add imagen deprecaton notice (#7988)

## Summary

This PR marks all classes and public methods starting with `Imagen` as
deprecated in the `ai-logic/firebase-ai` module. This is in preparation
for the planned shutdown of Imagen models in June 2026. Developers are
encouraged to migrate to Gemini Image models.

## Changes Made

### 1. Class-Level Deprecation
Added standard deprecation notices to the KDoc of all identified
`Imagen*` classes and interfaces. The notice reads:

> `@deprecated **Deprecation Notice:** All Imagen models are deprecated
and will shut down as early as June 2026. As a replacement, you can
[migrate your apps to use Gemini Image models (the 'Nano Banana'
models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)`

Updated files:
- `ImagenModel.kt`
- `ImagenEditMode.kt`
- `ImagenEditingConfig.kt`
- `ImagenImagePlacement.kt`
- `ImagenPersonFilterLevel.kt`
- `ImagenMaskMode.kt`
- `ImagenReferenceImage.kt`
- `ImagenMaskConfig.kt`
- `ImagenGCSImage.kt`
- `ImagenSubjectConfig.kt`
- `ImagenGenerationResponse.kt`
- `ImagenSubjectReferenceType.kt`
- `ImagenControlType.kt`
- `ImagenInlineImage.kt`
- `ImagenAspectRatio.kt`
- `ImagenImageFormat.kt`
- `ImagenGenerationConfig.kt`
- `ImagenSafetyFilterLevel.kt`
- `ImagenStyleConfig.kt`
- `ImagenSafetySettings.kt`
- `ImagenControlConfig.kt`
- `ImagenModelFutures.kt`
- `Request.kt` (Internal request classes `ImagenPrompt` and
`ImagenParameters`)

### 2. Method-Level Deprecation
Added the notice to public methods and helper functions within those
files to ensure developers are notified when using specific features:
- `ImagenInlineImage.kt` (`asBitmap`, `toImagenInlineImage`)
- `ImagenImagePlacement.kt` (`fromCoordinate`)
- `ImagenModelFutures.kt` (`generateImages`, `editImage`,
`inpaintImage`, `outpaintImage`, `getImageModel`, `from`)
- `ImagenImageFormat.kt` (`jpeg`, `png`)
- `ImagenGenerationConfig.kt` (`Builder` setters, `build`,
`imagenGenerationConfig`)
- `ImagenReferenceImage.kt` (`generateMaskAndPadForOutpainting`)

### 3. Verification
- Code formatted successfully with `./gradlew
:ai-logic:firebase-ai:spotlessApply`.

Author: VinayGuthal

ai-logic/firebase-ai/CHANGELOG.md

@@ -1,9 +1,11 @@
 # Unreleased
 
+- [deprecated] All Imagen models are deprecated and will shut down as early as June 2026.
+  As a replacement, you can [migrate your apps to use Gemini Image models (the "Nano Banana" models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration).
 - [feature] Added support for Chat interactions using server prompt templates (#7986)
 - [fixed] Fixed an issue causing network timeouts to throw the incorrect exception type, instead of
   `RequestTimeoutException` (#7966)
-- [fixed] Fixed missing `toString()` implemenation for `InferenceSource` (#7970)
+- [fixed] Fixed missing `toString()` implementation for `InferenceSource` (#7970)
 - [fixed] Fixed an issue causing the SDK to throw an exception if an unknown message was received
   from the LiveAPI model, instead of ignoring it (#7975)
 

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/ImagenModel.kt

@@ -44,7 +44,12 @@ import com.google.firebase.auth.internal.InternalAuthProvider
  *
  * See the documentation for a list of
  * [supported models](https://firebase.google.com/docs/ai-logic/models).
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
  */
+@Deprecated("All Imagen models are deprecated.")
 public class ImagenModel
 internal constructor(
   private val modelName: String,
@@ -86,7 +91,12 @@ internal constructor(
    * Generates an image, returning the result directly to the caller.
    *
    * @param prompt The input(s) given to the model as a prompt.
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public suspend fun generateImages(prompt: String): ImagenGenerationResponse<ImagenInlineImage> =
     try {
       controller
@@ -104,7 +114,12 @@ internal constructor(
    * @param referenceImages the image inputs given to the model as a prompt
    * @param prompt the text input given to the model as a prompt
    * @param config the editing configuration settings
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   @PublicPreviewAPI
   public suspend fun editImage(
     referenceImages: List<ImagenReferenceImage>,
@@ -129,7 +144,12 @@ internal constructor(
    * @param prompt the text input given to the model as a prompt
    * @param mask the mask which defines where in the image can be painted by Imagen.
    * @param config the editing configuration settings, it should include an [ImagenEditMode]
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   @PublicPreviewAPI
   public suspend fun inpaintImage(
     image: ImagenInlineImage,
@@ -154,7 +174,12 @@ internal constructor(
    * insufficient
    * @param config the editing configuration settings
    * @see [ImagenMaskReference.generateMaskAndPadForOutpainting]
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   @PublicPreviewAPI
   public suspend fun outpaintImage(
     image: ImagenInlineImage,

