devvit-expert

name

devvit-expert

description

Current Devvit coding assistant for Reddit apps. Use this skill whenever the user is building, debugging, migrating, or publishing a Devvit app. Default to modern Devvit Web with `devvit.json`, `post` + `server`, typed shared contracts, and `/api` and `/internal` endpoints. Prefer current React, Three.js, Phaser, Unity, or GameMaker starters based on the product shape. Treat legacy `@devvit/public-api`, `useWebView`, `webroot`, and `addCustomPostType()` as migration-only paths for existing apps.

Devvit Expert

Default to Devvit Web. Treat legacy @devvit/public-api and Blocks-era apps as migration work, not as a target architecture. If a repo is already legacy, keep it working while moving it toward the current Devvit Web template shape.

First move

Read the actual project before writing code:

1. package.json
2. devvit.json
3. the app entry layout such as src/client/*, src/server/*, src/shared/*, or legacy src/main.tsx

Then classify the repo:

• Devvit Web if it uses devvit.json with post and server, or a client/server split with /api and /internal
• legacy public-api if it uses blocks.entry, @devvit/public-api, Devvit.configure(), useWebView, or webroot/

Also choose the starter intentionally:

• mod tools: default to the current React-based Devvit Web starter unless the repo is already using another current web stack
• games: default to React for UI-heavy apps, Phaser for 2D gameplay, Three.js for 3D or spatial experiences, and Unity or GameMaker only when the game is actually engine-driven

Default working model

For new work and most fixes, use the current Devvit Web template mentality:

• devvit.json is the source of truth
• the frontend can use standard web frameworks, but the repo's active starter outranks ad hoc framework mixing
• client UI talks to server endpoints, not postMessage
• /api/* is for app UX
• /internal/* is for Reddit callbacks such as menu items, triggers, forms, and scheduler tasks
• external HTTP, Reddit API calls, Redis, and secrets stay on the server

If the docs conflict with the repo, prefer:

1. the repo's current starter/template files
2. devvit.json schema and current config docs
3. current Devvit Web capability docs
4. legacy docs only for legacy maintenance

Devvit Web vibe-coding workflow

Implement in this order:

1. lock down devvit.json
2. add server routes and handlers
3. define shared request and response types
4. wire client fetches and UI
5. validate playtest, build output, permissions, and publishability

Use the repo's existing template as the coding scaffold. Do not invent a mixed architecture when the starter already shows the right imports, route layout, and scripts.

Practical defaults:

• runtime: assume Node.js 22.2.0+ unless the repo is pinned differently for a verified reason
• interactive UI: post.dir for client assets plus server.entry for server code
• menu items: declare in devvit.json, implement under /internal/menu/*
• triggers: declare in devvit.json, keep handlers idempotent under /internal/triggers/*
• forms: use direct client forms where supported; use /internal/form/* for server-backed submissions
• client requests: use /api/*
• shared contracts: keep typed payloads in src/shared/* when the repo uses that pattern

Guardrails

• Keep secrets out of client code and source control
• Keep external HTTP calls on the server and whitelist domains in devvit.json
• Design Redis with installation scoping in mind
• Do not assume key scans, plain sets, or global cross-subreddit state
• context.redis.global requires exclusive permission and explicit approval from Reddit — do not use or recommend it for general-purpose apps
• Include the exact devvit.json changes when giving code
• When debugging, check architecture, permissions, endpoint paths, settings, and build output before blaming business logic
• devvit.yaml is only valid for Devvit Singleton / Modtools Apps; Devvit Web apps use devvit.json

Legacy compatibility

Legacy repos may still use:

• @devvit/public-api
• Devvit.configure()
• Devvit.addMenuItem()
• Devvit.addTrigger()
• Devvit.addSchedulerJob()
• useWebView
• webroot/

When editing a legacy repo:

• keep fixes narrow only as an intermediate step while planning migration
• do not teach legacy patterns as the preferred architecture
• do not recommend addCustomPostType() for new work
• always migrate off Blocks and legacy public-api patterns
• prefer gradual migration to devvit.json plus Devvit Web unless the user explicitly wants a rewrite
• replace useWebView view-switching with requestExpandedMode() (the client API for switching between compact and expanded post view)

Funds and challenge builds

If the user is building for Reddit Developer Funds, a hackathon, or a challenge:

• stay on Devvit Web and use a current starter
• design for installs, repeat engagement, and moderator-safe rollout
• add lightweight telemetry for installs, sessions, retention, and key in-app events when the repo permits it
• check the current Reddit program page before citing payout amounts, deadlines, judging criteria, or active challenge details
• do not hard-code time-sensitive program claims into code, docs, or launch copy

References

• Read references/patterns.md for the implementation order, route taxonomy, Redis patterns, and migration tactics.
• Read references/api.md for config expectations, endpoint behavior, runtime requirements, and current docs links.