[AjeshRPai]

Automated R8 & App Shrinking Regression Gates (android analyze)

Automated presubmit (Git hooks) and CI (GitHub Actions) regression gates powered by ANDROID_CLI_ANALYZE=1 android analyze to catch R8 configuration regressions, unshrunk libraries, and DEX size bloat before merge.

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1. Modular Check Scripts (scripts/)

Teams can adopt all three checks or pick only the ones that fit their workflow:

Script	Target	What It Checks	Typical Stage
check_staged_r8_diff.py	Staged git diff, *.pro, libs.versions.toml	Blocks enableR8.fullMode=false, newly added -keep class <pkg>.** { *; } rules, and audits newly added Maven dependencies in ~/.gradle/caches	Local pre-commit (<1s)
check_library_shrinking.py	.aar & .jar modules/libraries	Runs an isolated R8 dry-run ((1 - r8DexSize / d8DexSize) * 100) and flags consumer proguard.txt rules with package-wide wildcards	Local pre-commit / CI
check_app_r8_score.py	Release App Bundle (.aab)	Compares shrinkingRatio, optimizationRatio, obfuscationRatio (0–100) and uncompressedDexSizeBytes against r8-baseline.json	Local pre-push / CI

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2. GitHub Actions Workflow (.github/workflows/r8_regression_check.yml)

Triggers & Inputs

• pull_request / push (main): Runs automatically whenever ProGuard/R8 files (**/*.pro), Gradle build scripts (**/build.gradle.kts, gradle/libs.versions.toml, gradle.properties), r8-baseline.json, or scripts/check_*.py change.
• workflow_dispatch: Supports manual execution against any PR or commit with configurable thresholds:
  • pr_number: Optional PR number to checkout and comment on.
  • max_score_drop (default 2.0): Maximum allowed drop in R8 shrinking, optimization, or obfuscation scores (percentage points).
  • max_dex_growth_pct (default 5.0): Maximum allowed uncompressed DEX size increase (%).
  • min_lib_shrinking_pct (default 90.0): Minimum required isolated DEX shrinking percentage for module AARs (%).

Workflow Pipeline Steps

1. Prepare Review Context: Resolves the PR or commit diff range and extracts modified .pro, .gradle.kts, libs.versions.toml, and gradle.properties changes into .gemini/pr_diff.patch.
2. Install Android CLI & Skills: Installs the latest android CLI (https://dl.google.com/android/cli/latest/linux_x86_64/install.sh) and adds the r8-analyzer skill (android skills add --agent=gemini --project=. r8-analyzer).
3. Build Release Artifacts: Runs ./gradlew :app:bundleRelease assembleRelease to produce the release App Bundle (app-release.aab) and module AARs (*-release.aar).
4. Check App Bundle R8 Scores & DEX Size (app_r8_gate): Runs check_app_r8_score.py to compare the release .aab against r8-baseline.json and writes the scorecard to .gemini/r8_summary.md and $GITHUB_STEP_SUMMARY.
5. Check Module & Library Shrinking Percentage (lib_r8_gate): Runs check_library_shrinking.py (--scan-libraries --append-summary) across built module AARs to verify isolated R8 shrinking ratios and flag package-wide consumer keep rules.
6. Auto-Ratify Baseline on main: On push to main when both gates pass, runs check_app_r8_score.py --save-baseline and auto-commits updated metrics to r8-baseline.json.
7. AI-Assisted Diagnosis on Failure (gemini_review): If either gate fails, invokes google-github-actions/run-gemini-cli with the r8-analyzer skill to inspect .gemini/pr_diff.patch and pinpoint the exact keep rule or dependency causing the regression.
8. PR Comment & HTML Report Upload: Posts the combined R8 scorecard and r8-analyzer remediation recommendations directly to the PR via gh pr comment, uploads r8-config-analyzer-report (r8-config-analyzer-release.html), and fails the check if any regression threshold was breached.

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3. Presubmit Git Hooks (scripts/git-hooks/ & .pre-commit-config.yaml)

• scripts/git-hooks/pre-commit: Runs check_staged_r8_diff.py on staged changes and check_library_shrinking.py on built module AARs.
• scripts/git-hooks/pre-push: Runs check_app_r8_score.py against r8-baseline.json when a release .aab is present.
• .pre-commit-config.yaml: Exposes three independent hook IDs (r8-staged-diff-and-deps, r8-library-shrinking-gate, r8-app-bundle-score-gate) so teams using pre-commit can enable individual checks.

[github-actions]

🛡️ R8 Optimization & Shrinking Gate (android analyze)

📦 App Bundle R8 Scores & DEX Size

• Package: N/A
• Compiler: AGP 9.2.1 / R8 9.2.14 (Full Mode: True)
• Baseline: r8-baseline.json

Metric	Baseline	Current	Delta	Threshold	Status
Shrinking Score	51.15%	50.36%	-0.79% pts	max -2.00% pts	✅ PASS
Optimization Score	50.81%	50.02%	-0.79% pts	max -2.00% pts	✅ PASS
Obfuscation Score	51.11%	50.33%	-0.78% pts	max -2.00% pts	✅ PASS
Uncompressed DEX Size	18.32 MB	17.90 MB	-0.42 MB (-2.3%)	max +5.0% / +500KB	✅ PASS

📚 Library Shrinking Percentage (Min Threshold: 90.0%)

Library (.aar / .jar)	D8 DEX	R8 Kept DEX	DEX Shrinking %	Classes Shrunk	Methods Shrunk	Pkg-Wide Rules	Status
network-release.aar	64.35 KB	0.00 KB	100.00%	100.0% (49/49)	100.0% (250/250)	0	✅ PASS
testing-release.aar	29.22 KB	0.00 KB	100.00%	100.0% (17/17)	100.0% (119/119)	0	✅ PASS
theme-release.aar	209.49 KB	0.00 KB	100.00%	100.0% (51/51)	100.0% (405/405)	0	✅ PASS
util-release.aar	44.71 KB	0.00 KB	100.00%	100.0% (24/24)	100.0% (111/111)	0	✅ PASS
xr-release.aar	44.73 KB	0.00 KB	100.00%	100.0% (13/13)	100.0% (64/64)	0	✅ PASS
data-release.aar	55.13 KB	0.00 KB	100.00%	100.0% (54/54)	100.0% (193/193)	0	✅ PASS
camera-release.aar	289.75 KB	0.00 KB	100.00%	100.0% (93/93)	100.0% (550/550)	0	✅ PASS
creation-release.aar	343.21 KB	0.00 KB	100.00%	100.0% (86/86)	100.0% (610/610)	0	✅ PASS
home-release.aar	186.55 KB	0.00 KB	100.00%	100.0% (47/47)	100.0% (310/310)	0	✅ PASS
results-release.aar	602.10 KB	0.00 KB	100.00%	100.0% (200/200)	100.0% (1127/1127)	0	✅ PASS
watchface-release.aar	72.20 KB	2.73 KB	96.21%	100.0% (46/46)	100.0% (256/256)	0	✅ PASS
common-release.aar	45.32 KB	0.00 KB	100.00%	100.0% (31/31)	100.0% (229/229)	0	✅ PASS