Daangn Graplix Graplix

Graplix ReBAC Guide

Build relation-based access control with Graplix. This skill teaches you how to find current documentation and write correct Graplix code.

Critical: Do not trust internal knowledge

Everything you know about Graplix is likely outdated or wrong. Never rely on memory. Your training data may contain obsolete APIs. Always verify against the documentation referenced in this skill.

Prerequisites

Before writing code, verify package installation:

ls node_modules/@graplix/engine/

• Package exists: Use embedded docs (most reliable, matches exact installed version)
• No package: Install first using references/quick-start.md

Available Files Reference

Priority: Documentation Lookup Order

1. Embedded docs (if @graplix/engine is installed)

   • Most reliable, matches exact installed version
   • Read Markdown docs: node_modules/@graplix/engine/dist/docs/*.md
   • Read type declarations: node_modules/@graplix/engine/dist/index.d.mts

2. Source code (if packages installed)

   • Ultimate truth source when docs are unclear
   • Read: node_modules/@graplix/engine/dist/index.mjs

Core Architecture

Graplix has two runtime components:

.graplix schema  →  buildEngine()  →  engine.check() / engine.explain()
(relation model)    (async factory)    (permission evaluation)

Data flow for a permission check:

engine.check({ user, object, relation, context })
  → resolveType(user)  → EntityRef
  → resolveType(object) → EntityRef
  → evaluate relation graph (resolver.relations callbacks)
  → resolver.load() for any entity IDs encountered
  → true | false

Schema Syntax

Graplix schemas are .graplix text files. See references/schema-syntax.md for the full reference.

type user

type repository
  relations
    define owner: [user]
    define member: [user]
    define admin: owner or member
    define can_delete: owner from organization

Key rules:

• Types use snake_case
• [TypeA, TypeB] — direct relation (user must be one of these types)
• relation from source — transitive via another relation on source
• term or term — union of multiple terms
• No define = type with no relations (still valid)

Complete Example

import { buildEngine } from "@graplix/engine";

// 1. Define your entity types
type User = { id: string };
type Repository = { id: string; ownerIds: string[] };

// 2. Set up data (replace with your real data source)
const users = new Map<string, User>([
  ["user-1", { id: "user-1" }],
  ["user-2", { id: "user-2" }],
]);
const repos = new Map<string, Repository>([
  ["repo-1", { id: "repo-1", ownerIds: ["user-1"] }],
]);

// 3. Write your schema
const schema = `
  type user

  type repository
    relations
      define owner: [user]
      define can_delete: owner
`;

// 4. Build the engine (async — validates schema eagerly)
const engine = await buildEngine<object, User | Repository>({
  schema,

  resolveType: (value) => {
    if (typeof value !== "object" || value === null) return null;
    if ("ownerIds" in value) return "repository";
    return "user";
  },

  resolvers: {
    user: {
      id: (user: User) => user.id,
      async load(id) {
        return users.get(id) ?? null;
      },
    },
    repository: {
      id: (repo: Repository) => repo.id,
      async load(id) {
        return repos.get(id) ?? null;
      },
      relations: {
        // Return domain entities directly — NOT IDs or EntityRefs
        owner(repo: Repository) {
          return repo.ownerIds
            .map((id) => users.get(id))
            .filter((u): u is User => u !== undefined);
        },
      },
    },
  },
});

// 5. Check permissions
await engine.check({
  user: users.get("user-1")!,
  object: repos.get("repo-1")!,
  relation: "owner",
  context: {},
}); // → true

// 6. Explain traversal (for debugging)
const result = await engine.explain({
  user: users.get("user-2")!,
  object: repos.get("repo-1")!,
  relation: "can_delete",
  context: {},
});
result.allowed;       // false
result.exploredEdges; // CheckEdge[] — all traversed edges
result.matchedPath;   // CheckEdge[] | null — first matching path

buildEngine Options

const engine = await buildEngine<TContext, TEntityInput>({
  schema,          // string — raw .graplix schema text (required)
  resolvers,       // Resolvers<TContext> — keyed by type name (required)
  resolveType,     // ResolveType<TContext> — entity type discriminator (required)

  resolverTimeoutMs: 3000,   // timeout (ms) for load and relation resolvers
  maxCacheSize: 1000,        // per-request LRU cache size (default: 500)
  onError: (err) => {        // called when entity resolution silently fails
    console.error(err);      // throw here to escalate to a hard failure
  },
});

buildEngine is async. Schema validation happens at construction time — an invalid schema rejects immediately.