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/java/ImagenModelFutures.kt

@@ -33,14 +33,24 @@ import com.google.firebase.ai.type.PublicPreviewAPI
  * Wrapper class providing Java compatible methods for [ImagenModel].
  *
  * @see [ImagenModel]
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
  */
+@Deprecated("All Imagen models are deprecated.")
 @PublicPreviewAPI
 public abstract class ImagenModelFutures internal constructor() {
   /**
    * Generates an image, returning the result directly to the caller.
    *
    * @param prompt The main text prompt from which the image is generated.
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public abstract fun generateImages(
     prompt: String,
   ): ListenableFuture<ImagenGenerationResponse<ImagenInlineImage>>
@@ -52,7 +62,12 @@ public abstract class ImagenModelFutures internal constructor() {
    * @param prompt the text input given to the model as a prompt
    * @param referenceImages the image inputs given to the model as a prompt
    * @param config the editing configuration settings
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public abstract fun editImage(
     referenceImages: List<ImagenReferenceImage>,
     prompt: String,
@@ -65,7 +80,12 @@ public abstract class ImagenModelFutures internal constructor() {
    *
    * @param prompt the text input given to the model as a prompt
    * @param referenceImages the image inputs given to the model as a prompt
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public abstract fun editImage(
     referenceImages: List<ImagenReferenceImage>,
     prompt: String,
@@ -78,7 +98,12 @@ public abstract class ImagenModelFutures internal constructor() {
    * @param prompt the text input given to the model as a prompt
    * @param mask the mask which defines where in the image can be painted by imagen.
    * @param config the editing configuration settings, it should include an [ImagenEditMode]
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public abstract fun inpaintImage(
     image: ImagenInlineImage,
     prompt: String,
@@ -99,7 +124,12 @@ public abstract class ImagenModelFutures internal constructor() {
    * insufficient
    * @param config the editing configuration settings
    * @see [ImagenMaskReference.generateMaskAndPadForOutpainting]
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public abstract fun outpaintImage(
     image: ImagenInlineImage,
     newDimensions: Dimensions,
@@ -108,8 +138,14 @@ public abstract class ImagenModelFutures internal constructor() {
     config: ImagenEditingConfig? = null,
   ): ListenableFuture<ImagenGenerationResponse<ImagenInlineImage>>
 
-  /** Returns the [ImagenModel] object wrapped by this object. */
-  public abstract fun getImageModel(): ImagenModel
+  /**
+   * Returns the [ImagenModel] object wrapped by this object.
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+   */
+  @Deprecated("All Imagen models are deprecated.") public abstract fun getImageModel(): ImagenModel
 
   private class FuturesImpl(private val model: ImagenModel) : ImagenModelFutures() {
     override fun generateImages(
@@ -154,7 +190,15 @@ public abstract class ImagenModelFutures internal constructor() {
 
   public companion object {
 
-    /** @return a [ImagenModelFutures] created around the provided [ImagenModel] */
-    @JvmStatic public fun from(model: ImagenModel): ImagenModelFutures = FuturesImpl(model)
+    /**
+     * @return a [ImagenModelFutures] created around the provided [ImagenModel]
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+     */
+    @Deprecated("All Imagen models are deprecated.")
+    @JvmStatic
+    public fun from(model: ImagenModel): ImagenModelFutures = FuturesImpl(model)
   }
 }

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ImagenAspectRatio.kt

@@ -16,7 +16,14 @@
 
 package com.google.firebase.ai.type
 
-/** Represents the aspect ratio that the generated image should conform to. */
+/**
+ * Represents the aspect ratio that the generated image should conform to.
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+ */
+@Deprecated("All Imagen models are deprecated.")
 public class ImagenAspectRatio private constructor(internal val internalVal: String) {
   public companion object {
     /** A square image, useful for icons, profile pictures, etc. */

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ImagenControlType.kt

@@ -15,7 +15,14 @@
  */
 package com.google.firebase.ai.type
 
-/** Represents a control type for controlled Imagen generation/editing */
+/**
+ * Represents a control type for controlled Imagen generation/editing
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+ */
+@Deprecated("All Imagen models are deprecated.")
 public class ImagenControlType internal constructor(internal val value: String) {
   public companion object {
 

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ImagenEditMode.kt

@@ -15,7 +15,14 @@
  */
 package com.google.firebase.ai.type
 
-/** Represents the edit mode for Imagen */
+/**
+ * Represents the edit mode for Imagen
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+ */
+@Deprecated("All Imagen models are deprecated.")
 public class ImagenEditMode private constructor(internal val value: String) {
 
   public companion object {

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ImagenEditingConfig.kt

@@ -21,7 +21,12 @@ import kotlinx.serialization.Serializable
  * Contains the editing settings which are not specific to a reference image
  * @param editMode holds the editing mode if the request is for inpainting or outpainting
  * @param editSteps the number of intermediate steps to include in the editing process
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
  */
+@Deprecated("All Imagen models are deprecated.")
 @PublicPreviewAPI
 public class ImagenEditingConfig(
   internal val editMode: ImagenEditMode? = null,

