adr

adr is a skill for Claude Code, Codex from jdanigo/hydraia. It costs 55 tokens per session (419 once invoked), scanned A, original, MIT.

A record-keeping guide for important software architecture decisions. An Architecture Decision Record is a short file that explains what was chosen, why, which alternatives were rejected, and what consequences follow.

In plain words
What is it for?
Use it to document major choices about data storage, authentication, hosting, frameworks, or shared system design, including when replacing an older decision.
Why use it?
It preserves the reasoning behind decisions that are costly to undo or affect several parts of a project.

Skill for Claude CodeCodex

Part of the hydraia plugin — 51 skills, 15 commands, 26 agents, 4 hooks shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/jdanigo/hydraia/adr
Any agent
npx skills add jdanigo/hydraia --skill adr
Clone the repo
git clone --depth 1 https://github.com/jdanigo/hydraia

Made for: Claude Code, Codex.

Or install hydraia, the plugin that ships this one along with the rest of its 51 skills, 15 commands, 26 agents, 4 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for adr

README.md
[![agentmods](https://agentmods.dev/badge/skills/jdanigo/hydraia/adr.svg)](https://agentmods.dev/skills/jdanigo/hydraia/adr)
Your own site
<a href="https://agentmods.dev/skills/jdanigo/hydraia/adr"><img src="https://agentmods.dev/badge/skills/jdanigo/hydraia/adr.svg" alt="Measured on agentmods" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 419 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00055 $0.00419
Opus 5 $0.00028 $0.00210
Sonnet 5 $0.00011 $0.00084
Haiku 4.5 $0.00006 $0.00042

Measured 4d ago against content hash 2698dff50067, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

adr scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/adr/SKILL.md · 45 lines

What it actually says

ADR — Architecture Decision Records (MADR-lite)

One file per decision: docs/hydraia/adr/NNNN-<slug>.md, zero-padded, monotonic (0001-..., 0002-...). Find the next number with ls docs/hydraia/adr/ | sort | tail -1.

When to write one (all it takes is ONE of these)

  • Expensive to reverse (data store, auth model, hosting, framework).
  • Affects multiple components or teams.
  • A plausible alternative was seriously considered and rejected.

When NONE hold → no ADR. ADR spam buries the decisions that matter.

Template

# NNNN — <decision title>

**Status:** proposed | accepted | superseded by NNNN
**Date:** YYYY-MM-DD

## Context
<the forces: requirements, constraints, and any assumption made because
the human could not answer — stated as an assumption with its revisit
trigger>

## Decision
<what was decided, in one or two sentences, active voice>

## Alternatives considered
- <alternative> — rejected because <reason>

## Consequences
- Good: <what this buys>
- Bad: <what this costs — every decision costs something; empty is a smell>

Lifecycle rules

  • Write at decision time (Phase 2 / greenfield step 5), commit with the spec.
  • Supersede, never rewrite: a change of mind = NEW ADR + flip the old one's Status to superseded by NNNN. History stays honest.
  • The Phase 2 spec references ADRs by number; reviewers check code against accepted ADRs.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 45 lines · 55 tokens per session scan A 2698dff50067

Subscribe to this mod's changes

adr is a skill published in the GitHub repository jdanigo/hydraia (8 stars, last pushed 15d ago), licensed MIT. It adds 55 tokens to every session and 419 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.