tycho-build-and-target-platform

name	tycho-build-and-target-platform
description	Guidance for Tycho, target-platform, p2, feature, category, and Eclipse dependency/build alignment.

Tycho Build and Target Platform

Use this skill when working on tasks related to:

• .target files
• Tycho or Maven build configuration
• target-platform alignment
• p2 repositories
• installable units
• feature.xml
• category.xml
• dependency resolution in Eclipse plugin builds
• execution environment alignment
• bundle availability on the supported Eclipse baseline

Goal

Keep the build reproducible and compatible with the repository's minimum supported:

• Eclipse target-platform
• JDK
• bundle dependency set

Working Approach

1. Treat target-platform as the source of truth

When deciding whether a dependency, plugin, feature, or API can be used, first check whether it is available and compatible in the configured target-platform.

Do not assume a dependency is valid simply because it exists in Maven Central or works in a plain Java project.

2. Keep Tycho and metadata aligned

When build-related changes are made, check the consistency among:

• .target files
• parent and module pom.xml
• Tycho plugins and configuration
• META-INF/MANIFEST.MF
• feature.xml
• category.xml
• p2 repository definitions
• execution environment or compiler target settings

A correct solution usually requires these files to remain aligned, not just one of them.

3. Minimize dependency expansion

When adding dependencies:

• add only what is necessary
• prefer dependencies already available in the current target-platform
• avoid broadening bundle requirements unnecessarily
• avoid introducing optional complexity unless there is a clear need

Be careful with transitive assumptions. Tycho and OSGi resolution are stricter than plain Maven dependency resolution.

4. Respect execution environment and JDK boundaries

Do not change Java execution environment, compiler target level, or required JDK assumptions unless explicitly requested.

If the task requires a newer Java level or newer platform baseline, call that out clearly instead of silently upgrading constraints.

5. Feature and p2 consistency

If the repository publishes features, update sites, or p2 metadata:

• ensure newly required bundles are reflected where needed
• ensure features include the right plugins and fragments
• ensure category definitions remain valid
• keep installable content and runtime requirements synchronized

Do not update only the plugin dependency while forgetting the publishable artifacts.

6. Prefer stable build changes

For Tycho-related updates:

• prefer minimal version changes
• avoid unnecessary plugin upgrades
• avoid broad build modernization unless explicitly requested
• keep build configuration understandable and repository-consistent

7. Diagnose resolution issues carefully

When build failures are related to Tycho or target-platform, consider:

• missing bundles in the target-platform
• mismatched bundle versions
• execution environment mismatch
• missing feature inclusion
• wrong p2 repository or category content
• Require-Bundle vs Import-Package implications
• platform-specific fragments or native dependencies
• test bundles requiring additional runtime content

Build Alignment Checklist

Before considering a build-related task complete, check:

• dependency exists in the configured target-platform
• dependency is compatible with the minimum supported Eclipse version
• dependency is compatible with the minimum supported JDK
• MANIFEST.MF is aligned with actual usage
• .target files are still valid
• pom.xml and Tycho config remain consistent
• feature.xml is updated if installable content changed
• category.xml is updated if published content changed
• p2 repository definitions remain correct
• no unnecessary platform baseline upgrade was introduced

Output Expectations

When proposing or implementing Tycho or target-platform changes, include relevant notes about:

• why the dependency or bundle is expected to resolve in the configured target-platform
• whether MANIFEST.MF, .target, pom.xml, feature.xml, or category.xml also need updates
• whether the task changes the supported platform or JDK baseline
• any risk to reproducible builds, p2 publishing, or installable content