feat(settings): in-app chat font size setting (#1004) (#1005)

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/MainActivity.kt

@@ -54,10 +54,12 @@ class MainActivity : ComponentActivity() {
             val themePreference by AuthManager.themePreferenceFlow.collectAsState()
             val useDynamicColors by AuthManager.useDynamicColorsFlow.collectAsState()
             val themePreset by AuthManager.themePresetFlow.collectAsState()
+            val chatFontScale by AuthManager.chatFontScaleFlow.collectAsState()
             HermesControlTheme(
                 themePreference = themePreference,
                 useDynamicColors = useDynamicColors,
                 themePreset = themePreset,
+                chatFontScale = chatFontScale,
             ) {
                 Surface(
                     modifier = Modifier.fillMaxSize(),

app/src/main/java/com/m57/hermescontrol/data/config/ServerStoreState.kt

@@ -21,6 +21,7 @@ data class ServerStoreState(
     val wsAuthParam: String = "token",
     val typingEffectEnabled: Boolean = true,
     val typingEffectDelayMs: Int = 30,
+    val chatFontScale: Float = 1.0f,
     // App display language. "system" = follow device locale; otherwise a BCP-47
     // language code such as "en" or "ko". Applied via ContextWrapper in MainActivity.
     val appLanguage: String = "system",

app/src/main/java/com/m57/hermescontrol/data/local/AuthManager.kt

@@ -74,6 +74,9 @@ object AuthManager {
     private val _themePresetFlow = MutableStateFlow<ThemePreset>(ThemePreset.DEFAULT)
     val themePresetFlow: StateFlow<ThemePreset> = _themePresetFlow.asStateFlow()
 
+    private val _chatFontScaleFlow = MutableStateFlow<Float>(1.0f)
+    val chatFontScaleFlow: StateFlow<Float> = _chatFontScaleFlow.asStateFlow()
+
     private val _tokenFlow = MutableStateFlow<String?>(null)
     val tokenFlow: StateFlow<String?> = _tokenFlow.asStateFlow()
 
@@ -180,6 +183,7 @@ object AuthManager {
                     _themePreferenceFlow.value = state.themePreference
                     _useDynamicColorsFlow.value = state.useDynamicColors
                     _themePresetFlow.value = state.themePreset
+                    _chatFontScaleFlow.value = state.chatFontScale
                     // B7 (Jul 08 2026, kanban t_470): keep cookie scope aligned with active profile.
                     appScope?.launch { syncCookieStoreForProfile(state.selectedProfileId) }
                 }
@@ -640,6 +644,15 @@ object AuthManager {
         serverStore.update { it.copy(typingEffectDelayMs = delayMs) }
     }
 
+    // ── Chat Font Scale (issue #1004) ───────────────────────────────────
+
+    fun getChatFontScale(): Float = serverStore.getLatestState().chatFontScale
+
+    fun setChatFontScale(scale: Float) {
+        serverStore.update { it.copy(chatFontScale = scale) }
+        _chatFontScaleFlow.value = scale
+    }
+
     // ── In-app update check (issue #867) ─────────────────────────────────
 
     /** App version the silent update check last completed for (null = never). */

app/src/main/java/com/m57/hermescontrol/theme/Theme.kt

@@ -26,6 +26,7 @@ enum class ThemePreset { DEFAULT, MONOCHROME, GRUVBOX, CATPPUCCIN, AMOLED, NORD
 
 val LocalThemePreference = compositionLocalOf { ThemePreference.SYSTEM }
 val LocalThemePreset = compositionLocalOf { ThemePreset.DEFAULT }
+val LocalChatFontScale = compositionLocalOf { 1.0f }
 
