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securitycritical PriorityID: openfga-rebac-graph-fanout-depth-boundary

OpenFGA ReBAC Graph Traversal Fan-Out and Resolution Depth Boundary

Enforces strict bounds on OpenFGA authorization graph traversal depth, contextual tuple payload size, and evaluation concurrency. Prevents Zanzibar-style algorithmic Denial of Service (DoS), thread starvation, and latency spikes caused by unbounded transitive relationship expansion and recursive contextual tuple evaluations.

Prohibited Anti-Pattern: Unbounded Transitive Graph Traversal and Unvalidated Contextual Tuple Injection in ReBAC Checks

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---
description: OpenFGA ReBAC Graph Traversal Fan-Out and Resolution Depth Boundary - Enforces strict bounds on OpenFGA authorization graph traversal depth, contextual tuple payload size, and evaluation concurrency. Prevents Zanzibar-style algorithmic Denial of Service (DoS), thread starvation, and latency spikes caused by unbounded transitive relationship expansion and recursive contextual tuple evaluations.
globs: src/**/auth/**/*.{ts,js}, src/**/fga/**/*.{ts,js}, src/**/permissions/**/*.{ts,js}, src/**/guards/**/*.{ts,js}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/openfga-rebac-graph-fanout-depth-boundary"
---

# OpenFGA ReBAC Graph Traversal Fan-Out and Resolution Depth Boundary

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Unbounded Transitive Graph Traversal and Unvalidated Contextual Tuple Injection in ReBAC Checks

## System Constraints
You are a Principal Engineer enforcing OpenFGA ReBAC Graph Traversal Fan-Out Evaluation Boundaries. Mandate invariants that strictly limit evaluation depth, cap contextual tuple injections, enforce deterministic request timeouts with fail-closed semantics, and prevent transitive circular graph exhaustion attacks.

## Strict Guidelines
- Engineers MUST ALWAYS enforce strict limits on contextual tuple array size (e.g., maximum 20 tuples per request) prior to invoking OpenFGA evaluation APIs.
- Engineers MUST NOT permit arbitrary caller-supplied graph structures or unbounded nested memberships to dynamically populate contextual tuples without depth and schema validation.
- Code SHOULD enforce strict per-request execution timeouts (<= 150ms) using AbortController signals with absolute fail-closed authorization semantics.
- Services MUST configure OpenFGA client initialization with bounded concurrency settings, restricting max-retries and setting explicit connection-pool constraints to prevent thread starvation under fan-out.
- Components NEVER fall back to permissive or allow-all authorization responses when an OpenFGA evaluation yields a timeout, traversal depth exceeded error, or circuit-breaker trip.

## Bad vs Good Implementations
### Bounded Contextual Tuple Evaluation with Fail-Closed Timeout Signal

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Directly injecting untrusted, unbounded contextual tuples without depth checks allows attackers to construct deeply nested or cyclical relationship graphs. The lack of an AbortController or evaluation timeout causes Zanzibar-style recursive evaluation fan-out, resulting in thread pool exhaustion and catastrophic latency degradation.
```typescript
import { OpenFgaClient } from '@openfga/sdk';

export async function checkAccess(fga: OpenFgaClient, user: string, relation: string, docId: string, clientSuppliedTuples: any[]) {
  // VULNERABLE: Unbounded contextual tuples passed directly to engine.
  // No timeout, no depth boundary, leaves system vulnerable to algorithmic DoS.
  const response = await fga.check({
    user: `user:${user}`,
    relation,
    object: `document:${docId}`,
    contextualTuples: clientSuppliedTuples,
  });

  return response.allowed;
}
```

