OpenFGA CDC-Driven Local Graph Invalidation Boundary and Bounded-Staleness Enforcement

--- description: OpenFGA CDC-Driven Local Graph Invalidation Boundary and Bounded-Staleness Enforcement - Mandates strict monotonic log sequence number (LSN) fencing and bounded-staleness verification for local in-memory OpenFGA authorization graphs fed by PostgreSQL WAL logical decoding. Enforces immediate authoritative fallback to upstream OpenFGA clusters when replication lag exceeds SLA bounds or when monotonic WAL continuity is broken, preventing unauthorized access after permission revocation. globs: src/auth/**/*.{ts,js}, src/security/**/*.{ts,js}, src/cdc/**/*.{ts,js}, src/lib/fga/**/*.{ts,js} alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/openfga-cdc-local-graph-invalidation-boundary" --- # OpenFGA CDC-Driven Local Graph Invalidation Boundary and Bounded-Staleness Enforcement > **Severity**: CRITICAL | **Category**: security > **Anti-Pattern Warning**: Unsequenced In-Memory Auth Cache Mutated by Naive CDC Listeners Without LSN Watermarking or Upstream Fallback ## System Constraints You are a Principal Software Architect enforcing zero-trust authorization invariants for OpenFGA local graph caches populated by PostgreSQL WAL logical decoding (CDC). You must mandate strict bounded-staleness checks, monotonic LSN sequencing, atomic graph mutations, and mandatory upstream fallback when replication lag breaches critical boundaries. ## Strict Guidelines - Engineers MUST ALWAYS enforce monotonic LSN ordering on consumed WAL events before applying edge insertions or deletions to the local graph. - Engineers MUST ALWAYS reject local authorization evaluations and delegate to authoritative upstream OpenFGA APIs if current replication lag exceeds the bounded-staleness threshold (maxBoundedLagMs). - Engineers MUST NOT mutate local ReBAC graph state from CDC records lacking commit_lsn and transaction_timestamp metadata. - Services MUST execute atomic subgraph invalidations for transmutative relationship updates (e.g., role hierarchy or group re-nesting) rather than granular, non-atomic node-by-node updates. - Components NEVER assume local cache consistency across process boundaries; every local graph node MUST be pinned to the high-watermark LSN acknowledged by the local CDC consumer pipeline. ## Bad vs Good Implementations ### Insecure Asynchronous CDC Consumer vs. Monotonic LSN-Fenced Authorization Engine #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: The bad example applies WAL updates without verifying monotonic Log Sequence Numbers (LSN), causing out-of-order mutations to reinstate revoked access. Furthermore, it queries the local graph indefinitely without checking replication lag, violating bounded-staleness invariants and serving stale authorization decisions if the CDC consumer disconnects. ```typescript import { OpenFgaClient } from '@openfga/sdk'; interface SimpleTuple { user: string; relation: string; object: string; } export class LocalAuthGraph { private graph = new Map<string, Set<string>>(); // CRITICAL ANTI-PATTERN: Ingests CDC events out-of-order without LSN tracking // or bounded-staleness safety, leading to race-condition auth bypasses. public handleWalEvent(payload: { op: 'c' | 'd'; tuple: SimpleTuple }): void { const key = `${payload.tuple.object}#${payload.tuple.relation}`; if (payload.op === 'c') { const set = this.graph.get(key) || new Set(); set.add(payload.tuple.user); this.graph.set(key, set); } else if (payload.op === 'd') { this.graph.get(key)?.delete(payload.tuple.user); } } // Insecure: Always reads local state even if CDC listener died hours ago public async check(user: string, relation: string, object: string): Promise<boolean> { const allowedUsers = this.graph.get(`${object}#${relation}`); return allowedUsers ? allowedUsers.has(user) : false; } } ``` #### Production Standard (Correct) > **Standard**: The fixed implementation monotonically fences LSN writes to guard against out-of-order replayed WAL changes. It monitors the high-watermark timestamp against a strict SLA (e.g., 250ms), and checks caller-provided LSN fences. If stale or out-of-spec, it safely falls back to the authoritative upstream OpenFGA API. ```typescript import { OpenFgaClient, ClientCheckRequest } from '@openfga/sdk'; export interface WalAuthTupleEvent { commitLsn: bigint; commitTimestampMs: number; op: 'INSERT' | 'DELETE'; tupleKey: { user: string; relation: string; object: string; }; } export class ResilientLocalAuthGraph { private graph = new Map<string, Set<string>>(); private lastAppliedLsn: bigint = BigInt(0); private lastHeartbeatTimestampMs: number = Date.now(); constructor( private readonly upstreamClient: OpenFgaClient, private readonly maxBoundedLagMs: number = 250 ) {} public applyWalEvent(event: WalAuthTupleEvent): void { // Enforce monotonic LSN invariant to prevent out-of-order mutations if (event.commitLsn <= this.lastAppliedLsn) { return; } const key = `${event.tupleKey.object}#${event.tupleKey.relation}`; if (event.op === 'INSERT') { const users = this.graph.get(key) ?? new Set<string>(); users.add(event.tupleKey.user); this.graph.set(key, users); } else if (event.op === 'DELETE') { this.graph.get(key)?.delete(event.tupleKey.user); } this.lastAppliedLsn = event.commitLsn; this.lastHeartbeatTimestampMs = Math.max(this.lastHeartbeatTimestampMs, event.commitTimestampMs); } public async check( user: string, relation: string, object: string, minRequiredLsn?: bigint ): Promise<boolean> { const now = Date.now(); const replicationLagMs = now - this.lastHeartbeatTimestampMs; const violatesLsnFence = minRequiredLsn !== undefined && this.lastAppliedLsn < minRequiredLsn; // Fall back to upstream authoritative OpenFGA if bounded staleness is breached if (replicationLagMs > this.maxBoundedLagMs || violatesLsnFence) { const checkReq: ClientCheckRequest = { user, relation, object }; const response = await this.upstreamClient.check(checkReq); return response.allowed ?? false; } // Fast-path: Sub-millisecond evaluated against verified local bounded graph const users = this.graph.get(`${object}#${relation}`); return users !== undefined && users.has(user); } } ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: OpenFGA CDC-Driven Local Graph Invalidation Boundary and Bounded-Staleness Enforcement

OpenFGA CDC-Driven Local Graph Invalidation Boundary and Bounded-Staleness Enforcement defines an industrial-grade behavioral standard for security engineering. Mandates strict monotonic log sequence number (LSN) fencing and bounded-staleness verification for local in-memory OpenFGA authorization graphs fed by PostgreSQL WAL logical decoding. Enforces immediate authoritative fallback to upstream OpenFGA clusters when replication lag exceeds SLA bounds or when monotonic WAL continuity is broken, preventing unauthorized access after permission revocation. 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: Unsequenced In-Memory Auth Cache Mutated by Naive CDC Listeners Without LSN Watermarking or Upstream Fallback 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	Unsequenced In-Memory Auth Cache Mutated by Naive CDC Listeners Without LSN Watermarking or Upstream Fallback	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 enforce monotonic LSN ordering on consumed WAL events before applying edge insertions or deletions to the local graph.

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.