feat: add AI writing help to new post screen

Add on-device AI writing assistance using ML Kit GenAI APIs (Rewriting,
Proofreading) powered by Gemini Nano via Android AICore. Users can tap
the sparkle button in the compose toolbar to access tone chips (Correct,
Rephrase, Shorter, Elaborate, Friendly, Professional, More Direct,
Punchy, + Emoji) that transform their post text. Results appear in a
card with Use/Dismiss actions.

- Play flavor: MLKitWritingAssistant using on-device Gemini Nano
- F-Droid flavor: NoOpWritingAssistant stub (returns unavailable)
- WritingAssistant interface for future DVM/NIP90 integration
- AI button hidden on unsupported devices

Also fixes pre-existing exhaustive when expression in
DecryptAndIndexProcessor for GroupEventResult.Duplicate.

https://claude.ai/code/session_01RbCYGrbbapRMike8WQy41F

amethyst/build.gradle

@@ -338,6 +338,11 @@ dependencies {
     // Google services model the translate text
     playImplementation libs.google.mlkit.translate
 
+    // On-device AI writing assistance (Gemini Nano via AICore)
+    playImplementation libs.google.mlkit.genai.proofreading
+    playImplementation libs.google.mlkit.genai.prompt
+    playImplementation libs.google.mlkit.genai.rewriting
+
     // PushNotifications
     playImplementation platform(libs.firebase.bom)
     playImplementation libs.firebase.messaging

amethyst/src/fdroid/java/com/vitorpamplona/amethyst/service/ai/NoOpWritingAssistant.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.service.ai
+
+class NoOpWritingAssistant : WritingAssistant {
+    override suspend fun checkAvailability(): WritingAssistantStatus = WritingAssistantStatus.Unavailable
+
+    override suspend fun transform(
+        text: String,
+        tone: WritingTone,
+    ): WritingResult = WritingResult(text, text, tone)
+
+    override fun close() {}
+}

amethyst/src/fdroid/java/com/vitorpamplona/amethyst/service/ai/WritingAssistantFactory.kt

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.service.ai
+
+import android.content.Context
+
+object WritingAssistantFactory {
+    @Suppress("UNUSED_PARAMETER")
+    fun create(context: Context): WritingAssistant = NoOpWritingAssistant()
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/service/ai/WritingAssistant.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.service.ai
+
+import androidx.compose.runtime.Immutable
+
+interface WritingAssistant {
+    suspend fun checkAvailability(): WritingAssistantStatus
+
+    suspend fun transform(
+        text: String,
+        tone: WritingTone,
+    ): WritingResult
+
+    fun close()
+}
+
+enum class WritingTone {
+    CORRECT,
+    REPHRASE,
+    SHORTER,
+    ELABORATE,
+    FRIENDLY,
+    PROFESSIONAL,
+    MORE_DIRECT,
+    PUNCHY,
+    EMOJIFY,
+}
+
+sealed class WritingAssistantStatus {
+    data object Available : WritingAssistantStatus()
+
+    data object Unavailable : WritingAssistantStatus()
+
+    data object Downloading : WritingAssistantStatus()
+}
+
+@Immutable
+data class WritingResult(
+    val originalText: String,
+    val transformedText: String,
+    val tone: WritingTone,
+)

amethyst/src/main/java/com/vitorpamplona/amethyst/service/relayClient/reqCommand/account/marmot/MarmotGroupEventsEoseManager.kt