 /**
  * The 6 preset themes — one file each, all built from the same
@@ -75,6 +76,7 @@ fun HermesControlTheme(
     themePreference: ThemePreference = LocalThemePreference.current,
     useDynamicColors: Boolean = true,
     themePreset: ThemePreset = ThemePreset.DEFAULT,
+    chatFontScale: Float = LocalChatFontScale.current,
     content: @Composable () -> Unit,
 ) {
     val darkTheme =
@@ -103,6 +105,7 @@ fun HermesControlTheme(
     CompositionLocalProvider(
         LocalThemePreference provides themePreference,
         LocalThemePreset provides themePreset,
+        LocalChatFontScale provides chatFontScale,
         LocalHermesStatusColors provides statusColors,
         LocalSpacing provides SpacingDefaults,
         LocalMotion provides MotionDefaults,

app/src/main/java/com/m57/hermescontrol/ui/bots/group/GroupChatScreen.kt

@@ -32,6 +32,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
@@ -43,14 +44,17 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.focus.onFocusChanged
 import androidx.compose.ui.graphics.SolidColor
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.input.ImeAction
 import androidx.compose.ui.text.input.TextFieldValue
+import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.m57.hermescontrol.R
+import com.m57.hermescontrol.theme.LocalChatFontScale
 import com.m57.hermescontrol.ui.chat.MarkdownText
 import com.m57.hermescontrol.ui.common.BotAvatar
 import com.m57.hermescontrol.ui.common.EmptyState
@@ -141,38 +145,50 @@ fun GroupChatScreen(
                 }
 
                 else -> {
-                    LazyColumn(
+                    val currentDensity = LocalDensity.current
-                        state = listState,
+                    val chatFontScale = LocalChatFontScale.current
-                        modifier =
+                    val chatDensity =
-                            Modifier
+                        remember(currentDensity, chatFontScale) {
-                                .weight(1f)
+                            Density(
-                                .fillMaxWidth(),
+                                density = currentDensity.density,
-                        contentPadding = PaddingValues(horizontal = 16.dp, vertical = 8.dp),
+                                fontScale = currentDensity.fontScale * chatFontScale,
-                        verticalArrangement = Arrangement.spacedBy(12.dp),
+                            )
-                    ) {
-                        items(
-                            items = state.messages,
-                            key = { it.id },
-                        ) { message ->
-                            GroupMessageCard(message = message)
                         }
 
-                        state.activeSpeaker?.let { speaker ->
+                    CompositionLocalProvider(LocalDensity provides chatDensity) {
-                            item(key = "active_speaker") {
+                        LazyColumn(
-                                Row(
+                            state = listState,
-                                    modifier = Modifier.padding(start = 8.dp, top = 4.dp),
+                            modifier =
-                                    verticalAlignment = Alignment.CenterVertically,
+                                Modifier
-                                ) {
+                                    .weight(1f)
-                                    CircularProgressIndicator(
+                                    .fillMaxWidth(),
-                                        modifier = Modifier.size(14.dp),
+                            contentPadding = PaddingValues(horizontal = 16.dp, vertical = 8.dp),
-                                        strokeWidth = 2.dp,
+                            verticalArrangement = Arrangement.spacedBy(12.dp),
-                                    )
+                        ) {
-                                    Spacer(modifier = Modifier.width(8.dp))
+                            items(
-                                    Text(
+                                items = state.messages,
-                                        text = stringResource(R.string.group_chat_thinking, speaker),
+                                key = { it.id },
-                                        style = MaterialTheme.typography.bodySmall,
+                            ) { message ->
-                                        color = MaterialTheme.colorScheme.primary,
+                                GroupMessageCard(message = message)
-                                    )
+                            }
+
+                            state.activeSpeaker?.let { speaker ->
+                                item(key = "active_speaker") {
+                                    Row(
+                                        modifier = Modifier.padding(start = 8.dp, top = 4.dp),
+                                        verticalAlignment = Alignment.CenterVertically,
+                                    ) {
+                                        CircularProgressIndicator(
+                                            modifier = Modifier.size(14.dp),
+                                            strokeWidth = 2.dp,
+                                        )
+                                        Spacer(modifier = Modifier.width(8.dp))
+                                        Text(
+                                            text = stringResource(R.string.group_chat_thinking, speaker),
+                                            style = MaterialTheme.typography.bodySmall,
+                                            color = MaterialTheme.colorScheme.primary,
+                                        )
+                                    }
                                 }
                             }
                         }

