“EN-12-MCP-Ecosystem-Agentic-Dev-Toolchains”

Changelog entry in Keep a Changelog style, written for USERS (behavior changes,

Call out anything that looks like an accidental change in the diff (debug logs,

"Explain This Code" Tutor (Socratic)

Explains unfamiliar code at chosen depth using the Socratic method — great for learning code you must maintain.

Walk the execution path step by step with line refs; for each non-obvious

Highlight 3 things a junior would misunderstand, and ask me a checkpoint

End with: likely bug risks in this exact code, an interview-style hard question

System Design Interview / Real Design Partner

Produces a full design doc (requirements, capacity, API, data model, bottlenecks, trade-offs) and plays devil's advocate. Works for interviews and real projects.

ADR (Architecture Decision Record) Drafter

Turns an architectural choice into a concise ADR with context, options, trade-offs, and consequences — the artifact teams actually need later.

Distributed Systems Trade-off Analyst

For hard consistency/availability choices (CAP/PACELC, transactions, ordering) — produces requirement-driven decisions instead of buzzwords.

API-First / Schema-First Design Facilitator

Forces contract design before implementation, with evolution/versioning rules and consumer review — prevents costly API mistakes.

Multi-Tenancy Architecture Selector

Selects and details an isolation model (shared DB / schema per tenant / DB per tenant) against real requirements, including noisy-neighbor and backup isolation.

Event-Driven / CQRS / Saga Designer

Designs reliable event flows (Kafka/RabbitMQ/EventBridge): contracts, ordering, duplicates, sagas, and read models — including when NOT to use events.

Caching Architecture Advisor

Designs layered caching with explicit invalidation and consistency contracts — the hardest part of real systems.

Rate Limiting, Quota & Throttling Designer

Designs limiters (per-user/IP/tenant/API key), algorithm choice, and 429 contracts — including distributed counters and fairness.

File Upload / Media Pipeline Architect

Designs reliable uploads for large files with virus scanning, image/video processing, and storage lifecycle.

Search & Recommendation System Designer

Designs search (ES/OpenSearch/vector/hybrid) with relevance tuning pipelines — includes ranking eval and zero-result handling.

RAG / LLM-Application Architect

Designs a production retrieval-augmented generation system: chunking, embedding, hybrid retrieval, reranking, evaluation, and guardrails. (LLM-native dev category.)

LLM Evaluation / Hallucination Mitigation Planner

Builds an eval harness for LLM features: golden sets, metrics, red-team cases, and CI regression gates for prompts/chains.

Observability/SLO Architect

Defines SLOs, error budgets, alerting, and dashboards for a service from user journeys — symptom-based alerting, not noise.

Cost Optimization / FinOps Engineer

Finds and prioritizes cloud/infra spend reductions with risk and engineering cost.