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.
git clone --depth 1 https://github.com/GoranErhartic/cursor-development-rulesWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/rules/goranerhartic/cursor-development-rules/s3-presigned-urls-upload)<a href="https://agentmods.dev/rules/goranerhartic/cursor-development-rules/s3-presigned-urls-upload"><img src="https://agentmods.dev/badge/rules/goranerhartic/cursor-development-rules/s3-presigned-urls-upload/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/rules/goranerhartic/cursor-development-rules/s3-presigned-urls-upload"><img src="https://agentmods.dev/badge/rules/goranerhartic/cursor-development-rules/s3-presigned-urls-upload.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00016 | $0.00354 |
| Opus 5.5 | $0.00006 | $0.00142 |
| Sonnet 5.5 | $0.00003 | $0.00071 |
| Haiku 4.5 | $0.00002 | $0.00035 |
Grade A, and why
s3-presigned-urls-upload 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 1mo 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
S3 Presigned URLs (Upload)
Security
- Allowed types: Whitelist MIME types and extensions; enforce max size per type; reject unknown types
- Expiration: Short (5–15 min) for upload URLs
- Key generation: Server-generated key (e.g.
uploads/{userId}/{uuid}/{filename}); sanitize client filename; no path traversal - Validation: After upload, validate content-type (e.g. with file-type) and size server-side; do not trust client headers only
- Bucket: Private; access only via presigned URL or Lambda with IAM
Implementation
- Client:
@aws-sdk/client-s3,@aws-sdk/s3-request-presigner;PutObjectCommandwith Key, ContentType, ContentLength (optional but recommended); sign withgetSignedUrl(client, command, { expiresIn }) - Handler: Validate user/auth; check requested ContentType and size against allowlist; generate key; return presigned URL and key to client
- Post-upload: Client notifies API (key, optional hash); API validates object in S3 (headObject, content-type/size) and then processes
Conventions
- Always allowlist types and size; short expiry; server-generated keys; post-upload validation
Anti-Patterns
- Client-supplied key without sanitization; no MIME/size validation; long expiry; public bucket
See also: s3-presigned-urls-validation.mdc, s3-presigned-urls-cdk-client.mdc, security.mdc
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.
- 1mo ago First seen · 30 lines · 16 tokens per session scan A f726d1359d6d
s3-presigned-urls-upload is a cursor rule published in the GitHub repository GoranErhartic/cursor-development-rules (19 stars, last pushed 8mo ago), licensed MIT. It adds 16 tokens to every session and 354 once invoked, about $0.0001 per session on Opus 5.5. 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.
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