Block Kit | EmDash CMS Everything

EmDash’s Block Kit lets sandboxed plugins describe their admin UI as JSON. The host renders the blocks — no plugin-supplied JavaScript ever runs in the browser.

How it works

User navigates to a plugin’s admin page
The admin sends a page_load interaction to the plugin’s admin route
The plugin returns a BlockResponse containing an array of blocks
The admin renders the blocks using the BlockRenderer component
When the user interacts (clicks a button, submits a form), the admin sends the interaction back to the plugin
The plugin returns new blocks, and the cycle repeats

// Plugin admin route handler
routes: {
  admin: {
    handler: async (ctx, { request }) => {
      const interaction = await request.json();

      if (interaction.type === "page_load") {
        return {
          blocks: [
            { type: "header", text: "My Plugin Settings" },
            {
              type: "form",
              block_id: "settings",
              fields: [
                { type: "text_input", action_id: "api_url", label: "API URL" },
                { type: "toggle", action_id: "enabled", label: "Enabled", initial_value: true },
              ],
              submit: { label: "Save", action_id: "save" },
            },
          ],
        };
      }

      if (interaction.type === "form_submit" && interaction.action_id === "save") {
        await ctx.kv.set("settings", interaction.values);
        return {
          blocks: [/* ... updated blocks ... */],
          toast: { message: "Settings saved", type: "success" },
        };
      }
    },
  },
}

Block types

Type	Description
`header`	Large bold heading
`section`	Text with optional accessory element
`divider`	Horizontal rule
`fields`	Two-column label/value grid
`table`	Data table with formatting, sorting, pagination
`actions`	Horizontal row of buttons and controls
`stats`	Dashboard metric cards with trend indicators
`form`	Input fields with conditional visibility and submit
`image`	Block-level image with caption
`context`	Small muted help text
`columns`	2-3 column layout with nested blocks

Element types

Type	Description
`button`	Action button with optional confirmation dialog
`text_input`	Single-line or multiline text input
`number_input`	Numeric input with min/max
`select`	Dropdown select
`toggle`	On/off switch
`secret_input`	Masked input for API keys and tokens

Builder helpers

The @emdash-cms/blocks package exports builder helpers for cleaner code:

import { blocks, elements } from "@emdash-cms/blocks";

const { header, form, section, stats } = blocks;
const { textInput, toggle, select, button } = elements;

return {
  blocks: [
    header("SEO Settings"),
    form({
      blockId: "settings",
      fields: [
        textInput("site_title", "Site Title", { initialValue: "My Site" }),
        toggle("generate_sitemap", "Generate Sitemap", { initialValue: true }),
        select("robots", "Default Robots", [
          { label: "Index, Follow", value: "index,follow" },
          { label: "No Index", value: "noindex,follow" },
        ]),
      ],
      submit: { label: "Save", actionId: "save" },
    }),
  ],
};

Conditional fields

Form fields can be conditionally shown based on other field values:

{
  "type": "toggle",
  "action_id": "auth_enabled",
  "label": "Enable Authentication"
}

{
  "type": "secret_input",
  "action_id": "api_key",
  "label": "API Key",
  "condition": { "field": "auth_enabled", "eq": true }
}

The api_key field only appears when auth_enabled is toggled on. Conditions are evaluated client-side with no round-trip.

Try it

Use the Block Playground to interactively build and test block layouts.