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render thinking for the current transcript view state.
smelt.transcript.defaults.render_thinking_full :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render the full thinking block with the current gutter.
smelt.transcript.defaults.render_thinking_peek :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compact live preview of thinking: first rendered row, omitted rows, tail.
smelt.transcript.defaults.render_thinking_summary :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compact thinking summary.
smelt.transcript.defaults.render_tool :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a tool block for the current transcript view state.
smelt.transcript.defaults.render_tool_body :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context, opts: table?): smelt.layout.Node? Render a tool body.
smelt.transcript.defaults.render_tool_full :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a full tool block using the current generic primitives and explicit item construction.
smelt.transcript.defaults.render_tool_header :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context, opts: table?): smelt.layout.Node Render the default one-line tool header.
smelt.transcript.defaults.render_tool_output :: fun(output: smelt.transcript.ToolOutput?, ctx: smelt.transcript.Context?, opts: table?): smelt.layout.Node Render raw tool output using generic layout primitives: text, gutter, and a rendered-row cap.
smelt.transcript.defaults.render_tool_output_tail :: fun(output: smelt.transcript.ToolOutput?, ctx: smelt.transcript.Context?, opts: table?): smelt.layout.Node Render raw tool output without gutter using generic layout primitives: text/runs and a rendered-row cap.
smelt.transcript.defaults.render_tool_summary :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compact tool summary: header plus an optional detail line.
smelt.transcript.defaults.render_unknown :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render unknown block kinds without failing the transcript.
smelt.transcript.defaults.render_user :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a user block.
smelt.transcript.defaults.render_user_text :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render user text.
smelt.transcript.defaults.tool_collapsed_detail :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): string? Return a compact tool detail for collapsed tool blocks.

`smelt.transcript.groups`

Declarative transcript display grouping.

smelt.transcript.groups.cache_key :: fun(): integer? Current group-registry cache key, or nil when any active group opted out of persisted planning/layout caches.
smelt.transcript.groups.generation :: fun(): integer Current group-registry generation.
smelt.transcript.groups.list :: fun(): smelt.transcript.GroupSpec[] Return group specs in planner order: higher priority first, then registration order.
smelt.transcript.groups.register :: fun(spec: smelt.transcript.GroupSpec): smelt.Reg Register or replace a declarative transcript group type.

`smelt.trust`

Query and mutate the per-project content trust store.

smelt.trust.mark :: fun(): string Mark the current working directory as trusted, persisting it in the user's trust store.
smelt.trust.status :: fun(): string Return the trust state of the current working directory: "trusted", "untrusted", or "no_content".

UiHost tier

Requires a terminal UI; calling these from headless mode raises.

`smelt.buf`

Buffer handle constructor.

smelt.buf.new :: fun(opts: smelt.buf.NewOpts?): smelt.buf.Buf Create a buffer and return a Buf userdata.

`smelt.config`

Resolved application configuration introspection.

smelt.config.api_base :: fun(): string? Active API base URL.
smelt.config.api_key_env :: fun(): string? Name of the environment variable that supplies the API key for the active provider.
smelt.config.context_window :: fun(): integer? Configured context-window size in tokens for the active model, or nil when not declared.
smelt.config.model_config :: fun(): table? Resolved model-level sampling, capability, and cost overrides as a table.
smelt.config.provider_type :: fun(): string? Active provider type string, e.g.
smelt.config.runtime_status :: fun(): table Return sanitized runtime and reload diagnostics: committed Lua/runtime revisions, pending reload and last failure location, model selection, managed-provider freshness, and MCP/LSP/watcher/context controller convergence.

`smelt.confirm`

Confirm dialog primitives - preview dispatch, back-tab cycling, and choice resolution.

`smelt.dialog`

Root-docked modal dialog primitives.

smelt.dialog.content :: fun(opts: table?): smelt.win.Win, smelt.buf.Buf General-purpose body leaf.
smelt.dialog.current :: fun(): table | nil Return the topmost active dialog ctx (the same shape passed to on_submit/keymap handlers: { resolve, close, win, panels, focused_leaf }), or nil if no dialog is open.
smelt.dialog.input :: fun(placeholder: string?, opts: table?): smelt.win.Win, smelt.buf.Buf, smelt.input.Input Build a line-input leaf with a fresh buffer.
smelt.dialog.list :: fun(buf: smelt.buf.Buf, opts: table?): smelt.win.Win Wrap an existing buf as a selectable list leaf.
smelt.dialog.markdown :: fun(text: string): smelt.win.Win, smelt.buf.Buf Render text as a non-focusable markdown leaf.
smelt.dialog.menu :: fun(items: (string|smelt.dialog.MenuItem)[], opts: smelt.dialog.MenuOpts?): smelt.win.Win, table
smelt.dialog.open :: fun(opts: smelt.dialog.Opts): any Coroutine-blocking dialog opener.
smelt.dialog.open_handle :: fun(opts: smelt.dialog.Opts): table Non-coroutine open.
smelt.dialog.picker :: fun(opts: smelt.dialog.PickerOpts): any Coroutine-blocking Telescope-style picker.
smelt.dialog.title :: fun(title: string|table, opts?: { pad?: boolean }): table|string|nil Return a title spec styled for dialog/window chrome.
smelt.dialog.viewer :: fun(opts: table): table, smelt.buf.Buf, smelt.win.Win Open a read-only content dialog.

`smelt.engine`

LLM engine control - cancel, ask, inherited ask, submit commands, and request tool approval.

smelt.engine.ask :: fun(spec: smelt.engine.AskSpec): integer Run an out-of-band LLM request without touching the main turn.
smelt.engine.ask_inherited :: fun(spec: smelt.engine.InheritedAskSpec): integer Run an auxiliary LLM request that inherits the current session's assembled system prompt and active tool list.
smelt.engine.cancel :: fun(): nil Cancel the in-flight turn or foreground/background work.
smelt.engine.is_running :: fun(): boolean Return true if an agent turn is currently in flight (a request is being streamed or a tool is executing).
smelt.engine.on_context_limit :: fun(hook: fun(arg1: smelt.engine.AskMessage[], arg2: fun(value: any))): smelt.Reg Register a recovery hook the engine calls when a provider returns a context-window error mid-turn.
smelt.engine.on_prepare_request :: fun(hook: fun(arg1: smelt.engine.PrepareRequest, arg2: fun(value: any))): smelt.Reg Register a hook the engine calls immediately before each provider request.
smelt.engine.reload :: fun(): nil Queue a transactional Lua reload for the next safe point.
smelt.engine.reload_when_idle :: fun(): boolean Schedule a full config reload for the next safe idle point, including prompt inputs such as AGENTS.md, skills, and --system-prompt.
smelt.engine.submit_command :: fun(name: string, body: string, overrides: smelt.engine.CommandOverrides?, display: string?): nil Start an agent turn from a Lua-defined custom command (/name).
smelt.engine.submit_command_continuation :: fun(name: string, body: string, overrides: smelt.engine.CommandOverrides?, display: string?, continuation_token: integer?): boolean Start an idle custom-command continuation without using the prompt queue.
smelt.engine.summary_prefix :: fun(): string Return the canonical compaction-summary prefix used when a checkpoint summary is represented as a user message.

`smelt.history`

Prompt history entries and search.

smelt.history.entries :: fun(): table Return the prompt history as an array of strings, oldest first.
smelt.history.search :: fun(query: string): table Rank prompt history against query using the history-specific scorer (word-match boost, recency bonus, dedupe).

`smelt.input`

Single-line input handle constructor.

smelt.input.new :: fun(opts: table?): smelt.input.Input? Create a single-line input and return an Input handle.

`smelt.inspect`

Local session introspection web UI.

smelt.inspect.url :: fun(): any Return the URL of the running inspector server, or nil if it is not running.

`smelt.keymap`

smelt.keymap.help_sections :: fun(): table Return layered keybinding help as { title, entries = { { label, detail } } } rows.
smelt.keymap.leader :: fun(): string Return the current <leader> expansion used when registering keymaps.
smelt.keymap.list :: fun(): table Return the set of currently-bound { mode, chord, desc? } rows.
smelt.keymap.prefixes :: fun(pending: string, mode: string?): table Return effective keymaps that extend pending in mode as { mode, chord, suffix, desc? } rows.
smelt.keymap.set :: fun(mode: string, chord: string, handler: fun(), opts: table?): smelt.Reg Bind chord in mode to a Lua callback.
smelt.keymap.set_leader :: fun(leader: string): nil Set the <leader> expansion for subsequent keymap registrations.
smelt.keymap.unset :: fun(mode: string, chord: string): boolean Drop the binding for chord in mode.

`smelt.list`

Picker-style virtual list widget.

smelt.list.new :: fun(opts: smelt.list.Opts): smelt.list.List Build a structured list bound to the dialog-list opts.leaf and its backing opts.buf.

`smelt.metrics`

Metrics ledger access and live perf instrumentation.

smelt.metrics.entries :: fun(): table Return raw entries from the on-disk metrics ledger.

`smelt.metrics.perf`

Perf instrumentation toggle, clear, and snapshot.

smelt.metrics.perf.clear :: fun(): nil Clear all accumulated perf samples (durations and value gauges).
smelt.metrics.perf.enabled :: fun(): boolean Return whether perf instrumentation collection is enabled.
smelt.metrics.perf.set_enabled :: fun(on: boolean): nil Toggle perf instrumentation collection on/off.
smelt.metrics.perf.snapshot :: fun(): table Return the current perf snapshot as { durations, values, enabled } with per-label count, last, p50, p95, p99, max, total fields.
smelt.metrics.perf.snapshot_top :: fun(limit: integer?): table Return a cheap live perf snapshot with only the top limit duration rows and no value rows.

`smelt.model`

Model selector.

smelt.model.capabilities :: fun(): table? Resolved capabilities for the active model/provider as { input_modalities, supports_image, supports_pdf, supports_video, supports_reasoning, tool_calling, max_tokens, context_window, transport = { ... }, sources = { ... } }.
smelt.model.current :: fun(): string? Return the active model key, or nil when no active model exists.
smelt.model.input_modalities :: fun(): table? Resolved input modalities for the active model as an array such as { "text", "image", "pdf" }.
smelt.model.list :: fun(): table Return an array of { key, name, display_name?, provider, api_base, provider_type } records for every model the active config can switch to.
smelt.model.max_tokens :: fun(): integer? Resolved maximum output tokens for the active model.
smelt.model.preferred :: fun(name: any, value: any): any
smelt.model.pricing :: fun(): table? Resolved pricing for the active model as { input, output, cache_read, cache_write, source }.
smelt.model.set :: fun(name: string): nil Switch the active model by key.
smelt.model.status :: fun(): table Return { current, requested, availability, reason?, providers } for model selection.
smelt.model.supports_input :: fun(modality: string): boolean? Return whether the active model supports the named input modality, for example image or pdf.
smelt.model.transport :: fun(): table? Return { provider_type, api_base, api_key_env, multimodal_tool_results } for the active model transport.

