starsector-tech-stack

name	starsector-tech-stack
description	Information about the required technology stack, environment JVM flags, and build plugins.

Starsector Ship Editor — Technology Stack

Skill Directory Structure

This skill is organized as follows:

• SKILL.md: Main instructions (this file).
• resources/: Configurations and templates.
  • maven-toolchains.xml: Configuration showing how to bind Maven to Java 17/21 compiler paths.
• examples/: Code references.
  • pom-compilation-plugins.xml: Reference Maven plugin config for Java compiler and Lombok annotation processor.
• scripts/: Tooling.
  • check_java_home.sh: Script to verify environment compatibility.

Core Language & Runtime

Component	Version	Notes
Java	Source target 17 (maven.compiler.release=17)	Requires JDK 17–21 to compile. Lombok 1.18.36 crashes on JDK 25 with TypeTag :: UNKNOWN ExceptionInInitializerError.
Maven	3.x	Build tool. Fedora quirk: Fedora's mvn wrapper ignores update-alternatives and reads /etc/java/maven.conf. Set JAVA_HOME=/usr/lib/jvm/java-21-temurin-jdk in ~/.mavenrc to force Java 21.

JVM Flags (Production)

-Xmx512m -XX:+UseG1GC -XX:+UseStringDeduplication
-XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=20

Configured via exec-maven-plugin for development and the launcher scripts for production.

JVM Self-Relaunch (Quirk)

Main.java contains checkAndRelaunch() which detects if the JVM was launched with >1.1 GB max heap (e.g., by a system default) and relaunches itself with -Xmx1g to prevent excessive memory usage. The relaunched process is marked with -Dshipeditor.relaunched=true to prevent infinite relaunch loops.

Java2D Suppression

System.setProperty("sun.java2d.opengl", "false");
System.setProperty("sun.java2d.d3d", "false");
System.setProperty("sun.java2d.noddraw", "true");

Java2D's OpenGL and Direct3D pipelines are explicitly disabled because they conflict with the LWJGL GL context sharing through AWTGLCanvas. Without these flags, some drivers produce black canvases or segfaults.

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GUI Framework

Component	Version	Purpose
Swing/AWT	JDK built-in	Core UI framework
FlatLaf	3.1.1	Modern look-and-feel with dark mode, scalable DPI, and IntelliJ themes
Ikonli	12.3.1	Vector icon packs: FontAwesome5, FluentUI, Boxicons

FlatLaf Configuration (Quirks)

• JPopupMenu.setDefaultLightWeightPopupEnabled(false) — Required because lightweight popups render behind the AWTGLCanvas heavyweight component.
• ToolTipManager.sharedInstance().setLightWeightPopupEnabled(false) — Same issue for tooltips.
• UIManager.put("FileChooser.readOnly", true) — Prevents users from creating/deleting folders in the file chooser.
• Early JToolTip initialization: new JToolTip().updateUI() is called during startup to force the classloader to eagerly load ToolTip UI classes. Without this, the first tooltip display on EDT can trigger lazy classloading that causes a visible UI freeze.
• Shell Folder Filtering: A custom function removes the :: pseudo-path (SHELL_FOLDER_0_X_12) from the file chooser shortcuts on Windows.

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Graphics & Rendering Pipeline

Component	Version	Purpose
LWJGL 3 (BOM)	3.3.3	Core library, OpenGL bindings, GLFW, JAWT
lwjgl3-awt	0.2.3	AWTGLCanvas bridge between Swing and OpenGL
JOML	1.10.8	Matrix4f, Vector2f, Vector3f, Vector4f math

Native Classifiers

Both Linux and Windows natives are included in the POM:

• natives-linux for lwjgl, lwjgl-opengl, lwjgl-glfw
• natives-windows for the same

macOS is not supported (no native classifiers declared).

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Data Handling & Persistence

Component	Version	Purpose
Jackson Core	2.18.7	JSON parsing with extensive relaxed-mode features
Jackson Databind	2.18.7	Object mapping with custom coercion rules
Jackson CSV	2.18.7	CSV parsing/writing with custom serializers
Jackson Annotations	2.18.7	@JsonProperty, @JsonIgnoreProperties, etc.
SQLite JDBC	3.45.2.0	Embedded database for file indexing

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Utilities

Component	Version	Purpose
Lombok	1.18.36	@Getter, @Setter, @Builder, @Log4j2, @ToString
Log4j2	2.25.4	log4j-api, log4j-core, log4j-slf4j-impl
Apache Commons Collections 4	4.4	Advanced collection utilities
JHLabs Filters	2.0.235-1	Image manipulation filters

Lombok Inheritance Trap (Quirk)

When extending classes that use Lombok @Getter (e.g., LayerPainter), be careful of field shadowing. Always use polymorphic getter methods (getSprite()) in the base class rather than direct field access (this.sprite). Subclasses that override the getter will function correctly; direct field access bypasses the override and hits uninitialized base-class fields, causing NullPointerExceptions.

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Build Plugins

Plugin	Version	Purpose
maven-compiler-plugin	3.11.0	Java 17 target, Lombok + Log4j2 annotation processors
maven-surefire-plugin	3.2.5	Test execution (JUnit Jupiter + jqwik)
spotbugs-maven-plugin	4.8.3.1	Static analysis: Max effort, Low threshold
maven-jar-plugin	3.4.2	JAR packaging
exec-maven-plugin	3.1.0	Launch via mvn exec:exec with custom JVM flags
maven-shade-plugin	3.6.0	Uber-JAR generation

Shade Plugin Configuration (Quirks)

• Log4j2PluginCacheFileTransformer: Merges Log4j2 plugin caches from multiple JARs. Without this, Log4j2 fails to discover its appenders at runtime.
• ServicesResourceTransformer: Merges META-INF/services files. Required for JDBC driver auto-discovery and Ikonli icon pack loading.
• Exclusion Filters: Strips module-info.class, signature files (*.SF, *.DSA, *.RSA), and duplicate metadata to prevent SecurityException and classloading conflicts.
• Output: The shaded JAR is written to ${project.basedir}/ship_editor.jar (project root), not target/.

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Module System (JPMS)

module-info.java declares a full JPMS module named shipeditor.

Key Observations

• requires static lombok: Lombok is compile-time only (no runtime dependency).
• requires static com.github.spotbugs.annotations: SpotBugs annotations are retained in source but not needed at runtime.
• Extensive opens directives: Many packages are opened to com.fasterxml.jackson.databind for reflection-based deserialization. Without these, Jackson fails with InaccessibleObjectException on Java 17+.
• requires transitive java.desktop: Exposes AWT/Swing to downstream modules.
• Compiler warnings suppressed: @SuppressWarnings("module") on the module declaration, and -Xlint:-requires-automatic -Xlint:-module compiler args suppress warnings about automatic modules (LWJGL, Ikonli, etc. that lack proper module-info).
• IDE Access Diagnostics: Be sure to exports any internal packages (like shipeditor.utility.graphics.opengl) and use requires transitive for external libraries (like org.joml) if their classes are exposed in public method signatures. Without these, strict IDEs (like Eclipse/VSCode) will mass-report "not exported from this module" or "may not be accessible to clients" errors even if Maven compiles fine.