SkillVaultskills Browse all 500 skills

Architecture · Version 1.1.0 · Reviewed 2026-08-02

Event-Driven Boundary Designer

Make a defensible decision about event ownership design and outbox and dual-write review with evidence, explicit trade-offs, and a verification plan.

4 method steps 4 documented failure modes 4 diagnostic checks 7 quality gates

Defines event ownership, schema evolution, delivery semantics, and the outbox patterns that keep state and events consistent.

₹149 one-time

Get this skill archive

What this skill helps you do

  • Event ownership design
  • Outbox and dual-write review
  • Schema evolution policy

How Event-Driven Boundary Designer works

You provide

Service boundaries, event schemas, and consistency gaps

It inspects

Dual writes, ownership ambiguity, and delivery semantics

It decides

Outbox, ownership, and schema-evolution rules

You verify

Kill the broker mid-write and confirm no event is lost

What it checks first

Event-Driven Boundary Designer defines event ownership, schema evolution, delivery semantics, and the outbox patterns that keep state and events consistent. Use it when the work involves Event ownership design, Outbox and dual-write review, Schema evolution policy.

  1. The quality attribute that actually constrains the design: latency, consistency, availability, cost, or compliance.
  2. The critical path and the number of network hops on it.
  3. Where state lives and who owns it, since ownership ambiguity becomes a correctness problem.
  4. The failure behavior of every dependency: fail open, fail closed, or degrade.

Failure modes it recognizes

  • Synchronous coupling making availability the product of all dependency availabilities.
  • A shared database creating hidden coupling between nominally independent services.
  • A component with no clear owner, so its failure has no defined response.
  • Distributed transactions attempted across services without a saga or compensation model.

Answers it will reject

  • Selecting a technology before establishing the constraint it is meant to satisfy.
  • Presenting a diagram as a design without the failure and data-consistency model.
  • Optimizing for a hypothetical future scale at the cost of present operability.

Decision rules it applies

  • Make the consistency requirement explicit per operation, not per system.
  • Prefer designs whose failure modes are understood over designs whose peak performance is higher.
  • Record the decision, the rejected alternatives, and the conditions that would reverse it.

Evidence it asks for

  • Quantify load, growth, and latency budget with arithmetic and stated assumptions.
  • Define the rollout stages and the signal that gates each one.
  • Name the reversal path for the decision.

The method inside

  1. Turn event ownership design into explicit functional requirements and quality-attribute constraints.
  2. Model the critical path, state, trust, and failure boundaries that govern outbox and dual-write review.
  3. Compare viable designs for schema evolution policy against weighted constraints and operational ownership.
  4. Select a design with consequences, rollout stages, observability, and a reversible adoption path.

Deliverables

  • Event ownership design assessment
  • Outbox and dual-write review decision and action plan
  • Schema evolution policy verification checklist

Evidence requirements

  • Functional and quality requirements
  • Scale, latency, consistency, cost, and compliance constraints
  • Current topology and alternatives considered

Quality gates

  • Every material claim traces to supplied evidence or is labeled as a hypothesis.
  • The response follows the declared deliverable contract.
  • No execution, access, measurement, or verification is invented.
  • Secrets and personal data are redacted rather than repeated.
  • The user receives a concrete independent verification step.
  • The relevant failure modes in this domain were considered rather than only the reported symptom.
  • No listed anti-pattern was recommended as a solution.

Example task

Input

Our service writes to the database and publishes an event. Sometimes the event is missing after a failure.

Expected output

That is the dual-write problem and it cannot be solved with better error handling. The write and the publish are separate systems with no shared transaction. Use a transactional outbox: write the event to the same database in the same transaction and relay it asynchronously...

Boundaries and compatibility

Ideal for

  • Event ownership design: produce a decision or artifact grounded in supplied evidence.
  • Outbox and dual-write review: produce a decision or artifact grounded in supplied evidence.
  • Schema evolution policy: produce a decision or artifact grounded in supplied evidence.

Out of scope

  • Producing a generic reference architecture without requirements
  • Hiding material trade-offs behind best-practice language

Agent compatibility

  • GitHub Copilot custom agents
  • Claude Agent Skills / SKILL.md
  • Any instruction-following chat model

Tool policy: Advisory by default. No tools are assumed. If the host provides tools, use read-only evidence gathering unless the user explicitly approves a scoped write or execution action.