explicit-opt-in-over-diagnostics

A design rule that makes users explicitly request risky or surprising behaviour instead of allowing it by default and warning them every time.

In plain words
What is it for?
Use it for options that may cause performance problems, lifecycle leaks, or a wider-than-usual effect, such as a flag, method, or configuration setting.
Why use it?
It keeps diagnostics focused on real problems and makes deliberate choices visible in the code for future readers.

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/explicit-opt-in-over-diagnostics
Clone the repo
git clone --depth 1 https://github.com/prisma/orm

Made for: Codex.

Per session 730 This file is loaded in full into every session.
When invoked 730 The same file — it is already loaded in full.
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 $0.00730 $0.00730
Opus 5 $0.00365 $0.00365
Sonnet 5 $0.00146 $0.00146
Haiku 4.5 $0.00073 $0.00073

Measured 2d ago against content hash d1ddbe0e3453, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

explicit-opt-in-over-diagnostics 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 2d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.agents/rules/explicit-opt-in-over-diagnostics.mdc · 47 lines

How it starts

The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Explicit opt-in over noisy diagnostics

When designing a feature where a user choice has a non-obvious consequence (footgun, lifecycle leak, performance cliff, surprising blast radius), prefer requiring the user to explicitly opt in to the risky behaviour over permitting it by default and emitting a diagnostic on every use.

The principle:

  • A diagnostic on an intentional user path is noise. The user already declared intent by writing the code; warning them every build adds friction without adding signal.
  • An explicit opt-in (a flag, a method name, a config key) encodes the intent at the call site, where future readers can see it. The audit trail is the code itself; no diagnostic is needed because the choice is documented in place.
  • This trades a one-time authoring cost (the user has to type the opt-in) for ongoing review clarity (every reader sees the deliberate choice).

When to use which

Explicit opt-in, no diagnostic — the right answer when:

  • The behaviour is valid for some users (i.e., not a bug we want to discourage universally).
  • The user can reasonably be expected to know what they're doing if they opt in.
  • The opt-in is itself self-documenting (e.g., onDelete: 'cascade', allowCrossSchemaCascade: true, dangerouslyAllowX).
  • The diagnostic would fire on every build for a path the user already chose intentionally.

Diagnostic, no opt-in — the right answer when:

  • The behaviour is almost certainly a bug (e.g., shadowed variable, dead code).
  • The user has no realistic path to "yes, I meant that" — the diagnostic is the only signalling mechanism.
  • The cost of a false positive is low (one-time fix or suppression).

Both opt-in and diagnostic — rare, and usually wrong:

  • Only justified when the opt-in itself can be expressed correctly in many places but only intended in some (and even then, prefer narrowing the opt-in's scope so it can't be over-applied).
  • Default to dropping one of the two. If the user has to opt in, the opt-in is the audit trail; a diagnostic on top is double-charging the user for the same decision.

Read the full file on GitHub · 47 lines

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. 2d ago First seen · 47 lines · 730 tokens per session scan A d1ddbe0e3453

Subscribe to this mod's changes

explicit-opt-in-over-diagnostics is a cursor rule published in the GitHub repository prisma/orm (47,587 stars, last pushed today), licensed Apache-2.0. It adds 730 tokens to every session, about $0.0036 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 2026-08-30.