`smelt.notebook`

Parse, read, and apply notebook cell edits, plus compute preview data for the edit_notebook tool.

smelt.notebook.apply_edit :: fun(args: table): any?, string? Apply a notebook edit (cell insert/replace/delete) described by args and persist the new file.
smelt.notebook.apply_edit_async :: fun(args: table): table?, string? Apply a notebook edit off the main thread.
smelt.notebook.is_notebook_path :: fun(path: string): boolean Return true if path looks like a Jupyter notebook (.ipynb extension).
smelt.notebook.parse :: fun(json: string): table?, string? Parse a notebook JSON string.
smelt.notebook.read :: fun(path: string, offset: integer, limit: integer): string?, string? Render a Jupyter notebook at path as cell-by-cell text starting at offset for at most limit cells.
smelt.notebook.read_async :: fun(path: string, offset: integer, limit: integer): string?, string?, string?, integer? Render a notebook off the main thread.

`smelt.notify`

Status-area toasts.

smelt.notify.error :: fun(msg: string, source: string?): nil Show an error toast (highlighted with the error color) and append the body to the message log.
smelt.notify.info :: fun(msg: string, source: string?): nil Show an informational toast and append the body to the message log.
smelt.notify.scoped :: fun(source: string): smelt.notify.Scoped Bind source once and return a small bag that forwards to smelt.notify.info / smelt.notify.error / smelt.notify.warn with the source pinned.
smelt.notify.warn :: fun(msg: string, source: string?): nil Show a warning toast and append the body to the message log.

`smelt.overlay`

Overlay handle constructor.

smelt.overlay.new :: fun(opts: smelt.overlay.NewOpts): smelt.overlay.Overlay Open an overlay rendered from opts.layout (a smelt.ui.layout userdata) and return an Overlay userdata.

`smelt.paint`

smelt.paint.register :: fun(func: fun(arg1: smelt.paint.Slice, arg2: table), opts: table?): smelt.paint.Paint Register func as a paint callback and return an opaque Paint handle (userdata with :remove()).

`smelt.permissions`

List, sync, and extend permission policy state.

smelt.permissions.check :: fun(mode_str: string, bucket: string, value: string): string Decide a tool-specific pattern bucket (e.g.
smelt.permissions.check_tool :: fun(mode_str: string, name: string): string Decision primitives for tool decide callbacks.
smelt.permissions.extend :: fun(spec: smelt.permissions.PolicySpec): nil Extend the generated permission policy with user rules.
smelt.permissions.grant_session :: fun(grant: smelt.permissions.SessionPathGrant): nil Add one session-scoped grant.
smelt.permissions.list :: fun(): smelt.permissions.ListResult Return current permission rules as { session = { { tool, pattern } }, path_grants = { { kind = "path", mode?, tool, access, path_prefix } }, workspace = { { tool, patterns } } }.
smelt.permissions.sync :: fun(spec: smelt.permissions.SyncSpec): nil Replace runtime + workspace permission entries with spec.session, spec.path_grants, and spec.workspace.

`smelt.picker`

Picker handle constructor.

smelt.picker.fuzzy :: fun(opts: smelt.picker.FuzzyOpts): smelt.picker.FuzzyResult? Fuzzy-finder picker.
smelt.picker.new :: fun(opts: smelt.picker.NewOpts): smelt.picker.Picker Open a picker overlay and return a Picker userdata.
smelt.picker.open :: fun(opts: smelt.picker.NewOpts): smelt.picker.OpenResult? Open a floating picker over opts.items and yield until the user accepts or dismisses.

`smelt.prompt`

The main editable input surface: win handle, text get/set, and cursor control.

smelt.prompt.acquire :: fun(): smelt.Reg ── Modality lock ─────────────────────────────────────────────────────── Take a modality lock on the prompt area so completers/pickers don't pop while the caller owns the screen.
smelt.prompt.completer :: fun(spec: smelt.prompt.CompleterSpec|smelt.prompt.MatchesCompleterSpec): smelt.Reg Register a completer spec.
smelt.prompt.cursor :: fun(pos: integer?): integer Read or write the prompt cursor as a byte offset into text().
smelt.prompt.has_stash :: fun(): boolean Return whether the prompt currently holds a stashed input snapshot (Ctrl+S).
smelt.prompt.is_modal :: fun(): boolean True while at least one smelt.prompt.acquire() lock is outstanding.
smelt.prompt.open_picker :: fun(opts: smelt.prompt.PickerOpts): table? Prompt-docked picker.
smelt.prompt.queued :: fun(): string[] Return the queued prompt text rows.
smelt.prompt.queued_rows :: fun(): table[] Return queued prompt rows as { text, kind } tables.
smelt.prompt.replace_range :: fun(start: integer, end: integer, text: string): integer UTF-8-safe replace of the byte range [start, end) in the prompt with text.
smelt.prompt.set_text :: fun(text: string): nil Replace the prompt buffer with text.
smelt.prompt.text :: fun(): string Return the prompt input buffer's current text.
smelt.prompt.win :: fun(): smelt.win.Win Return a Win handle for the prompt input.

`smelt.render`

Paint text / markdown / syntax-highlighted code / split diffs into a Buf.

smelt.render.diff_split :: fun(left: smelt.buf.Buf, right: smelt.buf.Buf, opts: smelt.render.DiffSplitOpts): nil Paint a side-by-side diff between opts.old and opts.new into two buffers.
smelt.render.markdown :: fun(buf: smelt.buf.Buf, source: string): nil Render markdown source into the buffer using the same renderer the transcript uses for assistant text blocks.
smelt.render.syntax :: fun(buf: smelt.buf.Buf, opts: smelt.render.SyntaxOpts): nil Paint syntect-highlighted code from opts.content into the buffer as a plain block.
smelt.render.text :: fun(buf: smelt.buf.Buf, content: string, opts: smelt.render.TextOpts?): nil Paint plain text into a buffer.

`smelt.search`

Search controls for the active UI session.

smelt.search.clear :: fun(): nil Clear the active search session and remove search highlights from its target window.

`smelt.session`

Current session metadata, turn list, message snapshots, rewind, and persisted session management.

smelt.session.checkpoint :: fun(spec: table): boolean? Install a model-context checkpoint without deleting transcript history.
smelt.session.context_note :: fun(name: string, text: string?, opts: table?): nil Set or clear a named hidden model-visible context note.
smelt.session.context_tokens :: fun(): integer? Latest non-background provider-reported active-context token count, or nil before the first usage report.
smelt.session.context_window :: fun(): integer? Configured context-window size in tokens for the active model.
smelt.session.conversation :: fun(opts: table?): table Return user and assistant text from semantic history, excluding system messages, internal notes, and tool results.
smelt.session.cost :: fun(): number Cumulative session cost in USD across every model call this session has made.
smelt.session.created_at_ms :: fun(): integer Unix-epoch timestamp (milliseconds) at which this session was started.
smelt.session.cwd :: fun(): string Current working directory.
smelt.session.delete :: fun(id: string): nil Delete the persisted session with id.
smelt.session.dir :: fun(): string Absolute path of the current session directory.
smelt.session.enter_worktree :: fun(opts: table?): table Create or open a managed git worktree and request a coherent project-context transition.
smelt.session.fork :: fun(): nil Fork the current session: clone its messages into a new session id and switch to it.
smelt.session.history :: fun(opts: table?): table Return the semantic session history as compaction-safe items.
smelt.session.id :: fun(): string Stable session id (matches the on-disk session filename).
smelt.session.info :: fun(): table Return current session metadata as a table.
smelt.session.list :: fun(): table List persisted SQLite sessions other than the current one.
smelt.session.load :: fun(id: string): nil Switch the UI to the persisted session with id.
smelt.session.model_messages :: fun(): table Return the model-visible message list for the next request.
smelt.session.render_preview_into :: fun(id: string, opts: table): table? Render persisted session id into opts.buf using the same styled transcript projection as the live UI.
smelt.session.reset :: fun(): nil Cancel any in-flight agent and clear the session to a blank slate.
smelt.session.retry_persistence :: fun(): boolean Explicitly retry the latest unsaved generation after session persistence becomes blocked.
smelt.session.rewind_to :: fun(block_idx: integer?, opts: table?): nil Rewind the session to a prior user turn.

This SKILL.md is very large, so SkillsMP previews the first section here. View on GitHub

name	customize
description	Customize smelt. Change theme/colors, rebind keys, add slash commands, register tools/plugins, toggle settings, write skills. Includes the full Lua API surface (signatures, descriptions) and pointers to the on-disk built-in source.

Customizing smelt

This skill gives you:

The core principle for how to respond
Where customization files live
Concrete recipes for the common asks
The full Lua API surface (every namespace, signature, and one-line description) so you can look up the exact function before you write the edit

Core principle: persist the change, don't punt to slash commands

Your default workflow is:

Read the user's ~/.config/smelt/init.lua (create it if missing).
Edit in the specific Lua call that effects the change (e.g. smelt.theme.set("SmeltAccent", { fg = { ansi = 208 } })). Preserve every existing line.
Call smelt_reload so the edit takes effect now without waiting for the user to restart smelt.
Briefly tell the user what changed and where.

Mention runtime slash commands only for explicitly session-scoped choices such as /color.

When to use this skill

Load it whenever the user asks to persistently modify how smelt itself behaves:

"change the prompt color to X" / "switch theme to " / "make accents "
"rebind to " / "add a shortcut for X"
"add a /command that does X"
"set to X" / "turn on vim mode" / "disable thinking blocks"
"add an MCP server" / "register a provider" / "use OpenRouter"
"register a tool that "
"write a plugin that "
"write a skill that "

Do not load this skill for ordinary coding work in the user's project. Only load it when the target of the change is smelt's own config.

Where things live

User-editable

Smelt reads Lua from these locations, later sources overriding earlier:

Path	Purpose
Embedded in the binary	Built-in plugins, commands, colorschemes
`$XDG_CONFIG_HOME/smelt/` (default `~/.config/smelt/`)	Global user config
`<cwd>/.smelt/`	Project-local config (gated by `/trust`)

Inside each user dir, the layout is:

~/.config/smelt/
  init.lua                       -- main entry point, runs at startup
  plugins/*.lua                  -- extra Lua chunks loaded after init.lua
  commands/*.lua                 -- /command definitions
  completers/*.lua               -- prompt completers
  tools/*.lua                    -- agent tool registrations
  dialogs/*.lua                  -- custom dialogs
  colorschemes/<name>.lua        -- colorschemes (load via smelt.theme.use)
  skills/<name>/SKILL.md         -- skills (user-authored)
  AGENTS.md                      -- extra system-prompt content

Use ~/.config/smelt/ for changes that should apply everywhere. Use ./.smelt/ for changes that should only apply in the current project (run /trust once after creating it).

