OpenFGA ReBAC Causal Consistency & Bounded-Staleness Guardrail

--- description: OpenFGA ReBAC Causal Consistency & Bounded-Staleness Guardrail - Eliminates authorization race conditions in high-throughput microservices by enforcing causal consistency token propagation and strict bounded-staleness cache validation. Prevents unauthorized resource exposure caused by evaluating permission checks against stale relationship tuples immediately following state mutations (read-after-write anomalies). Mandates contextual consistency tokens or forced upstream read evaluation during high-integrity authorization transactions. globs: src/services/auth*/**/*.{ts,js}, src/middleware/**/*.{ts,js}, src/security/**/*.{ts,js}, src/modules/**/authorization/**/*.{ts,js}, src/api/guards/**/*.{ts,js} alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/openfga-rebac-causal-consistency-invariant" --- # OpenFGA ReBAC Causal Consistency & Bounded-Staleness Guardrail > **Severity**: CRITICAL | **Category**: backend > **Anti-Pattern Warning**: Blind ReBAC Checks Vulnerable to Read-After-Write Consistency Race Conditions ## System Constraints You are a Principal Software Architect enforcing the OpenFGA ReBAC Causal Consistency Invariant. In high-throughput distributed microservices, writes to OpenFGA tuples are asynchronously replicated or cached at edge layers. You must prohibit bare `check()` queries executed immediately after mutations without consistency assertions. Enforce the extraction, propagation, and verification of causal consistency tokens (e.g., higher transaction watermarks or write consistency tokens) to guarantee that authorization checks strictly reflect state changes made within the current or upstream causal chain. ## Strict Guidelines - Engineers MUST ALWAYS capture the consistency token or write transaction identifier returned by OpenFGA when inserting, updating, or deleting relationship tuples. - Engineers MUST NOT execute bare authorization checks (`openFga.check()`) in post-mutation workflows without passing `consistency: ConsistencyPreference.HIGHER_CONSISTENCY` or supplying a valid monotonic causal token. - Code SHOULD propagate causal consistency tokens across service boundaries via standardized HTTP metadata headers (e.g., `x-openfga-consistency-token` or `x-causal-watermark`) on transactional paths. - Services MUST bypass internal local tuple caches and fall back to strict upstream evaluation if the cached tuple version is older than the inbound causal consistency token watermark. - Components NEVER assume distributed relationship state has replicated instantly across multiple instances or read-replicas upon transaction commit. ## Bad vs Good Implementations ### Enforcing Causal Token Tracking and High Consistency Evaluation #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: The mutation ignores the write result's consistency token, and the authorization check uses default minimal consistency against potentially stale read replicas, leading to false negative authorization denials immediately after access grants. ```typescript import { OpenFgaClient } from '@openfga/sdk'; export class DocumentService { constructor(private readonly fgaClient: OpenFgaClient) {} async grantAccess(documentId: string, userId: string): Promise<void> { // Anti-Pattern: Fire-and-forget write without capturing causal state await this.fgaClient.write({ writes: [{ user: `user:${userId}`, relation: 'viewer', object: `document:${documentId}` }] }); } async verifyAccess(documentId: string, userId: string): Promise<boolean> { // Anti-Pattern: Bare check relying on cached read replica; // vulnerable to race conditions if invoked immediately after grantAccess const response = await this.fgaClient.check({ user: `user:${userId}`, relation: 'viewer', object: `document:${documentId}` }); return response.allowed ?? false; } } ``` #### Production Standard (Correct) > **Standard**: Captures the consistency watermark from the OpenFGA write response and explicitly demands HIGHER_CONSISTENCY during authorization checks when evaluated within an active causal window, completely eliminating stale-read race conditions. ```typescript import { OpenFgaClient, ConsistencyPreference } from '@openfga/sdk'; export interface AccessMutationResult { success: boolean; consistencyToken?: string; } export class DocumentService { constructor(private readonly fgaClient: OpenFgaClient) {} async grantAccess(documentId: string, userId: string): Promise<AccessMutationResult> { const writeResponse = await this.fgaClient.write({ writes: [{ user: `user:${userId}`, relation: 'viewer', object: `document:${documentId}` }] }); // Invariant: Capture and return monotonic causal watermark or token return { success: true, consistencyToken: writeResponse.continuation_token ?? undefined }; } async verifyAccess( documentId: string, userId: string, requiredConsistencyToken?: string ): Promise<boolean> { // Invariant: Enforce HIGHER_CONSISTENCY when evaluating causal chains const response = await this.fgaClient.check({ user: `user:${userId}`, relation: 'viewer', object: `document:${documentId}`, consistency: requiredConsistencyToken ? ConsistencyPreference.HIGHER_CONSISTENCY : ConsistencyPreference.UNSPECIFIED }); return response.allowed ?? false; } } ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: OpenFGA ReBAC Causal Consistency & Bounded-Staleness Guardrail

OpenFGA ReBAC Causal Consistency & Bounded-Staleness Guardrail defines an industrial-grade behavioral standard for backend engineering. Eliminates authorization race conditions in high-throughput microservices by enforcing causal consistency token propagation and strict bounded-staleness cache validation. Prevents unauthorized resource exposure caused by evaluating permission checks against stale relationship tuples immediately following state mutations (read-after-write anomalies). Mandates contextual consistency tokens or forced upstream read evaluation during high-integrity authorization transactions. 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: Blind ReBAC Checks Vulnerable to Read-After-Write Consistency Race Conditions 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 Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	Blind ReBAC Checks Vulnerable to Read-After-Write Consistency Race Conditions	Critical	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 Inconsistency	AI 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:

Engineers MUST ALWAYS capture the consistency token or write transaction identifier returned by OpenFGA when inserting, updating, or deleting relationship tuples.

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.