fix(android): restore compile-time selective install for text recognition and barcode scanning

The v2 hardening PR fixed a real compile failure by making
com.google.mlkit:text-recognition and com.google.mlkit:barcode-scanning
unconditional dependencies, defeating the library's selective-install
purpose: a consumer who only wants barcode scanning still got the
full text-recognition SDK bundled, and vice versa.

Root cause: Kotlin has no #if-equivalent preprocessor. Six Kotlin files
(TextRecognitionServiceFactory/MLKitTextRecognitionService/MLKitTextAdapter
and their barcode equivalents) import concrete MLKit types at file
scope, so they fail to compile whenever the corresponding artifact is
missing from the classpath - regardless of whether the runtime feature
flag ever lets that code execute. iOS never had this problem since its
Swift equivalents use #if MLKIT_TEXT_RECOGNITION_ANY / #if
MLKIT_BARCODE_SCANNING, which genuinely elides the guarded code (and
its imports) at compile time.

Fixed by giving Kotlin the same guarantee via Gradle conditional
source sets instead of reflection (MLKit's real client APIs return
async Task<T> objects with listener callbacks, which would need a
java.lang.reflect.Proxy to invoke reflectively - fragile under R8 and
adds reflection overhead to code that runs every camera frame):

- Moved the 6 MLKit-coupled files into textRecognitionEnabled/
  barcodeScanningEnabled source sets (content unchanged, path only).
- Added tiny stub factories in textRecognitionDisabled/
  barcodeScanningDisabled that throw if ever reached (they aren't -
  HybridVisionCameraMLKit already gates construction before this
  point), existing purely so the always-compiled Hybrid* classes have
  something to compile against.
- android/build.gradle picks the enabled/disabled source dir per flag,
  and re-gates the two base MLKit SDKs behind their flags again.
- Added com.google.mlkit:vision-common as an explicit, always-on
  dependency: three files (ProcessedImage, ImagePreprocessor,
  HybridFrameSpec+toProcessedImage) use its InputImage type
  unconditionally for the shared image-preprocessing pipeline. This
  isn't a version bump - it's already resolved transitively today at
  the same 17.3.0.
- Updated the README caveat that documented this exact limitation,
  since it's no longer true.

Verified locally (not just "it compiles"): with barcodeScanning:false,
com.google.mlkit:barcode-scanning is fully absent from the resolved
debugRuntimeClasspath; with textRecognition and all 4 language
variants false, com.google.mlkit:text-recognition is fully absent.
Full yarn test suite passes (93/93).

Author: pedrol2b

README.md

@@ -82,11 +82,11 @@ OCR languages you do not need to reduce binary size. Configuration keys for
 post-v2 roadmap features remain reserved and disabled; enabling one does not
 provide a public JS/Nitro API in v2.
 
-On Android, the Latin OCR and barcode base SDKs remain compile-time
-dependencies even when their feature flags are disabled because v2's native
-implementation references their API types. Those flags control runtime
-availability; the four optional OCR language modules are still omitted when
-disabled.
+Both `textRecognition` and `barcodeScanning` are fully optional at compile
+time on both platforms: disabling one removes its native SDK from the build
+entirely instead of only gating it at runtime, so consumers who only need
+barcode scanning (or only text recognition) do not pay for the other's
+dependencies or binary size.
 
 ### Android (Gradle)
 

android/build.gradle

@@ -166,7 +166,9 @@ android {
       java.srcDirs += [
         "generated/java",
         "generated/jni",
-        "../nitrogen/generated/android/kotlin/com/margelo/nitro/visioncameramlkit"
+        "../nitrogen/generated/android/kotlin/com/margelo/nitro/visioncameramlkit",
+        anyTextRecognition ? "src/textRecognitionEnabled/java" : "src/textRecognitionDisabled/java",
+        mlkitConfig.barcodeScanning ? "src/barcodeScanningEnabled/java" : "src/barcodeScanningDisabled/java",
       ]
     }
   }
@@ -188,14 +190,19 @@ dependencies {
   implementation "androidx.exifinterface:exifinterface:1.3.7"
 
