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R8 Analyzer

Free

Optimize Android build files and R8 keep rules effectively.

by android6.7k stars on android/skills
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Updated Aug 7, 2026
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Free · Opens the source repo

What R8 Analyzer does

R8 Analyzer is a specialized tool designed to help Android developers optimize their application's size by analyzing build files and R8 keep rules. It identifies redundancies, broad package-wide rules, and rules that may override library consumer keep rules. This skill is essential for developers looking to streamline their Proguard configurations and enhance build performance, especially when working with Android Gradle Plugin (AGP) versions 9.0 and above.

The analysis process begins with a thorough inspection of key files such as build.gradle, build.gradle.kts, and gradle.properties. Depending on the AGP and R8 versions, the tool provides different paths for analysis, including standalone tasks for newer versions and heuristic evaluations for older setups. This flexibility ensures that developers can effectively analyze their configurations regardless of the specific version they are using.

R8 Analyzer also guides users through the necessary steps to generate reports that detail the impact of keep rules on application size. By following the structured paths outlined in the skill, developers can convert analysis results into JSON format and extract meaningful metrics, such as scores and impacts, which are crucial for making informed decisions about rule adjustments.

Overall, R8 Analyzer is tailored for Android developers who want to optimize their applications, reduce build size, and troubleshoot configuration issues. Its systematic approach to analyzing R8 keep rules makes it a valuable addition to any Android development toolkit.

When to use it

Use R8 Analyzer when you want to optimize your Android app's size and troubleshoot Proguard configurations, especially with AGP versions 9.0 and above.

When not to use it

This tool is not suitable for developers who are not using R8 or those whose projects do not involve Android build configurations.

What you can build with it

Optimizing App Size

Use R8 Analyzer to identify and remove redundant keep rules, significantly reducing your Android app's size.

Troubleshooting Proguard Configurations

When facing issues with Proguard, R8 Analyzer helps pinpoint misconfigurations and suggests refinements.

Migrating to New AGP Versions

If you're upgrading your Android Gradle Plugin, R8 Analyzer can ensure your build files are optimized for the latest features.

How to install R8 Analyzer

View source

1. Install with the skills CLI

npx skills add android/skills/r8-analyzer --agent claude-code

2. Or install it manually

Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.

Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs

Inside SKILL.md

Written by android

Step 1. Setup and configuration check

  • Inspect build.gradle, build.gradle.kts, and gradle.properties.
  • Use references/CONFIGURATION.md to identify missing optimizations.
  • AGP : If version is lower than 9.0, suggest migration to 9.0 for build-time performance improvement.
  • Full Mode : Verify android.enableR8.fullMode=false is removed from gradle.properties.

Step 2. Analysis path selection

  • Inspect build.gradle, build.gradle.kts, and gradle.properties and libs.versions.toml to get the AGP and R8 versions.

  • If AGP >= 9.3.0 : Proceed to Path A (Standalone Task).

  • If AGP < 9.3.0 and R8 >= 9.3.7-dev : Proceed to Path B (Quantitative).

  • If none of the conditions are met, proceed to Path C (Heuristic).

Path A: Standalone Gradle task (AGP >= 9.3.0)

  • Step 1: Run standalone task : Run ./gradlew :app:analyzeReleaseR8Config to evaluate the R8 configuration. You MUST wait for this command to finish before proceeding.
  • Step 2: Convert to JSON : The report is generated at app/build/reports/r8/r8-config-analyzer-release.pb. You MUST explicitly run the conversion script by executing: python3 .agents/skills/r8-analyzer/scripts/convert_pb_to_json.py. Wait for this command to finish.
  • Step 3: Analyze : You MUST explicitly run the analysis script by executing: python3 .agents/skills/r8-analyzer/scripts/analyze.py. This outputs tmp/keepradius/analysis_result.txt. Wait for this command to finish.

Path B: Quantitative data generation (R8 >= 9.3.7-dev and AGP < 9.3.0)

  • Step 1: Check requirements : Python and protobuf package are mandatory.
  • Step 2: Generate and analyze : You MUST run the shell commands described in references/CONFIGURATION-ANALYZER.md to generate the proto file using R8 configuration analyzer, convert it to JSON and analyze the result.
  • Step 3: Analyze : You MUST ensure the analysis produces tmp/keepradius/analysis_result.txt for scores and rule impact metrics.

Path C: Heuristic evaluation and recommendation (R8 < 9.3.7-dev)

(Use ONLY if quantitative data generation is not possible)

Step 3. Report generation

  • Format : Follow references/REPORT_FORMAT.md strictly.
  • Input: Extract metrics (Scores, Impacts, Example Classes) directly from generated file analysis.txt if using Path A, or from manual findings if using Path B.
  • Output : Output ONLY the raw Markdown report in the chat. Do NOT output conversational filler (for example, "Here is your report..."). Do NOT provide recommendations, next steps, or any other text outside of the sections defined in references/REPORT_FORMAT.md Do NOT mention the path used for analysis of the configuration

Constraints

  • Strict output limit: The final output MUST strictly be the Markdown report and nothing else.
  • No code changes: Research and suggest only; Do not modify files.
  • No redundancy: Do not explain R8 benefits or reference skill internal files in the report.
  • Focus: Omit sections (for example, Subsumed Rules, Configuration) if no issues or items are found.

Frequently asked questions about R8 Analyzer

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