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.
npx agentmods add rules/prisma/prisma-next/explicit-opt-in-over-diagnosticsgit clone --depth 1 https://github.com/prisma/prisma-nextWhat 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.
| Model | Per session | Once 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 |
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 3d 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.
This is a copy
100% identical to explicit-opt-in-over-diagnostics — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
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.
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.
- 3d ago First seen · 47 lines · 730 tokens per session scan A d1ddbe0e3453
explicit-opt-in-over-diagnostics is a cursor rule published in the GitHub repository prisma/prisma-next (420 stars, last pushed 8d ago), 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. It is 100% identical to explicit-opt-in-over-diagnostics, differing in 0 lines, and is treated as a copy.
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