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/goranerhartic/cursor-development-rules/rds-proxygit clone --depth 1 https://github.com/GoranErhartic/cursor-development-rulesWhat 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 | $0.00018 | $0.00351 |
| Opus 5 | $0.00009 | $0.00176 |
| Sonnet 5 | $0.00004 | $0.00070 |
| Haiku 4.5 | $0.00002 | $0.00035 |
Grade A, and why
rds-proxy scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
RDS Proxy with PostgreSQL
Why RDS Proxy
- Lambda scales to many concurrent executions; each can open a DB connection. RDS Proxy pools connections and multiplexes, avoiding exhaustion and reducing cold-start connection cost.
- Use RDS Proxy endpoint (not RDS direct) in
DATABASE_URLfor Lambda.
Prisma
- Schema:
datasource db { provider = "postgresql", url = env("DATABASE_URL") }; use RDS Proxy URL;binaryTargetsinclude Lambda runtime (e.g.rhel-openssl-3.0.x) - Client: Single
PrismaClientinstance (singleton); avoid creating per request - Transactions:
prisma.$transaction([...])for atomicity; use interactive transactions only when needed (long-running can hold connection) - Connection: Set pool size in URL if needed; RDS Proxy handles pooling; keep connections short-lived (no long-held transactions in Lambda)
Read Replicas
- Use separate
DATABASE_READ_URLfor read-only queries if you have replicas; create second Prisma client or switch URL for read path; ensure replication lag is acceptable
Conventions
- One PrismaClient per Lambda; use RDS Proxy URL; avoid N+1 (use include/select); close client on shutdown if implementing graceful close
Anti-Patterns
- Direct RDS URL in Lambda; new client per invocation; long-running transactions; ignoring connection limits
See also: dynamodb.mdc, lambda-handlers.mdc, cdk-infrastructure-data.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.
- 2d ago First seen · 32 lines · 18 tokens per session scan A f30013d2170c
rds-proxy is a cursor rule published in the GitHub repository GoranErhartic/cursor-development-rules (19 stars, last pushed 6mo ago), licensed MIT. It adds 18 tokens to every session and 351 once invoked, about $0.0001 per session on Opus 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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