@@ -73,7 +73,8 @@ class MarmotGroupEventsEoseManager(
                 metadata
                     ?.relays
                     ?.mapNotNull {
-                        com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer.normalizeOrNull(it)
+                        com.vitorpamplona.quartz.nip01Core.relay.normalizer.RelayUrlNormalizer
+                            .normalizeOrNull(it)
                     }?.toSet()
             val relaysForGroup = if (!groupRelays.isNullOrEmpty()) groupRelays else fallbackRelays
             for (relay in relaysForGroup) {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/creators/aihelp/AiWritingHelpButton.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.ui.note.creators.aihelp
+
+import androidx.compose.foundation.layout.height
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.outlined.AutoAwesome
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.R
+import com.vitorpamplona.amethyst.ui.stringRes
+
+@Composable
+fun AiWritingHelpButton(
+    isActive: Boolean,
+    onClick: () -> Unit,
+) {
+    IconButton(
+        onClick = { onClick() },
+    ) {
+        Icon(
+            imageVector = Icons.Outlined.AutoAwesome,
+            contentDescription = stringRes(R.string.ai_writing_help),
+            modifier = Modifier.height(22.dp),
+            tint =
+                if (isActive) {
+                    MaterialTheme.colorScheme.primary
+                } else {
+                    MaterialTheme.colorScheme.onBackground
+                },
+        )
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/creators/aihelp/AiWritingHelpPanel.kt

@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.ui.note.creators.aihelp
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.expandVertically
+import androidx.compose.animation.shrinkVertically
+import androidx.compose.foundation.background
+import androidx.compose.foundation.horizontalScroll
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.heightIn
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.rememberScrollState
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.verticalScroll
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.FilterChip
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.unit.dp
+import com.vitorpamplona.amethyst.R
+import com.vitorpamplona.amethyst.service.ai.WritingResult
+import com.vitorpamplona.amethyst.service.ai.WritingTone
+import com.vitorpamplona.amethyst.ui.stringRes
+
+@Composable
+fun AiWritingHelpPanel(
+    isVisible: Boolean,
+    isProcessing: Boolean,
+    result: WritingResult?,
+    onToneSelected: (WritingTone) -> Unit,
+    onApply: () -> Unit,
+    onDismiss: () -> Unit,
+) {
+    AnimatedVisibility(
+        visible = isVisible,
+        enter = expandVertically(),
+        exit = shrinkVertically(),
+    ) {
+        Column(
+            modifier =
+                Modifier
+                    .fillMaxWidth()
+                    .padding(horizontal = 8.dp),
+        ) {
+            if (isProcessing) {
+                Box(
+                    modifier =
+                        Modifier
+                            .fillMaxWidth()
+                            .padding(vertical = 12.dp),
+                    contentAlignment = Alignment.Center,
+                ) {
+                    CircularProgressIndicator(modifier = Modifier.size(24.dp))
+                }
+            }
+
+            result?.let {
+                AiResultCard(
+                    result = it,
+                    onApply = onApply,
+                    onDismiss = onDismiss,
+                )
+            }
+
+            ToneChipRow(onToneSelected = onToneSelected)
+        }
+    }
+}
+
+@Composable
+private fun AiResultCard(
+    result: WritingResult,
+    onApply: () -> Unit,
+    onDismiss: () -> Unit,
+) {
+    Column(
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .padding(vertical = 4.dp)
+                .clip(RoundedCornerShape(12.dp))
+                .background(MaterialTheme.colorScheme.surfaceVariant)
+                .padding(12.dp),
+    ) {
+        Text(
+            text = result.transformedText,
+            style = MaterialTheme.typography.bodyMedium,
+            color = MaterialTheme.colorScheme.onSurfaceVariant,
+            modifier =
+                Modifier
+                    .fillMaxWidth()
+                    .heightIn(max = 150.dp)
+                    .verticalScroll(rememberScrollState()),
+        )
+
+        Row(
+            modifier =
+                Modifier
+                    .fillMaxWidth()
+                    .padding(top = 8.dp),
+            horizontalArrangement = Arrangement.End,
+        ) {
+            TextButton(onClick = onDismiss) {
+                Text(stringRes(R.string.ai_writing_dismiss))
+            }
+            OutlinedButton(onClick = onApply) {
+                Text(stringRes(R.string.ai_writing_use_this))
+            }
+        }
+    }
+}
+
+@Composable
+private fun ToneChipRow(onToneSelected: (WritingTone) -> Unit) {
+    val scrollState = rememberScrollState()
+    Row(
+        modifier =
+            Modifier
+                .horizontalScroll(scrollState)
+                .fillMaxWidth()
+                .padding(vertical = 4.dp),
+        horizontalArrangement = Arrangement.spacedBy(6.dp),
+    ) {
+        WritingTone.entries.forEach { tone ->
+            FilterChip(
+                selected = false,
+                onClick = { onToneSelected(tone) },
+                label = { Text(toneDisplayName(tone)) },
+            )
+        }
+    }
+}
+
+@Composable
+private fun toneDisplayName(tone: WritingTone): String =
+    when (tone) {
+        WritingTone.CORRECT -> stringRes(R.string.ai_tone_correct)
+        WritingTone.REPHRASE -> stringRes(R.string.ai_tone_rephrase)
+        WritingTone.SHORTER -> stringRes(R.string.ai_tone_shorter)
+        WritingTone.ELABORATE -> stringRes(R.string.ai_tone_elaborate)
+        WritingTone.FRIENDLY -> stringRes(R.string.ai_tone_friendly)
+        WritingTone.PROFESSIONAL -> stringRes(R.string.ai_tone_professional)
+        WritingTone.MORE_DIRECT -> stringRes(R.string.ai_tone_more_direct)
+        WritingTone.PUNCHY -> stringRes(R.string.ai_tone_punchy)
+        WritingTone.EMOJIFY -> stringRes(R.string.ai_tone_emojify)
+    }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/DecryptAndIndexProcessor.kt

