[build-tools] Use environment variable to enable Gradle cache instead of gradle.properties

[sjchmiela]

Instead of mutating gradle.properties which can influence fingerprint we can use environment variable to enable caching.

See https://docs.gradle.org/current/userguide/build_environment.html#setting_a_project_property and https://exponent-internal.slack.com/archives/C1QP38NQ5/p1781167813244859?thread_ts=1781160178.382929&cid=C1QP38NQ5.

[codecov]

Codecov Report

❌ Patch coverage is 31.25000% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.28%. Comparing base (1431a20) to head (4f5bdcf).

Files with missing lines	Patch %	Lines
...ild-tools/src/steps/functions/restoreBuildCache.ts	8.34%	10 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3849      +/-   ##
==========================================
+ Coverage   58.27%   58.28%   +0.02%     
==========================================
  Files         917      917              
  Lines       39840    39848       +8     
  Branches     8384     8359      -25     
==========================================
+ Hits        23212    23222      +10     
+ Misses      16533    15191    -1342     
- Partials       95     1435    +1340     

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[Copilot]

Pull request overview

This PR updates Android Gradle build-cache enablement in @expo/build-tools to avoid mutating android/gradle.properties (which can affect fingerprinting) and instead enables caching via environment variables that are propagated into the Gradle invocation.

Changes:

• Change restoreGradleCacheAsync to return Gradle-cache-related environment variables (instead of editing android/gradle.properties).
• Plumb returned env vars into both the workflow step (createRestoreBuildCacheFunction) and the Android builder restore-cache phase (androidBuilder).
• Add logging (and a unit test) to confirm the returned env vars are surfaced when present.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/build-tools/src/steps/functions/restoreBuildCache.ts	Return Gradle cache env vars from cache restore and update workflow global env; add helper to log env vars.
packages/build-tools/src/builders/android.ts	Apply returned Gradle cache env vars to the builder’s runtime environment and log them.
packages/build-tools/src/builders/tests/android.test.ts	Update mocks and add coverage for logging Gradle cache env vars returned by restoreGradleCacheAsync.

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[AbbanMustafa]

I'm not entirely certain this will truly enable the property still. ref gradle/gradle#18087

I will validate your branch locally to see

[AbbanMustafa]

I ran this locally and validated it does not enable gradle caching. In restore

Restoring Gradle cache key: android-gradle-cache-f0ece61fb139c94a5b03cfd08ced7227a2d238dc293484d692233893e90d8752
Matched cache key: android-gradle-cache-f0ece61fb139c94a5b03cfd08ced7227a2d238dc293484d692233893e90d8752. Downloading...
Gradle cache restored to /Users/mustafa/.gradle/caches (direct hit)
Enabling Gradle cache. Running Gradle with additional environment variables.
ORG_GRADLE_PROJECT_org.gradle.caching=true

in run gradle

[EAS] Gradle build cache entries before cleanup: 464
[EAS] Configured Gradle cache cleanup via init script
...

[EAS] Gradle build cache entries after build: 464 (was 464)

what I expected to see and what I saw with current setup

[EAS] Gradle build cache entries after build: 476 (was 464)

[AbbanMustafa]

ah but we can modify ~/.gradle/gradle.properties and leave the project untouched

[sjchmiela]

superseded by #3852