Respect incognito keyboard setting in Compose UIs.

core-ui/src/main/java/org/signal/core/ui/compose/BottomSheets.kt

@@ -16,7 +16,6 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
-import org.signal.core.ui.compose.theme.SignalTheme
 
 object BottomSheets {
   /**
@@ -37,7 +36,7 @@ object BottomSheets {
 @Preview
 @Composable
 private fun HandlePreview() {
-  SignalTheme(isDarkMode = false) {
+  Previews.Preview {
     BottomSheets.Handle()
   }
 }

core-ui/src/main/java/org/signal/core/ui/compose/Buttons.kt

@@ -231,7 +231,10 @@ private fun SampleBox(
   darkMode: Boolean,
   content: @Composable BoxScope.() -> Unit
 ) {
-  SignalTheme(isDarkMode = darkMode) {
+  SignalTheme(
+    isDarkMode = darkMode,
+    incognitoKeyboardEnabled = false
+  ) {
     Surface {
       Box(modifier = Modifier.padding(8.dp)) {
         content()

core-ui/src/main/java/org/signal/core/ui/compose/Dividers.kt

@@ -18,7 +18,6 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
-import org.signal.core.ui.compose.theme.SignalTheme
 
 /**
  * Thin divider lines for separating content.
@@ -55,7 +54,7 @@ object Dividers {
 @DayNightPreviews
 @Composable
 private fun DefaultPreview() {
-  SignalTheme {
+  Previews.Preview {
     Dividers.Default()
   }
 }
@@ -63,7 +62,7 @@ private fun DefaultPreview() {
 @DayNightPreviews
 @Composable
 private fun VerticalPreview() {
-  SignalTheme {
+  Previews.Preview {
     Dividers.Vertical(modifier = Modifier.height(20.dp))
   }
 }

core-ui/src/main/java/org/signal/core/ui/compose/Previews.kt

@@ -24,7 +24,9 @@ object Previews {
     val dir = if (forceRtl) LayoutDirection.Rtl else LocalLayoutDirection.current
 
     CompositionLocalProvider(LocalLayoutDirection provides dir) {
-      SignalTheme {
+      SignalTheme(
+        incognitoKeyboardEnabled = false
+      ) {
         Surface {
           content()
         }
@@ -40,7 +42,7 @@ object Previews {
     val dir = if (forceRtl) LayoutDirection.Rtl else LocalLayoutDirection.current
 
     CompositionLocalProvider(LocalLayoutDirection provides dir) {
-      SignalTheme {
+      SignalTheme(incognitoKeyboardEnabled = false) {
         Surface {
           Box(modifier = Modifier.background(color = SignalTheme.colors.colorSurface1)) {
             content()

core-ui/src/main/java/org/signal/core/ui/compose/ProvideIncognitoKeyboard.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2025 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.signal.core.ui.compose
+
+import android.os.Build
+import android.view.inputmethod.EditorInfo
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.platform.InterceptPlatformTextInput
+import androidx.compose.ui.platform.PlatformTextInputMethodRequest
+
+/**
+ * When [enabled]=true, this function sets the [EditorInfo.IME_FLAG_NO_PERSONALIZED_LEARNING] flag for all text fields within its content to enable the
+ * incognito keyboard.
+ *
+ * This workaround is needed until it's possible to configure granular IME options for a [androidx.compose.material3.TextField].
+ * https://issuetracker.google.com/issues/359257538
+ */
+@OptIn(ExperimentalComposeUiApi::class)
+@Composable
+fun ProvideIncognitoKeyboard(
+  enabled: Boolean,
+  content: @Composable () -> Unit
+) {
+  if (enabled) {
+    InterceptPlatformTextInput(
+      interceptor = { request, nextHandler ->
+        val modifiedRequest = PlatformTextInputMethodRequest { outAttributes ->
+          request.createInputConnection(outAttributes).also {
+            if (Build.VERSION.SDK_INT >= 26) {
+              outAttributes.imeOptions = outAttributes.imeOptions or EditorInfo.IME_FLAG_NO_PERSONALIZED_LEARNING
+            }
+          }
+        }
+        nextHandler.startInputMethod(modifiedRequest)
+      }
+    ) {
+      content()
+    }
+  } else {
+    content()
+  }
+}