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ImagenGenerationConfig.kt

@@ -25,9 +25,14 @@ package com.google.firebase.ai.type
  * @param aspectRatio The aspect ratio of the generated images.
  * @param imageFormat The file format/compression of the generated images.
  * @param addWatermark Adds an invisible watermark to mark the image as AI generated.
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
  */
 import kotlin.jvm.JvmField
 
+@Deprecated("All Imagen models are deprecated.")
 public class ImagenGenerationConfig(
   public val negativePrompt: String? = null,
   public val numberOfImages: Int? = 1,
@@ -40,35 +45,75 @@ public class ImagenGenerationConfig(
    *
    * This is mainly intended for Java interop. For Kotlin, use [imagenGenerationConfig] for a more
    * idiomatic experience.
+   *
+   * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+   * early as June 2026. As a replacement, you can
+   * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
    */
+  @Deprecated("All Imagen models are deprecated.")
   public class Builder {
     @JvmField public var negativePrompt: String? = null
     @JvmField public var numberOfImages: Int? = 1
     @JvmField public var aspectRatio: ImagenAspectRatio? = null
     @JvmField public var imageFormat: ImagenImageFormat? = null
     @JvmField public var addWatermark: Boolean? = null
 
-    /** See [ImagenGenerationConfig.negativePrompt]. */
+    /**
+     * See [ImagenGenerationConfig.negativePrompt].
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+     */
+    @Deprecated("All Imagen models are deprecated.")
     public fun setNegativePrompt(negativePrompt: String): Builder = apply {
       this.negativePrompt = negativePrompt
     }
 
-    /** See [ImagenGenerationConfig.numberOfImages]. */
+    /**
+     * See [ImagenGenerationConfig.numberOfImages].
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+     */
+    @Deprecated("All Imagen models are deprecated.")
     public fun setNumberOfImages(numberOfImages: Int): Builder = apply {
       this.numberOfImages = numberOfImages
     }
 
-    /** See [ImagenGenerationConfig.aspectRatio]. */
+    /**
+     * See [ImagenGenerationConfig.aspectRatio].
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+     */
+    @Deprecated("All Imagen models are deprecated.")
     public fun setAspectRatio(aspectRatio: ImagenAspectRatio): Builder = apply {
       this.aspectRatio = aspectRatio
     }
 
-    /** See [ImagenGenerationConfig.imageFormat]. */
+    /**
+     * See [ImagenGenerationConfig.imageFormat].
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+     */
+    @Deprecated("All Imagen models are deprecated.")
     public fun setImageFormat(imageFormat: ImagenImageFormat): Builder = apply {
       this.imageFormat = imageFormat
     }
 
-    /** See [ImagenGenerationConfig.addWatermark]. */
+    /**
+     * See [ImagenGenerationConfig.addWatermark].
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
+     */
+    @Deprecated("All Imagen models are deprecated.")
     public fun setAddWatermark(addWatermark: Boolean): Builder = apply {
       this.addWatermark = addWatermark
     }
@@ -78,7 +123,12 @@ public class ImagenGenerationConfig(
      * ```
      * val config = GenerationConfig.builder()
      * ```
+     *
+     * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as
+     * early as June 2026. As a replacement, you can
+     * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
      */
+    @Deprecated("All Imagen models are deprecated.")
     public fun build(): ImagenGenerationConfig =
       ImagenGenerationConfig(
         negativePrompt = negativePrompt,
@@ -107,7 +157,12 @@ public class ImagenGenerationConfig(
  *   addWatermark = false
  * }
  * ```
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
  */
+@Deprecated("All Imagen models are deprecated.")
 public fun imagenGenerationConfig(
   init: ImagenGenerationConfig.Builder.() -> Unit
 ): ImagenGenerationConfig {

ai-logic/firebase-ai/src/main/kotlin/com/google/firebase/ai/type/ImagenGenerationResponse.kt

@@ -26,7 +26,12 @@ import kotlinx.serialization.Serializable
  * @param images contains the generated images
  * @param filteredReason if fewer images were generated than were requested, this field will contain
  * the reason they were filtered out.
+ *
+ * @deprecated **Deprecation Notice:** All Imagen models are deprecated and will shut down as early
+ * as June 2026. As a replacement, you can
+ * [migrate your apps to use Gemini Image models (the 'Nano Banana' models)](https://firebase.google.com/docs/ai-logic/imagen-models-migration)
  */
+@Deprecated("All Imagen models are deprecated.")
 public class ImagenGenerationResponse<T>
 internal constructor(public val images: List<T>, public val filteredReason: String?) {