Generating Baseline Profiles

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 87cfb886f00d · 16 Oct 2026Report an issue or request a re-scan

• Publisherskydoves GitHub userOwner of the repository this skill is read from
• Source folderskydoves/compose-performance-skills/measurement/generating-baseline-profilesThe exact folder we audited
• LicenceApache-2.0As the repository states it
• Commit pinned for this verdict87cfb886f00dA new audit runs when the source changes
• Repository statusNot archivedLast push 121 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Use this skill to generate and measure Jetpack Compose Baseline Profiles end-to-end with the AGP 8.2+ Baseline Profile Generator module and the Macrobenchmark harness. Covers writing the `BaselineProfileRule` journey…

---
name: generating-baseline-profiles
description: Use this skill to generate and measure Jetpack Compose Baseline Profiles end-to-end with the AGP 8.2+ Baseline Profile Generator module and the Macrobenchmark harness. Covers writing the `BaselineProfileRule` journey for cold startup plus first-scroll, generating `baseline-prof.txt`, verifying it shipped at `assets/dexopt/baseline.prof`, measuring with `MacrobenchmarkRule` under `CompilationMode.Partial(BaselineProfileMode.Require)`, and emitting accurate time-to-fully-drawn via `ReportDrawn` / `ReportDrawnWhen` / `ReportDrawnAfter` from `androidx.activity.compose`. Compose ships unbundled, so every Compose UI app benefits — cited gains around 30% faster startup and 40% smoother first-scroll. Use when the user mentions "baseline profile", "macrobenchmark", "slow cold startup", "first-scroll jank", "StartupTimingMetric", "FrameTimingMetric", "ReportDrawn", "TTFD", or preparing a release build for performance measurement.
license: Apache-2.0. See LICENSE for complete terms.
metadata:
  author: Jaewoong Eum (skydoves)
  keywords:
  - jetpack-compose
  - performance
  - baseline-profiles
  - macrobenchmark
  - startup
  - frame-timing
  - report-drawn
  - ttfd
  - aot-compilation
---

# Generating Baseline Profiles — ship the AOT compilation hint list and prove it moved the needle

Baseline Profiles ship an AOT compilation hint list inside the APK so ART pre-compiles hot Compose code paths on install instead of relying on JIT during the first runs. Cited gains: roughly 30% faster cold startup and 40% smoother first-scroll on the journeys that were profiled. Compose ships **unbundled** from the platform, so every Compose UI app benefits — there is no version of Android where Compose is already AOT-compiled by the system image.

This skill is the measurement spine for the rest of the performance work. Profiles are generated with `BaselineProfileRule` from `androidx.benchmark:benchmark-macro-junit4` and measured with `MacrobenchmarkRule` from the same artifact. Generation and measurement are two distinct `@Test` files in a separate `:baselineprofile` module that AGP 8.2+ scaffolds via **New Module → Baseline Profile Generator**.

## When to use this skill

- Cold startup is slow and the developer wants AOT-compiled hot paths on first launch.
- First-scroll on a `LazyColumn` / `LazyVerticalGrid` is janky on real devices even after stability fixes.
- Preparing a release build and the developer needs a perf baseline before shipping.
- Verifying that a stability or strong-skipping fix actually moved cold-startup or frame-timing numbers — Macrobenchmark is the ground truth.
- The user mentions "baseline profile", "macrobenchmark", "TTFD", "time-to-fully-drawn", "StartupTimingMetric", "FrameTimingMetric", "CompilationMode", `aosp_cf_x86_64_phone-userdebug`, or "ReportDrawn".

## When NOT to use this skill

- Still in early prototyping with no release-ready user journeys yet — Baseline Profiles encode hot paths, and there are no hot paths to encode while screens are still churning.
- The developer wants per-composable recomposition counts — that is `../../recomposition/debugging-recompositions/SKILL.md` (debug Layout Inspector) or `../tracing-recompositions-at-runtime/SKILL.md` (release `@TraceRecomposition`).
- The developer wants a CI gate against stability regressions — that is `../../stability/enforcing-stability-in-ci/SKILL.md`. Baseline Profiles measure runtime; `stabilityCheck` measures compile-time skippability.
- Numbers are being collected from a debug build — debug builds run interpreted with Live Literals and produce non-representative numbers. See `../testing-compose-in-release-mode/SKILL.md`.

## Prerequisites

- **AGP 8.2+** so the **New Module → Baseline Profile Generator** template is available (it scaffolds the `androidx.baselineprofile` Gradle plugin and a `:baselineprofile` module).
- A **physical low-end test device** or a Cuttlefish emulator (`aosp_cf_x86_64_phone-userdebug`). High-end pixel devices mask perf wins; emulators with default API images are not representative.
- A **release** variant configured (`isMinifyEnabled = true`, `isShrinkResources = true`, `proguard-android-optimize.txt`). Debug builds are not measurable. See `../../build/configuring-r8-for-compose/SKILL.md` for R8 setup if missing.
- `<profileable android:shell="true"/>` in the app `AndroidManifest.xml` under `<application>` so the Macrobenchmark process can attach simpleperf. The `android:` namespace prefix is required — without it, manifest merger fails.
- At least one **scroll journey** identified beyond startup — a feed list, a paginated grid, opening a detail screen. Profiling startup alone leaves first-scroll uncompiled.
- Familiarity with `../../stability/diagnosing-compose-stability/SKILL.md` and `../../recomposition/debugging-recompositions/SKILL.md` if startup is dominated by avoidable recomposition rather than initial composition.

## Workflow

### 1. Add the Baseline Profile Generator module

In Android Studio: **File → New → New Module → Baseline Profile Generator**. Pick the target application module. AGP scaffolds:

- A new `:baselineprofile` module with the `androidx.baselineprofile` Gradle plugin applied.
- A `BaselineProfileGenerator.kt` skeleton with a `BaselineProfileRule` `@Test`.
- A `StartupBenchmarks.kt` skeleton with a `MacrobenchmarkRule` `@Test`.
- The `androidx.baselineprofile` plugin applied in the **app** module too, so `./gradlew :app:generateBaselineProfile` is wired up.

If editing manually instead of using the template, add to `:baselineprofile/build.gradle.kts`:

```kotlin
plugins {
    id("com.android.test")
    id("org.jetbrains.kotlin.android")
    id("androidx.baselineprofile")
}
android { targetProjectPath = ":app" }
dependencies {
    implementation("androidx.benchmark:benchmark-macro-junit4:1.3.0")
    implementation("androidx.test.ext:junit:1.2.1")
    implementation("androidx.test.uiautomator:uiautomator:2.3.0")
 

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/skydoves/compose-performance-skills
git -C compose-performance-skills checkout 87cfb886f00d

Works in

1. 2026-10-16
   ✓SAFE B 89 / 100

   first audit · source 87cfb886f00d

Questions about Generating Baseline Profiles

• github.com/skydoves/compose-performance-skills/tree/main/measure — the audited source at commit 87cfb886f00d and every finding aboveObserved · 16 Oct 2026

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