adr-writing

Guidelines for writing an architecture decision record (ADR), a document that records an important software design decision and its consequences.

In plain words
What is it for?
They help structure ADRs, explain responsibility boundaries, describe alternatives, and document decisions in a lasting way.
Why use it?
They make decisions easier to understand later by presenting the choice early, keeping examples accurate, and avoiding temporary project details.

Cursor rule for Codex

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 rules/prisma/orm/adr-writing
Clone the repo
git clone --depth 1 https://github.com/prisma/orm

Made for: Codex.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 480 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 $0.00000 $0.00480
Opus 5 $0.00000 $0.00240
Sonnet 5 $0.00000 $0.00096
Haiku 4.5 $0.00000 $0.00048

Measured yesterday against content hash 6053d442ad9f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

adr-writing 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 yesterday.

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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.agents/rules/adr-writing.mdc · 17 lines

What it actually says

  • Lead with the decision and a grounding example. Open with a representative code/usage sample and the decision itself, then build up why → how → consequences, and put alternatives considered last. Don't front-load context/problem/rejected designs — a reader should see what the decision is before the information being made irrelevant. (Context still belongs in the doc; it just doesn't lead.)
  • ADRs are long-lived — no transient references. No PR numbers, and no "before this refactor / earlier implementation / as-shipped / what we used to do" preceding-state framing. The shape you replaced is a legitimate alternative considered, stated timelessly — not narrated as a project event. (Ticket / milestone / task IDs are already banned in ADRs by no-transient-project-ids-in-code.mdc.)
  • Keep responsibility splits explicit (e.g. adapter lowering vs codec encode/decode vs driver transport/normalization)
  • If an ADR discusses capabilities, follow .cursor/rules/capabilities-ownership.mdc for wording
  • If you need to describe sequencing (order of operations), keep it short and place it near the responsibilities/decision; avoid long procedural sections that read out-of-place
  • Use fenced code blocks for SQL (```sql) and TS (```ts); avoid nested backticks inside inline code
  • Worked examples should be end-to-end and make it obvious which layer owns each step (lane, adapter, codec, driver, runtime)
  • If the decision instantiates a structural pattern recorded in docs/architecture docs/patterns/, link forward to the pattern entry from the ADR (existing ADRs are not retroactively edited)
  • Maintain the ADR in the PR that changes the decision. When a decision evolves mid-project, update its ADR (and add supersession notes to any ADR it displaces) in the same PR — not in a follow-up. An ADR whose examples drift from the shipped surface violates adr-examples-must-match-code.mdc and misleads longer than it informs.
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. yesterday First seen · 17 lines · 0 tokens per session scan A 6053d442ad9f

Subscribe to this mod's changes

adr-writing is a cursor rule published in the GitHub repository prisma/orm (47,579 stars, last pushed today), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 480 tokens. 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 2026-08-30.