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Cross-Disciplinary Software Team Spaces

A Pattern Language

Architecture Decision Records (ADR)

Summary

Write down key architecture decisions with context, reasons, and results. This keeps the team clear, aligned, and helps remember why choices were made.

Context

Software teams make many architecture decisions that affect system design, team work, and long-term care. These decisions often involve important trade-offs and need clear explanations.

Problem

Important architecture decisions often go unwritten, half-remembered, or get mixed up in communication. This leads to confusion, repeated talks, and lost context over time. Teams struggle to understand why certain approaches were picked and if they still make sense.

Solution

Create Architecture Decision Records (ADRs) for decisions with big results, trade-offs, or that require people to change how they work. Use a team process with open discussion among the team and with stakeholders.

Forces

Implementation

  1. Sense the Need: Find decisions that have big results or require behavior changes
  2. Create ADR Document: Use consistent template with Title, Status, Context, Decision, Consequences
  3. Research and Gather Input: Ask around for input, capture relevant context and constraints
  4. Propose Decision: Think through results and document both positive and negative impacts
  5. Decide with Participants: Include necessary stakeholders in the decision process
  6. Communicate Decision: Share the ADR with affected teams and store it with the code
  7. Maintain Under Version Control: Keep ADRs findable and up-to-date

When NOT to Create an ADR

Skip ADRs for:

Red flags indicating ADR overload:

Maintenance Strategy:

ADR Template Variations

Standard ADR Template (General Decisions)

# ADR-XXXX: [Title in imperative form, <50 characters]

Status: [In Progress/Proposed/Accepted/Overridden/Obsolete]
Accepted by: [Names of decision makers]
Date: [Decision date]
Supersedes: [ADR-YYYY if replacing previous decision]

## Context
[Neutral factual description of the challenge. What forces 
(technical, political, social) affect the decision? What is 
the current situation?]

## Decision
[What change(s) are we making in response to the challenge?]

## Consequences
[What becomes easier or more difficult after this decision? 
Include both positive and negative consequences.]

Technical Infrastructure ADR Template

# ADR-XXXX: [Infrastructure Decision Title]

Status: [In Progress/Proposed/Accepted/Overridden/Obsolete]
Accepted by: [Names of decision makers]
Date: [Decision date]
Review Date: [When to revisit this decision]

## Problem Statement
[What technical problem are we solving?]

## Decision Drivers
- [Key factor 1, e.g., Performance requirements]
- [Key factor 2, e.g., Cost constraints]
- [Key factor 3, e.g., Team expertise]

## Considered Options
1. **Option A**: [Brief description]
   - Pros: [Advantages]
   - Cons: [Disadvantages]
   - Cost: [Estimated cost/effort]

2. **Option B**: [Brief description]
   - Pros: [Advantages]
   - Cons: [Disadvantages]
   - Cost: [Estimated cost/effort]

## Decision
[Chosen option and rationale]

## Implementation Plan
- [ ] Step 1: [Specific action]
- [ ] Step 2: [Specific action]
- [ ] Step 3: [Specific action]

## Acceptance Criteria
- [Measurable success criterion 1]
- [Measurable success criterion 2]

## Risks and Mitigation
- **Risk**: [Potential issue]
  - **Likelihood**: [High/Medium/Low]
  - **Impact**: [High/Medium/Low]
  - **Mitigation**: [How we'll address it]

Process/Team ADR Template

# ADR-XXXX: [Process Decision Title]

Status: [In Progress/Proposed/Accepted/Overridden/Obsolete]
Accepted by: [Names of decision makers]
Date: [Decision date]
Trial Period: [If experimental, when to evaluate]

## Current State
[How do we currently handle this process/situation?]

## Desired Outcome
[What do we want to achieve?]

## Decision
[What process/approach are we adopting?]

## Implementation
- **When**: [Timeline for rollout]
- **Who**: [Responsible parties]
- **How**: [Specific steps]
- **Training**: [What support is needed]

## Success Metrics
- [How we'll measure if this is working]
- [Specific metrics and targets]

## Rollback Plan
[If this doesn't work, how do we revert?]

Security ADR Template

# ADR-XXXX: [Security Decision Title]

Status: [In Progress/Proposed/Accepted/Overridden/Obsolete]
Accepted by: [Names of decision makers + Security Review]
Date: [Decision date]
Compliance: [Relevant standards/regulations]

