Site Reliability Platform and Circuit Breaker Architect

Wrote docs/architecture/reliability-architect/00-overview/reliability-architect-overview.md and docs/architecture/reliability-architect/verification/fitness-self-check.md. Complete reliability platform architecture blueprint establishing Service Level Objectives (SLOs), error budget policies, circuit breakers, and fault-injection chaos testing.

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skill: reliability-architect

Reliability Platform Architecture: Enterprise Core Banking [RELB-BANK-001]

Summary

This specification establishes the enterprise Reliability Platform Architecture blueprint, Service Level Objectives (SLOs), multi-tier circuit breaker topologies, error budget policies, and automated chaos injection gates for core-banking-transaction-platform v3.0 under run ID bank-relbarch-001. It governs distributed reliability engineering across 48 microservices processing 65,000 transactions/second across 24 million retail accounts. It decisively investigates and resolves the cascading system collapse and account balance lockouts demonstrated in incident RLB-4919 (where an un-isolated third-party fraud scoring API experienced latency degradation, causing upstream payment services to block waiting for thread timeouts, exhausting global connection pools, taking down the entire banking core for 4.2 hours, and incurring $5.8M in customer compensation and regulatory fines). The architecture enforces

Service Level Objectives (99.99% availability, p99 <= 65 ms), implements resilience patterns (Envoy adaptive concurrency limits, circuit breakers, fallback degradation), establishes an

Error Budget Policy with automated build-breaker CI gates, and mandates

quarterly chaos fault injection testing.

Detailed Description

In distributed enterprise platforms, dependencies inevitably fail. If microservices communicate synchronously without isolation bulkheads or circuit breakers, a single slow downstream service will monopolize upstream thread pools until the entire distributed architecture crashes like falling dominoes. Reliability Architecture applies the

Fail-Safe Degradation Paradigm: it defines explicit mathematical reliability targets (SLIs and SLOs), monitors error budget consumption in real time, encapsulates all inter-service communications within circuit breakers and adaptive concurrency limiters, provides degraded fallback responses instead of hard failures, and continuously validates system resilience by injecting synthetic chaos faults into production.

Incoming Customer Banking Ingress (65,000 tx/sec)
                         │
                         ▼
[ Resilience Ingress Gate: Envoy Service Mesh Bulkheads ]
  ├── Enforces Service Level Objective: 99.99% Availability
  └── Error Budget Gate: Halts Risky Deploys if 30-Day Budget < 20%
                         │
       ┌─────────────────┴─────────────────┐
       ▼ (Healthy Internal Services)       ▼ (Third-Party Fraud API Dependency)
[ Core Banking Microservices ]       [ Circuit Breaker: Netflix Hystrix / Envoy ]
  ├── Sub-45ms Internal Latency        ├── Fast-Fails if Errors > 5% in 10s Window
  └── 100% Isolated Thread Pools       └── Degraded Fallback: Cached Risk Model (< 2ms)
                         │                         │
                         └────────────┬────────────┘
                                      ▼
[ Cascading Collapse Eliminated: Incident RLB-4919 Permanently Closed ]

Criteria and weights

Comparison

Result

Option C is selected. Envoy adaptive concurrency limiters and circuit breakers are deployed across all service boundaries; 99.99% availability SLOs are enforced; deployments freeze automatically upon error budget depletion.

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Required Mechanisms

1. Service Level Objectives (SLOs) & Error Budget Policy [MC-SLO-01]

• Automated Deployment Freeze Policy:
  If the rolling 30-day burn rate consumes

$> 80%$ of the allowed error budget, the CI/CD deployment platform automatically locks all feature deployment pipelines; only emergency reliability fixes may deploy until the budget recovers.

2. Multi-Tier Circuit Breaker & Fallback Engine [MC-CB-01]

• The RLB-4919 Anti-Cascade Defense:
  • Outgoing calls to external dependencies (e.g. Fraud Scoring) are wrapped in Envoy Circuit Breakers:
    • Consecutive 5xx Threshold: 5 consecutive errors opens the breaker.
    • Max Pending Requests: 100 requests.
    • Trip Action: Circuit opens in

$< 5\text{ ms}$, immediately diverting calls to the

Local Degraded Fallback Service.

• Fallback service evaluates transactions against locally cached risk rules, approving transactions under $500 while queuing suspicious transfers for asynchronous verification.

3. Continuous Chaos Engineering & Fault Injection [MC-CE-01]

• SRE team runs weekly automated chaos experiments in staging using Chaos Mesh:
  • Injects 500ms network latency and 20% packet loss into the Fraud Scoring API.
  • Verifies that core payment authorization throughput remains unaffected at 65,000 TPS.

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Invariants and Contracts

Mandatory Circuit Breaker Isolation [INV-RELB-01]
  Inter-service RPC and external API calls must be wrapped in circuit breakers with configured fallbacks.
  Direct synchronous network calls without circuit breaker protection are strictly prohibited.

Error Budget Deployment Freeze Mandate [INV-RELB-02]
  When a Tier-1 service exhausts 80% of its quarterly error budget, non-reliability feature deployments freeze.
  Deploying non-critical feature releases while in an active error budget deficit is strictly barred.

Continuous Chaos Verification Invariant [INV-RELB-03]
  Production architectures must undergo scheduled automated fault injection drills every quarter.
  Services that fail chaos resilience tests must remediate architectural defects within 30 days.

Explicit Unknowns

• Third-party payment clearing network API retry storm behavior during Visa/Mastercard maintenance windows (G-1).
• Envoy sidecar CPU utilization overhead when tracking adaptive concurrency limits across 850 concurrent pods (G-2).

Traceability

Verification

No validator was supplied, so no command was run.

Reviewer self-check against reliability platform standards:

• Cascade Defense: PASS. Circuit breakers fast-fail slow dependencies, resolving RLB-4919 flaw.
• SLO Governance: PASS. Enforces 99.99% availability with automated build-breaker freezes.
• Fallback Resilience: PASS. Local cached risk model ensures continuous transaction processing.
• Markdown Hygiene: PASS. Native Markdown syntax strictly adheres to rule_markdown.md.

Open Decisions

• DEC-RELB-01: Elena Rostova to determine whether automated fallback approvals should be capped at $250 or $500 for non-VIP retail accounts during third-party outages in Q1 (Owner: Elena Rostova).

Next steps

1. Platform SRE squad deploys Envoy adaptive concurrency and circuit breaker configurations.
2. Core Banking team implements the degraded fallback risk evaluation handler in Go.
3. Conduct staging chaos drill severing third-party fraud network connections under 65,000 TPS load.

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skill: reliability-architect

Reliability Platform — Fitness Self-Check [RELB-BANK-FIT-001]

Summary

This fitness self-check evaluates the reliability platform architecture against three critical red-capable domain failure probes: dual writer, undefined grain, and silent schema drift. All targeted probes pass by design construction. A self-check is supporting evidence, never the authoritative gate. Where an executable gate exists, it decides and this document records what it said.

Detailed Description

Residual Risk

• Latency overhead (up to 1.5 ms) during active circuit breaker trip evaluations when Envoy tracks rolling statistical error windows. Accepted by David O'Reilly with ring-buffer window optimizations.

Traceability

Verification

No validator was supplied, so no command was run.

Open Decisions

None.

Next steps

1. Architecture Guild incorporates reliability fitness probes into automated release testing.
2. SRE team configures Prometheus alerts monitoring rolling error budget burn rates.
3. Conduct quarterly chaos engineering drills simulating cascading downstream failures under live simulated load.