app/src/main/java/com/m57/hermescontrol/ui/chat/fullbleed/FullBleedChatList.kt

@@ -10,13 +10,17 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
 import com.m57.hermescontrol.R
+import com.m57.hermescontrol.theme.LocalChatFontScale
 import com.m57.hermescontrol.ui.chat.ChatBubble
 import com.m57.hermescontrol.ui.chat.ChatMessage
 import com.m57.hermescontrol.ui.chat.ChatSearchState
@@ -116,179 +120,191 @@ fun FullBleedChatList(
             }
         }
 
-        LazyColumn(
+        val currentDensity = LocalDensity.current
-            state = listState,
+        val chatFontScale = LocalChatFontScale.current
-            modifier = Modifier.fillMaxSize(),
+        val chatDensity =
-            contentPadding = PaddingValues(vertical = 8.dp),
+            remember(currentDensity, chatFontScale) {
-        ) {
+                Density(
-            if (isLoadingOlder) {
+                    density = currentDensity.density,
-                item(key = "loading-older") {
+                    fontScale = currentDensity.fontScale * chatFontScale,
-                    Box(
+                )
-                        modifier = Modifier.fillMaxWidth().padding(12.dp),
-                        contentAlignment = Alignment.Center,
-                    ) {
-                        CircularProgressIndicator(modifier = Modifier.size(24.dp))
-                    }
-                }
             }
 
-            var entryIndex = 0
+        CompositionLocalProvider(LocalDensity provides chatDensity) {
-            turns.forEach { turn ->
+            LazyColumn(
-                when (turn) {
+                state = listState,
-                    is ChatTurn.User -> {
+                modifier = Modifier.fillMaxSize(),
-                        // Eager captures: item lambda reads these at
+                contentPadding = PaddingValues(vertical = 8.dp),
-                        // composition time (lazy), so capture now.
+            ) {
-                        val userMessage = turn.message
+                if (isLoadingOlder) {
-                        val milestone = toolMilestones[entryIndex]
+                    item(key = "loading-older") {
-                        item(key = "user-${userMessage.id}") {
+                        Box(
-                            Column(modifier = Modifier.padding(bottom = 12.dp)) {
+                            modifier = Modifier.fillMaxWidth().padding(12.dp),
-                                renderChatBubble(
+                            contentAlignment = Alignment.Center,
-                                    message = userMessage,
+                        ) {
-                                    searchQuery = if (searchState.isActive) searchState.query else "",
+                            CircularProgressIndicator(modifier = Modifier.size(24.dp))
-                                    isCurrentMatch =
-                                        searchState.currentMatchId != null &&
-                                            searchState.currentMatchId == userMessage.id,
-                                    onOpenAttachment = viewModel::openAttachment,
-                                    onSaveAttachment = onSaveAttachment,
-                                    savingAttachmentPath = savingAttachmentPath,
-                                    openingAttachmentPath = openingAttachmentPath,
-                                    onImageClick = onImageClick,
-                                )
-                                milestone?.let { count ->
-                                    ToolCallDivider(count = count, maxPerTurn = maxToolCallsPerTurn)
-                                }
-                            }
                         }
-                        entryIndex++
                     }
+                }
 