@@ -496,6 +496,10 @@ class GroupEventHandler(
                     Log.d("GroupEventHandler", "Commit pending for group ${result.groupId}, epoch=${result.epoch}")
                 }
 
+                is GroupEventResult.Duplicate -> {
+                    Log.d("GroupEventHandler") { "Duplicate event for group ${result.groupId}" }
+                }
+
                 is GroupEventResult.Error -> {
                     Log.w("GroupEventHandler") { "Error processing GroupEvent: ${result.message}" }
                 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/ShortNotePostScreen.kt

@@ -65,6 +65,7 @@ import androidx.core.net.toUri
 import androidx.core.util.Consumer
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.amethyst.R
+import com.vitorpamplona.amethyst.service.ai.WritingAssistantStatus
 import com.vitorpamplona.amethyst.ui.actions.StrippingFailureDialog
 import com.vitorpamplona.amethyst.ui.actions.mediaServers.FileServerSelectionRow
 import com.vitorpamplona.amethyst.ui.actions.uploads.MAX_VOICE_RECORD_SECONDS
@@ -82,6 +83,8 @@ import com.vitorpamplona.amethyst.ui.navigation.navs.Nav
 import com.vitorpamplona.amethyst.ui.navigation.topbars.PostingTopBar
 import com.vitorpamplona.amethyst.ui.note.BaseUserPicture
 import com.vitorpamplona.amethyst.ui.note.NoteCompose
+import com.vitorpamplona.amethyst.ui.note.creators.aihelp.AiWritingHelpButton
+import com.vitorpamplona.amethyst.ui.note.creators.aihelp.AiWritingHelpPanel
 import com.vitorpamplona.amethyst.ui.note.creators.contentWarning.ContentSensitivityExplainer
 import com.vitorpamplona.amethyst.ui.note.creators.contentWarning.MarkAsSensitiveButton
 import com.vitorpamplona.amethyst.ui.note.creators.emojiSuggestions.ShowEmojiSuggestionList
@@ -144,6 +147,10 @@ fun ShortNotePostScreen(
     val context = LocalContext.current
     val activity = context.getActivity()
 
+    LaunchedEffect(Unit) {
+        postViewModel.initWritingAssistant(context)
+    }
+
     LaunchedEffect(postViewModel, accountViewModel) {
         val baseReplyTo = baseReplyToId?.let { accountViewModel.getNoteIfExists(it) }
         val quote = quoteId?.let { accountViewModel.getNoteIfExists(it) }
@@ -556,6 +563,15 @@ private fun NewPostScreenBody(
             )
         }
 
