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LeTrain: Instructions file for Gemini CLI

GEMINI.md

LeTrain GEMINI.md is an instructions file for Gemini CLI from antoniovazquezaraujo/LeTrain. It costs 790 tokens per session, scanned A, original, Apache-2.0.

Project-specific instructions for Gemini CLI, a command-line tool that uses Gemini to help with software work. They document how to build, test, run, navigate, and contribute to the LeTrain Java game project.

In plain words
What is it for?
Use them to find Maven build and test commands, understand the Java 17 and LibGDX setup, and locate the project's major components and files.
Why use it?
They give an unfamiliar coding agent the project's structure and working conventions, reducing guesswork when changing or running the code.

Instructions file for Gemini CLI

Written for Gemini CLI: the file is GEMINI.md. Also seen: mentions Gemini CLI.

This is antoniovazquezaraujo/LeTrain's own configuration. It tells Gemini CLI how to work on LeTrain itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything LeTrain configures →

not rated 13repo +1 today A scan 790 tokens original Apache-2.0
View source ↗ antoniovazquezaraujo/LeTrain
Reuse

Borrowing it

Nothing to install: this file belongs to antoniovazquezaraujo/LeTrain. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/antoniovazquezaraujo/LeTrain/develop/GEMINI.md
Clone the repo
git clone --depth 1 https://github.com/antoniovazquezaraujo/LeTrain

Made for: Gemini CLI.

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Per session 790 This file is loaded in full into every session.
When invoked 790 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00790 $0.00790
Opus 5 $0.00395 $0.00395
Sonnet 5 $0.00158 $0.00158
Haiku 4.5 $0.00079 $0.00079

Measured 4d ago against content hash e72705110aea, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

LeTrain GEMINI.md 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 4d 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.

GEMINI.md · 44 lines

How it starts

The opening of the file, as written. The whole thing — 44 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GEMINI.md

Project Overview

LeTrain is a procedural train simulator combining classic ASCII aesthetics with a modern 3D engine (LibGDX). Players manage rail networks, logistics, and economies in an infinite, procedurally generated world.

Building and Running

  • Build & Package: mvn package -DskipTests
    • This command generates a distribution in the output/LeTrain directory.
  • Tests: mvn test
  • Running: The project includes two main launchers, created via jpackage during the Maven build phase:
    • LeTrain: Launches the modern 3D experience.
    • LeTrain2D: Launches the classic terminal view.

Development Conventions

  • Language: Java 17.
  • Build Tool: Maven.
  • Testing: JUnit 5 with Mockito for mocking dependencies.
  • Architecture:
    • Core: Procedural generation (Perlin noise), economy management, and rail logistics.
    • 3D Engine: LibGDX.
    • UI: Lanterna for terminal interfaces.
    • Automation: ANTLR4 is used for a custom rail automation language (Grammar: src/main/antlr4/letrain/command/LeTrainProgram.g4).
    • Serialization: Uses Jackson (jackson-databind) for JSON serialization/deserialization.
  • Project Structure (Multi-module):
    • core/: Core engine, game model, economy, audio, and all business logic.
    • ui-terminal/: Text-based UI implementation using Lanterna.
    • ui-graphic/: 3D UI implementation using LibGDX.
    • launcher-terminal/: Entrypoint and fat JAR generator for the terminal version.
    • launcher-graphic/: Entrypoint and fat JAR generator for the 3D version.
    • economy.properties: Central configuration file for game economy tuning.
  • Git Workflow & Merging:
    • CRITICAL RULE (ABSOLUTE PROHIBITION): You are STRICTLY FORBIDDEN from merging any branch into develop or main on your own initiative.
    • main is the sacred release branch. develop is the integration branch. YOU CANNOT TOUCH THEM without explicit, unambiguous permission from the user AFTER they have tested the changes.
    • When writing code, you MUST commit it to a separate branch (feature/... or fix/...) and STOP.
    • Do NOT chain git merge commands in your terminal tools (e.g., NEVER run git commit && git checkout develop && git merge).
    • CRITICAL RULE: After the user approves and the branch has been successfully merged, ALWAYS delete the branch both locally and remotely (git branch -d and git push origin --delete) to keep the repository clean.
    • Issue Linking: When creating a PR that resolves an issue, you MUST include keywords like Fixes #ID or Resolves #ID in the PR description (e.g. gh pr create --body "Fixes #..."). If a PR was merged without doing this, you MUST add a comment to the Issue linking to the PR before closing it.

Read the full file on GitHub · 44 lines

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. 4d ago First seen · 44 lines · 790 tokens per session scan A e72705110aea

Subscribe to this mod's changes

LeTrain GEMINI.md is an instructions file published in the GitHub repository antoniovazquezaraujo/LeTrain (13 stars, last pushed today), licensed Apache-2.0. It adds 790 tokens to every session, about $0.0040 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 2026-09-04.

ASCIIJavaLanguagesWriting and docsascii-gamegamesimulatorterminal
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