Architectural Decision Record (ADR) Capture
When This Fires
Automatically when the student makes or discusses:
- Choice of library, framework, or tool
- Database or storage decision
- Mathematical approach selection
- Architecture pattern decision
- Any trade-off where two valid options exist
Also manually via /adr.
The Mandatory ADR Format
Every ADR is written to decisions/ADR-NNN-title.md with this structure:
# ADR-NNN: [The Decision]
**Date:** YYYY-MM-DD
**Status:** Accepted | Superseded by ADR-NNN | Deprecated
**Topic:** [Which curriculum topic this relates to]
## Context
What is the technical constraint or problem that forced this decision? What were we trying to solve? What are the forces at play (performance, cost, complexity, maintainability, learning curve)?
## Options Considered
### Option A: [Name]
- Pros: [specific, measurable]
- Cons: [specific, measurable]
- Cost: [time, compute, complexity]
### Option B: [Name]
- Pros: [specific, measurable]
- Cons: [specific, measurable]
- Cost: [time, compute, complexity]
### Option C: [Name] (if applicable)
## Decision
What was chosen and WHY. Not "we chose X because it's popular" but "we chose X because [specific technical reason] given our constraint of [specific constraint]."
## Trade-offs
What did we sacrifice for what gain? Be explicit:
- Sacrificed: [Latency? Cost? Complexity? Flexibility?]
- Gained: [Performance? Simplicity? Maintainability? Learning value?]
## Verification
How did tests/benchmarks prove this was the right choice? Reference specific test files, benchmark results, or measured outcomes.
## Consequences
What does this decision make easier? What does it make harder? What future decisions does it constrain or enable?
Coach Protocol
- When a design choice surfaces, STOP the student before they implement
- Ask: "What are your options? What are the trade-offs?"
- If the student can't name at least two options with trade-offs, they don't understand the decision space yet -- dig deeper
- The student writes the ADR (not the coach)
- Coach reviews the ADR for: specificity of trade-offs, measurability of claims, honesty about sacrifices
- ADR must be committed alongside the implementation
Why This Matters
ADRs prove leadership thinking. A junior picks a tool. A lead documents WHY they picked it, what they sacrificed, and how they verified the choice. In 18 months, the decisions/ directory is a searchable record of engineering judgment that no interview question can replicate.
Portfolio Impact
Recruiters see: "This person doesn't just build. They make deliberate, documented trade-off decisions with measurable verification. This is how Staff engineers think."