Read-only built-in source (for reference)

On every launch, smelt mirrors its embedded runtime/lua/smelt/ tree to:

$XDG_DATA_HOME/smelt/builtins/lua/smelt/

What's inside that's useful when authoring custom Lua:

Path under `builtins/lua/smelt/`	What it gives you
`_meta/<module>.lua`	LuaCATS type stubs. Best place to look up exact signatures + field shapes.
`_meta/_types.lua`	Every class / alias used in `_meta/*.lua` (e.g. `smelt.theme.ThemeSpec`).
`commands/<name>.lua`	Worked `smelt.cmd.register` examples (e.g. `docs.lua`).
`colorschemes/<name>.lua`	Worked `ThemeSpec` tables. `default.lua` is the canonical reference.
`plugins/<name>.lua`	Bundled plugin patterns (e.g. background commands, plan mode).
`completers/<name>.lua`	Built-in completer patterns.
`dialogs/<name>.lua`	Built-in dialog patterns.

Reach for these before writing new Lua: copy the closest worked example, then adapt.

Reference docs

For deep details on a specific function (parameter shapes, return tables, opts records), read the LuaCATS type stubs under the builtins mirror:

$XDG_DATA_HOME/smelt/builtins/lua/smelt/_meta/

Finding the config + builtins dirs from a shell

# config dir (where init.lua lives):
echo "${XDG_CONFIG_HOME:-$HOME/.config}/smelt"

# builtins dir (read-only worked examples):
echo "${XDG_DATA_HOME:-$HOME/.local/share}/smelt/builtins/lua/smelt"

If init.lua doesn't exist, create the directory and the file. The first-launch wizard does this normally, but you may be invoked when neither has happened yet.

Hot reload

Do not silently flip smelt.settings.auto_reload in the user's config. It is enabled by default, but if the user disabled it, respect that choice.

For reference (don't recommend these unless the user asks):

How	Triggered by	When it fires
`smelt_reload` tool	You, the agent	At end of the current turn (the path you should use)
`/reload`	User typing	Immediately (blocks if agent is busy)
`F5`	User keypress	Immediately (blocks if agent is busy)
`auto_reload` setting	User setting	Lua-file changes, debounced and deferred until the agent is idle

Recipes

Rebind a key

smelt.keymap.set(mode, chord, handler) -> Reg. Modes are "n" (normal), "i" (insert), "v" (visual), or "" (all). Chord syntax follows nvim conventions: <C-y>, <S-Tab>, <leader>x, etc.

-- In ~/.config/smelt/init.lua
smelt.keymap.set_leader("<space>")
smelt.keymap.set("n", "<leader>r", function()
  smelt.cmd.run("resume")
end)

<leader> expands when the binding is registered; existing bindings keep the leader value they were created with. The default leader is a single backslash (\\).

-- In ~/.config/smelt/init.lua
smelt.keymap.set("n", "<C-y>", function()
  local text = smelt.transcript.loaded_text_expensive()
  smelt.clipboard.write(text)
  smelt.notify.info("copied transcript")
end)

To remove a binding programmatically use smelt.keymap.unset(mode, chord). For permanent removal, just delete the registration line.

smelt.keymap.list() returns every currently-bound chord. Useful when the user asks "what's bound to X?".

Change the accent color

Edit ~/.config/smelt/init.lua and add (or update) a smelt.theme.set call for the relevant highlight group:

-- In ~/.config/smelt/init.lua
smelt.theme.set("SmeltAccent", { fg = { ansi = 208 }, bold = true })

smelt.theme.set("SmeltAccent", { fg = { ansi = 208 } })

The runtime command /color <preset> is session-only and exists to distinguish parallel sessions. Use it only when the user explicitly asks for a current-session color.

Write a full colorscheme

Drop a Lua file at ~/.config/smelt/lua/smelt/colorschemes/<name>.lua that returns a ThemeSpec table:

return {
  groups = {
    SmeltAccent      = { fg = { ansi = 208 }, bold = true },
    Comment          = { fg = { ansi = 244 } },
    SmeltDiffAddBg   = { bg = { ansi = 22 } },
    -- string-valued entries reference another group in this spec:
    SmeltDiffAdd     = "SmeltAccent",
  },
}

Add a /command

Drop a file at ~/.config/smelt/commands/<name>.lua (or inline in init.lua):

smelt.cmd.register("greet", function(arg)
  smelt.notify.info("hello " .. (arg or "world"))
end, {
  desc = "say hello",
  args = "[name]",      -- shown in /command help
  busy = "run",         -- run (default), reject, queue_request, or queue_command
  startup_ok = false,   -- runnable before init is complete (default false)
  hidden = false,       -- hide from completer + help (default false)
})

The handler receives the trailing argument string (or nil). Errors are surfaced as in-app notifications.

Toggle/set a setting

Write the assignment into ~/.config/smelt/init.lua. Assigning an unknown key or wrong type raises at the call site.

-- In ~/.config/smelt/init.lua
smelt.settings.vim = true
smelt.settings.auto_compact = true
smelt.settings.compact_threshold = 0.65
smelt.settings.show_tps = true

The full table of settings (key, type, default, description) is in the Settings section further down; use it to confirm a key exists and is spelled correctly before writing.

/settings and --set KEY=VALUE exist as runtime/CLI overrides but do not persist; always make the change in init.lua so it survives a restart.

Customize the status line

The status line is a pure-Lua module that ships as smelt.statusline. Register a named source via M.add(name, handler) and the renderer calls it each frame:

local sl = require("smelt.statusline")
sl.add("greeting", function()
  return { { text = "hi ", hl_group = "SmeltAccent" } }
end)

Pin startup defaults (model / mode / reasoning)

smelt.defaults.set({
  model = "openai/gpt-5.5",
  mode = "plan",
  reasoning_effort = "high",
})

CLI flags still win over this. Each field is optional.

Register a provider

smelt.provider.register("openai", {
  type = "openai",
  api_base = "https://api.openai.com/v1",
  api_key_env = "OPENAI_API_KEY",
  models = { "gpt-5.5", { name = "gpt-5-mini", temperature = 0.7 } },
})

type is one of openai-compatible, openai, codex, anthropic-compatible, anthropic, copilot. Re-registering the same name replaces the previous entry.

Register an MCP server

smelt.mcp.register("filesystem", {
  command = { "npx", "-y", "@modelcontextprotocol/server-filesystem", "/tmp" },
  env = { DEBUG = "true" },
  timeout = 30000,
  enabled = true,
})

MCP tool names get prefixed with the server name (filesystem_read_file) and default to ask-permission.

Register an agent tool

smelt.tools.register({
  name = "weather",
  description = "Look up the current weather for a city.",
  parameters = {
    type = "object",
    properties = {
      city = { type = "string", description = "City name" },
    },
    required = { "city" },
  },
  execute = function(args, ctx)
    local resp = smelt.http.get("https://wttr.in/" .. args.city .. "?format=3")
    return resp.body
  end,
  summary = function(args) return "weather: " .. args.city end,
  -- optional: approval_patterns, preflight, render, decide, override
})

Pass override = true to replace a built-in tool with the same name.

Permission rules

smelt.permissions.extend({
  default = { patterns = { bash = { allow = { "git log *", "git status *" } } } },
  apply   = { patterns = { bash = { allow = { "git commit *", "git push *" } } } },
  yolo    = { patterns = { mcp  = { allow = { "*" } } } },
})

Write a project-local skill

When the user wants the agent to know something only inside this project:

<project>/.smelt/skills/<name>/SKILL.md

With frontmatter:

---
name: my-skill
description: One-line summary the agent reads to decide whether to load.
---

# Skill body in markdown

Any reference content the agent should consult on demand.

Then run /trust once after creating .smelt/. The agent will see the skill in its # Skills listing and can load it via load_skill.

Bundled plugins

Bundled with smelt. Drop a file under ~/.config/smelt/plugins/ to add your own.

Autoloaded

Loaded on every launch unless opted out via smelt.builtins.disable({ plugins = { "<name>" } }) in early.lua.

Plugin	Summary
`smelt.plugins.banner`	Empty-state logo decoration + shutdown logo/resume-hint banner.
`smelt.plugins.compact`	Compaction plugin.
`smelt.plugins.debug_panel`	F3 debug panel.
`smelt.plugins.esc_chord`	Esc-Esc: cancel in-flight foreground/background work (`smelt.work.busy` tokens, e.g. /compact), or rewind to the previous turn when idle.
`smelt.plugins.goal`	Goal lifecycle plugin.
`smelt.plugins.perf_panel`	F12 perf panel.
`smelt.plugins.plan_mode`	Plan-mode plugin: registers the `plan` mode and `present_plan` tool.
`smelt.plugins.predict`	Input prediction plugin.
`smelt.plugins.process_control`	Ctrl-G: move a foreground bash command to the background registry.
`smelt.plugins.scroll_pills`	Scroll-pill overlays for transcript navigation: * Bottom pill - " ↓ jump to bottom " while scrolled off-tail; click re-pins to tail. * Top pill - first line of the nearest user message above the viewport; click reveals it with one row of gap so repeated clicks walk back.
`smelt.plugins.terminal_title`	Static terminal window/tab title.
`smelt.plugins.title`	Session title plugin.
`smelt.plugins.turn_notifications`	Optional terminal desktop notification when an agent turn ends.
`smelt.plugins.upgrade`	Autoupgrade plugin.
`smelt.plugins.version`	/version - surface the running smelt build identity as a notification.

Opt-in

Shipped but not autoloaded. Add require("smelt.plugins.<name>") to ~/.config/smelt/init.lua to enable.

Plugin	Summary
`smelt.plugins.inspect`	Optional plugin: `/inspect` opens a local web UI for browsing sessions, their history, and provider request/response audit data.
`smelt.plugins.lsp`	Optional LSP tool facade for agent code navigation.
`smelt.plugins.which_key`	Which-key style popup for pending global Lua keymaps.

