feat: add relay search suggestions to all Add a Relay fields

When the user types in any "Add a Relay" field in AllRelayListScreen,
the app now searches HintIndexer's relayDB for matching relay URLs
and displays them as clickable suggestions below the text field.

Clicking a suggestion fills the field with the relay URL, matching
the design pattern of ShowUserSuggestionList in ShortNotePostScreen.

New files:
- RelaySuggestionState: debounced Flow-based state filtering relayDB
- ShowRelaySuggestionList: Column of clickable RelayUrlLine rows

https://claude.ai/code/session_0115sYZGVQBZLX7s9oCDcKoi

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/RelaySuggestionState.kt

@@ -0,0 +1,62 @@
+/*
+ * 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.screen.loggedIn.relays.common
+
+import androidx.compose.runtime.Stable
+import com.vitorpamplona.amethyst.model.LocalCache
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.debounce
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.map
+
+@Stable
+class RelaySuggestionState {
+    val currentInput = MutableStateFlow("")
+
+    @OptIn(FlowPreview::class)
+    val results =
+        currentInput
+            .debounce(300)
+            .distinctUntilChanged()
+            .map { input ->
+                if (input.length > 1) {
+                    val lower = input.lowercase()
+                    LocalCache.relayHints.relayDB
+                        .filter { _, relay -> relay.url.contains(lower) }
+                        .sortedBy { it.url }
+                        .take(20)
+                } else {
+                    emptyList<NormalizedRelayUrl>()
+                }
+            }.flowOn(Dispatchers.IO)
+
+    fun processInput(input: String) {
+        currentInput.tryEmit(input)
+    }
+
+    fun reset() {
+        currentInput.tryEmit("")
+    }
+}

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/RelayUrlEditField.kt

@@ -21,6 +21,7 @@
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.relays.common
 
 import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.text.KeyboardActions
 import androidx.compose.foundation.text.KeyboardOptions
@@ -61,64 +62,73 @@ fun RelayUrlEditFieldPreview() {
 @Composable
 fun RelayUrlEditField(onNewRelay: (NormalizedRelayUrl) -> Unit) {
     var url by remember { mutableStateOf("") }
+    val relaySuggestions = remember { RelaySuggestionState() }
 
-    Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(Size10dp)) {
+    fun submitRelay() {
-        OutlinedTextField(
+        if (url.isNotBlank() && url != "/") {
-            label = { Text(text = stringRes(R.string.add_a_relay)) },
+            val relay = RelayUrlNormalizer.normalizeOrNull(url)
-            modifier = Modifier.weight(1f),
+            if (relay != null) {
-            value = url,
+                onNewRelay(relay)
-            onValueChange = { url = it },
+                url = ""
-            placeholder = {
+                relaySuggestions.reset()
-                Text(
+            }
-                    text = "server.com",
-                    color = MaterialTheme.colorScheme.placeholderText,
-                    maxLines = 1,
-                )
-            },
-            singleLine = true,
-            keyboardOptions =
-                KeyboardOptions.Default.copy(
-                    autoCorrectEnabled = false,
-                    imeAction = ImeAction.Go,
-                    capitalization = KeyboardCapitalization.None,
-                    keyboardType = KeyboardType.Text,
-                ),
-            keyboardActions =
-                KeyboardActions(
-                    onGo = {
-                        if (url.isNotBlank() && url != "/") {
-                            val relay = RelayUrlNormalizer.normalizeOrNull(url)
-                            if (relay != null) {
-                                onNewRelay(relay)
-                                url = ""
-                            }
-                        }
-                    },
-                ),
-        )
-
-        Button(
-            onClick = {
-                if (url.isNotBlank() && url != "/") {
-                    val relay = RelayUrlNormalizer.normalizeOrNull(url)
-                    if (relay != null) {
-                        onNewRelay(relay)
-                        url = ""
-                    }
-                }
-            },
-            shape = ButtonBorder,
-            colors =
-                ButtonDefaults.buttonColors(
-                    containerColor =
-                        if (url.isNotBlank()) {
-                            MaterialTheme.colorScheme.primary
-                        } else {
-                            MaterialTheme.colorScheme.placeholderText
-                        },
-                ),
-        ) {
-            Text(text = stringRes(id = R.string.add), color = Color.White)
         }
     }
+
+    Column {
+        Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(Size10dp)) {
+            OutlinedTextField(
+                label = { Text(text = stringRes(R.string.add_a_relay)) },
+                modifier = Modifier.weight(1f),
+                value = url,
+                onValueChange = {
+                    url = it
+                    relaySuggestions.processInput(it)
+                },
+                placeholder = {
+                    Text(
+                        text = "server.com",
+                        color = MaterialTheme.colorScheme.placeholderText,
+                        maxLines = 1,
+                    )
+                },
+                singleLine = true,
+                keyboardOptions =
+                    KeyboardOptions.Default.copy(
+                        autoCorrectEnabled = false,
+                        imeAction = ImeAction.Go,
+                        capitalization = KeyboardCapitalization.None,
+                        keyboardType = KeyboardType.Text,
+                    ),
+                keyboardActions =
+                    KeyboardActions(
+                        onGo = { submitRelay() },
+                    ),
+            )
+
+            Button(
+                onClick = { submitRelay() },
+                shape = ButtonBorder,
+                colors =
+                    ButtonDefaults.buttonColors(
+                        containerColor =
+                            if (url.isNotBlank()) {
+                                MaterialTheme.colorScheme.primary
+                            } else {
+                                MaterialTheme.colorScheme.placeholderText
+                            },
+                    ),
+            ) {
+                Text(text = stringRes(id = R.string.add), color = Color.White)
+            }
+        }
+
+        ShowRelaySuggestionList(
+            relaySuggestions = relaySuggestions,
+            onSelect = { relay ->
+                url = relay.url
+                relaySuggestions.reset()
+            },
+        )
+    }
 }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/common/ShowRelaySuggestionList.kt

@@ -0,0 +1,78 @@
+/*
+ * 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.screen.loggedIn.relays.common
+
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.HorizontalDivider
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
+import com.vitorpamplona.amethyst.ui.theme.DividerThickness
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import com.vitorpamplona.quartz.nip01Core.relay.normalizer.displayUrl
+
+@Composable
+fun ShowRelaySuggestionList(
+    relaySuggestions: RelaySuggestionState,
+    onSelect: (NormalizedRelayUrl) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val suggestions by relaySuggestions.results.collectAsStateWithLifecycle(emptyList())
+
+    if (suggestions.isNotEmpty()) {
+        Column(modifier = modifier) {
+            suggestions.forEachIndexed { index, relay ->
+                RelayUrlLine(relay) { onSelect(relay) }
+                if (index < suggestions.lastIndex) {
+                    HorizontalDivider(thickness = DividerThickness)
+                }
+            }
+        }
+    }
+}
+
+@Composable
+fun RelayUrlLine(
+    relay: NormalizedRelayUrl,
+    onClick: () -> Unit,
+) {
+    Text(
+        text = relay.displayUrl(),
+        fontWeight = FontWeight.Bold,
+        maxLines = 1,
+        overflow = TextOverflow.Ellipsis,
+        style = MaterialTheme.typography.bodyMedium,
+        modifier =
+            Modifier
+                .fillMaxWidth()
+                .clickable(onClick = onClick)
+                .padding(horizontal = 12.dp, vertical = 10.dp),
+    )
+}