   // ===== GoogleMLKit Vision =====
-  // Base SDKs for the two v2 features are compile-time dependencies because
-  // their public types are referenced by unconditional Kotlin sources. Feature
-  // flags still control runtime availability; optional OCR language models stay
-  // selective so consumers can trim those larger model artifacts.
+  // vision-common is always present: it's a small shared-types artifact (InputImage,
+  // etc.) used by the image-preprocessing pipeline regardless of which MLKit feature
+  // is enabled, and carries no OCR/barcode model weights. Every feature-specific SDK
+  // below stays properly gated behind its own flag and its own conditional Kotlin
+  // source set (see sourceSets above), so enabling only one feature (e.g. barcode
+  // scanning) does not pull in or compile against the others.
+  implementation "com.google.mlkit:vision-common:17.3.0"
 
   // Text recognition v2
   // https://developers.google.com/ml-kit/vision/text-recognition/v2/android
-  implementation "com.google.mlkit:text-recognition:16.0.1"
+  if (anyTextRecognition) {
+    implementation "com.google.mlkit:text-recognition:16.0.1"
+  }
   if (mlkitConfig.textRecognitionChinese) {
     implementation "com.google.mlkit:text-recognition-chinese:16.0.1"
   }
@@ -250,7 +257,9 @@ dependencies {
 
   // Barcode scanning
   // https://developers.google.com/ml-kit/vision/barcode-scanning/android
-  implementation "com.google.mlkit:barcode-scanning:17.3.0"
+  if (mlkitConfig.barcodeScanning) {
+    implementation "com.google.mlkit:barcode-scanning:17.3.0"
+  }
 
   // Image labeling (Base Model) -> Custom models will be added soon
   // https://developers.google.com/ml-kit/vision/image-labeling/android

android/src/barcodeScanningDisabled/java/com/visioncameramlkit/infrastructure/mlkit/factories/BarcodeScanningServiceFactory.kt

@@ -0,0 +1,14 @@
+package com.visioncameramlkit.infrastructure.mlkit.factories
+
+import com.visioncameramlkit.domain.models.BarcodeScanningOptions
+import com.visioncameramlkit.domain.models.BarcodeScanningResult
+import com.visioncameramlkit.domain.services.IRecognitionService
+
+object BarcodeScanningServiceFactory {
+  fun create(options: BarcodeScanningOptions = BarcodeScanningOptions()): IRecognitionService<BarcodeScanningResult> {
+    throw IllegalStateException(
+      "Barcode scanning is not enabled in this build. Enable barcodeScanning in your MLKit " +
+        "configuration to use this feature.",
+    )
+  }
+}

…ure/mlkit/MLKitBarcodeScanningService.kt …ure/mlkit/MLKitBarcodeScanningService.ktandroid/src/main/java/com/visioncameramlkit/infrastructure/mlkit/MLKitBarcodeScanningService.kt renamed to android/src/barcodeScanningEnabled/java/com/visioncameramlkit/infrastructure/mlkit/MLKitBarcodeScanningService.kt android/src/main/java/com/visioncameramlkit/infrastructure/mlkit/MLKitBarcodeScanningService.kt renamed to android/src/barcodeScanningEnabled/java/com/visioncameramlkit/infrastructure/mlkit/MLKitBarcodeScanningService.kt

@@ -0,0 +1,14 @@
+package com.visioncameramlkit.infrastructure.mlkit.factories
+
+import com.visioncameramlkit.domain.models.TextRecognitionLanguage
+import com.visioncameramlkit.domain.models.TextRecognitionResult
+import com.visioncameramlkit.domain.services.IRecognitionService
+
+object TextRecognitionServiceFactory {
+  fun create(language: TextRecognitionLanguage = TextRecognitionLanguage.LATIN): IRecognitionService<TextRecognitionResult> {
+    throw IllegalStateException(
+      "Text recognition is not enabled in this build. Enable textRecognition (or a language " +
+        "variant) in your MLKit configuration to use this feature.",
+    )
+  }
+}