Settings

Key	Type	Default	Description
`vim`	`bool`	`false`	Vi keybindings in the prompt.
`system_clipboard`	`bool`	`true`	Sync prompt kills and yanks with the OS clipboard. Disable to keep `C-w`/`C-k`/`C-u`/`C-y` and vim `y`/`p` internal when OSC 52 clipboard writes are unreliable. Bracketed terminal paste still works.
`auto_compact`	`bool`	`true`	Auto-summarize when request context usage crosses `compact_threshold` (forced on in headless).
`auto_continue`	`"off"` \| `"goal"` \| `"always"`	`"goal"`	Idle auto-continue policy: `off` disables it, `goal` continues active auto goals, and `always` continues any idle session.
`show_tps`	`bool`	`true`	Tokens/sec in status bar.
`show_tokens`	`bool`	`true`	Context token count in status bar.
`show_cost`	`bool`	`true`	Session cost in status bar.
`show_prediction`	`bool`	`true`	Ghost-text input predictions in the prompt.
`show_tips`	`bool`	`true`	Curated discovery tips in the start banner and prompt chrome.
`file_icons`	`bool`	`false`	Show Nerd Font file-type icons before inline-code paths that point at existing files.
`file_icon_colors`	`bool`	`true`	Color inline-code file icons with nvim-web-devicons colors when `file_icons` is enabled.
`show_slug`	`bool`	`true`	Task-slug label in status bar.
`terminal_title`	`bool`	`true`	Keep the terminal window/tab title in sync with the current session title.
`restrict_to_workspace`	`bool`	`true`	Downgrade `Allow` to `Ask` for paths outside the workspace.
`redact_secrets`	`bool`	`false`	Scrub detected secrets from user input and tool results before they reach the LLM.
`auto_reload`	`bool`	`true`	Watch Lua config inputs (init.lua, plugins/, commands/, completers/, tools/, dialogs/, runtime overrides) and dispatch `/reload` when any of them changes. Prompt inputs such as AGENTS.md, SKILL.md, and `--system-prompt` stay manual via `/reload`.
`compact_threshold`	`number`	`0.8`	Fraction of the configured context window (0, 1] at which the bundled compact plugin auto-triggers before oversized requests.
`compact_keep_recent_groups`	`number`	`1`	Minimum number of trailing message groups kept verbatim after compaction. A group is a user message, a plain assistant message, or an assistant tool-use step together with its tool outputs.
`request_audit`	`"off"` \| `"summary"` \| `"full"`	`"summary"`	Request audit storage mode. `summary` keeps timing, token, cost, and size metadata only; `full` stores reconstructable provider payloads; `off` disables request audit writes.
`fast_mode`	`bool`	`false`	Request the provider's accelerated inference mode when supported.
`cache_ttl_long`	`bool`	`false`	Anthropic prompt cache TTL. `false` uses the 5-minute ephemeral TTL; `true` opts into the 1-hour TTL. Has no effect on non-Anthropic providers.
`web_search_provider`	`"duckduckgo"` \| `"brave"`	`"duckduckgo"`	Search provider used by the built-in `web_search` tool.
`brave_search_api_key_env`	string	`"BRAVE_SEARCH_API_KEY"`	Environment variable containing the Brave Search API key.
`worktree_root`	string	`".worktrees"`	Root directory for managed git worktrees. Relative paths are resolved inside the git root and contain worktrees directly; absolute paths are external roots and get a per-repository bucket. Supports leading `~`, `$VAR`, and `${VAR}` expansion; relative roots may not escape the repo.
`autoupgrade`	`"off"` \| `"notify"` \| `"auto"`	`"notify"`	Autoupgrade behavior. `"off"` skips checks; `"notify"` shows a pill when an update is available; `"auto"` installs in background on detection.
`autoupgrade_channel`	`"stable"` \| `"unstable"`	`"stable"`	Release channel autoupgrade tracks: `"stable"` (tagged releases, including prereleases) or `"unstable"` (`main` HEAD).
`autoupgrade_interval`	`number`	`3600`	Seconds between background autoupgrade checks. The upgrade plugin clamps to a 60-second minimum to avoid hammering GitHub.

Tier rule: Host vs UiHost

Two tiers exist:

Host: works everywhere, including headless (smelt -p '...').
UiHost: needs the TUI; calling these from a headless run raises.

Gotchas

Reg-returning registrations. smelt.keymap.set, smelt.cmd.register, smelt.tools.register, etc. return a Reg table with :remove(). Hold onto it if you want to unregister later; otherwise reload simply re-runs init.lua and re-registers.
Unknown setting/chord/mode keys raise. Better to fail loud than silently no-op. Check the recipes above for valid values.
Hot reload wipes the Lua context. Don't rely on module-local state surviving a /reload. Use smelt.state / smelt.signal for state that needs to persist.
.smelt/ requires trust. After creating or editing project config, the user must run /trust. The next reload after an edit fails until they do.
Don't hand-edit _meta/ stubs or docs/docs/reference/api/. Those are auto-generated by cargo xtask gen-lua-docs from the Rust side. The same is true for the API index region of this skill.
The builtins dir is read-only. Edits to $XDG_DATA_HOME/smelt/builtins/ are wiped on the next smelt upgrade. Make changes under ~/.config/smelt/ or ./.smelt/.
Preserve existing config when editing init.lua. Always Read the file first, then Edit the specific lines you're changing. Never overwrite the whole file from a template, you'll wipe the user's providers, MCP servers, permissions, and custom plugins. If init.lua doesn't exist, create a minimal one with only the lines the request needs.

Lua API surface

Host tier

Available in every runtime, including headless mode.

`smelt.agent`

Agent-facing prompt customization for Lua plugins.

smelt.agent.add_system_prompt :: fun(text: string): smelt.Reg Append concise guidance to the system prompt while this Lua runtime is active.

`smelt.auth`

Authenticated provider helpers.

smelt.auth.managed_usage :: fun(provider: string): { summary: table?, limits: table[] }?, string? Fetch parsed managed-provider usage.
smelt.auth.request :: fun(provider: string, opts: { path: string, method: string?, body: string? }): { status: integer, body: string }?, string? Run an authenticated request against a provider-owned endpoint using smelt-managed credentials.

`smelt.builtins`

Opt out of bundled smelt.<dotted> modules.

smelt.builtins.disable :: fun(selector: smelt.builtins.Selector): integer Mark the bundled modules in selector as disabled.
smelt.builtins.enable :: fun(selector: smelt.builtins.Selector): integer Undo a prior disable for the bundled modules in selector.
smelt.builtins.is_disabled :: fun(module: string): boolean Return true if the dotted module name (e.g.
smelt.builtins.list :: fun(): table Return the sorted dotted module names that are currently disabled.

`smelt.cli`

Declare and read CLI flags from Lua.

smelt.cli.get :: fun(name: string): any Return the parsed value of the Lua-declared CLI flag name.
smelt.cli.list :: fun(): table Return the names of every Lua-declared CLI flag, in registration order.
smelt.cli.register_flag :: fun(opts: smelt.cli.RegisterFlagOpts): nil Register a CLI flag.

`smelt.clipboard`

Read and write the system clipboard.

smelt.clipboard.read :: fun(): string? Read the current clipboard contents as a string, or nil if empty/unavailable.
smelt.clipboard.write :: fun(text: string): nil Write text to the system clipboard.

`smelt.defaults`

Startup fallbacks for new sessions.

smelt.defaults.set :: fun(cfg: smelt.defaults.Config): nil Set startup defaults for fresh sessions.

`smelt.events`

Occurrence-oriented subscriptions over event-shaped signals such as turn_start, tool_start, and turn_complete.

smelt.events.emit :: fun(event: smelt.events.Name, payload: any): nil Publish payload for the event named event.
smelt.events.new :: fun(event: smelt.events.Name): nil Declare an event named event.
smelt.events.on :: fun(event: smelt.events.Name, handler: fun(value: any)): smelt.Reg Register handler(payload) for the event named event.

`smelt.files`

Workspace file search.

smelt.files.accept :: fun(item: table, opts: table?): boolean, string? Record a selected file result for recent-selection ranking.
smelt.files.rescan :: fun(opts: table?): boolean, string? Trigger an asynchronous full rescan for the current workspace or opts.cwd.
smelt.files.search :: fun(query: string, opts: table?): table Search workspace files.
smelt.files.status :: fun(opts: table?): table Return indexing status for the current workspace or opts.cwd: { root, initialized, files, scanned, scanning, watcher_ready, warmup_complete }.

`smelt.frontend`

Query which frontend is active (TUI vs headless).

smelt.frontend.is_interactive :: fun(): boolean Return true when the frontend supports interactive prompts (a TTY user is present).
smelt.frontend.kind :: fun(): string Return the active frontend kind (e.g.

`smelt.fs`

Sync filesystem primitives.

smelt.fs.complete_path :: fun(dir: string, prefix: string, opts: table?): table?, string? List immediate filesystem completions under dir matching prefix.
smelt.fs.copy :: fun(from: string, to: string): integer?, string? Copy file from to to.
smelt.fs.exists :: fun(p: string): boolean Return true if a filesystem entry exists at p.
smelt.fs.file_info_async :: fun(path: string): table?, string? Return { is_file, len, mtime_ms } for path off the main thread, or (nil, err).
smelt.fs.glob :: fun(pattern: string, path: string?, opts: table?): string[]?, string? Find paths matching pattern under path (defaults to cwd).
smelt.fs.glob_async :: fun(pattern: string, path: string?, opts: table?): table?, string? Find paths matching pattern under path off the main thread.
smelt.fs.is_dir :: fun(p: string): boolean Return true if p exists and refers to a directory.
smelt.fs.is_file :: fun(p: string): boolean Return true if p exists and refers to a regular file.
smelt.fs.mkdir :: fun(p: string): boolean, string? Create directory p (parents must exist).
smelt.fs.mkdir_all :: fun(p: string): boolean, string? Create directory p along with any missing parent directories.
smelt.fs.mkdir_all_async :: fun(path: string): boolean, string? Create path and parents off the main thread.
smelt.fs.read :: fun(p: string): string?, string? Read p into a string.
smelt.fs.read_async :: fun(path: string): string?, string?, integer? Read path off the main thread.
smelt.fs.read_dir :: fun(p: string): string[]?, string? List the immediate entries of directory p.
smelt.fs.read_limited :: fun(p: string, max_bytes: integer): table?, string? Read at most max_bytes bytes from p.
smelt.fs.remove_dir :: fun(p: string): boolean, string? Delete the empty directory at p.
smelt.fs.remove_dir_all :: fun(p: string): boolean, string? Recursively delete the directory tree rooted at p.
smelt.fs.remove_file :: fun(p: string): boolean, string? Delete the file at p.
smelt.fs.rename :: fun(from: string, to: string): boolean, string? Rename or move from to to.
smelt.fs.size :: fun(p: string): integer?, string? Return the size of file p in bytes.
smelt.fs.watch :: fun(path: string, handler: fun(event: { kind: string, detail: string?, paths: string[] }), opts: table?): smelt.Reg Filesystem watcher.
smelt.fs.write :: fun(p: string, contents: string): boolean, string? Write contents to file p, creating it if necessary.
smelt.fs.write_async :: fun(path: string, contents: string): boolean, string?, integer? Write contents to path off the main thread.

`smelt.fs.file_state`

Cached file-state tracker used by tools to detect external modifications between reads and writes.

smelt.fs.file_state.get :: fun(p: string): any Look up the cached file-state entry for p.
smelt.fs.file_state.has :: fun(p: string): boolean Return true if the file-state cache has a recorded entry for p.
smelt.fs.file_state.mtime_ms :: fun(p: string): integer?, string? Return the modification time of p in milliseconds since the UNIX epoch.
smelt.fs.file_state.record_read :: fun(p: string, content: string, offset: integer, limit: integer): nil Record that p was read at byte range [offset, offset+limit) with content so subsequent staleness checks know what the agent has seen.
smelt.fs.file_state.record_read_with_mtime :: fun(p: string, content: string, offset: integer, limit: integer, mtime_ms: integer): nil Record that p was read with a caller-provided mtime in milliseconds, avoiding an extra stat call.
smelt.fs.file_state.record_write :: fun(p: string, content: string): nil Record that p was written with content so subsequent staleness checks see the latest state.
smelt.fs.file_state.staleness_error :: fun(p: string, noun: string?): string? Return an error message describing why the cached state of p is stale relative to disk, or nil if it is up to date.