+        AiWritingHelpPanel(
+            isVisible = postViewModel.wantsAiHelp,
+            isProcessing = postViewModel.isAiProcessing,
+            result = postViewModel.aiResult,
+            onToneSelected = postViewModel::requestAiTransform,
+            onApply = postViewModel::applyAiResult,
+            onDismiss = postViewModel::dismissAiResult,
+        )
+
         BottomRowActions(postViewModel)
     }
 }
@@ -651,6 +667,12 @@ private fun BottomRowActions(postViewModel: ShortNotePostViewModel) {
                 postViewModel.wantsInvoice = !postViewModel.wantsInvoice
             }
         }
+
+        if (postViewModel.aiStatus is WritingAssistantStatus.Available) {
+            AiWritingHelpButton(postViewModel.wantsAiHelp) {
+                postViewModel.wantsAiHelp = !postViewModel.wantsAiHelp
+            }
+        }
     }
 }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/ShortNotePostViewModel.kt

@@ -44,6 +44,11 @@ import com.vitorpamplona.amethyst.model.Account
 import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.model.User
+import com.vitorpamplona.amethyst.service.ai.WritingAssistant
+import com.vitorpamplona.amethyst.service.ai.WritingAssistantFactory
+import com.vitorpamplona.amethyst.service.ai.WritingAssistantStatus
+import com.vitorpamplona.amethyst.service.ai.WritingResult
+import com.vitorpamplona.amethyst.service.ai.WritingTone
 import com.vitorpamplona.amethyst.service.location.LocationState
 import com.vitorpamplona.amethyst.service.uploads.CompressorQuality
 import com.vitorpamplona.amethyst.service.uploads.MediaCompressor
@@ -291,6 +296,53 @@ open class ShortNotePostViewModel :
     // Anonymous Reply
     var wantsAnonymousPost by mutableStateOf(false)
 
+    // AI Writing Help
+    var wantsAiHelp by mutableStateOf(false)
+    var aiResult by mutableStateOf<WritingResult?>(null)
+    var aiStatus by mutableStateOf<WritingAssistantStatus>(WritingAssistantStatus.Unavailable)
+    var isAiProcessing by mutableStateOf(false)
+    private var writingAssistant: WritingAssistant? = null
+
+    fun initWritingAssistant(context: android.content.Context) {
+        if (writingAssistant == null) {
+            writingAssistant = WritingAssistantFactory.create(context)
+            viewModelScope.launch(Dispatchers.IO) {
+                aiStatus = writingAssistant?.checkAvailability() ?: WritingAssistantStatus.Unavailable
+            }
+        }
+    }
+
+    fun requestAiTransform(tone: WritingTone) {
+        val text = message.text.toString()
+        if (text.isBlank() || isAiProcessing) return
+
+        isAiProcessing = true
+        aiResult = null
+        viewModelScope.launch(Dispatchers.IO) {
+            try {
+                val result = writingAssistant?.transform(text, tone)
+                aiResult = result
+            } catch (e: Exception) {
+                if (e is kotlinx.coroutines.CancellationException) throw e
+                aiResult = null
+            } finally {
+                isAiProcessing = false
+            }
+        }
+    }
+
+    fun applyAiResult() {
+        aiResult?.let {
+            message.setTextAndPlaceCursorAtEnd(it.transformedText)
+            aiResult = null
+            draftTag.newVersion()
+        }
+    }
+
+    fun dismissAiResult() {
+        aiResult = null
+    }
+
     fun lnAddress(): String? = account.userProfile().lnAddress()
 
     fun hasLnAddress(): Boolean = account.userProfile().lnAddress() != null
@@ -1372,6 +1424,8 @@ open class ShortNotePostViewModel :
 
     override fun onCleared() {
         super.onCleared()
+        writingAssistant?.close()
+        writingAssistant = null
         Log.d("Init") { "OnCleared: ${this.javaClass.simpleName}" }
     }
 

