# Architecture Decision Records (ADRs)

## Overview

Architecture Decision Records (ADRs) are lightweight documents that capture important architectural decisions made during the development of the ISA-Frontend project. They provide context for why certain decisions were made, helping current and future team members understand the reasoning behind architectural choices.

## What are ADRs?

An Architecture Decision Record is a document that captures a single architectural decision and its rationale. The goal of an ADR is to document the architectural decisions that are being made so that:

- **Future team members** can understand why certain decisions were made
- **Current team members** can refer back to the reasoning behind decisions
- **Architectural evolution** can be tracked over time
- **Knowledge transfer** is facilitated during team changes

## ADR Structure

Each ADR follows a consistent structure based on our [TEMPLATE.md](./TEMPLATE.md) and includes:

- **Problem Statement**: What architectural challenge needs to be addressed
- **Decision**: The architectural decision made
- **Rationale**: Why this decision was chosen
- **Consequences**: Both positive and negative outcomes of the decision
- **Alternatives**: Other options that were considered
- **Implementation**: Technical details and examples
- **Status**: Current state of the decision (Draft, Approved, Superseded, etc.)

## Naming Convention

ADRs should follow this naming pattern:

```
NNNN-short-descriptive-title.md
```

Where:
- `NNNN` is a 4-digit sequential number (e.g., 0001, 0002, 0003...)
- `short-descriptive-title` uses kebab-case and briefly describes the decision
- `.md` indicates it's a Markdown file

### Examples:
- `0001-use-standalone-components.md`
- `0002-adopt-ngrx-signals.md`
- `0003-implement-micro-frontend-architecture.md`
- `0004-choose-vitest-over-jest.md`

## Process Guidelines

### 1. When to Create an ADR

Create an ADR when making decisions about:

- **Architecture patterns** (e.g., micro-frontends, monorepo structure)
- **Technology choices** (e.g., testing frameworks, state management)
- **Development practices** (e.g., code organization, build processes)
- **Technical standards** (e.g., coding conventions, performance requirements)
- **Infrastructure decisions** (e.g., deployment strategies, CI/CD processes)

### 2. ADR Lifecycle

```
Draft → Under Review → Approved → [Superseded/Deprecated]
```

- **Draft**: Initial version, being written
- **Under Review**: Shared with team for feedback and discussion
- **Approved**: Team has agreed and decision is implemented
- **Superseded**: Replaced by a newer ADR
- **Deprecated**: No longer applicable but kept for historical reference

### 3. Creation Process

1. **Identify the Need**: Recognize an architectural decision needs documentation
2. **Create from Template**: Copy [TEMPLATE.md](./TEMPLATE.md) to create new ADR
3. **Fill in Content**: Complete all sections with relevant information
4. **Set Status to Draft**: Mark the document as "Draft" initially
5. **Share for Review**: Present to team for discussion and feedback
6. **Iterate**: Update based on team input
7. **Approve**: Once consensus is reached, mark as "Approved"
8. **Implement**: Begin implementation of the architectural decision

### 4. Review Process

- **Author Review**: Self-review for completeness and clarity
- **Peer Review**: Share with relevant team members for technical review
- **Architecture Review**: Present in architecture meetings if significant
- **Final Approval**: Get sign-off from technical leads/architects

## Angular/Nx Specific Considerations

When writing ADRs for this project, consider these Angular/Nx specific aspects:

### Architecture Decisions
- **Library organization** in the monorepo structure
- **Dependency management** between applications and libraries
- **Feature module vs. standalone component** approaches
- **State management patterns** (NgRx, Signals, Services)
- **Routing strategies** for large applications

### Technical Decisions
- **Build optimization** strategies using Nx
- **Testing approaches** for different types of libraries
- **Code sharing patterns** across applications
- **Performance optimization** techniques
- **Bundle splitting** and lazy loading strategies

### Development Workflow
- **Nx executor usage** for custom tasks
- **Generator patterns** for code scaffolding
- **Linting and formatting** configurations
- **CI/CD pipeline** optimizations using Nx affected commands

## Template Usage

### Getting Started

1. Copy the [TEMPLATE.md](./TEMPLATE.md) file
2. Rename it following the naming convention
3. Replace placeholder text with actual content
4. Focus on the "why" not just the "what"
5. Include concrete examples and code snippets
6. Consider both immediate and long-term consequences

### Key Template Sections

- **Decision**: State the architectural decision clearly and concisely
- **Context**: Provide background information and constraints
- **Consequences**: Be honest about both benefits and drawbacks
- **Implementation**: Include practical examples relevant to Angular/Nx
- **Alternatives**: Show you considered other options

## Examples of Good ADRs

Here are some example titles that would make good ADRs for this project:

- **State Management**: "0001-adopt-ngrx-signals-for-component-state.md"
- **Testing Strategy**: "0002-use-angular-testing-utilities-over-spectator.md"
- **Code Organization**: "0003-implement-domain-driven-library-structure.md"
- **Performance**: "0004-implement-lazy-loading-for-feature-modules.md"
- **Build Process**: "0005-use-nx-cloud-for-distributed-task-execution.md"

## Best Practices

### Writing Effective ADRs

1. **Be Concise**: Keep it focused and to the point
2. **Be Specific**: Include concrete examples and implementation details
3. **Be Honest**: Document both pros and cons honestly
4. **Be Timely**: Write ADRs close to when decisions are made
5. **Be Collaborative**: Involve relevant team members in the process

### Maintenance

- **Review Regularly**: Check ADRs during architecture reviews
- **Update Status**: Keep status current as decisions evolve
- **Link Related ADRs**: Reference connected decisions
- **Archive Outdated**: Mark superseded ADRs appropriately

### Code Examples

When including code examples:
- Use actual project syntax and patterns
- Include both TypeScript and template examples where relevant
- Show before/after scenarios for changes
- Reference specific files in the codebase when possible

## Tools and Integration

### Recommended Tools

- **Markdown Editor**: Use any markdown-capable editor
- **Version Control**: All ADRs are tracked in Git
- **Review Process**: Use PR reviews for ADR approval
- **Documentation**: Link ADRs from relevant code comments

### Integration with Development

- Reference ADR numbers in commit messages when implementing decisions
- Include ADR links in PR descriptions for architectural changes
- Update ADRs when decisions need modification
- Use ADRs as reference during code reviews

## Getting Help

### Questions or Issues?

- **Team Discussions**: Bring up in team meetings or Slack
- **Architecture Review**: Present in architecture meetings
- **Documentation**: Update this README if process improvements are needed

### Resources

- [Architecture Decision Records (ADRs) - Michael Nygard](https://cognitect.com/blog/2011/11/15/documenting-architecture-decisions)
- [ADR GitHub Organization](https://adr.github.io/)
- [Nx Documentation](https://nx.dev/getting-started/intro)
- [Angular Architecture Guide](https://angular.dev/guide/architecture)

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*This ADR system helps maintain architectural consistency and knowledge sharing across the ISA-Frontend project. Keep it updated and use it regularly for the best results.*