`smelt.fuzzy`

Fuzzy-match scoring backed by neo_frizbee (SIMD Smith-Waterman).

smelt.fuzzy.rank :: fun(items: table, query: string): integer[] Rank items by fuzzy match against query.
smelt.fuzzy.score :: fun(text: string, query: string): integer? Fuzzy-match score for text against query.

`smelt.grep`

Ripgrep wrapper for searching files.

smelt.grep.run :: fun(pattern: string, path: string, opts: table?): { stdout: string, stderr: string, exit_code: integer, timed_out: boolean }?, string? Run ripgrep with pattern over path off the main thread.

`smelt.html`

HTML parsing: title extraction, link scraping, to_text, to_markdown, DDG results.

smelt.html.links :: fun(source: string, base: string?): string[] Extract all anchor href links from source.
smelt.html.parse_ddg_results :: fun(source: string): table Parse a DuckDuckGo HTML results page into rows of { title, link, description }.
smelt.html.title :: fun(source: string): string? Return the <title> text of source, or nil if no title element is present.
smelt.html.to_markdown :: fun(source: string, base: string?): table Convert source HTML to a { title, content, links } table where content is markdown.
smelt.html.to_text :: fun(source: string): string Strip HTML tags from source and return the visible text content.

`smelt.http`

Asynchronous HTTP get/post.

smelt.http.get :: fun(url: string, opts: table?): { status: integer, final_url: string, body: string, headers: table }?, string? Perform an HTTP GET against url.
smelt.http.post :: fun(url: string, body: string?, opts: table?): { status: integer, final_url: string, body: string, headers: table }?, string? Perform an HTTP POST against url with body bytes.
smelt.http.random_user_agent :: fun(): string Return a randomly selected User-Agent string from the built-in pool.

`smelt.http.cache`

Process-wide HTTP response cache.

smelt.http.cache.read :: fun(key: string): string? Look up a cached HTTP response by key.
smelt.http.cache.write :: fun(key: string, value: string): nil Store value in the HTTP response cache under key.

`smelt.image`

Image file detection and base64 data-URL loading.

smelt.image.data_url_from_bytes :: fun(bytes: string, mime: string): string Encode raw bytes as a base64 data: URL with the given mime type.
smelt.image.is_image_file :: fun(p: string): boolean Return true if p looks like an image file (matched by extension/sniffing).
smelt.image.label_from_path :: fun(p: string): string Return a display label for an image path.
smelt.image.mime_from_path :: fun(p: string): string Return the image MIME type inferred from p's extension.
smelt.image.read_as_data_url :: fun(p: string): string?, string? Read the image at p and encode it as a data: URL.
smelt.image.read_as_data_url_async :: fun(path: string): string?, string? Read and base64-encode an image off the main thread.

`smelt.json`

Encode/decode JSON for Lua plugins.

smelt.json.decode :: fun(text: string): any, string? Decode JSON into a Lua value.
smelt.json.encode :: fun(value: any, opts: table?): string Encode a Lua value as JSON.

`smelt.layout`

Declarative, width-independent content layout primitives for transcript/tool display.

smelt.layout.cap :: fun(child: any, opts: table): smelt.layout.Node Cap a child by rendered rows.
smelt.layout.code :: fun(content: string, opts: table?): smelt.layout.Node Syntax-highlighted code layout leaf.
smelt.layout.diff :: fun(opts: table): smelt.layout.Node Inline-diff render directive.
smelt.layout.elapsed :: fun(elapsed: any, opts: table?): smelt.layout.Node Dynamic elapsed-time text leaf.
smelt.layout.empty :: fun(): smelt.layout.Node Explicit zero-row layout node.
smelt.layout.file_view :: fun(opts: table): smelt.layout.Node Syntax-highlighted file-view render directive.
smelt.layout.gutter :: fun(child: any, opts: table?): smelt.layout.Node Render child with an explicit non-selectable gutter prefix on each emitted row.
smelt.layout.hbox :: fun(items: table): smelt.layout.Node Lay items out horizontally.
smelt.layout.line :: fun(spans: any, opts: table?): smelt.layout.Node Single styled line layout leaf.
smelt.layout.markdown :: fun(content: string, opts: table?): smelt.layout.Node Markdown layout leaf.
smelt.layout.panel :: fun(child: any, opts: table?): smelt.layout.Node Render child inside a full-width background panel.
smelt.layout.row_prefix :: fun(child: any, opts: table): smelt.layout.Node Apply row chrome to child after the child has produced rows.
smelt.layout.runs :: fun(lines: any, opts: table?): smelt.layout.Node Styled inline text layout leaf.
smelt.layout.separator :: fun(opts: table?): smelt.layout.Node Full-width horizontal separator.
smelt.layout.style :: fun(child: any, opts: table?): smelt.layout.Node Apply inherited style to a child layout.
smelt.layout.text :: fun(content: string, opts: table?): smelt.layout.Node Plain text layout leaf.
smelt.layout.vbox :: fun(items: table): smelt.layout.Node Stack items vertically into a single block layout.

`smelt.lifecycle`

Host-phase hooks keyed by event name.

smelt.lifecycle.guard :: fun(scopes: string|string[]|table?): smelt.lifecycle.Guard Create a guard whose :alive() flips false when any scoped epoch changes.
smelt.lifecycle.on :: fun(event: string, fn: function): smelt.Reg Queue fn(ctx) for the lifecycle event named event.
smelt.lifecycle.on_ready :: fun(fn: function): smelt.Reg Shorthand for lifecycle.on("ready", fn).
smelt.lifecycle.on_shutdown :: fun(fn: function): smelt.Reg Shorthand for lifecycle.on("shutdown", fn).

`smelt.log`

Structured JSONL log entries written to the engine log file.

smelt.log.error :: fun(event: string, data: any?): nil Write a JSONL log entry at Error level.
smelt.log.info :: fun(event: string, data: any?): nil Write a JSONL log entry at Info level.
smelt.log.warn :: fun(event: string, data: any?): nil Write a JSONL log entry at Warn level.

`smelt.lsp`

Generic stdio Language Server Protocol client.

smelt.lsp.configure :: fun(config: table): nil Configure available language servers.

`smelt.mcp`

Config-time MCP server registration.

smelt.mcp.list :: fun(): table Snapshot every declared MCP server.
smelt.mcp.register :: fun(name: string, cfg: smelt.mcp.Config): smelt.Reg Declare an MCP server named name.
smelt.mcp.status :: fun(name: string): string? Return the lifecycle status for server name: "disabled", "connecting", "connected", or "error".
smelt.mcp.tools :: fun(server: string?): table Snapshot every discovered MCP tool.

`smelt.messages`

Persistent message log with full bodies and tracebacks.

smelt.messages.append :: fun(kind: string, source: string, msg: string): nil Append a new message of kind ("error", "warn"/"warning", anything else falls back to "info") attributed to source with body msg.
smelt.messages.clear :: fun(): nil Drop every message from the log.
smelt.messages.count :: fun(): integer Return the total number of messages currently in the log.
smelt.messages.list :: fun(): table Return every persisted message as rows of { kind, source, summary, full, ts_ms }, ordered oldest-first.
smelt.messages.mark_read :: fun(): nil Mark every message in the log as read so unread_count returns 0 until new errors arrive.
smelt.messages.unread_count :: fun(): integer Return the number of unread error messages in the log.

`smelt.os`

Environment and system primitives: getenv, setenv, platform, cwd, pid, etc.

smelt.os.arch :: fun(): string Return the target CPU architecture as reported by std::env::consts::ARCH (e.g.
smelt.os.cwd :: fun(): string?, string? Return the current working directory as (path, nil), or (nil, err_string) on failure.
smelt.os.exe_path :: fun(): string?, string? Return the filesystem path to the running smelt binary as (path, nil) on success, or (nil, err_string) on failure.
smelt.os.getenv :: fun(name: string): string? Return the value of the environment variable name, or nil if it is not set.
smelt.os.home :: fun(): string? Return the user's home directory, or nil if it cannot be determined.
smelt.os.open_url :: fun(url: string): boolean, string? Open url in the system's default browser.
smelt.os.open_url_if_available :: fun(url: string): table Open url only when the host environment can auto-open a browser.
smelt.os.pid :: fun(): integer Return the OS process id of the running smelt instance.
smelt.os.platform :: fun(): string Return the target operating system as reported by std::env::consts::OS (e.g.
smelt.os.set_cwd :: fun(p: string): boolean, string? Change the process working directory to p.
smelt.os.setenv :: fun(name: string, value: string): nil Set the process environment variable name to value.
smelt.os.tempdir :: fun(): string Return the platform temporary directory path.
smelt.os.unsetenv :: fun(name: string): nil Remove the environment variable name from the process environment.

`smelt.parse`

Pure parsers: frontmatter extraction from markdown documents.

smelt.parse.frontmatter :: fun(content: string): any, string Split ----delimited YAML frontmatter from a markdown document.
smelt.parse.json :: fun(content: string): any Parse a JSON document into a Lua value.

`smelt.path`

Pure path arithmetic: normalize, join, relative, expand, display, etc.

smelt.path.basename :: fun(p: string): string? Return the final component (file name) of p, or nil if p ends in ...
smelt.path.canonical :: fun(p: string): string?, string? Resolve p to its canonical absolute form (following symlinks).
smelt.path.commands_dir :: fun(): string Return the absolute path to the slash-commands directory under the user config root.
smelt.path.config_dir :: fun(): string Return the absolute path to smelt's user config directory.
smelt.path.display :: fun(p: string): string Return a user-friendly rendering of p for UI display (e.g. with the home dir abbreviated to ~).
smelt.path.display_streaming :: fun(p: string): string Return a user-friendly rendering of a possibly partial path for streaming tool summaries.
smelt.path.expand :: fun(p: string): string Expand config-path syntax in p: leading ~, $VAR, and ${VAR}.
smelt.path.extension :: fun(p: string): string? Return the file extension of p (without the leading dot), or nil if there is none.
smelt.path.is_absolute :: fun(p: string): boolean Return true if p is an absolute path on the current platform.
smelt.path.join :: fun(...: string): string Join the variadic parts into a single path using the platform separator.
smelt.path.normalize :: fun(p: string): string Normalize p by collapsing redundant ., .., and separator components without touching the filesystem.
smelt.path.parent :: fun(p: string): string? Return the parent directory of p, or nil if p has no parent component.
smelt.path.relative :: fun(base: string, target: string): string Return the path of target expressed relative to base.

`smelt.perf`

Lightweight scope timers that feed smelt.metrics.perf_snapshot.

smelt.perf.time :: fun(label: string, fn: fun(): any): any Run fn() and record its elapsed time under label.

