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securitycritical PriorityID: openfga-rebac-depth-fencing-guardrail

OpenFGA Recursive Tuple Graph Evaluation Depth Fencing & Cycle Detection

Prevents catastrophic denial-of-service, unconstrained graph traversals, and thread-pool exhaustion during relationship-based access control (ReBAC) evaluations. Enforces mandatory cycle detection via visited-node memoization, strict bounded depth-fencing budgets, and fail-closed timeout signals across all recursive OpenFGA tuple resolutions.

Prohibited Anti-Pattern: Unbounded Transitive Graph Traversal and Missing Cycle Detection in ReBAC Resolvers

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---
description: OpenFGA Recursive Tuple Graph Evaluation Depth Fencing & Cycle Detection - Prevents catastrophic denial-of-service, unconstrained graph traversals, and thread-pool exhaustion during relationship-based access control (ReBAC) evaluations. Enforces mandatory cycle detection via visited-node memoization, strict bounded depth-fencing budgets, and fail-closed timeout signals across all recursive OpenFGA tuple resolutions.
globs: src/**/auth*/**/*.{ts,tsx}, src/**/fga*/**/*.{ts,tsx}, src/**/access-control/**/*.{ts,tsx}, src/**/permissions/**/*.{ts,tsx}
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/openfga-rebac-depth-fencing-guardrail"
---

# OpenFGA Recursive Tuple Graph Evaluation Depth Fencing & Cycle Detection

> **Severity**: CRITICAL | **Category**: security
> **Anti-Pattern Warning**: Unbounded Transitive Graph Traversal and Missing Cycle Detection in ReBAC Resolvers

## System Constraints
You are a Principal Security Architect enforcing OpenFGA Recursive Tuple Graph Evaluation Depth Fencing. Mandate strict graph-budget invariant fencing, visited-state cycle detection, and fail-closed timeout primitives on all ReBAC evaluations.

## Strict Guidelines
- Engineers MUST ALWAYS enforce an immutable maximum recursion depth limit (depth budget <= 10) on all recursive relationship graph traversals.
- Engineers MUST track visited object-relation tuples using a Set or bitmask to detect and immediately abort on cycles, failing closed with a deterministic CycleDetectedError.
- Engineers MUST NOT execute unconstrained recursion or rely solely on default engine timeouts when expanding nested user-set or folder hierarchies.
- Services MUST propagate an AbortSignal or context deadline through every step of tuple resolution to prevent dangling asynchronous graph exploration.
- Components NEVER interpret depth-fence exhaustion or cycle errors as permissive access; traversal termination MUST fail closed with authorization denied.

## Bad vs Good Implementations
### Recursive ReBAC Hierarchy Evaluation with Depth Fencing and Cycle Guardrails

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: The resolution recurses through parent object tuples without a visited tracker, depth fence, or context cancellation. Any circular dependency or deep graph hierarchy triggers exponential query fan-out and process-killing stack or memory exhaustion.
```typescript
import { OpenFgaClient } from '@openfga/sdk';

interface CheckRequest {
  user: string;
  relation: string;
  object: string;
}

// CRITICAL FLAW: Unbounded recursion with no visited set or depth limit.
// A circular graph (e.g., Folder:A -> Folder:B -> Folder:A) causes infinite recursion,
// exhausting the event loop, stack frames, and memory.
export async function checkAccessUnsafe(
  fgaClient: OpenFgaClient,
  req: CheckRequest
): Promise<boolean> {
  const response = await fgaClient.check({
    user: req.user,
    relation: req.relation,
    object: req.object,
  });

  if (response.allowed) {
    return true;
  }

  // Manually traversing parent hierarchies without boundaries
  const { tuples } = await fgaClient.read({
    object: req.object,
    relation: 'parent',
  });

  for (const tuple of tuples) {
    const parentObject = tuple.key.user;
    const parentAllowed = await checkAccessUnsafe(fgaClient, {
      user: req.user,
      relation: req.relation,
      object: parentObject,
    });
    if (parentAllowed) return true;
  }

  return false;
}
```