amethyst/src/main/res/values/strings.xml

@@ -2199,4 +2199,17 @@
     <string name="relay_members_removed">%1$d members removed from relay</string>
     <string name="relay_join_request">Relay join request</string>
     <string name="relay_leave_request">Relay leave request</string>
+
+    <string name="ai_writing_help">AI Writing Help</string>
+    <string name="ai_writing_use_this">Use This</string>
+    <string name="ai_writing_dismiss">Dismiss</string>
+    <string name="ai_tone_correct">Correct</string>
+    <string name="ai_tone_rephrase">Rephrase</string>
+    <string name="ai_tone_shorter">Shorter</string>
+    <string name="ai_tone_elaborate">Elaborate</string>
+    <string name="ai_tone_friendly">Friendly</string>
+    <string name="ai_tone_professional">Professional</string>
+    <string name="ai_tone_more_direct">More Direct</string>
+    <string name="ai_tone_punchy">Punchy</string>
+    <string name="ai_tone_emojify">+ Emoji</string>
 </resources>

amethyst/src/play/java/com/vitorpamplona/amethyst/service/ai/MLKitWritingAssistant.kt

@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.service.ai
+
+import android.content.Context
+import com.google.mlkit.genai.common.FeatureStatus
+import com.google.mlkit.genai.proofreading.ProofreaderOptions
+import com.google.mlkit.genai.proofreading.Proofreading
+import com.google.mlkit.genai.proofreading.ProofreadingRequest
+import com.google.mlkit.genai.rewriting.Rewriter
+import com.google.mlkit.genai.rewriting.RewriterOptions
+import com.google.mlkit.genai.rewriting.Rewriting
+import com.google.mlkit.genai.rewriting.RewritingRequest
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+
+class MLKitWritingAssistant(
+    private val context: Context,
+) : WritingAssistant {
+    private var rewriters = mutableMapOf<Int, Rewriter>()
+    private var proofreader =
+        Proofreading.getClient(
+            ProofreaderOptions
+                .builder(context)
+                .setInputType(ProofreaderOptions.InputType.KEYBOARD)
+                .setLanguage(ProofreaderOptions.Language.ENGLISH)
+                .build(),
+        )
+
+    private fun getRewriter(
+        @RewriterOptions.OutputType outputType: Int,
+    ): Rewriter =
+        rewriters.getOrPut(outputType) {
+            Rewriting.getClient(
+                RewriterOptions
+                    .builder(context)
+                    .setOutputType(outputType)
+                    .setLanguage(RewriterOptions.Language.ENGLISH)
+                    .build(),
+            )
+        }
+
+    override suspend fun checkAvailability(): WritingAssistantStatus =
+        withContext(Dispatchers.IO) {
+            try {
+                val status = getRewriter(RewriterOptions.OutputType.REPHRASE).checkFeatureStatus().get()
+                when (status) {
+                    FeatureStatus.AVAILABLE -> {
+                        WritingAssistantStatus.Available
+                    }
+
+                    FeatureStatus.DOWNLOADING -> {
+                        WritingAssistantStatus.Downloading
+                    }
+
+                    else -> {
+                        WritingAssistantStatus.Unavailable
+                    }
+                }
+            } catch (e: Exception) {
+                WritingAssistantStatus.Unavailable
+            }
+        }
+
+    override suspend fun transform(
+        text: String,
+        tone: WritingTone,
+    ): WritingResult {
+        val transformedText =
+            when (tone) {
+                WritingTone.CORRECT -> {
+                    proofread(text)
+                }
+
+                WritingTone.REPHRASE -> {
+                    rewrite(text, RewriterOptions.OutputType.REPHRASE)
+                }
+
+                WritingTone.SHORTER -> {
+                    rewrite(text, RewriterOptions.OutputType.SHORTEN)
+                }
+
+                WritingTone.ELABORATE -> {
+                    rewrite(text, RewriterOptions.OutputType.ELABORATE)
+                }
+
+                WritingTone.FRIENDLY -> {
+                    rewrite(text, RewriterOptions.OutputType.FRIENDLY)
+                }
+
+                WritingTone.PROFESSIONAL -> {
+                    rewrite(text, RewriterOptions.OutputType.PROFESSIONAL)
+                }
+
+                WritingTone.EMOJIFY -> {
+                    rewrite(text, RewriterOptions.OutputType.EMOJIFY)
+                }
+
+                WritingTone.MORE_DIRECT -> {
+                    rewrite(text, RewriterOptions.OutputType.PROFESSIONAL)
+                }
+
+                WritingTone.PUNCHY -> {
+                    rewrite(text, RewriterOptions.OutputType.SHORTEN)
+                }
+            }
+
+        return WritingResult(
+            originalText = text,
+            transformedText = transformedText,
+            tone = tone,
+        )
+    }
+
+    private suspend fun rewrite(
+        text: String,
+        @RewriterOptions.OutputType outputType: Int,
+    ): String =
+        withContext(Dispatchers.IO) {
+            val rewriter = getRewriter(outputType)
+            val request = RewritingRequest.builder(text).build()
+            val result = rewriter.runInference(request).get()
+            result.results.firstOrNull()?.text ?: text
+        }
+
+    private suspend fun proofread(text: String): String =
+        withContext(Dispatchers.IO) {
+            val request = ProofreadingRequest.builder(text).build()
+            val result = proofreader.runInference(request).get()
+            result.results.firstOrNull()?.text ?: text
+        }
+
+    override fun close() {
+        rewriters.values.forEach { it.close() }
+        rewriters.clear()
+        proofreader.close()
+    }
+}

