Add Block Kit rendering engine, showcase bot, and channel management

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## What is Botarium
+
+Botarium is a local Slack bot development simulator. Build, test, and debug Slack bots entirely on your machine without deploying to real Slack.
+
+- Emulator app that runs in the browser or as a native desktop app (Electron)
+- CLI tools to scaffold bots from scratch
+- Development tools: persistence layer, Slack mrkdwn converter, and AI integration
+
+## Commands
+
+```sh
+bun run dev              # Start web UI dev server (Vite, port 5173)
+bun run dev:electron     # Start desktop app (Electron + Vite + emulator)
+bun run build            # Build all packages and apps
+bun run test             # Run all tests (bun test)
+bun test <file>          # Run a single test file
+bun run check            # typecheck + format:check + lint (CI runs this)
+bun run typecheck        # TypeScript check across all workspaces
+bun run lint             # ESLint
+bun run format           # Prettier (write)
+bun run cli create       # Scaffold a new bot interactively
+```
+
+Run the emulator standalone: `bun run packages/slack/src/server/index.ts`
+
+## Architecture
+
+Bun monorepo with workspaces in `apps/` and `packages/`.
+
+### Packages
+
+- **`packages/core`** — Plugin system and CLI entry point. Defines the `BotariumPlugin` interface that platform plugins implement (`createEmulator`, `defaultPort`, `envVarName`). Currently, only Slack is implemented, but the design supports adding other platforms.
+- **`packages/slack`** — Slack API emulator. A Bun HTTP + WebSocket server that implements Slack Web API endpoints, Socket Mode protocol, SSE event broadcasting to the frontend, and optional SQLite persistence. Key files: `server/state.ts` (in-memory state), `server/web-api.ts` (API handlers), `server/socket-mode.ts` (WebSocket protocol), `server/persistence.ts` (SQLite).
+- **`packages/mrkdwn`** — Bidirectional converters: Slack mrkdwn to HTML (for rendering in UI) and Markdown to mrkdwn (for AI responses). Uses `marked` for Markdown parsing.
+- **`packages/create-bot`** — CLI tool (`create-botarium`) that scaffolds new bots via Handlebars templates in `templates/`.
+
+### Apps
+
+- **`apps/ui`** — Svelte 5 + Tailwind CSS 4 chat interface. Uses Svelte 5 runes (`$state`, `$derived`, `$effect`) for reactivity. Key state files: `lib/state.svelte.ts` (reactive UI state), `lib/dispatcher.svelte.ts` (SSE connection to emulator, API calls), `lib/backend-state.svelte.ts` (Electron IPC bridge). Uses `$lib` path alias for `src/lib/`.
+- **`apps/electron`** — Desktop wrapper. Manages emulator and bot child processes, provides IPC for settings (encrypted via OS keychain), and bundles everything into a native app.
+
+### Data Flow
+
+1. User types in UI → HTTP POST to emulator `/api/simulator/user-message`
+2. Emulator creates Slack event → sends via WebSocket (Socket Mode) to connected bot
+3. Bot processes event → calls Slack Web API endpoints (e.g., `chat.postMessage`) on the emulator
+4. Emulator broadcasts SSE event → UI updates reactively
+
+## Code Style
+
+- No semicolons, single quotes, trailing commas (es5) — enforced by Prettier
+- `{@html}` is intentionally used in Svelte for mrkdwn rendering (ESLint rule disabled)
+- Prefix unused variables with `_`
+- Svelte components use runes (`$state`, `$derived`, `$effect`), not legacy stores
+- TypeScript strict mode with `noUncheckedIndexedAccess`
+
+## Testing
+
+Tests use Bun's built-in test runner (`bun:test`). Test files are colocated with source as `*.test.ts`. Main test areas:
+
+- `packages/mrkdwn/src/` — mrkdwn/HTML conversion tests
+- `packages/create-bot/src/` — scaffold and template utility tests
+- `apps/ui/src/lib/` — UI state tests

apps/electron/bots.json

@@ -1,3 +1,8 @@
 {
-  "bots": []
+  "bots": [
+    {
+      "source": "../showcase-bot",
+      "name": "showcase"
+    }
+  ]
 }