`smelt.process`

Run, spawn, list, and kill processes against the ProcessRegistry. spawned processes are non-blocking; run processes wait for completion.

smelt.process.detach_foreground :: fun(): boolean Move the most recently started foreground streaming process to the background process registry.
smelt.process.get_default_shell :: fun(): any Return the current default shell as { program, args }, or nil when the built-in sh -c default is in effect.
smelt.process.kill :: fun(id: string): nil Stop the registered process with id.
smelt.process.list :: fun(): table Return the registry of running processes as rows of { id, pid?, command, elapsed_secs }.
smelt.process.output :: fun(id: string): table Return the buffered output snapshot for registered process id without draining it.
smelt.process.read_output :: fun(id: string): table Drain buffered output from the registered process id.
smelt.process.run :: fun(cmd: string, args: string[]?, opts: table?): { stdout: string, stderr: string, exit_code: integer, timed_out: boolean }?, string? Run cmd with args off the main thread.
smelt.process.run_streaming :: fun(task_id: integer, call_id: string, command: string, timeout_ms: integer, background_on_timeout: boolean): nil Run command with a timeout_ms deadline, streaming each output line into the live tool call call_id and resolving task task_id with { content, is_error, timed_out, background_id? } (or { __cancelled = true } if cancelled).
smelt.process.set_default_shell :: fun(opts: table?): nil Override the wrapping shell used by spawn_bg and run_streaming for string-form commands.
smelt.process.spawn_bg :: fun(command: string): string Spawn command as a background child registered with the process registry.
smelt.process.stop :: fun(id: string): { text: string }?, string? Stop a registered background process and return its buffered output.

`smelt.provider`

List built-in model providers and register custom ones.

smelt.provider.has_real_rows :: fun(rows: table[]?): boolean Return true when the row list contains at least one non-synthetic row.
smelt.provider.is_loading :: fun(result: table?): boolean Return true when a provider or normalized result is still loading.
smelt.provider.item_key :: fun(item: table?): string? Return the stable identity key used to preserve selection across provider refreshes.
smelt.provider.list :: fun(): table Return every registered provider as an array of tables.
smelt.provider.middleware :: fun(mw: table): smelt.Reg Register provider middleware.
smelt.provider.normalize :: fun(result: table[]|table?, opts?: { show_message?: boolean, loading_message?: string }): smelt.provider.NormalizedResult Normalize a provider result or plain row list into renderable rows plus loading state.
smelt.provider.register :: fun(name: string, cfg: smelt.provider.Config): smelt.Reg Declare a provider named name.
smelt.provider.synthetic_only :: fun(rows: table[]?): boolean Return true when the row list is exactly one synthetic status/message row.

`smelt.reg`

Helpers for constructing Reg handles.

smelt.reg.compose :: fun(...: smelt.Reg?): smelt.Reg Combine variadic Regs into one.
smelt.reg.new :: fun(undo: fun()): smelt.Reg Wrap undo as a Reg.

`smelt.remember`

Per-key opt-in to last-used recall on launch.

smelt.remember.set :: fun(cfg: smelt.remember.Config): nil Set which startup choices are remembered across launches.

`smelt.shell`

Shell command splitting and interactive/background-operator validators.

smelt.shell.check_background_op :: fun(command: string): string? Return a user-facing error message if command uses the shell & background operator, or nil otherwise.
smelt.shell.check_interactive :: fun(command: string): string? Return a user-facing error message if command would invoke an interactive program (editor, REPL, pager, git -i, etc.), or nil if it is safe to run non-interactively.
smelt.shell.extract_paths :: fun(command: string): string[] Extract filesystem paths referenced by command for workspace permission checks.
smelt.shell.has_output_redirection :: fun(command: string): boolean Return true when command contains shell output redirection such as > or >>.
smelt.shell.split :: fun(command: string): string[] Split command into the sequence of subcommands separated by shell operators (;, &&, ||, |).
smelt.shell.split_with_ops :: fun(command: string): table Split command into subcommands and pair each with the operator that followed it.

`smelt.signal`

Named reactive values.

smelt.signal.get :: fun(name: smelt.signal.Name): any Return the current value of signal name, or nil when the signal is not declared.
smelt.signal.glob :: fun(pattern: string, handler: fun(arg1: string, arg2: any, arg3: any)): smelt.Reg Register handler(name, value, previous) for every signal whose name matches pattern (glob syntax).
smelt.signal.new :: fun(name: smelt.signal.Name, initial: any): nil Declare a signal named name with initial as its starting value.
smelt.signal.set :: fun(name: smelt.signal.Name, value: any): nil Publish value for signal name.
smelt.signal.subscribe :: fun(name: smelt.signal.Name, handler: fun(arg1: any, arg2: any)): smelt.Reg Register handler(value, previous) for signal name.

`smelt.skills`

List and load skill content from the SkillLoader populated at startup.

smelt.skills.content :: fun(name: string): string?, string? Load the skill named name and return (content, nil) on success or (nil, err_string) if the skill is missing or failed to load.
smelt.skills.info :: fun(): table Return every discovered skill as { name, description, source, location, shadowed } rows sorted by name.
smelt.skills.list :: fun(): table Return the names of every skill discovered by the loader as a Lua array.

`smelt.state`

Per-plugin state.

smelt.state.get :: fun(name?: string): table Return an ephemeral state table.
smelt.state.persistent :: fun(name: string, opts: { debounce_ms: integer? }?): table

`smelt.task`

Yield-then-resume coroutine bridge: alloc and resume external tasks.

smelt.task.all :: fun(...: fun(): any): any[] Run fns concurrently; wait for all to finish.
smelt.task.alloc :: fun(): integer Allocate and return a fresh external task id used to pair a yielded coroutine with a later task.resume call.
smelt.task.external :: fun(start: fun(id: integer)): any Allocate an external task id, invoke start(id) to kick off whatever will eventually call smelt.task.resume(id, value) (or resolve through the Rust resume sink), and park until that resolution arrives.
smelt.task.is_cancelled :: fun(err: any): boolean Check whether an error value represents a task or engine-ask cancellation.
smelt.task.race :: fun(...: fun(): any): integer, any Run fns concurrently; first to return wins.
smelt.task.resume :: fun(id: integer, value: any): nil Resume the yielded task id with value.
smelt.task.timeout :: fun(ms: integer, fn: fun(): any): any, string? Run fn with an ms-millisecond deadline.
smelt.task.wait :: fun(id: integer, opts?: table): any Park the running task until smelt.task.resume(id, value) fires.

`smelt.tick`

Reload-safe periodic work.

smelt.tick.every :: fun(secs: integer, fn: fun()): smelt.Reg Reload-safe periodic work.

`smelt.time`

Wall-clock time parsing and formatting.

smelt.time.format :: fun(timestamp: integer, format: string): string? Format Unix seconds in the user's local time zone with a strftime-style format string.
smelt.time.format_utc :: fun(timestamp: integer, format: string): string? Format Unix seconds in UTC with a strftime-style format string.
smelt.time.now :: fun(): integer Return the current Unix timestamp in seconds.
smelt.time.now_ms :: fun(): integer Return the current Unix timestamp in milliseconds.
smelt.time.parse_iso8601 :: fun(timestamp: string): integer? Parse an ISO-8601 / RFC3339 timestamp and return Unix seconds, not milliseconds, or nil when the input is invalid.

`smelt.timer`

One-shot and recurring timer callbacks.

smelt.timer.every :: fun(ms: integer, handler: fun()): smelt.Reg Schedule handler to fire repeatedly every ms milliseconds.
smelt.timer.set :: fun(ms: integer, handler: fun()): smelt.Reg Schedule handler to run once after ms milliseconds.

`smelt.tools`

smelt.tools.call :: fun(name: string, args: table?, parent_call_id: string?): { content: string, is_error: boolean?, metadata: table? } Call another tool from within execute.
smelt.tools.default_summary :: fun(args: table?): string Best-effort one-liner summary of a tool call's arguments.
smelt.tools.list :: fun(): table Return the names of every registered plugin tool, sorted.
smelt.tools.middleware :: fun(name: string, mw: table): smelt.Reg Register middleware for tool name.
smelt.tools.patch :: fun(name: string, patch: table): smelt.Reg Patch metadata for an already-registered tool without replacing its handler.
smelt.tools.path_summary :: fun(path: string, ctx?: { final: boolean }, opts?: { prefix: string?, suffix: string? }): string Format a path for a tool summary.
smelt.tools.register :: fun(def: smelt.tools.ToolDef): smelt.Reg Register a plugin tool.
smelt.tools.resolve :: fun(request_id: integer, call_id: string, result: table): nil Resolve the pending tool call call_id from request request_id with { content, is_error, metadata? }.
smelt.tools.unregister :: fun(name: string): boolean Unregister a previously-registered tool by name.

`smelt.transcript.defaults`

Bundled default transcript renderers.

smelt.transcript.defaults.child_failed :: fun(child: smelt.transcript.Block): boolean True when a grouped child represents a failed or denied tool result.
smelt.transcript.defaults.group_children :: fun(group: smelt.transcript.Group): smelt.transcript.Block[] Return child snapshots for a transcript group snapshot.
smelt.transcript.defaults.group_failure_counts :: fun(group: smelt.transcript.Group): integer, integer Count failed and denied tool children in a transcript group snapshot.
smelt.transcript.defaults.render :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render any semantic transcript block with the bundled default policy.
smelt.transcript.defaults.render_assistant :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render assistant text.
smelt.transcript.defaults.render_code :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a code block with syntax highlighting.
smelt.transcript.defaults.render_compacted :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compacted-history marker.
smelt.transcript.defaults.render_compaction_preview :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render an in-flight compaction summary preview.
smelt.transcript.defaults.render_exec :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render an exec block.
smelt.transcript.defaults.render_group_child_list :: fun(group: smelt.transcript.Group, ctx: smelt.transcript.Context, opts: table?): smelt.layout.Node Render a compact ordered child list for collapsed group nodes.
smelt.transcript.defaults.render_group_children :: fun(group: smelt.transcript.Group, ctx: smelt.transcript.Context): smelt.layout.Node Render all group children through the bundled default block renderer.
smelt.transcript.defaults.render_llm_markdown :: fun(content: string?, opts: table?): smelt.layout.Node Render LLM-authored Markdown with the shared transcript Markdown path.
smelt.transcript.defaults.render_llm_markdown_tail :: fun(content: string?, ctx: smelt.transcript.Context?, opts: table?): smelt.layout.Node Render capped LLM-authored Markdown for tool bodies and other long outputs.
smelt.transcript.defaults.render_mode :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a mode note.
smelt.transcript.defaults.render_process_status :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a process-status note.
smelt.transcript.defaults.render_thinking :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render thinking for the current transcript view state.
smelt.transcript.defaults.render_thinking_full :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render the full thinking block with the current gutter.
smelt.transcript.defaults.render_thinking_peek :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compact live preview of thinking: first rendered row, omitted rows, tail.
smelt.transcript.defaults.render_thinking_summary :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compact thinking summary.
smelt.transcript.defaults.render_tool :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a tool block for the current transcript view state.
smelt.transcript.defaults.render_tool_body :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context, opts: table?): smelt.layout.Node? Render a tool body.
smelt.transcript.defaults.render_tool_full :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a full tool block using the current generic primitives and explicit item construction.
smelt.transcript.defaults.render_tool_header :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context, opts: table?): smelt.layout.Node Render the default one-line tool header.
smelt.transcript.defaults.render_tool_output :: fun(output: smelt.transcript.ToolOutput?, ctx: smelt.transcript.Context?, opts: table?): smelt.layout.Node Render raw tool output using generic layout primitives: text, gutter, and a rendered-row cap.
smelt.transcript.defaults.render_tool_output_tail :: fun(output: smelt.transcript.ToolOutput?, ctx: smelt.transcript.Context?, opts: table?): smelt.layout.Node Render raw tool output without gutter using generic layout primitives: text/runs and a rendered-row cap.
smelt.transcript.defaults.render_tool_summary :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a compact tool summary: header plus an optional detail line.
smelt.transcript.defaults.render_unknown :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render unknown block kinds without failing the transcript.
smelt.transcript.defaults.render_user :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render a user block.
smelt.transcript.defaults.render_user_text :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): smelt.layout.Node Render user text.
smelt.transcript.defaults.tool_collapsed_detail :: fun(block: smelt.transcript.Block, ctx: smelt.transcript.Context): string? Return a compact tool detail for collapsed tool blocks.

