Limrun Gradle

Remote Gradle build

Build Android projects on Limrun's remote Gradle sandboxes, from any environment (Linux, Windows, macOS, VM, container). lim gradle build syncs your sources to a remote instance, runs the project's own Gradle wrapper there, and streams the build output. Never fall back to local Gradle, a local Android SDK, or a local emulator. Your job doesn't end at a green build: get the app running or the artifact delivered, and iterate until the user is satisfied.

For iOS builds, use limrun-xcode instead of this skill. For the Expo dev-client loop (Metro, hot reload) on either platform, use limrun-expo-development; it comes back here for the Android Debug build.

Auth and CLI

Install if needed: npm install --global lim. Auth is lim login or LIM_API_KEY (it may be set outside the project, so don't ask for it just because it's missing from .env or the shell). The CLI is the source of truth: the commands in this skill are verified, but if a flag errors or you need one not shown here, check --help instead of guessing:

lim gradle --help
lim gradle build --help

Build an APK

Instead of ./gradlew, build with:

lim gradle build .

This creates or reuses the remembered Gradle instance, syncs the current directory, and runs assembleDebug by default. Pick tasks explicitly with --task (repeatable):

lim gradle build . --task :app:assembleRelease

Use --project-path when the Gradle root is nested and auto-discovery is ambiguous (for example a bare React Native repo where Gradle lives in android/; the server usually finds it on its own):

lim gradle build . --project-path android

Expo managed-workflow projects (no android/ directory) are detected automatically: the sandbox installs dependencies and runs expo prebuild before Gradle. Setting --expo-app-dir (monorepos) or --abi forces that pipeline and errors when no Expo app is detected:

lim gradle build ./my-monorepo --expo-app-dir apps/mobile

For iterating on an Expo app with Metro and hot reload rather than plain builds, use limrun-expo-development.

Run it on an emulator

Upload the built APK as a named asset, then install it on an Android instance:

lim gradle build . --upload myapp.apk
lim android create --install-asset=myapp.apk

Build uploads default to a 14-day TTL: each build pushes the asset's expiry to 14 days from that upload. Pass --upload-ttl with a Go duration (e.g. 720h; 1d is invalid) to change it.

Share the signed stream URL from the create output with the user as a Markdown link, such as [Live emulator](<signed-stream-url>). For rebuild iterations, patch the installed APK in place instead of recreating the instance:

lim android sync ./path/to/app-debug.apk

For everything else on the device (tapping, typing, element tree, screenshots, video, logcat over adb), use limrun-android-emulator.

Sign a release AAB

The default signing path needs NO credentials from the user:

lim gradle build . --sign --upload myapp.aab

On first use, Limrun generates an upload keystore, escrows it as the organization's signing key for this app, and signs with it. Every later --sign build of the same app, from any machine or CI, uses the same key, so Play Store uploads keep matching. The key is named by the Android application ID, detected from app.json (Expo) or app/build.gradle(.kts); pass --application-id <id> when detection fails or picks the wrong flavor.

--sign makes bundleRelease the default task and the build fails before starting if an explicit --task list contains no bundle task. A SUCCEEDED build means the AAB carries the signature (the server verifies it before upload), so don't re-verify the artifact unless the user asks.

Expect one of these lines before the build starts and relay its meaning:

• Signing with the organization's upload key for <app> (newly generated).: first build of this app; the key now exists for the whole organization.
• Signing with the organization's upload key for <app> (existing).: reusing the escrowed key, as intended.

Bring your own upload key

When the app already has a registered upload key (an existing Play listing), sign with the user's keystore instead:

lim gradle build . \
  --keystore upload.jks --keystore-password "$KS_PASS" \
  --key-alias upload --key-password "$KEY_PASS" \
  --upload myapp.aab

All four flags travel together; the passwords can come from LIM_KEYSTORE_PASSWORD and LIM_KEY_PASSWORD instead of argv. Add --save-key to escrow the provided key so later builds can drop the flags and use plain --sign. --save-key refuses to overwrite: if a DIFFERENT key is already escrowed for the app it fails before any instance is created.

