Merge pull request #3610 from vitorpamplona/claude/save-button-switcher-colors-7vnmm5

Fix onPrimary contrast and add color scheme preview tool

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/nests/create/CreateNestSheet.kt

@@ -38,6 +38,7 @@ import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.ModalBottomSheet
 import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Switch
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.material3.rememberModalBottomSheetState
@@ -170,7 +171,7 @@ fun CreateNestSheet(
                 modifier = Modifier.fillMaxWidth(),
                 verticalAlignment = androidx.compose.ui.Alignment.CenterVertically,
             ) {
-                androidx.compose.material3.Switch(
+                Switch(
                     checked = state.scheduled,
                     onCheckedChange = viewModel::onScheduledToggle,
                 )

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/theme/ColorSchemePreview.kt

@@ -0,0 +1,239 @@
+/*
+ * 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.theme
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+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.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.ColorScheme
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+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.graphics.Color
+import androidx.compose.ui.graphics.luminance
+import androidx.compose.ui.graphics.toArgb
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import kotlin.math.max
+import kotlin.math.min
+
+// Living reference of every foreground/background pair the mobile theme uses, listed by its
+// ColorScheme role name and rendered with the real AmethystTheme colors (dark | light). Each row
+// previews the foreground on its background, the live WCAG contrast, the two hexes, and the app
+// surfaces that consume the pair. Reads the live scheme, so editing Theme.kt re-renders it.
+
+private class RolePair(
+    val name: String,
+    val bg: (ColorScheme) -> Color,
+    val fg: (ColorScheme) -> Color,
+    val usage: String,
+    val highlight: Boolean = false,
+)
+
+private val ROLE_PAIRS =
+    listOf(
+        RolePair(
+            "primary / onPrimary",
+            { it.primary },
+            { it.onPrimary },
+            "Top-bar Save button, FABs, filled buttons, checked switch, sliders, progress.",
+            highlight = true,
+        ),
+        RolePair(
+            "primaryContainer / onPrimaryContainer",
+            { it.primaryContainer },
+            { it.onPrimaryContainer },
+            "Settings icon tiles, tonal cards, tonal chips.",
+        ),
+        RolePair(
+            "secondaryContainer / onSecondaryContainer",
+            { it.secondaryContainer },
+            { it.onSecondaryContainer },
+            "Selected-reaction highlight, relay-group chips, chat header, reply toggle.",
+        ),
+        RolePair(
+            "secondary / onSecondary",
+            { it.secondary },
+            { it.onSecondary },
+            "Teal accent (purple theme); tertiary mirrors it.",
+        ),
+        RolePair(
+            "tertiaryContainer / onTertiaryContainer",
+            { it.tertiaryContainer },
+            { it.onTertiaryContainer },
+            "Tertiary tonal surfaces; derived from the accent.",
+        ),
+        RolePair(
+            "error / onError",
+            { it.error },
+            { it.onError },
+            "Destructive dialogs and error states. Material baseline.",
+        ),
+        RolePair(
+            "surface / onSurface",
+            { it.surface },
+            { it.onSurface },
+            "App background and primary body text.",
+        ),
+        RolePair(
+            "surface / onSurfaceVariant",
+            { it.surface },
+            { it.onSurfaceVariant },
+            "Secondary text, timestamps, subtitles, icons.",
+        ),
+        RolePair(
+            "surfaceContainer / onSurface",
+            { it.surfaceContainer },
+            { it.onSurface },
+            "Cards, bottom sheets, elevated rows.",
+        ),
+        RolePair(
+            "surfaceVariant / onSurfaceVariant",
+            { it.surfaceVariant },
+            { it.onSurfaceVariant },
+            "Subtle filled areas — code blocks, inset panels.",
+        ),
+        RolePair(
+            "surfaceContainerHighest / outline",
+            { it.surfaceContainerHighest },
+            { it.outline },
+            "Unchecked switch (off-track + thumb), inactive controls.",
+        ),
+    )
+
