architecture-decision-record

Architecture Decision Record (ADR) Skill

This skill produces a complete Architecture Decision Record (ADR) following the Nygard format — the most widely adopted standard. ADRs document the reasoning behind significant technical decisions so future team members understand not just what was decided, but why.

Required Inputs

Ask the user for these if not provided:

• Decision title (brief, e.g. "Use PostgreSQL as primary datastore")
• Context (what situation led to this decision needing to be made?)
• Options considered (at least 2; if only 1 is given, prompt for alternatives that were considered or ruled out)
• Decision made (which option was chosen)
• Reason for choice
• Status (Proposed / Accepted / Deprecated / Superseded)
• Author and date

Output Structure

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ADR-[NNN]: [Decision Title]

Date: [YYYY-MM-DD] Status: [Proposed / Accepted / Deprecated / Superseded by ADR-NNN] Author(s): [Name(s)] Deciders: [Who had final say — individual or team]

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Context

[3–6 sentences. Describe the situation, constraints, and forces at play that made this decision necessary. Include: the problem being solved, relevant system state, team constraints, timeline pressures, or non-negotiable requirements. Write as if explaining to someone joining the team 18 months from now who has no prior context.]

Key constraints:

• [Constraint 1: e.g. "Must be deployable on-premise for enterprise customers"]
• [Constraint 2: e.g. "Team has no prior Go experience"]
• [Add as many as are relevant]

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Options Considered

For each option, produce:

Option [N]: [Name]

Description: [What this option is — 1–3 sentences]

Pros:

• [Pro 1]
• [Pro 2]

Cons:

• [Con 1]
• [Con 2]

Why this was ruled out (if not chosen): [Honest reason]

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Decision

We will [chosen option].

[2–4 sentences explaining the decision in plain language. This should be readable in isolation — someone should understand the decision from this paragraph alone without reading the full document.]

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Consequences

Positive Consequences

• [What this decision enables or improves]
• [What risk it mitigates]

Negative Consequences / Accepted Tradeoffs

• [What we're giving up or taking on as a result of this decision]
• [Technical debt or limitations introduced]
• [What must now be true for this decision to remain valid]

Risks

• [What could cause this decision to be wrong in hindsight]
• [What would trigger us to revisit this decision]

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Implementation Notes

[Optional but valuable: any specific patterns, gotchas, or guidance for the team implementing based on this decision. Link to relevant tickets, RFCs, or design docs if applicable.]

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Review Date

[Optional: "This decision should be reviewed if [condition] — e.g. team grows beyond 20 engineers, or traffic exceeds 10M requests/day."]

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Quality Checks

• Context explains the why — not just the what
• At least 2 options are documented (including the rejected ones)
• Rejected options include honest reasons for rejection
• Consequences include negative consequences — no decision is consequence-free
• Decision is stated in plain language in the Decision section
• Risks section identifies what would invalidate this decision
• Written for someone with no prior context on this decision

Example Trigger Phrases

• "Write an ADR for using [technology]"
• "Document our decision to [architectural choice]"
• "Create an architecture decision record for [topic]"
• "Help me write up why we chose [option] over [alternative]"