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Write and manage Architecture Decision Records — ADR format, status lifecycle, tradeoff analysis, templates, and integration with project workflow.
| name | Architecture Decision Records |
| description | Write and manage Architecture Decision Records — ADR format, status lifecycle, tradeoff analysis, templates, and integration with project workflow. |
Write and manage Architecture Decision Records — ADR format, status lifecycle, tradeoff analysis, templates, and integration with project workflow.
Use this skill when making non-trivial architecture or design decisions — choosing between technologies, designing system structure, adopting patterns, or changing existing approaches. ADRs capture the context, options, and rationale so future contributors understand why a decision was made.
The most important part of a decision is not what was chosen, but why. ADRs document the context, alternatives considered, and rationale so that:
# ADR-[number]: [Title]
## Status
[Proposed | Accepted | Deprecated | Superseded]
## Context
[What is the issue motivating this decision? What forces are at play?
Include relevant background, constraints, and assumptions.]
## Decision
[What was decided? Use active voice: "We will..." rather than passive.]
## Consequences
[What are the tradeoffs? What becomes easier, harder, or different?
Include both benefits and costs.]
## Options considered
### Option A: [name]
- **Pros:** [list of advantages]
- **Cons:** [list of disadvantages]
### Option B: [name]
- **Pros:** [list of advantages]
- **Cons:** [list of disadvantages]
## Rationale
[Why was the chosen option selected over the alternatives?]
# ADR-7: Use PostgreSQL over MongoDB for the product catalog
## Status
Accepted
## Context
We need a database for the product catalog service. The catalog
has complex relationships (products, categories, variants, attributes)
with evolving schema requirements. We expect heavy read traffic
with moderate writes.
Initial team discussion explored both relational and document options.
## Decision
We will use PostgreSQL for the product catalog.
## Consequences
Positive:
- Strong schema enforcement catches data inconsistencies early
- Native JSONB support handles flexible product attributes
- Mature migration tooling (e.g., Flyway, pgroll)
- ACID transactions make inventory management reliable
Negative:
- Schema changes require migrations (more process than MongoDB)
- JOIN-heavy queries may need optimization at scale
- Team needs PostgreSQL expertise (one member has MongoDB background)
## Options considered
### Option A: PostgreSQL (chosen)
- **Pros:** Strong consistency, JSONB for flexible attributes,
excellent tooling, team mostly familiar
- **Cons:** Schema changes need migrations, slightly higher
operational overhead for replication
### Option B: MongoDB
- **Pros:** Schema-less fits evolving product attributes,
horizontal scaling built-in
- **Cons:** No built-in JOINs (app-level joins needed),
weaker consistency guarantees, no team experience
## Rationale
PostgreSQL's JSONB column gives us the schema flexibility
we need, while maintaining relational integrity for the
structured parts of the catalog. The team's existing
PostgreSQL knowledge and mature migration tooling outweigh
MongoDB's scaling advantages for our expected volume.
┌──────────┐
│ Proposed │
└────┬─────┘
│
▼
┌──────────┐
│ Accepted │ ◄── Active decision (most ADRs live here)
└────┬─────┘
│
┌─────────┴──────────┐
▼ ▼
┌────────────┐ ┌──────────────┐
│ Superseded │ │ Deprecated │
│ (by ADR-N) │ │ (no longer │
└────────────┘ │ recommended)│
└──────────────┘
| Write an ADR | Don't write an ADR |
|---|---|
| Choosing a technology or library | Which CSS framework to use (unless it's a major architectural decision) |
| Designing system structure (monolith vs microservices, sync vs async) | A specific API endpoint design |
| Changing a previous decision | Day-to-day implementation details |
| Introducing a new pattern or convention | Bug fixes |
| Significant infrastructure decisions | Minor refactoring |
| External integration strategy | Code formatting conventions |
Store ADRs in the repository:
docs/adr/
├── README.md # Index with status table
├── 001-use-postgres.md
├── 002-frontend-framework.md
├── 003-api-design.md
└── index.md # Auto-generated or manually maintained
# Architecture Decision Records
| # | Title | Status | Date |
|---|-------|--------|------|
| 7 | Use PostgreSQL over MongoDB | Accepted | 2024-01-15 |
| 6 | Adopt event-driven messaging | Superseded by ADR-8 | 2023-11-20 |
| 5 | TypeScript for frontend | Accepted | 2023-10-01 |
| Document | Scope | When to use |
|---|---|---|
| ADR | Single decision | Choosing between options |
| RFC | Feature/systems design | Designing a new system with multiple decisions |
| Design doc | Full architecture | Before starting a major project |
| Wiki page | Ongoing reference | Documenting how something works (not decisions) |
An ADR should be reviewed before acceptance:
Review criteria:
[ ] Context is complete enough to understand the decision
[ ] Multiple alternatives were considered
[ ] Chosen option is clearly justified
[ ] Consequences are honestly assessed
[ ] Tradeoffs are acknowledged (no perfect option)
[ ] Links to relevant resources, spikes, or research
Split any task into small, reviewable subtasks — atomic units of work that are easy to track, easy to review, and hard to get wrong.
Use the gh CLI to fetch issues, discussions, and linked issues — analyze the problem, find relevant code, and implement a fix with a PR.
Design effective database schemas — normalization, indexing strategies, relationships, migrations, query optimization, and data modeling patterns for SQL and NoSQL.
Write clear completion criteria before starting work — acceptance criteria formats, quality gates, scope boundaries, and the done checklist pattern.
Design and manage deployments — CI/CD pipelines, Docker, zero-downtime strategies, rollback plans, environment management, and release automation.
Systematically recover from failures — isolate, diagnose, fix, verify, prevent. The three-attempts rule, evidence gathering before guessing, and when to roll back vs push forward.