+private fun Color.hex(): String = "#%06X".format(0xFFFFFF and toArgb())
+
+private fun contrastRatio(
+    a: Color,
+    b: Color,
+): Float {
+    val la = a.luminance()
+    val lb = b.luminance()
+    return (max(la, lb) + 0.05f) / (min(la, lb) + 0.05f)
+}
+
+private fun contrastLabel(ratio: Float): String =
+    when {
+        ratio >= 4.5f -> "AA"
+        ratio >= 3f -> "AA-lg"
+        else -> "low"
+    }
+
+@Composable
+private fun RolePairRow(pair: RolePair) {
+    val scheme = MaterialTheme.colorScheme
+    val bg = pair.bg(scheme)
+    val fg = pair.fg(scheme)
+    val ratio = contrastRatio(bg, fg)
+
+    Row(
+        modifier = Modifier.fillMaxWidth().padding(horizontal = 10.dp, vertical = 5.dp),
+        verticalAlignment = Alignment.CenterVertically,
+    ) {
+        Box(
+            modifier =
+                Modifier
+                    .width(92.dp)
+                    .height(58.dp)
+                    .clip(RoundedCornerShape(10.dp))
+                    .background(bg)
+                    .border(
+                        if (pair.highlight) 2.dp else 1.dp,
+                        if (pair.highlight) scheme.onBackground else scheme.outlineVariant,
+                        RoundedCornerShape(10.dp),
+                    ).padding(8.dp),
+        ) {
+            Text("Aa", color = fg, fontSize = 19.sp, fontWeight = FontWeight.Bold)
+            Text(
+                "%.1f:1 %s".format(ratio, contrastLabel(ratio)),
+                color = fg,
+                fontSize = 8.5.sp,
+                fontFamily = FontFamily.Monospace,
+                modifier = Modifier.align(Alignment.BottomEnd),
+            )
+        }
+
+        Spacer(Modifier.width(10.dp))
+
+        Column(modifier = Modifier.weight(1f)) {
+            Text(
+                pair.name,
+                color = scheme.onBackground,
+                fontSize = 12.5.sp,
+                fontWeight = if (pair.highlight) FontWeight.Bold else FontWeight.Medium,
+            )
+            Text(
+                "${bg.hex()}  /  ${fg.hex()}",
+                color = scheme.onSurfaceVariant,
+                fontSize = 10.5.sp,
+                fontFamily = FontFamily.Monospace,
+            )
+            Text(
+                pair.usage,
+                color = scheme.onSurfaceVariant,
+                fontSize = 10.sp,
+                maxLines = 2,
+                overflow = TextOverflow.Ellipsis,
+            )
+        }
+    }
+}
+
+@Composable
+private fun RolePairList() {
+    Column(
+        modifier = Modifier.padding(vertical = 8.dp),
+        verticalArrangement = Arrangement.spacedBy(2.dp),
+    ) {
+        Text(
+            "fg / bg pairs by role",
+            color = MaterialTheme.colorScheme.onBackground,
+            fontSize = 13.sp,
+            fontWeight = FontWeight.Bold,
+            modifier = Modifier.padding(horizontal = 10.dp, vertical = 4.dp),
+        )
+        ROLE_PAIRS.forEach { RolePairRow(it) }
+    }
+}
+
+@Preview(name = "Theme color pairs by role · dark | light", widthDp = 820, heightDp = 980, showBackground = true)
+@Composable
+fun ThemeColorPairsPreview() {
+    ThemeComparisonRow {
+        RolePairList()
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/theme/Theme.kt

@@ -136,7 +136,10 @@ private fun darkColors(accent: AccentColorType): ColorScheme {
     val secondary = accentSecondary(accent, dark = true)
     return darkColorScheme(
         primary = primary,
-        onPrimary = Color.White,
+        // Content on a primary fill (filled buttons, FAB glyphs). Picked by contrast against the
+        // fill: on the dark theme `primary` is a light pastel, so this resolves to black (white on
+        // it is only ~2.6:1). Left as white it washed out every filled button/FAB.
+        onPrimary = onAccent(primary),
         primaryContainer = accentContainer(primary, dark = true),
         onPrimaryContainer = onAccentContainer(primary, dark = true),
         secondary = secondary,
@@ -178,7 +181,9 @@ private fun lightColors(accent: AccentColorType): ColorScheme {
     val secondary = accentSecondary(accent, dark = false)
     return lightColorScheme(
         primary = primary,
-        onPrimary = Color.White,
+        // Contrast-picked content on the primary fill; the light theme's deep primary resolves to
+        // white (unchanged), while keeping the rule identical across both schemes.
+        onPrimary = onAccent(primary),
         primaryContainer = accentContainer(primary, dark = false),
         onPrimaryContainer = onAccentContainer(primary, dark = false),
         secondary = secondary,