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/popoloni/non_deterministic_sw_eng/api-validationgit clone --depth 1 https://github.com/popoloni/non_deterministic_sw_engWhat 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 | $0.00284 |
| Opus 5 | $0.00000 | $0.00142 |
| Sonnet 5 | $0.00000 | $0.00057 |
| Haiku 4.5 | $0.00000 | $0.00028 |
Grade A, and why
api-validation 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.
What it actually says
API Validation Guidelines
When working with API endpoints:
- Use zod schemas for all request validation
- Return standardized error responses
- Include rate limiting on public endpoints
Request Validation Pattern
import { z } from 'zod';
import { validateRequest } from '@/middleware/validation';
const createUserSchema = z.object({
body: z.object({
email: z.string().email(),
name: z.string().min(1).max(100),
role: z.enum(['user', 'admin']).default('user'),
}),
});
router.post('/users',
validateRequest(createUserSchema),
async (req, res) => {
// req.body is now typed and validated
}
);
Error Response Format
// All errors should use this format
interface ErrorResponse {
error: {
code: string; // Machine-readable code
message: string; // Human-readable message
details?: unknown; // Optional validation details
};
requestId: string; // For tracing
}
Reference Implementation
See @src/api/users/validation.ts for the canonical pattern.
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 · 55 lines · 0 tokens per session scan A 39e8f234e42f
api-validation is a cursor rule published in the GitHub repository popoloni/non_deterministic_sw_eng (6 stars, last pushed 8mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 284 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 2026-08-31.
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