ADR Skill

Capture architectural decisions as they happen, so the why lives next to the code instead of in a Slack thread or someone's memory. Produces lightweight ADR documents under docs/adr/.

Keywords

adr, architecture decision record, decision, rationale, trade-off, alternatives, we decided, why did we choose, design decision, supersede, decision log, nygard

When to record a decision

• The user says "record this", "ADR this", "let's document this decision".
• A choice is made between significant alternatives: framework, library, database,

language, pattern, API shape, infra/deploy approach, build vs buy.

• The user says "we decided to…" or "the reason we're doing X instead of Y is…".
• The user asks "why did we choose X?" → read and summarize the existing ADR.

For trivial or easily-reversible choices, don't create an ADR — note it inline and move on.

Output Artifacts

Format

Lightweight Nygard ADR, adapted for AI-assisted work:

# ADR-NNNN: <Decision Title>

**Date**: YYYY-MM-DD
**Status**: proposed | accepted | deprecated | superseded by ADR-NNNN
**Deciders**: <who was involved>

## Context

What is the issue motivating this decision? The situation, constraints, and forces at
play. 2–5 sentences.

## Decision

What we are doing. 1–3 sentences, stated clearly.

## Alternatives Considered

### <Alternative>
- **Pros**: …
- **Cons**: …
- **Why not**: the specific reason it was rejected.

(Repeat per alternative.)

## Consequences

### Positive
- …

### Negative / trade-offs
- …

### Risks
- <risk and its mitigation>

NEW — Record a decision

1. Initialize once. If docs/adr/ does not exist, ask the user to confirm before

creating it. On confirmation, create the directory, a README.md seeded with the index table header (below), and a template.md copy of the format above. Never create files without explicit consent.

1. Number it. Next zero-padded number after the highest existing docs/adr/NNNN-*.md

(start at 0001). Slug = kebab-case of the title.

1. Fill it from the conversation — extract the decision, the context that prompted it,

the alternatives actually weighed, and the consequences. Do not invent alternatives that were never discussed; if context is thin, ask one or two targeted questions.

1. Default status accepted when the user states a decision; proposed when still

weighing. Date = today.

1. Update the index in docs/adr/README.md.

Index format

docs/adr/README.md:

# Architecture Decision Records

| ID | Title | Status | Date |
|----|-------|--------|------|
| [ADR-0001](0001-use-eks-over-ecs.md) | Use EKS over ECS | accepted | 2026-06-10 |

SUPERSEDE — Replace a decision

1. Read the old ADR.
2. Create a new ADR that references it: "Supersedes ADR-NNNN" in Context.
3. Flip the old ADR's Status to superseded by ADR-MMMM.
4. Update both rows in the index.

Never delete or rewrite a past ADR's decision — superseding preserves the history of why it changed, which is the whole point.