Authoring Bento decks

A Bento deck is one self-contained .bento.html file. The document is plain JSON in a single block:

html
<script type="application/bento+json" id="bento-doc"> { "format":"bento/slides", ... } </script>

Edit that block only, in place. Escape every < in the JSON as \u003c so it can never contain a literal </script>. Leave the rest of the file — the compressed runtime — untouched. In a chat context the user copies the JSON out instead (Save ▾ → Copy document JSON) and pastes the replacement back (Save ▾ → Replace from JSON…); window.bento.loadDoc(json) does the same from the console.

Adapted from the Bento project's own skill, https://bento.page/skills/bento-slides/SKILL.md (MIT, © 2026 The Bento/Suite authors). The authoritative schema and recipe reference is https://bento.page/agents.md.

Before you start

If the user's message only invokes this skill (e.g. "use bento-slides skill") without a concrete request, ask what deck they want before doing anything: the topic, the source material to build it from, and whether to start from scratch or edit an existing .bento.html. Do not download anything or write a document until the goal is clear.

Starting from nothing

The user does not need Bento installed — the app ships inside every deck. When there is no .bento.html to edit, fetch the latest signed release and author into it:

bash
# name the file after the deck's topic, e.g. Q4_Review.bento.html
curl -fsSL https://bento.page/releases/slides/Bento_Slides.bento.html -o "<Topic>.bento.html"

On Windows without curl: iwr https://bento.page/releases/slides/Bento_Slides.bento.html -OutFile <Topic>.bento.html.

Verify the download contains id="bento-doc", then replace that block's JSON — it ships with a showcase deck, which is discarded. For a fresh document:

• Fetch https://bento.page/agents.md before authoring and start from its "Minimal valid document" skeleton. size and theme (including theme.fontFamily) are required; the app will not boot without them.
• Fully specify element fields as the skeleton shows — shapes need stroke / strokeWidth, text needs fontFamily / align / valign. Missing fields render wrong or not at all.
• Omit docId and collab entirely. The app mints a fresh identity and dormant collaboration credentials on first open.

When done, offer to open it (open / xdg-open / start): the file boots straight into the editor with the finished deck. Aim for one pass from request to opened deck.

Workflow

1. Find the document. Locate the #bento-doc block and parse its JSON. Note doc.size (canonical 1280×720), doc.theme, existing element ids, and whether doc.template / doc.readonly are set.
2. Read the source material the user gave you and classify each piece — a stat, a table, a process, a definition to expand, a photo.
3. Map material to a feature; do not default to bullet text. This is the step that makes it a Bento deck rather than a slideshow of paragraphs:

• numbers to compare visually (trend, magnitude, share) — a chart element
• a comparison, spec, pricing or feature grid — a table element (columns weights, rows of cells, a style object)
• consecutive slides about the same thing changing — morph: give shared elements the same id on both slides and transition:"morph" on the later one (Bento's signature move; reach for it liberally)
• a point to drill into — a state slide (stateOf plus an element link)
• a hero or full-slide image — full-bleed image, scrim rect and text, with ken-burns drift
• a sequence, flow or timeline — a line or path with a dash-march loop, or morph a highlight through the steps
• a headline number — big text with fx:{countUp:true}
• every cover and divider — at least one ambient motion
• repeated chrome or a logo — keep its id stable across slides so it morphs in place
• a demo clip, recording or soundbite — a media element (kind: video|audio); embed short clips as a data URI, link big ones by URL to keep the file small

1. Author using the schema, keeping https://bento.page/agents.md open for the element shapes, the morph / chart / state / ken-burns snippets and the gotchas. Respect one accent colour, at most two typefaces, 96px side margins (right-most x ≤ 1184), and write speaker notes on every slide.
2. Self-audit before finishing:

• ] any numbers rendered as text that should be a chart?
• ] do consecutive slides on one subject share ids and transition:"morph"?
• ] at least one motion moment (ken-burns, loop, count-up), especially on the cover?
• ] a drill-down that would work better as a state slide?
• ] one accent colour, at most two typefaces, 96px margins?
• ] speaker notes on every slide?

1. Write back the edited #bento-doc block (escaping < as \u003c), or return the replacement JSON. Never regenerate the whole HTML file.

Critical gotchas

• Charts: bar and line series data must be plain numbers — {value,…} item objects coerce to 0, and only pie takes {name,value}. Colour by series, not per bar. option is pure JSON: template formatters only ({b} / {c} / {d}), never functions.
• Morph needs deterministic, stable ids shared across the slides that should animate together. Different ids mean no morph — the elements just cut.
• Images and fonts must be embedded as data URIs in doc.assets and referenced by "asset:<key>", so the file stays self-contained.
• Media: a media element (kind: video|audio) embeds short clips as a data URI in src, or references a URL for big files. autoplay runs only in present mode and needs muted:true for video. Do not embed large videos — they bloat the file.
• Never regenerate docId when editing an existing deck; it is the document's identity. Fresh decks omit it and the app mints one.
• template:true means every open mints a fresh deck; readonly:true means the file boots straight into the show with no editor.

Working examples of every technique: open any template at https://bento.page and read its #bento-doc block.