[#5] Implement command service skeleton with Kafka producer

[igorsatsyuk]

Description

Implements Issue #5 MVP skeleton for command-service.

What was added

• WebFlux command endpoint: POST /commands/user/login
• Kafka producer publishing UserLoggedInEvent to topic user.login.events
• Temporary in-memory event storage for accepted events
• Validation and API error handling (CommandResponse envelope)
• Unit tests for controller and service behavior
• Module README for local run/test steps

Docs/process alignment included

• Unified branch naming rule across docs: <type>/#XX-description (feature|fix|docs|test)

Closes

• Closes [BACKEND] Command Service - скелет #5

Related

• Relates to [BACKEND] Инициализация Maven проекта #4
• Relates to [INFRA] Docker Compose для инфраструктуры #2

Checklist

• Code follows style guidelines
• Self-review completed
• Tests added/updated
• Documentation updated

Testing

Set-Location backend
mvn -pl command-service -am test

[Copilot]

Pull request overview

Implements the MVP command-service skeleton for the backend CQRS flow, adding a WebFlux command endpoint that turns login commands into UserLoggedInEvents and publishes them to Kafka.

Changes:

• Added login command controller/service, Kafka topic configuration, publish exception handling, and temporary in-memory event storage.
• Added unit tests for controller success flow and service publish/store behavior.
• Updated module README and workflow documentation for branch naming and issue progress.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
START_HERE.md	Updates branch naming guidance.
GITHUB_ISSUES_PLAN.md	Marks issue #5 subtasks complete and updates branch strategy.
CONTRIBUTING.md	Expands mandatory branch naming convention.
AGENTS.md	Aligns agent guidance with branch naming convention.
backend/command-service/README.md	Documents command-service run, quick check, and test steps.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/CommandServiceApplication.java	Enables configuration properties scanning.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/api/CommandController.java	Adds POST /commands/user/login.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/api/GlobalExceptionHandler.java	Adds API error handling.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/config/KafkaTopicsProperties.java	Adds externalized Kafka topic properties.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/repository/InMemoryEventStorage.java	Adds temporary in-memory event storage.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/service/CommandPublishException.java	Adds publish failure exception type.
backend/command-service/src/main/java/lt/satsyuk/distributed/audit/command/service/UserLoginCommandService.java	Creates and publishes login events, then stores accepted events.
backend/command-service/src/test/java/lt/satsyuk/distributed/audit/command/api/CommandControllerTest.java	Adds controller success-flow unit test.
backend/command-service/src/test/java/lt/satsyuk/distributed/audit/command/service/UserLoginCommandServiceTest.java	Adds service publish/store and failure tests.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[igorsatsyuk]

@copilot-pull-request-reviewer review

[Copilot]

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 5 comments.

[Copilot]

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 17 out of 17 changed files in this pull request and generated no new comments.