## Threat Model
[What threats are we addressing?]

## Security Requirements
- [Requirement 1]
- [Requirement 2]
- [Requirement 3]

## Decision
[Security approach/solution chosen]

## Risk Assessment
- **Residual Risks**: [Risks that remain after implementation]
- **Risk Level**: [High/Medium/Low]
- **Acceptance**: [Who accepts the residual risk]

## Implementation
- [ ] Security control 1
- [ ] Security control 2
- [ ] Testing and validation
- [ ] Documentation update

## Monitoring
[How we'll detect if security posture changes]

Visualization Techniques

Note: Not every ADR needs diagrams. Use visuals only when they clarify complex decisions or multiple options. Simple decisions often work better with plain text.

Decision Flow Diagrams

Include Mermaid diagrams to show decision logic:

flowchart TD
    A[High Traffic Load] --> B{Performance Issue?}
    B -->|Yes| C[Scale Horizontally]
    B -->|No| D[Optimize Code]
    C --> E[Load Balancer + Multiple Instances]
    D --> F[Profiling + Code Optimization]

Option Comparison Tables

| Criteria | Option A (REST) | Option B (GraphQL) | Weight |
|----------|----------------|-------------------|---------|
| Team Expertise | ✅ High | ❌ Low | 3 |
| Performance | ✅ Good | ⚠️ Variable | 2 |
| Client Flexibility | ❌ Limited | ✅ High | 2 |
| **Total Score** | **9** | **6** | |

Timeline and Impact Diagrams

## Implementation Timeline

Week 1-2: API design Week 3-4: Core implementation
Week 5-6: Testing and docs Week 7-8: Migration and rollout


## Impact Map
- **Frontend Team**: Must update API calls → 2 weeks effort
- **Mobile Team**: New SDK needed → 3 weeks effort  
- **QA Team**: New test scenarios → 1 week effort

Architecture Diagrams

Embed relevant system diagrams showing before/after states:

## Before: Monolithic Database
[App] → [Database]

## After: Microservices Pattern  
[App] → [Service A] → [DB A]
     → [Service B] → [DB B]

Discovery Mechanisms

ADR Index Generation

Maintain an auto-generated index of all ADRs:

# Generate ADR index script
#!/bin/bash
echo "# Architecture Decision Records" > ADR-INDEX.md
echo "" >> ADR-INDEX.md
echo "## By Status" >> ADR-INDEX.md
for status in "Proposed" "Accepted" "Overridden" "Obsolete"; do
    echo "### $status" >> ADR-INDEX.md
    grep -l "Status: $status" ADR-*.md | sort | while read file; do
        title=$(grep "^# " "$file" | cut -d' ' -f2-)
        echo "- [$title]($file)" >> ADR-INDEX.md
    done
done

Tagging System

Add tags to make ADRs searchable:

---
title: "Adopt REST API Architecture"
tags: [api, backend, integration, rest]
components: [user-service, auth-service]
stakeholders: [frontend-team, mobile-team]
impact: high
effort: medium
---

ADR Search Tools

GitHub/GitLab Search Techniques:

Command Line Discovery:

# Find all ADRs by topic
grep -r "database" docs/adr/

# Find recent decisions
find docs/adr/ -name "*.md" -newer $(date -d '30 days ago' +%Y-%m-%d)

# List by status
grep -l "Status: Accepted" docs/adr/*.md

Integration with Development Tools

IDE Integration:

Git Hooks:

# Pre-commit hook to validate ADR format
#!/bin/bash
for file in $(git diff --cached --name-only | grep "docs/adr/.*\.md$"); do
    if ! grep -q "^## Decision$" "$file"; then
        echo "ADR $file missing required Decision section"
        exit 1
    fi
done

Pull Request Integration:

Notification and Review Systems

ADR Review Process:

Automated Reminders (adapt to your tech stack):

# Example: GitHub Action for ADR reviews
name: ADR Review Reminder
on:
  schedule:
    - cron: '0 9 * * MON'  # Every Monday at 9 AM
jobs:
  remind:
    runs-on: ubuntu-latest
    steps:
      - name: Find pending ADRs
        run: |
          grep -l "Status: Proposed" docs/adr/*.md | \
          xargs -I {} echo "Review needed: {}"

Alternative implementations:

Examples

API Architecture Decision (with visualization):

Database Migration (with timeline):

Sources