apps/showcase-bot/README.md

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+# Showcase Bot
+
+A Slack bot that populates a channel with [Block Kit](https://api.slack.com/block-kit) examples and echoes back interactive element payloads. Built with [@slack/bolt](https://slack.dev/bolt-js/) and [Bun](https://bun.sh).
+
+## How it works
+
+On startup (in simulator mode), the bot automatically posts a series of Block Kit messages to the `#showcase` channel. These messages demonstrate various block types and interactive elements. When a user interacts with any element, the bot responds with the raw action payload so you can inspect exactly what Slack sends.
+
+### Block Kit samples
+
+Message definitions live in `src/messages/blocks/` as numbered JSON files, loaded and posted in order:
+
+| #   | File                         | What it shows                                            |
+| --- | ---------------------------- | -------------------------------------------------------- |
+| 01  | `text-and-layout.json`       | Headers, sections, dividers, context, images             |
+| 02  | `button-variations.json`     | Primary, danger, and default buttons                     |
+| 03  | `selection-elements.json`    | Static selects, multi-selects, overflow menus            |
+| 04  | `radio-and-checkboxes.json`  | Radio buttons and checkbox groups                        |
+| 05  | `date-and-time-pickers.json` | Date pickers, time pickers, datetime pickers             |
+| 06  | `section-accessories.json`   | Buttons, selects, and overflows as section accessories   |
+| 07  | `combined-actions.json`      | Multiple interactive elements in a single actions block  |
+| 08  | `rich-text.json`             | Rich text with formatting, lists, quotes, code blocks    |
+| 09  | `template-newsletter.json`   | A realistic newsletter-style message template            |
+| 10  | `kitchen-sink.json`          | Mixed rich text, actions, selects, and feedback elements |
+
+JSON files support template variables (`{{TODAY_DATE}}`, `{{TODAY_NOON_UNIX}}`) that are resolved at load time.
+
+You can try pasting examples from Slack's [Block Kit Builder](https://app.slack.com/block-kit-builder) to show them in the emulator.
+
+### Action responses
+
+All interactive elements use action IDs prefixed with `showcase_`. A single catch-all handler matches this prefix:
+
+```js
+app.action(/^showcase_/, ...)
+```
+
+When triggered, the handler acknowledges the action and posts a reply containing the action type, action ID, and the full JSON payload. This makes it easy to see exactly what data each interactive element produces.
+
+Modal submissions (callback ID `showcase_modal`) are handled the same way -- the bot posts the `view.state.values` back to the channel.
+
+### Slash command
+
+The bot registers a `/showcase` command with the following subcommands:
+
+| Subcommand | Description                                              |
+| ---------- | -------------------------------------------------------- |
+| `generate` | Clear and re-populate `#showcase` with all block samples |
+| `clear`    | Remove all messages from `#showcase`                     |
+| `modal`    | Open a modal with various input elements                 |
+| `help`     | Show available subcommands                               |
+
+## Running
+
+```sh
+# With the Botarium simulator
+bun run dev:local
+
+# With real Slack credentials
+SLACK_BOT_TOKEN=xoxb-... SLACK_APP_TOKEN=xapp-... bun run dev
+```
+
+### Environment variables
+
+| Variable               | Required         | Description                                                     |
+| ---------------------- | ---------------- | --------------------------------------------------------------- |
+| `SLACK_BOT_TOKEN`      | Yes (production) | Bot user OAuth token                                            |
+| `SLACK_APP_TOKEN`      | Yes (production) | App-level token for Socket Mode                                 |
+| `SLACK_SIGNING_SECRET` | Yes (production) | Signing secret for request verification                         |
+| `SLACK_API_URL`        | No               | Set automatically in simulator mode                             |
+| `BOT_NAME`             | No               | Display name (default: `Showcase Bot`)                          |
+| `PORT`                 | No               | Server port (default: `3000`)                                   |
+| `LOG_LEVEL`            | No               | `silent`, `debug`, `info`, `warn`, or `error` (default: `info`) |
+
+In simulator mode, token and secret values are generated automatically.
+
+## Project structure
+
+```text
+src/
+  app.ts                          # Entry point, Bolt app setup, startup sequence
+  settings.ts                     # Environment variable validation (zod)
+  config/
+    loader.ts                     # Bot configuration loader
+    http-server.ts                # Config server for simulator registration
+  listeners/
+    index.ts                      # Registers commands and actions
+    commands/showcase.ts          # /showcase command and message posting
+    actions/showcase-actions.ts   # block_actions and view_submission handlers
+  messages/
+    showcase-messages.ts          # Loads and templates block JSON files
+    blocks/*.json                 # Block Kit message definitions
+  utils/
+    logger.ts                     # Pino logger setup
+```

apps/showcase-bot/config.yaml

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+# Showcase Bot Configuration
+# Sends categorized Block Kit example messages for visual verification.
+
+# Simulator-specific configuration (not sent to Slack)
+simulator:
+  id: showcase # Isolates DM messages per-bot in the simulator
+
+# Slack app configuration
+slack:
+  commands:
+    - command: /showcase
+      description: Block Kit showcase commands
+      usage_hint: '[generate|clear|modal|help]'
+  shortcuts: []
+  actions: {}
+  modals:
+    showcase_modal: showcase_modal
+
+# Settings with schema metadata for UI generation
+settings:
+  bot_name:
+    value: Showcase Bot
+    schema:
+      type: string
+      label: Bot Name
+      description: Display name for the bot in conversations
+      group: bot
+      required: true
+
+  bot_description:
+    value: Sends categorized Block Kit example messages for visual verification.
+    schema:
+      type: string
+      label: Bot Description
+      description: Short description shown in the DM about section
+      group: bot
+
+# Group definitions with display order
+groups:
+  - id: bot
+    label: Bot Configuration
+    order: 1

apps/showcase-bot/package.json

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+{
+  "name": "showcase-bot",
+  "version": "0.1.0",
+  "description": "Block Kit showcase bot for Botarium",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "start": "bun run src/app.ts",
+    "dev": "bun --watch run src/app.ts",
+    "dev:local": "SLACK_API_URL=http://localhost:7557 bun --watch run src/app.ts",
+    "typecheck": "tsc --noEmit",
+    "test": "echo 'No tests yet'"
+  },
+  "dependencies": {
+    "@slack/bolt": "^4.6.0",
+    "@slack/types": "^2.15.0",
+    "@slack/web-api": "^7.10.0",
+    "pino": "^10.1.0",
+    "zod": "^4.3.5"
+  },
+  "devDependencies": {
+    "@types/bun": "^1.3.6",
+    "pino-pretty": "^13.1.3",
+    "typescript": "^5"
+  }
+}