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summer-apps-design is a skill from the Summer skill library: a guide your AI agent reads when the task matches, so it builds the good version on the first try. How a Summer App should look: layout, Summer UI kit components, tables, charts, states, pre-ship check.

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When your agent uses it

  • Building or changing the UI of a Summer App (agent-built team tool inside Summer Studio)
  • An app looks generic, cluttered or off-brand
  • Choosing layout for a table, chart, board, pick grid or settings tool

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Install

summer setup installs every skill for your agent. To add only this one:
Swap claude-code for your agent, such as codex or cursor. See Skills for every option.

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The skill

A Summer App is a tool a game team uses every day inside Summer Studio. It should feel like a calm, precise studio instrument around colourful game content. The chrome is ink on paper; colour comes from the game (art, renders, waveforms) and from data that means something. You have freedom inside the app. Use it for the task, not for decoration.

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The catalog is the API

The kit ships summer-ui/v1/catalog.json next to ui.js on the kit origin (the summer-apps skill says how to load the kit). It lists every component’s attributes with value shapes, events with their detail, slots, methods, a working example, the icon names and the tokens. Read the entry before you use a component and copy its example. Never guess an attribute.
  • JSON attributes take a JSON string, or set the same-named property: table.rows = rows. Prefer properties for data.
  • Events bubble out of the components; read event.detail.
  • Icons: only names in icons.names (lucide: plus, check, pencil, trash-2, search, sparkles, download, ellipsis, …). Never draw SVG.
  • Colours: only the tokens in tokens (var(--se-text), …). No hex.

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Do this

  1. Write one line: what the person came to do, and the one action that finishes it. That action is the primary button.
  2. Build the page from the recipe below. Every part is a kit component; write your own CSS only for layout glue (a grid, a gap), from tokens, under 30 lines.
  3. Read real data through the SDK. No lorem ipsum, no invented numbers.
  4. Wire loading, empty and error for every data component.
  5. Run the checklist. Look at light and dark, 390px and 1440px.

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Page recipe

  • summer-page gives the canvas, width (1280px; forms 640px), padding and spacing, and the header. The purpose line says what the tool does and where data goes. Header actions, in order: avatars, one meta (.summer-meta or summer-progress), secondary buttons, the primary.
  • One summer-section per part, with a short noun heading. Extras for the title row (a select, a count) go in slot="aside"; a select there turns compact by itself.
  • A chart gets its own heading (its legend then sits in the title row). A chart without a heading as the first thing in a section moves its legend into the section’s title row.
  • A page with one part needs no section heading and no card around it.
  • Tables and lists are always framed; charts never. Do not set frame="false" on a page.

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Pick the component

If you play Web Audio yourself, call summer.app.busy(true) while it plays and busy(false) after.

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Patterns

Dashboard (numbers, chart, table). Stats, then one chart answering the main question with the problem bars highlighted and a reference line for the target, then the table with a bar column for the value that matters. Columns a phone can do without get priority: "secondary". Badges in tables. Two kinds, one rule each:
  • A workflow status column (draft, in review, done, needs art) shows every value as a badge with badges. Neutral steps are quiet, work in progress info, done ok; only values that need someone to act get warn or bad.
  • A health column (balance, over target, errors) shows a badge only on the rows that need attention and stays empty on the rest. Never “OK” on every row.
Edit flow. A row click (summer-row) or the header’s primary opens a summer-dialog holding a summer-form. For an edit, call form.setValues(record) before dialog.show(); for a new item, show it empty. Listen for submit (detail.values; number fields give numbers, empty gives null); set busy while saving and error if it fails; close the dialog on success and toast the result (“Note saved”). The rule is one primary per region: the page header, an open dialog, a form that is the whole page, and the save bar are separate regions. A page whose job is the form puts Save in the form and no primary in the header. Empty page and the header. One primary on screen. When the whole page is empty, the empty state holds the primary (“Add note” or “Ask your agent”) and the header shows no primary until there is data. When only one section is empty, its empty-state button is secondary and the header keeps its primary. List with row actions. summer-list with checkable for done or fixed, one action for the most common step (\{id: "fix", label: "Mark fixed", icon: "check"\}: a quiet button that shows on hover and on touch), and menu for the rest (Edit, Copy, Delete with tone: "danger"). Never a bordered button on every row. Delete asks first in a summer-dialog with summer-form destructive. Data your agent fills in. When the app waits on an agent (an import, an analysis), the empty state says what is missing and offers the request: summer-empty-state heading="No playtest data yet" body="Your agent can import last night's playtest." with a summer-button icon="sparkles" “Ask your agent” (primary or secondary per the empty-page rule above). On click call summer.agent.send("playtest.import", {}), swap the button for summer-notice tone="info" “Your agent was asked. This fills in when it answers.”, and subscribe so rows appear live: summer.data.collection("levels").subscribe(render) (there is no summer.data.list(name)). Who added it, who changed it. People and agents edit the same data. Every record carries createdBy (set once, when it was added) and actor (the last writer), both {userId, kind: "person" | "agent" | "seed", agent, via} or null on old records. A “By” column or list meta shows createdBy: the person’s name, or the agent’s name (“Claude Code”) with an “Agent” badge when createdBy.kind is “agent”. Show nothing for “seed” (starter data) or null. Add “Last changed by” from actor only when it helps the task. Say “You” when the userId is info.viewer.userId. Flash a row or card that someone else just changed. Changes from subscribe carry actor but not createdBy: read the record again (get(id)) to show who added it. Board. Lanes per stage, art on cards from the asset, owner initial and comment count. Move cards with summer-move; write the new stage to data at once. Pick grid. One summer-choice-grid layout="row" per need; the header shows summer-progress and the primary sends the picks (“Send 7 to game”).

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States

  • Loading: set loading on stats, chart, table, list and select until the data arrives. Never show “No data yet” or ”-” while loading.
  • Empty: empty-text, or empty-heading + empty-body, on the component, or summer-empty-state for a whole page. Say what to do next.
  • Error: summer-notice tone="error" text="The notes could not load." action="Try again" in place of the part that failed; retry on its action event. The rest keeps working.
  • Saving: busy on the form or save bar, loading on a button.

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Type, colour, copy

  • The kit sets type. In your own glue use 14px body, 12px muted meta, weights 400, 500, 600, tabular-nums for numbers. Never 700, never all caps.
  • Colour means something: quiet by default, ink or a status tone for what needs attention, always with words.
  • Plain words, sentence case, no full stop on labels. Name actions by result (“Save note”, “Write to game”). Errors do not apologise. Never “AI-generated”.

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Never

Grey boxes around numbers. Cards around every section, cards inside cards. Native audio, video, select or range controls. Two primaries in one region. A labelled button on every row. A health badge on every row that only says all is well. Hand-drawn icons, emoji. Hex colours, gradients, glows, shadows on cards. Mono font for numbers. “No data yet” while loading.

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Checklist

  • The purpose line says what the tool does; one primary per region finishes it.
  • Every component and attribute matches its catalog entry.
  • Numbers line up; long text wraps; on a phone nothing scrolls off.
  • Loading, empty (including “waiting for your agent”) and error states exist and keep the layout in place.
  • Subtract: remove each badge, icon, helper line and frame; keep it only if the task gets worse without it.
  • Works by keyboard; icon buttons have labels.
  • Looked at light and dark, 390px and 1440px; nothing scrolls sideways except a board or a wide table inside its frame.
  • summer-apps: Build a Summer App, a team tool inside Summer Studio (balance table, quest editor, tracker), data and tools.
Source: library/skills/summer-apps-design/SKILL.md, rendered from summer-engine@4.3.0 on npm.