CI Integration

CI Integration

Catch recomposition regressions in your CI pipeline. Rebound captures runtime recomposition profiles, compares them across builds, and fails the pull request if budgets regress.

Quick start

1. Create a baseline (once, on your main branch)

Run your app with Rebound enabled, exercise the UI (manually or via instrumented tests), then save a snapshot:

./gradlew reboundSave -Ptag=baseline

This writes .rebound/baseline.json. Commit it to the repo.

2. Gate your PRs

Add one Gradle task to your CI pipeline:

./gradlew reboundGate -Pbaseline=.rebound/baseline.json

This connects to the running app, captures a fresh snapshot, diffs it against the baseline, and fails the build if any composable’s peak recomposition rate regressed beyond the threshold (default: 20%).

Options

Flag	Default	Description
-Pbaseline=<path>	(required)	Path to committed baseline JSON
-Pthreshold=<int>	20	Minimum % change to flag as regression
-Pport=<int>	18462	Rebound socket port

GitHub Actions example

name: Rebound Budget Check

on:
  pull_request:
    branches: [master]

jobs:
  rebound-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Set up JDK
        uses: actions/setup-java@v4
        with:
          distribution: 'temurin'
          java-version: '17'

      - name: Start emulator and run budget gate
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: 34
          script: |
            # Build and install
            ./gradlew :app:installDebug
            adb shell am start -n com.example.app/.MainActivity
            sleep 10

            # Run UI tests to exercise composables
            ./gradlew :app:connectedDebugAndroidTest

            # Budget gate — fails the build on regression
            ./gradlew reboundGate -Pbaseline=.rebound/baseline.json

Output

Captured 29 composables to .rebound/gate-20260409-143022.json

=== Rebound Gate: baseline.json -> gate-20260409-143022.json (threshold: 20%) ===

REGRESSIONS (1):
  ProfileHeader [SCREEN]
    peak: 3/s -> 11/s (+267%) budget=3/s !!OVER!!
    skip: 80.0% -> 45.0% (-35.0%)
    forced: 0 -> 7

IMPROVED (1):
  UserCard [LEAF]
    peak: 9/s -> 4/s (-56%)
    skip: 30.0% -> 85.0% (+55.0%)

Summary: 29 composables (1 improved, 1 regressed, 25 unchanged, 2 new, 0 removed)
Result: FAIL

FAILURE: Build failed with exception.
  Rebound: 1 regression(s) exceeded 20% threshold — build failed

Updating the baseline

When you intentionally change recomposition behavior (e.g., adding animation to a composable that was previously static), update the baseline:

./gradlew reboundSave -Ptag=baseline
git add .rebound/baseline.json
git commit -m "update rebound baseline"

Alternative: CLI diff

If you prefer shell scripts over Gradle tasks, the CLI works the same way:

# Save snapshots
./rebound-cli.sh save .rebound/baseline.json
./rebound-cli.sh save .rebound/current.json

# Compare — exits 1 on regression
./rebound-cli.sh diff .rebound/baseline.json .rebound/current.json

Alternative: standalone diff (no device)

Compare two previously saved snapshots without a running app:

./gradlew reboundDiff \
  -Pbefore=.rebound/baseline.json \
  -Pafter=.rebound/current.json \
  -Pthreshold=10

This also fails the build on regression. To print results without failing, add -PfailOnRegression=false.