ADR Templates: Minimal, Extended & MADR 4.0

The format controls how you express a decision; the decision category describes what the decision is about. A security decision can use Minimal, Extended, Custom, or MADR 4.0 depending on its risk and the team’s standard.

02

Compare the same decision

The reasoning stays coherent; depth and structural contract change.

# 0042. Adopt Redis for distributed caching

Date: 2026-10-09

## Status

Proposed

## Context

Repeated reads put pressure on the database.

## Decision

We will use Redis with the cache-aside pattern.

## Consequences

We reduce latency but operate a new service.

# 0042. Adopt Redis for distributed caching

## Status
Proposed

## Context
Repeated reads put pressure on the database.

## Decision Drivers
- p95 latency
- Stale-data tolerance
- Operational cost

## Considered Options
- Managed Redis
- In-process cache
- No cache

## Decision Outcome
Managed Redis with cache-aside and domain-specific TTLs.

## Consequences
Lower load; added invalidation and observability.

# Adopt Redis for distributed caching

## Context and Problem Statement
How can we reduce repeated reads while controlling consistency?

## Decision Drivers
* p95 latency
* Failure tolerance

## Considered Options
* Managed Redis
* In-process cache

## Decision Outcome
Chosen option: managed Redis, because it shares cache across replicas.

### Consequences
* Good, because it lowers database load.
* Bad, because it adds an operational dependency.

Capability matrix

Format	Best for	Detail	ADR Guard support	Important boundary
Minimal	Focused, lower-risk choices	Context, decision, consequences	Generated and validated as canonical	Keep the choice precise despite the shorter record
Extended	High-impact or multi-option choices	Drivers, alternatives, outcome, consequences	Generated and validated as canonical	Extended is not MADR
Custom	Organization-specific canonical structure	Depends on the template	`new --template-file` with invariant structural requirements	Arbitrary Markdown is not automatically valid
MADR 4.0	Teams already standardized on MADR	Drivers, options, outcome, pros/cons	Opt-in validation with `--adr-format madr-4`	Validate separately from canonical ADR sets; automatic MADR generation is not claimed

A practical selection rule

Use the lightest format that preserves the reasoning your future readers will need. Increase detail when impact, irreversibility, number of alternatives, risk, or organizational coordination increases. If your team already has an explicit standard, consistency may matter more than personal preference.

Read the detailed format and template guide and MADR 4.0 reference.