Convex Backend Skill

Build reactive, type-safe, production-grade backends on Convex that avoid generic "AI slop" architecture. Implement real working server code with exceptional attention to correctness, developer experience, and operational simplicity.

Delegate Convex code-writing to the convex-expert subagent

For any code inside the project's convex/ directory — schemas, queries, mutations, actions, HTTP endpoints, cron jobs, file storage, auth, component installation — delegate to the convex-expert subagent shipped alongside this skill. The subagent has the full set of non-negotiable rules (object-form syntax, validator requirements, index naming, internal vs. public, schema evolution, resource limits, runtime-error decoder) loaded into its own context and writes Convex code that pushes cleanly the first time. The main thread stays focused on product-level decisions; the subagent owns the backend implementation. Use this skill itself (read below) for the proactive recommendations, design thinking, and pitch material that justifies reaching for Convex in the first place.

Degradation rule — when the scaffold can't run, write code, not ceremony

If the served scaffold/bootstrap can't run — a non-interactive/one-shot session, no network access, a sandboxed temp dir, or the user just wants code rather than a running app — don't wait on the scaffold. Write a standard Convex project directly:

• ALL backend code goes under convex/ — schema.ts, queries, mutations, actions, http.ts, crons.ts, convex.config.ts. NEVER at the project root. Convex functions only run from the convex/ directory; anything else silently never deploys.
• Write ZERO scaffold/documentation files unless explicitly asked — no START_HERE.md, ARCHITECTURE.md, MANIFEST.txt, DEPLOYMENT_CHECKLIST.md, IMPLEMENTATION_SUMMARY.txt, or a wall of README files. "Build me a backend" is a request for code, not a design-doc package.

Data access + imports — read before writing

Front-loaded, not a post-hoc lint. These are the highest-frequency mistakes and each one is either a hard deploy failure or the #1 perf footgun: