--- name: convex-security-3678e2e56443 description: Security best practices for Convex functions including ConvexError handling, argument/return validation, authentication helpers, access control, rate limiting, and internal functions. Use when writing public queries/mutations/actions, implementing authentication, adding authorization checks, handling errors, or reviewing Convex functions for security. --- # Convex Security ## Error Handling with ConvexError Use `ConvexError` for user-facing errors with structured error codes: ```typescript import { ConvexError } from "convex/values"; export const updateTask = mutation({ args: { taskId: v.id("tasks"), title: v.string() }, returns: v.null(), handler: async (ctx, args) => { const task = await ctx.db.get("tasks", args.taskId); if (!task) { throw new ConvexError({ code: "NOT_FOUND", message: "Task not found", }); } await ctx.db.patch("tasks", args.taskId, { title: args.title }); return null; }, }); ``` **Common error codes:** `UNAUTHENTICATED`, `FORBIDDEN`, `NOT_FOUND`, `RATE_LIMITED`, `VALIDATION_ERROR` ## Argument AND Return Validators Always define both `args` and `returns` validators: ```typescript export const createTask = mutation({ args: { title: v.string(), priority: v.union(v.literal("low"), v.literal("medium"), v.literal("high")), }, returns: v.id("tasks"), // Always include returns! handler: async (ctx, args) => { return await ctx.db.insert("tasks", { title: args.title, priority: args.priority, completed: false, }); }, }); ``` **ESLint:** Use `@convex-dev/require-argument-validators` rule. ## Authentication Helpers Create reusable auth helpers: ```typescript // convex/lib/auth.ts import { QueryCtx, MutationCtx } from "./_generated/server"; import { ConvexError } from "convex/values"; import { Doc } from "./_generated/dataModel"; export async function getUser(ctx: QueryCtx | MutationCtx): Promise | null> { const identity = await ctx.auth.getUserIdentity(); if (!identity) return null; return await ctx.db .query("users") .withIndex("by_tokenIdentifier", (q) => q.eq("tokenIdentifier", identity.tokenIdentifier) ) .unique(); } export async function requireAuth(ctx: QueryCtx | MutationCtx): Promise> { const user = await getUser(ctx); if (!user) { throw new ConvexError({ code: "UNAUTHENTICATED", message: "Authentication required", }); } return user; } type UserRole = "user" | "moderator" | "admin"; const roleHierarchy: Record = { user: 0, moderator: 1, admin: 2 }; export async function requireRole( ctx: QueryCtx | MutationCtx, minRole: UserRole ): Promise> { const user = await requireAuth(ctx); const userLevel = roleHierarchy[user.role as UserRole] ?? 0; if (userLevel < roleHierarchy[minRole]) { throw new ConvexError({ code: "FORBIDDEN", message: `Role '${minRole}' or higher required`, }); } return user; } ``` **Usage:** ```typescript export const adminOnly = mutation({ args: {}, returns: v.null(), handler: async (ctx) => { await requireRole(ctx, "admin"); // ... admin logic return null; }, }); ``` ## Row-Level Access Control Verify ownership before operations: ```typescript export const updateTask = mutation({ args: { taskId: v.id("tasks"), title: v.string() }, returns: v.null(), handler: async (ctx, args) => { const user = await requireAuth(ctx); const task = await ctx.db.get("tasks", args.taskId); if (!task || task.userId !== user._id) { throw new ConvexError({ code: "FORBIDDEN", message: "Not authorized" }); } await ctx.db.patch("tasks", args.taskId, { title: args.title }); return null; }, }); ``` ## Rate Limiting Prevent abuse with rate limiting: ```typescript const RATE_LIMITS = { message: { requests: 10, windowMs: 60000 }, // 10 per minute upload: { requests: 5, windowMs: 300000 }, // 5 per 5 minutes }; export const checkRateLimit = mutation({ args: { userId: v.string(), action: v.string() }, returns: v.object({ allowed: v.boolean(), retryAfter: v.optional(v.number()) }), handler: async (ctx, args) => { const limit = RATE_LIMITS[args.action]; const windowStart = Date.now() - limit.windowMs; const requests = await ctx.db .query("rateLimits") .withIndex("by_user_and_action", (q) => q.eq("userId", args.userId).eq("action", args.action) ) .filter((q) => q.gt(q.field("timestamp"), windowStart)) .collect(); if (requests.length >= limit.requests) { return { allowed: false, retryAfter: requests[0].timestamp + limit.windowMs - Date.now() }; } await ctx.db.insert("rateLimits", { userId: args.userId, action: args.action, timestamp: Date.now(), }); return { allowed: true }; }, }); ``` ## Internal Functions Only for Scheduling Always use `internal.*` for `ctx.run*` and scheduling: ```typescript // Bad - exposes public function await ctx.scheduler.runAfter(0, api.tasks.process, { id }); // Good - uses internal function await ctx.scheduler.runAfter(0, internal.tasks.process, { id }); // Internal function definition export const process = internalMutation({ args: { id: v.id("tasks") }, returns: v.null(), handler: async (ctx, args) => { // ... processing logic return null; }, }); ``` **Tip:** Never import `api` from `_generated/api.ts` in Convex functions. ## Include Table Name in ctx.db Always include table name as first argument: ```typescript // Bad await ctx.db.get(movieId); await ctx.db.patch(movieId, { title: "Whiplash" }); // Good await ctx.db.get("movies", movieId); await ctx.db.patch("movies", movieId, { title: "Whiplash" }); ``` **ESLint:** Use `@convex-dev/explicit-table-ids` rule with autofix. ## References - Error Handling: https://docs.convex.dev/functions/error-handling - Authentication: https://docs.convex.dev/auth/functions-auth - Production Security: https://docs.convex.dev/production --- Source attribution: aaronvanston Original project: https://github.com/aaronvanston/skills-convex/blob/5ea8c54ce73b814da9d50d384765c1501c76d999/skills/convex-security/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice MIT License Copyright (c) 2026 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Mega AI Hub resource metadata Creator / publisher: aaronvanston Original project: https://github.com/aaronvanston/skills-convex/blob/5ea8c54ce73b814da9d50d384765c1501c76d999/skills/convex-security/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering Roles: Backend Developer, DevOps / SRE, Security Engineer Specialties: Backend Tools: Convex Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: aaef9fe108b01f7c7197ed4dd63e266b5aa7af588a0cd4bc70d2cc3bf14ee2bf