`smelt.transcript.groups`

Declarative transcript display grouping.

smelt.transcript.groups.cache_key :: fun(): integer? Current group-registry cache key, or nil when any active group opted out of persisted planning/layout caches.
smelt.transcript.groups.generation :: fun(): integer Current group-registry generation.
smelt.transcript.groups.list :: fun(): smelt.transcript.GroupSpec[] Return group specs in planner order: higher priority first, then registration order.
smelt.transcript.groups.register :: fun(spec: smelt.transcript.GroupSpec): smelt.Reg Register or replace a declarative transcript group type.

`smelt.trust`

Query and mutate the per-project content trust store.

smelt.trust.mark :: fun(): string Mark the current working directory as trusted, persisting it in the user's trust store.
smelt.trust.status :: fun(): string Return the trust state of the current working directory: "trusted", "untrusted", or "no_content".

UiHost tier

Requires a terminal UI; calling these from headless mode raises.

`smelt.buf`

Buffer handle constructor.

smelt.buf.new :: fun(opts: smelt.buf.NewOpts?): smelt.buf.Buf Create a buffer and return a Buf userdata.

`smelt.config`

Resolved application configuration introspection.

smelt.config.api_base :: fun(): string? Active API base URL.
smelt.config.api_key_env :: fun(): string? Name of the environment variable that supplies the API key for the active provider.
smelt.config.context_window :: fun(): integer? Configured context-window size in tokens for the active model, or nil when not declared.
smelt.config.model_config :: fun(): table? Resolved model-level sampling, capability, and cost overrides as a table.
smelt.config.provider_type :: fun(): string? Active provider type string, e.g.
smelt.config.runtime_status :: fun(): table Return sanitized runtime and reload diagnostics: committed Lua/runtime revisions, pending reload and last failure location, model selection, managed-provider freshness, and MCP/LSP/watcher/context controller convergence.

`smelt.confirm`

Confirm dialog primitives - preview dispatch, back-tab cycling, and choice resolution.

`smelt.dialog`

Root-docked modal dialog primitives.

smelt.dialog.content :: fun(opts: table?): smelt.win.Win, smelt.buf.Buf General-purpose body leaf.
smelt.dialog.current :: fun(): table | nil Return the topmost active dialog ctx (the same shape passed to on_submit/keymap handlers: { resolve, close, win, panels, focused_leaf }), or nil if no dialog is open.
smelt.dialog.input :: fun(placeholder: string?, opts: table?): smelt.win.Win, smelt.buf.Buf, smelt.input.Input Build a line-input leaf with a fresh buffer.
smelt.dialog.list :: fun(buf: smelt.buf.Buf, opts: table?): smelt.win.Win Wrap an existing buf as a selectable list leaf.
smelt.dialog.markdown :: fun(text: string): smelt.win.Win, smelt.buf.Buf Render text as a non-focusable markdown leaf.
smelt.dialog.menu :: fun(items: (string|smelt.dialog.MenuItem)[], opts: smelt.dialog.MenuOpts?): smelt.win.Win, table
smelt.dialog.open :: fun(opts: smelt.dialog.Opts): any Coroutine-blocking dialog opener.
smelt.dialog.open_handle :: fun(opts: smelt.dialog.Opts): table Non-coroutine open.
smelt.dialog.picker :: fun(opts: smelt.dialog.PickerOpts): any Coroutine-blocking Telescope-style picker.
smelt.dialog.title :: fun(title: string|table, opts?: { pad?: boolean }): table|string|nil Return a title spec styled for dialog/window chrome.
smelt.dialog.viewer :: fun(opts: table): table, smelt.buf.Buf, smelt.win.Win Open a read-only content dialog.

`smelt.engine`

LLM engine control - cancel, ask, inherited ask, submit commands, and request tool approval.

smelt.engine.ask :: fun(spec: smelt.engine.AskSpec): integer Run an out-of-band LLM request without touching the main turn.
smelt.engine.ask_inherited :: fun(spec: smelt.engine.InheritedAskSpec): integer Run an auxiliary LLM request that inherits the current session's assembled system prompt and active tool list.
smelt.engine.cancel :: fun(): nil Cancel the in-flight turn or foreground/background work.
smelt.engine.is_running :: fun(): boolean Return true if an agent turn is currently in flight (a request is being streamed or a tool is executing).
smelt.engine.on_context_limit :: fun(hook: fun(arg1: smelt.engine.AskMessage[], arg2: fun(value: any))): smelt.Reg Register a recovery hook the engine calls when a provider returns a context-window error mid-turn.
smelt.engine.on_prepare_request :: fun(hook: fun(arg1: smelt.engine.PrepareRequest, arg2: fun(value: any))): smelt.Reg Register a hook the engine calls immediately before each provider request.
smelt.engine.reload :: fun(): nil Queue a transactional Lua reload for the next safe point.
smelt.engine.reload_when_idle :: fun(): boolean Schedule a full config reload for the next safe idle point, including prompt inputs such as AGENTS.md, skills, and --system-prompt.
smelt.engine.submit_command :: fun(name: string, body: string, overrides: smelt.engine.CommandOverrides?, display: string?): nil Start an agent turn from a Lua-defined custom command (/name).
smelt.engine.submit_command_continuation :: fun(name: string, body: string, overrides: smelt.engine.CommandOverrides?, display: string?, continuation_token: integer?): boolean Start an idle custom-command continuation without using the prompt queue.
smelt.engine.summary_prefix :: fun(): string Return the canonical compaction-summary prefix used when a checkpoint summary is represented as a user message.

`smelt.history`

Prompt history entries and search.

smelt.history.entries :: fun(): table Return the prompt history as an array of strings, oldest first.
smelt.history.search :: fun(query: string): table Rank prompt history against query using the history-specific scorer (word-match boost, recency bonus, dedupe).

`smelt.input`

Single-line input handle constructor.

smelt.input.new :: fun(opts: table?): smelt.input.Input? Create a single-line input and return an Input handle.

`smelt.inspect`

Local session introspection web UI.

smelt.inspect.url :: fun(): any Return the URL of the running inspector server, or nil if it is not running.

`smelt.keymap`

smelt.keymap.help_sections :: fun(): table Return layered keybinding help as { title, entries = { { label, detail } } } rows.
smelt.keymap.leader :: fun(): string Return the current <leader> expansion used when registering keymaps.
smelt.keymap.list :: fun(): table Return the set of currently-bound { mode, chord, desc? } rows.
smelt.keymap.prefixes :: fun(pending: string, mode: string?): table Return effective keymaps that extend pending in mode as { mode, chord, suffix, desc? } rows.
smelt.keymap.set :: fun(mode: string, chord: string, handler: fun(), opts: table?): smelt.Reg Bind chord in mode to a Lua callback.
smelt.keymap.set_leader :: fun(leader: string): nil Set the <leader> expansion for subsequent keymap registrations.
smelt.keymap.unset :: fun(mode: string, chord: string): boolean Drop the binding for chord in mode.

`smelt.list`

Picker-style virtual list widget.

smelt.list.new :: fun(opts: smelt.list.Opts): smelt.list.List Build a structured list bound to the dialog-list opts.leaf and its backing opts.buf.

`smelt.metrics`

Metrics ledger access and live perf instrumentation.

smelt.metrics.entries :: fun(): table Return raw entries from the on-disk metrics ledger.

`smelt.metrics.perf`

Perf instrumentation toggle, clear, and snapshot.

smelt.metrics.perf.clear :: fun(): nil Clear all accumulated perf samples (durations and value gauges).
smelt.metrics.perf.enabled :: fun(): boolean Return whether perf instrumentation collection is enabled.
smelt.metrics.perf.set_enabled :: fun(on: boolean): nil Toggle perf instrumentation collection on/off.
smelt.metrics.perf.snapshot :: fun(): table Return the current perf snapshot as { durations, values, enabled } with per-label count, last, p50, p95, p99, max, total fields.
smelt.metrics.perf.snapshot_top :: fun(limit: integer?): table Return a cheap live perf snapshot with only the top limit duration rows and no value rows.

`smelt.model`

Model selector.

smelt.model.capabilities :: fun(): table? Resolved capabilities for the active model/provider as { input_modalities, supports_image, supports_pdf, supports_video, supports_reasoning, tool_calling, max_tokens, context_window, transport = { ... }, sources = { ... } }.
smelt.model.current :: fun(): string? Return the active model key, or nil when no active model exists.
smelt.model.input_modalities :: fun(): table? Resolved input modalities for the active model as an array such as { "text", "image", "pdf" }.
smelt.model.list :: fun(): table Return an array of { key, name, display_name?, provider, api_base, provider_type } records for every model the active config can switch to.
smelt.model.max_tokens :: fun(): integer? Resolved maximum output tokens for the active model.
smelt.model.preferred :: fun(name: any, value: any): any
smelt.model.pricing :: fun(): table? Resolved pricing for the active model as { input, output, cache_read, cache_write, source }.
smelt.model.set :: fun(name: string): nil Switch the active model by key.
smelt.model.status :: fun(): table Return { current, requested, availability, reason?, providers } for model selection.
smelt.model.supports_input :: fun(modality: string): boolean? Return whether the active model supports the named input modality, for example image or pdf.
smelt.model.transport :: fun(): table? Return { provider_type, api_base, api_key_env, multimodal_tool_results } for the active model transport.

`smelt.notebook`

Parse, read, and apply notebook cell edits, plus compute preview data for the edit_notebook tool.

smelt.notebook.apply_edit :: fun(args: table): any?, string? Apply a notebook edit (cell insert/replace/delete) described by args and persist the new file.
smelt.notebook.apply_edit_async :: fun(args: table): table?, string? Apply a notebook edit off the main thread.
smelt.notebook.is_notebook_path :: fun(path: string): boolean Return true if path looks like a Jupyter notebook (.ipynb extension).
smelt.notebook.parse :: fun(json: string): table?, string? Parse a notebook JSON string.
smelt.notebook.read :: fun(path: string, offset: integer, limit: integer): string?, string? Render a Jupyter notebook at path as cell-by-cell text starting at offset for at most limit cells.
smelt.notebook.read_async :: fun(path: string, offset: integer, limit: integer): string?, string?, string?, integer? Render a notebook off the main thread.