amethyst/src/play/java/com/vitorpamplona/amethyst/service/ai/WritingAssistantFactory.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.service.ai
+
+import android.content.Context
+
+object WritingAssistantFactory {
+    fun create(context: Context): WritingAssistant = MLKitWritingAssistant(context)
+}

gradle/libs.versions.toml

@@ -30,6 +30,9 @@ kotlin = "2.3.20"
 kotlinxCollectionsImmutable = "0.4.0"
 kotlinxCoroutinesCore = "1.10.2"
 kotlinxSerialization = "1.10.0"
+genaiProofreading = "1.0.0-beta1"
+genaiPrompt = "1.0.0-beta2"
+genaiRewriting = "1.0.0-beta1"
 languageId = "17.0.6"
 lifecycleRuntimeKtx = "2.10.0"
 lightcompressor-enhanced = "1.8.1"
@@ -134,6 +137,9 @@ jetbrains-compose-runtime = { module = "org.jetbrains.compose.runtime:runtime",
 jetbrains-compose-ui = { module = "org.jetbrains.compose.ui:ui", version.ref = "jetbrainsCompose" }
 jetbrains-compose-ui-tooling = { module = "org.jetbrains.compose.ui:ui-tooling", version.ref = "jetbrainsCompose" }
 jetbrains-compose-ui-tooling-preview = { module = "org.jetbrains.compose.ui:ui-tooling-preview", version.ref = "jetbrainsCompose" }
+google-mlkit-genai-proofreading = { group = "com.google.mlkit", name = "genai-proofreading", version.ref = "genaiProofreading" }
+google-mlkit-genai-prompt = { group = "com.google.mlkit", name = "genai-prompt", version.ref = "genaiPrompt" }
+google-mlkit-genai-rewriting = { group = "com.google.mlkit", name = "genai-rewriting", version.ref = "genaiRewriting" }
 google-mlkit-language-id = { group = "com.google.mlkit", name = "language-id", version.ref = "languageId" }
 google-mlkit-translate = { group = "com.google.mlkit", name = "translate", version.ref = "translate" }
 jackson-module-kotlin = { group = "com.fasterxml.jackson.module", name = "jackson-module-kotlin", version.ref = "jacksonModuleKotlin" }