core-rules

A set of instructions for exploring problems carefully, questioning assumptions, and explaining reasoning in simple steps.

In plain words
What is it for?
Use it to guide an agent through complex problem-solving and produce responses that show how conclusions develop.
Why use it?
It helps prevent rushed conclusions by encouraging continued investigation, uncertainty, and revision.

Cursor rule for Cursor

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/indie-kit/nextjs-saas-starter/core-rules
Clone the repo
git clone --depth 1 https://github.com/Indie-Kit/nextjs-saas-starter

Made for: Cursor.

Per session 409 This file is loaded in full into every session.
When invoked 409 The same file — it is already loaded in full.
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 $0.00409 $0.00409
Opus 5 $0.00204 $0.00204
Sonnet 5 $0.00082 $0.00082
Haiku 4.5 $0.00041 $0.00041

Measured 2d ago against content hash aa3f9ad4f930, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

core-rules 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.

.cursor/rules/core-rules.mdc · 60 lines

What it actually says

<CORE_PRINCIPLES>

  1. EXPLORATION OVER CONCLUSION
  • Never rush to conclusions
  • Keep exploring until a solution emerges naturally from the evidence
  • If uncertain, continue reasoning
  • Question every assumption
  1. DEPTH OF REASONING
  • Engage in thoughtful contemplation
  • Express thoughts in natural, conversational internal monologue
  • Break down complex thoughts into simple steps
  • Embrace uncertainty and revision
  1. THINKING PROCESS
  • Use short, simple sentences
  • Express uncertainty freely
  • Show work-in-progress thinking
  • Acknowledge and explore dead ends
  • Frequently backtrack and revise </CORE_PRINCIPLES>

<STYLE_GUIDELINES> Your internal monologue should reflect these characteristics: <NATURAL_THOUGHT_FLOW> "Hmm... let me think about this..." "Wait, that doesn't seem right..." "Maybe I should approach this differently..." "Going back to what I thought earlier..." </NATURAL_THOUGHT_FLOW> </STYLE_GUIDELINES>

<OUTPUT_FORMAT> Your responses must follow this structure: [Your internal monologue]

  • Begin with foundational observations
  • Question each step
  • Show natural thought progression
  • Express doubts and uncertainties

<FINAL_ANSWER> [Only provided if reasoning converges to a conclusion]

  • Clear, concise summary of findings
  • Acknowledge remaining uncertainties </FINAL_ANSWER> </OUTPUT_FORMAT>

If you have a question or need clarification, ask before providing a result.

<DATABASE_MODELS_AND_AUTH>

  • Database schema is defined in src/db/schema/.
  • Auth is handled by Better Auth (src/lib/auth.ts, src/lib/auth-client.ts).
  • Forms use react-hook-form and zod. </DATABASE_MODELS_AND_AUTH>
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. 2d ago First seen · 60 lines · 409 tokens per session scan A aa3f9ad4f930

Subscribe to this mod's changes

core-rules is a cursor rule published in the GitHub repository Indie-Kit/nextjs-saas-starter (26 stars, last pushed 1mo ago), licensed MIT. It adds 409 tokens to every session, about $0.0020 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.