Collect from the user:

• the keystore file path (.jks or .p12); never commit it or paste its bytes into files,
• the keystore password and the key password (often the same value),
• the key alias (keytool -list -keystore <file> shows it if unknown).

Failure strings to recognize on the bring-your-own path:

• The organization already has a different upload key escrowed for <app>: --save-key conflict. Builds with --sign use the escrowed key; drop --save-key to sign with the provided keystore for this build only, or ask the user which key is the real upload key.
• Signing with your own key requires ... as well: the BYO flag group is incomplete; the message lists exactly the missing flags.
• signing <field> contains an unsupported character: the password or alias has characters outside ISO-8859-1. Change it in place with keytool (-storepasswd, -keypasswd, or -changealias) to a Latin-1 value. Never regenerate the key itself: that changes the upload key.

Publish to Play Store

With Play credentials (a service-account JSON via --playstore-service-account, or an access token via --playstore-access-token), the build publishes the signed release AAB directly, no browser involved:

lim gradle build . --sign --upload-to-playstore --playstore-service-account sa.json --auto-version-code

--auto-version-code makes the server resolve the next free versionCode from Google Play before the build and stamp it into the workspace copy (expo.android.versionCode in app.json for Expo projects, the single literal versionCode in the conventional app/ module build script for native Gradle projects), so repeat publishes never collide. Without it, or on projects with computed or flavor-split versionCodes (which it rejects at request time), manage the versionCode yourself as below. Without Play credentials you cannot run the publish itself: it is a browser flow with a Google sign-in. Prepare the artifact, upload it as an asset, and hand off:

lim gradle build . --sign --upload <app>-v<versionCode>.aab

Tell the user to open https://console.limrun.com and, on the Secrets page, click Connect Play Console to sign in with a Google account that has release access to the app (the session lives in the browser only; nothing is stored). Then on the Registry page they click Publish to Play Store on the uploaded AAB and enter the package name (the application ID). The app listing must already exist in Play Console. Google Play requires a versionCode it has never seen: --auto-version-code handles that on publish builds; without it, bump versionCode in app/build.gradle(.kts) (Expo: expo.android.versionCode in app.json) before the build.

Failure strings to recognize on the --sign path:

• Cannot determine the Android application ID for signing: detection found no app.json android.package and no applicationId in app/build.gradle(.kts); pass --application-id <id>.
• --sign produces a Play-ready signed AAB; include a bundle task: the explicit --task list has no bundle task; add bundleRelease or drop --task.
• the built AAB carries no signature: the server's post-build check found an unsigned bundle; the signing config was not applied. Not a problem in the user's code; retry, and report it if it persists.

Gotchas

• Build errors are your job to fix. If a build fails, read the error output, fix the code, and rebuild. Don't ask the user to fix build errors.
• Instance reuse is per git worktree. Commands resolve the remembered instance from the worktree of your cwd; pass --id <gradle-instance-id> (from lim gradle list) to target a specific one.
• versionCode must increase for every Play upload. Prefer --auto-version-code on publish builds. A rejected publish saying the version code already exists means bump, rebuild, republish. If a publish RETRY reports it, the earlier attempt already succeeded; don't publish again.
• Application ID detection reads the first uncommented applicationId. Flavor-specific IDs and dynamic Gradle logic are out of its scope; use --application-id there.
• Keystore passwords must be non-empty and ISO-8859-1. Empty passwords and characters outside Latin-1 are rejected at request time instead of failing minutes into the build.
• Keep synced files small and out of build dirs. Root-level build/, .gradle, .kotlin and any local.properties never sync, and .gitignore files (including nested ones) are honored. Use --ignore <regex> for other large local artifacts and --include <regex> to force-sync gitignored inputs the build needs.