A set of coding rules for Sruja's core Rust libraries, including its language, engine, diagnostics, graph, and scanning components. These libraries contain reusable program logic rather than command-line code.

Use it when editing files in the listed core crates, especially for designing library APIs, handling errors, adding serialization, writing module documentation, or testing non-trivial logic.

It separates reusable logic from input/output and command-line concerns, while setting common expectations for errors, public interfaces, data formats, documentation, and tests.

core-engine — Cursor rule for Cursor by sruja-ai/sruja

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.

Clone the repo

git clone --depth 1 https://github.com/sruja-ai/sruja

Made for: Cursor.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/rules/sruja-ai/sruja/core-engine/github.svg)](https://agentmods.dev/rules/sruja-ai/sruja/core-engine)

Your own site

<a href="https://agentmods.dev/rules/sruja-ai/sruja/core-engine"><img src="https://agentmods.dev/badge/rules/sruja-ai/sruja/core-engine/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.

Your own site · 80×15

<a href="https://agentmods.dev/rules/sruja-ai/sruja/core-engine"><img src="https://agentmods.dev/badge/rules/sruja-ai/sruja/core-engine.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 374 This file is loaded in full into every session.

When invoked 374 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00374	$0.00374
Opus 5.5	$0.00150	$0.00150
Sonnet 5.5	$0.00075	$0.00075
Haiku 4.5	$0.00037	$0.00037

Measured 1mo ago against content hash 9a9f28a31722, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

core-engine 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.

.cursor/rules/core-engine.mdc · 27 lines

What it actually says

Core Engine Constraints

Patterns for Core Engine crates (language, engine, diagnostics, graph, graph-core, scan).

Scopes

crates/sruja-language/**/*.rs
crates/sruja-engine/**/*.rs
crates/sruja-diagnostics/**/*.rs
crates/sruja-graph/**/*.rs
crates/sruja-graph-core/**/*.rs
crates/sruja-scan/**/*.rs

Rules

Pure functions preferred: Core functions should be deterministic and side-effect free. I/O belongs in CLI or scan crates.
No CLI dependencies: Core crates must never depend on sruja-cli or clap.
No WASM dependencies: Core crates must never depend on sruja-wasm or wasm-bindgen.
Error types: Use thiserror for all error enums. Never use anyhow in library crates.
Public API surface: Keep lib.rs as the public API surface. Implementation details go in submodules.
Serde everywhere: All public types that cross boundaries should derive Serialize + Deserialize.
Module docs: Every lib.rs and mod.rs starts with //! doc comments describing the module's purpose.
Test coverage: Files with non-trivial logic should have a #[cfg(test)] mod tests with unit tests. Pure re-export or type-definition files are exempt.

Layer Boundary

Core Engine crates have no external dependencies allowed (per classification). They form the foundation that all other layers build upon. If you need functionality from another layer, it belongs here — not pulled in as a dependency.

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.

1mo ago First seen · 27 lines · 374 tokens per session scan A 9a9f28a31722

Subscribe to this mod's changes

core-engine is a cursor rule published in the GitHub repository sruja-ai/sruja (24 stars, last pushed 5d ago), licensed Apache-2.0. It adds 374 tokens to every session, about $0.0015 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.

Languages Rust agent-loop agent-skills ai architecture developer-tools rust-lang

core-engine

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

What it actually says

Core Engine Constraints

Scopes

Rules

Layer Boundary

What this file has done since we first saw it

Other cursor rules, from other repositories

rust-development

rust-module-refactor

rust-architect

table-of-contents-standard

wrap-vs-specify

spec-fn-naming