#### Production Standard (Correct)
> **Standard**: The safe pattern enforces an immutable MAX_TRAVERSAL_DEPTH barrier, passes an explicit visited set to detect cycles instantly, propagates an AbortSignal for deterministic timeout termination, and strictly fails closed on boundary violations.
```typescript
import { OpenFgaClient } from '@openfga/sdk';

interface CheckRequest {
  user: string;
  relation: string;
  object: string;
}

export class AuthorizationGraphError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'AuthorizationGraphError';
  }
}

const MAX_TRAVERSAL_DEPTH = 8;

export async function checkAccessSafe(
  fgaClient: OpenFgaClient,
  req: CheckRequest,
  depth: number = 0,
  visited: Set<string> = new Set<string>(),
  signal?: AbortSignal
): Promise<boolean> {
  signal?.throwIfAborted();

  if (depth > MAX_TRAVERSAL_DEPTH) {
    // Fail-closed invariant: Reject access rather than hanging or blowing the stack
    throw new AuthorizationGraphError(
      `ReBAC evaluation depth limit exceeded (${MAX_TRAVERSAL_DEPTH}) for ${req.object}`
    );
  }

  const tupleKey = `${req.object}#${req.relation}@${req.user}`;
  if (visited.has(tupleKey)) {
    // Cycle detected: Fail-closed to prevent circular traversal DoS
    throw new AuthorizationGraphError(`Cyclic relationship detected at node: ${tupleKey}`);
  }
  visited.add(tupleKey);

  const { allowed } = await fgaClient.check(
    {
      user: req.user,
      relation: req.relation,
      object: req.object,
    },
    { signal }
  );

  if (allowed) {
    return true;
  }

  const { tuples } = await fgaClient.read(
    {
      object: req.object,
      relation: 'parent',
    },
    { signal }
  );

  for (const tuple of tuples) {
    const parentObject = tuple.key.user;
    const isAllowed = await checkAccessSafe(
      fgaClient,
      {
        user: req.user,
        relation: req.relation,
        object: parentObject,
      },
      depth + 1,
      visited,
      signal
    );
    if (isAllowed) return true;
  }

  return false;
}
```
Recommended MCP Servers (mcp-serverlist.com)

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

OpenFGA DSL & Model Validator
Model syntax and circular relation checker for OpenFGA schema files and relationship tuples.
Recommended Agent Skills (askills.dev)

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

FGA CLI Linter
CLI utility to run fga model test and static tuple cycle detection during CI/CD.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: OpenFGA Recursive Tuple Graph Evaluation Depth Fencing & Cycle Detection

OpenFGA Recursive Tuple Graph Evaluation Depth Fencing & Cycle Detection defines an industrial-grade behavioral standard for security engineering. Prevents catastrophic denial-of-service, unconstrained graph traversals, and thread-pool exhaustion during relationship-based access control (ReBAC) evaluations. Enforces mandatory cycle detection via visited-node memoization, strict bounded depth-fencing budgets, and fail-closed timeout signals across all recursive OpenFGA tuple resolutions. 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 Missing Cycle Detection in ReBAC Resolvers 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 Missing Cycle Detection in ReBAC ResolversCritical
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 an immutable maximum recursion depth limit (depth budget <= 10) on all recursive relationship graph traversals.

Engineers MUST ALWAYS enforce an immutable maximum recursion depth limit (depth budget <= 10) on all recursive relationship graph traversals.

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 track visited object-relation tuples using a Set or bitmask to detect and immediately abort on cycles, failing closed with a deterministic CycleDetectedError.

Engineers MUST track visited object-relation tuples using a Set or bitmask to detect and immediately abort on cycles, failing closed with a deterministic CycleDetectedError.

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

Engineers MUST NOT execute unconstrained recursion or rely solely on default engine timeouts when expanding nested user-set or folder hierarchies.

Engineers MUST NOT execute unconstrained recursion or rely solely on default engine timeouts when expanding nested user-set or folder hierarchies.

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 propagate an AbortSignal or context deadline through every step of tuple resolution to prevent dangling asynchronous graph exploration.

Services MUST propagate an AbortSignal or context deadline through every step of tuple resolution to prevent dangling asynchronous graph exploration.

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 interpret depth-fence exhaustion or cycle errors as permissive access

Components NEVER interpret depth-fence exhaustion or cycle errors as permissive access; traversal termination MUST fail closed with authorization denied.

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 Recursive Tuple Graph Evaluation Depth Fencing & Cycle Detection critical for AI coding assistants?

Prevents catastrophic denial-of-service, unconstrained graph traversals, and thread-pool exhaustion during relationship-based access control (ReBAC) evaluations. Enforces mandatory cycle detection via visited-node memoization, strict bounded depth-fencing budgets, and fail-closed timeout signals across all recursive OpenFGA tuple resolutions. 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 Missing Cycle Detection in ReBAC Resolvers) 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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