core-engine

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.

In plain words
What is it for?
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.
Why use it?
It separates reusable logic from input/output and command-line concerns, while setting common expectations for errors, public interfaces, data formats, documentation, and tests.

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/sruja-ai/sruja/core-engine
Clone the repo
git clone --depth 1 https://github.com/sruja-ai/sruja

Made for: Cursor.

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. 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 $0.00374 $0.00374
Opus 5 $0.00187 $0.00187
Sonnet 5 $0.00075 $0.00075
Haiku 4.5 $0.00037 $0.00037

Measured 2d ago against content hash 9a9f28a31722, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 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-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

  1. Pure functions preferred: Core functions should be deterministic and side-effect free. I/O belongs in CLI or scan crates.
  2. No CLI dependencies: Core crates must never depend on sruja-cli or clap.
  3. No WASM dependencies: Core crates must never depend on sruja-wasm or wasm-bindgen.
  4. Error types: Use thiserror for all error enums. Never use anyhow in library crates.
  5. Public API surface: Keep lib.rs as the public API surface. Implementation details go in submodules.
  6. Serde everywhere: All public types that cross boundaries should derive Serialize + Deserialize.
  7. Module docs: Every lib.rs and mod.rs starts with //! doc comments describing the module's purpose.
  8. 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.

  1. 2d 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 (22 stars, last pushed 9d ago), licensed Apache-2.0. It adds 374 tokens to every session, about $0.0019 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.