`smelt.notify`

Status-area toasts.

smelt.notify.error :: fun(msg: string, source: string?): nil Show an error toast (highlighted with the error color) and append the body to the message log.
smelt.notify.info :: fun(msg: string, source: string?): nil Show an informational toast and append the body to the message log.
smelt.notify.scoped :: fun(source: string): smelt.notify.Scoped Bind source once and return a small bag that forwards to smelt.notify.info / smelt.notify.error / smelt.notify.warn with the source pinned.
smelt.notify.warn :: fun(msg: string, source: string?): nil Show a warning toast and append the body to the message log.

`smelt.overlay`

Overlay handle constructor.

smelt.overlay.new :: fun(opts: smelt.overlay.NewOpts): smelt.overlay.Overlay Open an overlay rendered from opts.layout (a smelt.ui.layout userdata) and return an Overlay userdata.

`smelt.paint`

smelt.paint.register :: fun(func: fun(arg1: smelt.paint.Slice, arg2: table), opts: table?): smelt.paint.Paint Register func as a paint callback and return an opaque Paint handle (userdata with :remove()).

`smelt.permissions`

List, sync, and extend permission policy state.

smelt.permissions.check :: fun(mode_str: string, bucket: string, value: string): string Decide a tool-specific pattern bucket (e.g.
smelt.permissions.check_tool :: fun(mode_str: string, name: string): string Decision primitives for tool decide callbacks.
smelt.permissions.extend :: fun(spec: smelt.permissions.PolicySpec): nil Extend the generated permission policy with user rules.
smelt.permissions.grant_session :: fun(grant: smelt.permissions.SessionPathGrant): nil Add one session-scoped grant.
smelt.permissions.list :: fun(): smelt.permissions.ListResult Return current permission rules as { session = { { tool, pattern } }, path_grants = { { kind = "path", mode?, tool, access, path_prefix } }, workspace = { { tool, patterns } } }.
smelt.permissions.sync :: fun(spec: smelt.permissions.SyncSpec): nil Replace runtime + workspace permission entries with spec.session, spec.path_grants, and spec.workspace.

`smelt.picker`

Picker handle constructor.

smelt.picker.fuzzy :: fun(opts: smelt.picker.FuzzyOpts): smelt.picker.FuzzyResult? Fuzzy-finder picker.
smelt.picker.new :: fun(opts: smelt.picker.NewOpts): smelt.picker.Picker Open a picker overlay and return a Picker userdata.
smelt.picker.open :: fun(opts: smelt.picker.NewOpts): smelt.picker.OpenResult? Open a floating picker over opts.items and yield until the user accepts or dismisses.

`smelt.prompt`

The main editable input surface: win handle, text get/set, and cursor control.

smelt.prompt.acquire :: fun(): smelt.Reg ── Modality lock ─────────────────────────────────────────────────────── Take a modality lock on the prompt area so completers/pickers don't pop while the caller owns the screen.
smelt.prompt.completer :: fun(spec: smelt.prompt.CompleterSpec|smelt.prompt.MatchesCompleterSpec): smelt.Reg Register a completer spec.
smelt.prompt.cursor :: fun(pos: integer?): integer Read or write the prompt cursor as a byte offset into text().
smelt.prompt.has_stash :: fun(): boolean Return whether the prompt currently holds a stashed input snapshot (Ctrl+S).
smelt.prompt.is_modal :: fun(): boolean True while at least one smelt.prompt.acquire() lock is outstanding.
smelt.prompt.open_picker :: fun(opts: smelt.prompt.PickerOpts): table? Prompt-docked picker.
smelt.prompt.queued :: fun(): string[] Return the queued prompt text rows.
smelt.prompt.queued_rows :: fun(): table[] Return queued prompt rows as { text, kind } tables.
smelt.prompt.replace_range :: fun(start: integer, end: integer, text: string): integer UTF-8-safe replace of the byte range [start, end) in the prompt with text.
smelt.prompt.set_text :: fun(text: string): nil Replace the prompt buffer with text.
smelt.prompt.text :: fun(): string Return the prompt input buffer's current text.
smelt.prompt.win :: fun(): smelt.win.Win Return a Win handle for the prompt input.

`smelt.render`

Paint text / markdown / syntax-highlighted code / split diffs into a Buf.

smelt.render.diff_split :: fun(left: smelt.buf.Buf, right: smelt.buf.Buf, opts: smelt.render.DiffSplitOpts): nil Paint a side-by-side diff between opts.old and opts.new into two buffers.
smelt.render.markdown :: fun(buf: smelt.buf.Buf, source: string): nil Render markdown source into the buffer using the same renderer the transcript uses for assistant text blocks.
smelt.render.syntax :: fun(buf: smelt.buf.Buf, opts: smelt.render.SyntaxOpts): nil Paint syntect-highlighted code from opts.content into the buffer as a plain block.
smelt.render.text :: fun(buf: smelt.buf.Buf, content: string, opts: smelt.render.TextOpts?): nil Paint plain text into a buffer.

`smelt.search`

Search controls for the active UI session.

smelt.search.clear :: fun(): nil Clear the active search session and remove search highlights from its target window.

`smelt.session`

Current session metadata, turn list, message snapshots, rewind, and persisted session management.

smelt.session.checkpoint :: fun(spec: table): boolean? Install a model-context checkpoint without deleting transcript history.
smelt.session.context_note :: fun(name: string, text: string?, opts: table?): nil Set or clear a named hidden model-visible context note.
smelt.session.context_tokens :: fun(): integer? Latest non-background provider-reported active-context token count, or nil before the first usage report.
smelt.session.context_window :: fun(): integer? Configured context-window size in tokens for the active model.
smelt.session.conversation :: fun(opts: table?): table Return user and assistant text from semantic history, excluding system messages, internal notes, and tool results.
smelt.session.cost :: fun(): number Cumulative session cost in USD across every model call this session has made.
smelt.session.created_at_ms :: fun(): integer Unix-epoch timestamp (milliseconds) at which this session was started.
smelt.session.cwd :: fun(): string Current working directory.
smelt.session.delete :: fun(id: string): nil Delete the persisted session with id.
smelt.session.dir :: fun(): string Absolute path of the current session directory.
smelt.session.enter_worktree :: fun(opts: table?): table Create or open a managed git worktree and request a coherent project-context transition.
smelt.session.fork :: fun(): nil Fork the current session: clone its messages into a new session id and switch to it.
smelt.session.history :: fun(opts: table?): table Return the semantic session history as compaction-safe items.
smelt.session.id :: fun(): string Stable session id (matches the on-disk session filename).
smelt.session.info :: fun(): table Return current session metadata as a table.
smelt.session.list :: fun(): table List persisted SQLite sessions other than the current one.
smelt.session.load :: fun(id: string): nil Switch the UI to the persisted session with id.
smelt.session.model_messages :: fun(): table Return the model-visible message list for the next request.
smelt.session.render_preview_into :: fun(id: string, opts: table): table? Render persisted session id into opts.buf using the same styled transcript projection as the live UI.
smelt.session.reset :: fun(): nil Cancel any in-flight agent and clear the session to a blank slate.
smelt.session.retry_persistence :: fun(): boolean Explicitly retry the latest unsaved generation after session persistence becomes blocked.
smelt.session.rewind_to :: fun(block_idx: integer?, opts: table?): nil Rewind the session to a prior user turn.

customize

More from this repository

More from this repository

Customizing smelt

Core principle: persist the change, don't punt to slash commands

When to use this skill

Where things live

User-editable

Read-only built-in source (for reference)

Reference docs

Finding the config + builtins dirs from a shell

Hot reload

Recipes

Rebind a key

Change the accent color

Write a full colorscheme

Add a /command

Toggle/set a setting

Customize the status line

Pin startup defaults (model / mode / reasoning)

Register a provider

Register an MCP server

Register an agent tool

Permission rules

Write a project-local skill

Bundled plugins

Autoloaded

Opt-in

Settings

Tier rule: Host vs UiHost

Gotchas

Lua API surface

Host tier

smelt.agent

smelt.auth

smelt.builtins

smelt.cli

smelt.clipboard

smelt.defaults

smelt.events

smelt.files

smelt.frontend

smelt.fs

smelt.fs.file_state

smelt.fuzzy

smelt.grep

smelt.html

smelt.http

smelt.http.cache

smelt.image

smelt.json

smelt.layout

smelt.lifecycle

smelt.log

smelt.lsp

smelt.mcp

smelt.messages

smelt.os

smelt.parse

smelt.path

smelt.perf

smelt.process

smelt.provider

smelt.reg

smelt.remember

smelt.shell

smelt.signal

smelt.skills

smelt.state

smelt.task

smelt.tick

smelt.time

smelt.timer

smelt.tools

smelt.transcript.defaults

smelt.transcript.groups

smelt.trust

UiHost tier

smelt.buf

smelt.config

`smelt.agent`

`smelt.auth`

`smelt.builtins`

`smelt.cli`

`smelt.clipboard`

`smelt.defaults`

`smelt.events`

`smelt.files`

`smelt.frontend`

`smelt.fs`

`smelt.fs.file_state`

`smelt.fuzzy`

`smelt.grep`

`smelt.html`

`smelt.http`

`smelt.http.cache`

`smelt.image`

`smelt.json`

`smelt.layout`

`smelt.lifecycle`

`smelt.log`

`smelt.lsp`

`smelt.mcp`

`smelt.messages`

`smelt.os`

`smelt.parse`

`smelt.path`

`smelt.perf`

`smelt.process`

`smelt.provider`

`smelt.reg`

`smelt.remember`

`smelt.shell`

`smelt.signal`

`smelt.skills`

`smelt.state`

`smelt.task`

`smelt.tick`

`smelt.time`

`smelt.timer`

`smelt.tools`

`smelt.transcript.defaults`

`smelt.transcript.groups`

`smelt.trust`

`smelt.buf`

`smelt.config`

`smelt.confirm`

`smelt.dialog`

`smelt.engine`

`smelt.history`

`smelt.input`

`smelt.inspect`

`smelt.keymap`

`smelt.list`

`smelt.metrics`

`smelt.metrics.perf`

`smelt.model`

`smelt.notebook`

`smelt.notify`

`smelt.overlay`

`smelt.paint`

`smelt.permissions`

`smelt.picker`

`smelt.prompt`

`smelt.render`

`smelt.search`

`smelt.session`

`smelt.agent`

`smelt.auth`

`smelt.builtins`

`smelt.cli`

`smelt.clipboard`

`smelt.defaults`

`smelt.events`

`smelt.files`

`smelt.frontend`

`smelt.fs`

`smelt.fs.file_state`

`smelt.fuzzy`

`smelt.grep`