builder-skills

Routes Convex work to the right builder skill and covers the handful of rules that apply everywhere: validators on every function, withIndex over filter, idempotent mutations, internal functions for scheduling. Use when a task mentions Convex and no more specific skill matches, or as the first stop before picking one.

Production patterns for Convex apps and the rules the @convex-dev/eslint-plugin enforces: validators, indexes, idempotent mutations, avoiding OCC conflicts, thin function wrappers, error handling. Use when reviewing Convex code, asking whether a pattern is right, setting up ESLint, or fixing write conflicts and slow queries.

Writes Convex queries, mutations, actions, and internal functions in the object form with args and returns validators, correct ctx usage, runtime boundaries, and error handling. Use when adding or changing anything in convex/.ts that exports a function, or when deciding between query, mutation, and action.

Designs convex/schema.ts tables, validators, indexes, and relationships, and keeps the schema honest as data evolves. Use when creating tables, adding fields, choosing index fields, modeling relationships, or when a validator error appears at deploy time.

Builds reactive UIs on Convex subscriptions: useQuery patterns, optimistic updates, pagination that stays live, presence, and avoiding subscription churn. Use when wiring the frontend to Convex, when data does not update live, or when a page rerenders too much.

Schedules work in Convex: cron jobs in convex/crons.ts, one off scheduled functions with runAfter and runAt, batching large jobs, and cancelling or inspecting the queue. Use when something needs to run on a timer, later, or in the background, or when a cron is not firing.

Adds HTTP endpoints in convex/http.ts: webhook receivers with signature checks, REST style routes, CORS, auth headers, streaming responses, and file uploads over HTTP. Use when integrating Stripe, Clerk, Resend, or any service that calls back into the app, or when a client needs a plain HTTP API.

Ten minute security pass over a Convex backend: public functions that should be internal, missing auth checks, unvalidated args, IDs from the client trusted without ownership checks, secrets in code. Use before merging a pull request, after adding new public functions, or when the user says 'quick security check'.

Handles files in Convex: upload URLs, storing blobs from actions, serving with getUrl or an HTTP action, metadata from the storage table, and deletion. Use when users upload images or documents, when an action fetches a file from a third party, or when a file URL expires unexpectedly.

Changes a live Convex schema without downtime: make a field optional, backfill in batches, flip the validator, then clean up. Uses the @convex-dev/migrations component where it fits. Use when renaming or removing a field, changing a type, splitting a table, or when deploy fails with a schema validation error on existing documents.

Keeps a change scoped to what was asked. Flags extra features, refactors, and 'while we are here' edits, and moves them to a suggestions list instead of the diff. Use when a request is small and the agent is about to expand it, when a PRD grows beyond its problem statement, or when the user says 'just do what I asked'.

Creates reusable Convex components with defineComponent, a clean client wrapper, their own schema, and an npm publish setup. Use when extracting a feature into a package, building something for the Convex component directory, or when a component's functions are not showing up in the parent app.