TUI Widgets — Live Panels for the Ink TUI Dock

Author widget apps for the Hermes TUI (hermes --tui): glanceable ambient panels docked above the status bar, or modal overlays that own the keyboard. Widgets are plain ESM files the TUI loads at startup — no build step, no repo changes. This skill does not cover desktop-app or web-dashboard widgets.

When to Use

The user asks for a live panel in the TUI (ticker, clock, countdown, status card, API-backed readout).
The user wants a custom modal tool (picker, calculator, viewer) bound to a slash command.

Prerequisites

The TUI must be in use (hermes --tui). Widgets do not render in the classic CLI or messaging platforms.
Network-backed widgets need whatever credentials their API needs; fetch failures must land as an error phase, never a crash.

How to Run

Use write_file to create ~/.hermes/tui-widgets/<name>.mjs (see templates/clock.mjs for a complete working widget).
If the TUI is running it hot-loads the file within ~a second (the widgets directory is watched); /widgets-reload forces a rescan.
The widget's id becomes its slash command automatically (/<id>), with its help in the / completion popover. No other registration exists.
Auto-open (no command needed): end register(sdk) with sdk.openWidget(app, app.init('')) — the widget docks itself the moment the file loads. Only do this when the user asked for it; note it re-docks on every /widgets-reload.

Quick Reference

A widget file default-exports register(sdk):

export default function register(sdk) {
  const { Box, Text, defineWidgetApp, h } = sdk

  defineWidgetApp({
    id: 'clock',                    // slash command name
    help: 'live clock in the dock', // `/` completion metadata
    mode: 'ambient',                // 'ambient' docks; 'modal' takes input
    init: arg => ({ label: arg.trim() || 'UTC' }),   // null = print usage
    reduce: (state, { ch, key }) => (key.escape || ch === 'q' ? null : state),
    render: ({ state, t }) => h(sdk.Dialog, { width: 24 }, h(Text, { color: t.color.label }, state.label))
  })
}

sdk contents: defineWidgetApp, openWidget, updateWidget, isCtrl, React, h (createElement — no JSX in .mjs), components Box, Text, Dialog, Overlay, WidgetGrid, GridAreas, and loaders Shimmer, ShimmerRows, useShimmerPhase — use ShimmerRows for loading phases instead of a bare "loading…" line.

Expand/collapse: sdk.Accordion — the same primitive the session panel's tool/skill sections use. h(Accordion, { t, title: 'details', count: 3, defaultOpen: false }, body) toggles on CLICK (works in ambient widgets, which receive no keys); modal apps may pass open + onToggle to drive it from reducer state instead.

Stable sizing (cards must NEVER resize while ticking):

Give Dialog an explicit width; charts already return exactly the width you ask for (short series pad-left while history warms up).
Pad dynamic numbers: String(v).padStart(6) — 51 ms → 112 ms must not change the line length.
Keep row counts constant per phase; swap content, not structure.

Charts (pure string builders — color the result with theme tones):

sdk.sparkline(series, width?) → ▂▃▅▇█▆ one-row trend
sdk.sparkRows(series, width, rows) → multi-row column chart (top line first) — the mission-control panel look; taller cells gain resolution
sdk.gauge(ratio, width) → █████░░░ fill bar for a 0..1 value
sdk.hbars(values, width) → horizontal bar chart, one bar per value, eighth-block tips, scaled to the max

Keep a rolling series in component state (push per tick, cap ~120 samples) and render sparkRows for dashboard panels, sparkline for one-liners.

Contract essentials:

mode: 'ambient' — captures no input, the command toggles it; render returns a CARD (usually Dialog), never Overlay. Placement via zone — every zone RESERVES real space (nothing ever paints over the transcript):
- Docks (chrome rows): dock-top (under the top status bar), dock-bottom (default — above the bottom one).
- Rails (side columns beside the transcript; text reflows around them): top-left, top-right, bottom-left, bottom-right — corner names pick the rail side and its top/bottom anchor. Set width on the app to the card's width (match your Dialog width; default 44) — the rail reserves exactly that many columns. Map the user's words to the nearest zone: "top right" → top-right, "above/next to the status bar" → a dock. Rails suit narrow cards (~30-46 cols); full-width or short-and-wide content belongs in a dock.
mode: 'modal' (default) — owns every keypress; reduce returns next state, the same reference to swallow a key, or null to close; render wraps content in Overlay for placement.
Async data: fire the fetch from init, land results with sdk.updateWidget(app, fn) — it no-ops if the widget was closed, so a late reply can never resurrect it.
Animation: own a timer inside a component via React.useState + React.useEffect (see the template); keep intervals ≥ 250ms.
Colors: ALWAYS theme tones (t.color.primary/label/muted/ok/error/…), never hardcoded hexes — widgets must survive /skin and light/dark.

Procedure

Pick id, mode, and the state shape; keep state serializable.
Write the file from the template; wire data via init + updateWidget.
/<id> to launch (hot-loaded on write); relaunch /<id> to dismiss an ambient widget.
Iterate: edit the file — it hot-reloads on save (last-writer-wins, the fresh definition shadows the old one). Relaunch /<id> to remount.

Pitfalls

No JSX and no bare imports in .mjs — everything comes from the sdk parameter; h(...) builds elements.
Don't ship a modal without a close path (Esc/q returning null).
Ambient widgets must stay small (≤ ~6 rows) — the dock sits between the transcript and the status bar.
A thrown register() is logged and skipped; check ~/.hermes/logs/tui_gateway_crash.log if a widget never appears.

Verification

Run /widgets-reload — the transcript line must list the file under loaded:. Then /<id>: an ambient widget appears docked right, above the status bar, while the composer keeps accepting input; /<id> again removes it.

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