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/interface-factory-patterngit 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 | $0.00000 | $0.00207 |
| Opus 5 | $0.00000 | $0.00103 |
| Sonnet 5 | $0.00000 | $0.00041 |
| Haiku 4.5 | $0.00000 | $0.00021 |
Grade A, and why
interface-factory-pattern 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.
This is a copy
100% identical to interface-factory-pattern — 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.
What it actually says
Interface-Based Design with Factory Functions
Pattern: Export interfaces and factory functions. Keep classes as private implementation details.
Do
export interface CodecRegistry {
get(id: string): unknown | undefined;
register(codec: unknown): void;
}
export function createCodecRegistry(): CodecRegistry {
return new CodecRegistryImpl();
}
class CodecRegistryImpl implements CodecRegistry {
// ...
}
Avoid
// Avoid exporting concrete classes as the primary surface.
export class CodecRegistry {
// ...
}
Why this matters
- Keeps public APIs stable while allowing private implementation changes
- Makes mocking/testing easier (tests can target interfaces)
- Encourages “thin core, fat targets” and clean layering
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.
- 2d ago First seen · 43 lines · 0 tokens per session scan A 4e2401e3ac7c
interface-factory-pattern is a cursor rule published in the GitHub repository prisma/prisma-next (421 stars, last pushed 7d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 207 tokens. A static security scan graded it A with 0 findings. It is 100% identical to interface-factory-pattern, differing in 0 lines, and is treated as a copy.
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