feat: wire workspace custom emoji into the template

[StephenTangCook]

Summary

Wires workspace custom emoji into the template end-to-end, so it demonstrates the customEmojis pattern downstream adopters copy from. The template now sources custom emoji live from Slack emoji.list (it has no DB, so the live API is the natural source vs. a synced table) and passes them into <BlockKitchen> via the new customEmojis prop added in @tightknitai/block-kitchen@0.8.4 (ENG-4792). With it set, the picker offers a Custom category and the preview resolves :custom: directives to workspace images.

• Backend (src/worker/index.ts): new GET /api/slack/emojis proxies emoji.list (bot token) and normalizes the { name: value } map into { name, url, alias }[] — alias:<target> values split into the alias field, everything else is a hosted url. Guarded by requireBotInstall and the bot emoji:read scope.
• Frontend (src/client/App.tsx): fetches the endpoint once on mount and hands the array to the builder in both message and modal modes (custom emoji are workspace-level). Non-blocking — any failure (not installed, missing scope) falls back to an empty list and the library's defaults.
• Scope (manifest.json + SLACK_BOT_SCOPES in wrangler.jsonc): add emoji:read.
• Docs / tooling: README documents the prop + endpoint wiring; scripts/doctor.sh now checks for emoji:read and the reinstall reminder calls it out.
• Dep: bump @tightknitai/block-kitchen 0.8.3 → 0.8.4.

Type of change

• New feature
• Docs
• Build / CI / deps

Area

• Builder UI / React SPA (src/)
• Worker API routes (/api/slack/*)
• Setup scripts (scripts/)
• Deploy / CI (.github/workflows, wrangler.jsonc)
• Docs

Test plan

• pnpm run typecheck passes
• pnpm run build passes (Vite client + worker)
• pnpm run dev:tunnel exercised end-to-end against a real workspace — needs a Slack install with the new emoji:read scope (reinstall via pnpm run install-app after re-pushing the manifest)

Manual checks to run against a live workspace:

• Picker shows the workspace's custom emoji under the Custom category
• Preview renders a custom emoji as its workspace image; an alias resolves to its target
• Sending a message containing a custom emoji posts successfully

Related issues

Implements ENG-4794. Depends on ENG-4792 (the customEmojis prop), shipped in block-kitchen 0.8.4.

Checklist

• No secrets, tokens, or signing keys committed
• Updated README.md / wrangler.jsonc for the new scope + endpoint (no .dev.vars.example change — SLACK_BOT_SCOPES lives in wrangler.jsonc)
• Considered backwards compatibility — customEmojis is optional; the template builds unchanged when the array is empty

Note

Existing installs must be reinstalled to grant the new emoji:read bot scope: re-push manifest.json at api.slack.com, then pnpm run install-app. Until then, /api/slack/emojis returns an error and the builder degrades gracefully to standard emoji only.

https://claude.ai/code/session_01KSTrh3sekyiozbhH8tAZeM

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