resolveType

type ResolveType<TContext> = (value: unknown, context: TContext) => string | null;

• Synchronous and required
• Returns the Graplix type name for any entity value, or null if unknown
• Called for query.user and query.object — must return the correct type
• For relation resolver outputs, null is acceptable (engine uses schema hints)

// ✅ Structural field discrimination
const resolveType: ResolveType<MyContext> = (value) => {
  if (typeof value !== "object" || value === null) return null;
  const v = value as Record<string, unknown>;
  if ("adminIds" in v) return "organization";
  if ("ownerIds" in v && "organizationId" in v) return "repository";
  if ("ownerIds" in v) return "team";
  return "user";
};

// ✅ instanceof checks (class-based models)
const resolveType: ResolveType<MyContext> = (value) => {
  if (value instanceof Organization) return "organization";
  if (value instanceof Repository) return "repository";
  if (value instanceof User) return "user";
  return null;
};

Resolver Interface

interface Resolver<TEntity, TContext> {
  id(entity: TEntity): string;

  load(
    id: string,
    context: TContext,
    info: ResolverInfo,  // info.signal for timeout cancellation
  ): Promise<TEntity | null>;

  relations?: {
    [relation: string]: (
      entity: TEntity,
      context: TContext,
      info: ResolverInfo,
    ) => TEntity | TEntity[] | null | Promise<TEntity | TEntity[] | null>;
  };
}

context

Passed to every check/explain call and forwarded to all resolver functions. Use for request-scoped data: database connections, auth info, tenant IDs, etc.

type MyContext = { db: DB; userId: string };

const engine = await buildEngine<MyContext, User | Repo>({ ... });

await engine.check({
  user: currentUser,
  object: targetRepo,
  relation: "owner",
  context: { db, userId: "user-1" },  // required on every call
});

If resolvers need no context, use object and pass {}.

Using Codegen (Optional)

@graplix/codegen generates a fully-typed buildEngine wrapper from your schema:

npx @graplix/codegen ./schema.graplix

The generated file provides typed GraplixResolvers<TContext> and GraplixEntityInput so TypeScript enforces exhaustiveness:

import { buildEngine } from "./schema.generated";

const engine = await buildEngine({
  resolvers: { ... },  // typed per schema + mappers
  resolveType: (value) => { ... },
});

Critical Rules

EntityRef

• Never pass EntityRef directly to check/explain. query.user and query.object accept TEntityInput (your domain types) only.
• Import EntityRef as a type only when working with CheckEdge.from/to in explain results.

Relation Resolvers

• Return domain entities (or arrays, or null) — not IDs, not EntityRef instances.
• The engine calls resolveType (or uses schema hints) to determine the returned entity's type.
• resolver.load() is never called inside toEntityRef — it is only called when an entity needs to be loaded by ID.

resolveType Precedence

1. resolveType(value) is always tried first.
2. If it returns null, schema type hints (from relation definitions) are used as fallback.
3. For query.user and query.object, resolveType must return the correct type — no fallback.

Caching

• Both entity cache and relation values cache are per-request (not shared across calls).
• Cache size is controlled by maxCacheSize (default: 500).

Import Reference

// Runtime engine
import { buildEngine } from "@graplix/engine";
import type {
  BuildEngineOptions,
  GraplixEngine,
  Query,
  Resolver,
  Resolvers,
  ResolverInfo,
  ResolveType,
  CheckEdge,
  CheckExplainResult,
  EntityRef,  // for CheckEdge.from/to type annotations
} from "@graplix/engine";

// Schema parsing (lower-level)
import { parse } from "@graplix/language";

// Codegen (CLI or programmatic)
import { generateTypeScript } from "@graplix/codegen";

Error Handling

Type errors often signal outdated knowledge. Common indicators: "Property X does not exist," module not found, incorrect generic parameters.

Response approach:

1. Check references/common-errors.md
2. Verify current API in embedded docs (node_modules/@graplix/engine/dist/docs/)
3. Recognize errors may reflect knowledge gaps, not user mistakes

Source: daangn/graplix — distributed by TomeVault.