generic-parameters

A TypeScript rule for default type parameters, which are optional types supplied automatically when callers provide none.

In plain words
What is it for?
Use it when designing generic interfaces and types to decide whether a type parameter should have a meaningful default or be required.
Why use it?
It prevents missing type details from silently becoming overly broad types such as plain strings or booleans.

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/generic-parameters
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 229 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 $0.00229
Opus 5 $0.00000 $0.00114
Sonnet 5 $0.00000 $0.00046
Haiku 4.5 $0.00000 $0.00023

Measured yesterday against content hash 8869caee7275, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

generic-parameters 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/generic-parameters.mdc · 42 lines

What it actually says

Generic Parameter Defaults

Rule: Don’t add generic defaults unless the type is meaningfully usable with the default.

Good defaults

Defaults are fine when they represent a real “no-specialization” mode:

interface EventEmitter<T = unknown> {
  emit(event: string, data: T): void;
}

Bad defaults

If the type is pointless without concrete generics, defaults create a false “optional” API:

interface ColumnBuilderState<
  Name extends string,
  Nullable extends boolean,
  Type extends string,
> {
  readonly name: Name;
  readonly nullable: Nullable;
  readonly type: Type;
}

Why this matters

  • Avoids accidental “too-wide” types (string, boolean) leaking into core surfaces
  • Makes intent clear: the generic is required for correctness, not flexibility
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 · 42 lines · 0 tokens per session scan A 8869caee7275

Subscribe to this mod's changes

generic-parameters 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 229 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.