#### Production Standard (Correct)
> **Standard**: Imposes a hard cap on contextual tuples before dispatching, sets an explicit 150ms timeout via AbortController to mitigate recursive fan-out spikes, and enforces strict fail-closed authorization semantics on errors.
```typescript
import { OpenFgaClient, ClientCheckRequest } from '@openfga/sdk';

const MAX_CONTEXTUAL_TUPLES = 10;
const EVALUATION_TIMEOUT_MS = 150;

export async function checkAccess(
  fga: OpenFgaClient,
  userId: string,
  relation: string,
  docId: string,
  contextTuples: Array<{ user: string; relation: string; object: string }> = []
): Promise<boolean> {
  // INVARIANT: Bound contextual tuple fan-out to prevent graph expansion abuse
  if (contextTuples.length > MAX_CONTEXTUAL_TUPLES) {
    throw new Error(`SecurityBoundaryViolation: Contextual tuples exceed safe maximum of ${MAX_CONTEXTUAL_TUPLES}`);
  }

  const controller = new AbortController();
  const timeoutHandle = setTimeout(() => controller.abort(), EVALUATION_TIMEOUT_MS);

  try {
    const payload: ClientCheckRequest = {
      user: `user:${userId}`,
      relation,
      object: `document:${docId}`,
      contextualTuples: contextTuples,
    };

    const response = await fga.check(payload, {
      signal: controller.signal,
    });

    return Boolean(response.allowed);
  } catch (err: unknown) {
    // INVARIANT: Fail-closed on timeout, cancellation, or graph resolution depth failure
    return false;
  } finally {
    clearTimeout(timeoutHandle);
  }
}
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

OpenFGA Policy and Schema Inspector MCP
Validates OpenFGA authorization models for unbounded recursive cycles and evaluates traversal complexity boundaries.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

OpenFGA CLI Validator
Command-line tool to run static analysis and model testing on OpenFGA authorization models against cyclic dependencies.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: OpenFGA ReBAC Graph Traversal Fan-Out and Resolution Depth Boundary

OpenFGA ReBAC Graph Traversal Fan-Out and Resolution Depth Boundary defines an industrial-grade behavioral standard for security engineering. Enforces strict bounds on OpenFGA authorization graph traversal depth, contextual tuple payload size, and evaluation concurrency. Prevents Zanzibar-style algorithmic Denial of Service (DoS), thread starvation, and latency spikes caused by unbounded transitive relationship expansion and recursive contextual tuple evaluations. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Unbounded Transitive Graph Traversal and Unvalidated Contextual Tuple Injection in ReBAC Checks Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftUnbounded Transitive Graph Traversal and Unvalidated Contextual Tuple Injection in ReBAC ChecksCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Engineers MUST ALWAYS enforce strict limits on contextual tuple array size (e.g., maximum 20 tuples per request) prior to invoking OpenFGA evaluation APIs.

Engineers MUST ALWAYS enforce strict limits on contextual tuple array size (e.g., maximum 20 tuples per request) prior to invoking OpenFGA evaluation APIs.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST NOT permit arbitrary caller-supplied graph structures or unbounded nested memberships to dynamically populate contextual tuples without depth and schema validation.

Engineers MUST NOT permit arbitrary caller-supplied graph structures or unbounded nested memberships to dynamically populate contextual tuples without depth and schema validation.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Code SHOULD enforce strict per-request execution timeouts (<= 150ms) using AbortController signals with absolute fail-closed authorization semantics.

Code SHOULD enforce strict per-request execution timeouts (<= 150ms) using AbortController signals with absolute fail-closed authorization semantics.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Services MUST configure OpenFGA client initialization with bounded concurrency settings, restricting max-retries and setting explicit connection-pool constraints to prevent thread starvation under fan-out.

Services MUST configure OpenFGA client initialization with bounded concurrency settings, restricting max-retries and setting explicit connection-pool constraints to prevent thread starvation under fan-out.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Components NEVER fall back to permissive or allow-all authorization responses when an OpenFGA evaluation yields a timeout, traversal depth exceeded error, or circuit-breaker trip.

Components NEVER fall back to permissive or allow-all authorization responses when an OpenFGA evaluation yields a timeout, traversal depth exceeded error, or circuit-breaker trip.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is OpenFGA ReBAC Graph Traversal Fan-Out and Resolution Depth Boundary critical for AI coding assistants?

Enforces strict bounds on OpenFGA authorization graph traversal depth, contextual tuple payload size, and evaluation concurrency. Prevents Zanzibar-style algorithmic Denial of Service (DoS), thread starvation, and latency spikes caused by unbounded transitive relationship expansion and recursive contextual tuple evaluations. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Unbounded Transitive Graph Traversal and Unvalidated Contextual Tuple Injection in ReBAC Checks) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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