Your first patch

One patch from nothing to a patched APK: remove a "rate this app" prompt from an imaginary com.example.app.

1. Create the bundle

my-bundle/
  manifest.toml
  settings.gradle.kts
  gradlew
  gradle/
  apps/example/patch/src/main/kotlin/app/example/patches/RatePromptPatch.kt

settings.gradle.kts and manifest.toml are the two files from Bundles. gradlew and gradle/ come from gradle wrapper.

2. Find what to change

Open the APK in a decompiler and find the code that shows the prompt. Names are obfuscated and change every release, so note what does not: the strings the method loads, its return type, its parameters, what it calls. Say the prompt is shown by a method that loads "rate_prompt_shown" and returns nothing.

3. Write the patch

package app.example.patches

import app.reseam.patch.Type
import app.reseam.patch.before
import app.reseam.patch.method
import app.reseam.patch.patch

val hideRatePrompt = patch("Hide rate prompt") {
    description("Never asks you to rate the app.")
    compatibleWith("com.example.app")

    execute {
        showRatePrompt.before {
            returnVoid()
        }
    }
}

val showRatePrompt = method("showRatePrompt") {
    strings("rate_prompt_shown")
    returns(Type.Void)
}

The patch says what it is and which app it is for, execute says what changes, the target below says what to look for. "showRatePrompt" is a label for error messages; the app's method has some other name.

4. Build, apply, install

./gradlew bundle
reseam patch app.apk \
  --bundle build/reseam/my-bundle.reseam \
  --trust <PUBLIC_KEY_HEX> \
  --output patched.apk
adb install patched.apk

The log ends with one line per patch (applied, skipped, failed). Each resolved target is logged with level=debug and the method it picked.

5. When it does not match

No match fails the patch with a report:

No method matched 'showRatePrompt'. Searched 3 candidate(s).
Reasons: strings("rate_prompt_shown"): 3 candidate method(s); no candidate satisfied the full structural query
Near misses: Lcom/example/a/b;->c()Z [missed: return type mismatch]; ...

The near miss says the method returns a boolean, so returns(Type.Void) was wrong. Too many matches fail too:

2 methods matched 'showRatePrompt'; add constraints, rank them, or take first(): ...

Add a constraint that separates them, or rankBy when one is preferable. Finding code in the app has the details.

Next: Patches.