core-ui/src/main/java/org/signal/core/ui/compose/Scaffolds.kt

@@ -113,7 +113,7 @@ object Scaffolds {
 @DayNightPreviews
 @Composable
 private fun SettingsScaffoldPreview() {
-  SignalTheme {
+  Previews.Preview {
     val vector = remember {
       ImageVector.Builder(
         defaultWidth = 24.dp,
@@ -148,7 +148,7 @@ private fun SettingsScaffoldPreview() {
 @DayNightPreviews
 @Composable
 private fun SettingsScaffoldNoNavIconPreview() {
-  SignalTheme {
+  Previews.Preview {
     Scaffolds.Settings(
       "Settings Scaffold",
       onNavigationClick = {},

core-ui/src/main/java/org/signal/core/ui/compose/Snackbars.kt

@@ -14,7 +14,6 @@ import androidx.compose.material3.SnackbarVisuals
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import org.signal.core.ui.compose.theme.LocalSnackbarColors
-import org.signal.core.ui.compose.theme.SignalTheme
 
 /**
  * Properly themed Snackbars. Since these use internal color state, we need to
@@ -46,7 +45,7 @@ object Snackbars {
 @DayNightPreviews
 @Composable
 private fun SnackbarPreview() {
-  SignalTheme {
+  Previews.Preview {
     Snackbars.Default(snackbarData = SampleSnackbarData)
   }
 }

core-ui/src/main/java/org/signal/core/ui/compose/Texts.kt

@@ -22,7 +22,6 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.core.text.getSpans
 import org.signal.core.ui.R
-import org.signal.core.ui.compose.theme.SignalTheme
 
 object Texts {
   /**
@@ -85,7 +84,7 @@ object Texts {
 @Preview
 @Composable
 private fun SectionHeaderPreview() {
-  SignalTheme(isDarkMode = false) {
+  Previews.Preview {
     Texts.SectionHeader("Header")
   }
 }

core-ui/src/main/java/org/signal/core/ui/compose/theme/SignalTheme.kt

@@ -1,6 +1,7 @@
 package org.signal.core.ui.compose.theme
 
 import android.content.res.Configuration
+import androidx.annotation.Discouraged
 import androidx.compose.foundation.layout.Column
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
@@ -15,6 +16,7 @@ import androidx.compose.ui.text.font.FontFamily
 import androidx.compose.ui.text.font.FontStyle
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.sp
+import org.signal.core.ui.compose.ProvideIncognitoKeyboard
 
 private val typography = Typography().run {
   copy(
@@ -184,27 +186,34 @@ private val darkSnackbarColors = SnackbarColors(
   dismissActionContentColor = darkColorScheme.onSurfaceVariant
 )
 
+@Discouraged("Use org.thoughtcrime.securesms.compose.SignalTheme instead.")
 @Composable
 fun SignalTheme(
   isDarkMode: Boolean = LocalConfiguration.current.uiMode and Configuration.UI_MODE_NIGHT_MASK == Configuration.UI_MODE_NIGHT_YES,
+  incognitoKeyboardEnabled: Boolean,
   content: @Composable () -> Unit
 ) {
   val extendedColors = if (isDarkMode) darkExtendedColors else lightExtendedColors
   val snackbarColors = if (isDarkMode) darkSnackbarColors else lightSnackbarColors
 
-  CompositionLocalProvider(LocalExtendedColors provides extendedColors, LocalSnackbarColors provides snackbarColors) {
-    MaterialTheme(
-      colorScheme = if (isDarkMode) darkColorScheme else lightColorScheme,
-      typography = typography,
-      content = content
-    )
+  ProvideIncognitoKeyboard(enabled = incognitoKeyboardEnabled) {
+    CompositionLocalProvider(LocalExtendedColors provides extendedColors, LocalSnackbarColors provides snackbarColors) {
+      MaterialTheme(
+        colorScheme = if (isDarkMode) darkColorScheme else lightColorScheme,
+        typography = typography,
+        content = content
+      )
+    }
   }
 }
 
 @Preview(showBackground = true)
 @Composable
 private fun TypographyPreview() {
-  SignalTheme(isDarkMode = false) {
+  SignalTheme(
+    isDarkMode = false,
+    incognitoKeyboardEnabled = false
+  ) {
     Column {
       Text(
         text = "Headline Small",
@@ -258,6 +267,7 @@ private fun TypographyPreview() {
   }
 }
 
+@Discouraged("Use org.thoughtcrime.securesms.compose.SignalTheme instead.")
 object SignalTheme {
   val colors: ExtendedColors
     @Composable