-                    is ChatTurn.Agent -> {
+                var entryIndex = 0
-                        var firstProseSeen = false
+                turns.forEach { turn ->
-                        // Reasoning hoist: the turn's reasoning renders at the
+                    when (turn) {
-                        // TOP of the turn — above tool rows — so thinking
+                        is ChatTurn.User -> {
-                        // leads, then the tool work, then the answer. The
+                            // Eager captures: item lambda reads these at
-                        // matching prose entry renders without its own card.
+                            // composition time (lazy), so capture now.
-                        val turnReasoning =
+                            val userMessage = turn.message
-                            turn.entries
+                            val milestone = toolMilestones[entryIndex]
-                                .filterIsInstance<AgentEntry.Prose>()
+                            item(key = "user-${userMessage.id}") {
-                                .firstOrNull { it.message.reasoningText.isNotBlank() }
+                                Column(modifier = Modifier.padding(bottom = 12.dp)) {
-                        if (turnReasoning != null) {
+                                    renderChatBubble(
-                            val reasoning = turnReasoning.message
+                                        message = userMessage,
-                            item(key = "reasoning-${reasoning.id}") {
+                                        searchQuery = if (searchState.isActive) searchState.query else "",
-                                Column(modifier = Modifier.padding(bottom = 6.dp)) {
+                                        isCurrentMatch =
-                                    // Lead the turn with the assistant identity
+                                            searchState.currentMatchId != null &&
-                                    // and timestamp, then the thinking block.
+                                                searchState.currentMatchId == userMessage.id,
-                                    AssistantTurnHeader(timestamp = reasoning.timestamp)
+                                        onOpenAttachment = viewModel::openAttachment,
-                                    ReasoningCard(
+                                        onSaveAttachment = onSaveAttachment,
-                                        reasoningText = reasoning.reasoningText,
+                                        savingAttachmentPath = savingAttachmentPath,
-                                        isStreaming = reasoning.isStreaming,
+                                        openingAttachmentPath = openingAttachmentPath,
+                                        onImageClick = onImageClick,
                                     )
+                                    milestone?.let { count ->
+                                        ToolCallDivider(count = count, maxPerTurn = maxToolCallsPerTurn)
+                                    }
                                 }
                             }
+                            entryIndex++
                         }
-                        turn.entries.forEach { entry ->
-                            when (entry) {
-                                is AgentEntry.Prose -> {
-                                    val proseMessage = entry.message
-                                    val showTurnHeader = !firstProseSeen && turnReasoning == null
-                                    val hoistedReasoning =
-                                        turnReasoning != null &&
-                                            proseMessage.id == turnReasoning.message.id
-                                    val milestone = toolMilestones[entryIndex]
-                                    item(key = "prose-${proseMessage.id}") {
-                                        Column(modifier = Modifier.padding(bottom = 12.dp)) {
-                                            if (proseMessage.isStreaming && typingEffectEnabled) {
-                                                StreamingFullBleedWithTypingEffect(
-                                                    streaming = proseMessage,
-                                                    typingDelayMs = typingEffectDelayMs,
-                                                    isDark = isDark,
-                                                    showTurnHeader = showTurnHeader,
-                                                    showReasoning = !hoistedReasoning,
-                                                )
-                                            } else {
-                                                FullBleedAgentMessage(
-                                                    message = proseMessage,
-                                                    showTurnHeader = showTurnHeader,
-                                                    isDarkTheme = isDark,
-                                                    // Highlight only bubbles that actually contain a match —
-                                                    // the rest skip the highlight scan entirely.
-                                                    searchQuery =
-                                                        if (searchState.isActive &&
-                                                            proseMessage.id in searchState.matchedIds
-                                                        ) {
-                                                            searchState.query
-                                                        } else {
-                                                            ""
-                                                        },
-                                                    isCurrentMatch =
-                                                        searchState.currentMatchId != null &&
-                                                            searchState.currentMatchId == proseMessage.id,
-                                                    showReasoning = !hoistedReasoning,
-                                                    onOpenAttachment = viewModel::openAttachment,
-                                                    onSaveAttachment = onSaveAttachment,
-                                                    savingAttachmentPath = savingAttachmentPath,
-                                                    openingAttachmentPath = openingAttachmentPath,
-                                                    canSaveAttachment = savingAttachmentPath == null,
-                                                    onImageClick = onImageClick,
-                                                )
-                                            }
-                                            milestone?.let { count ->
-                                                ToolCallDivider(count = count, maxPerTurn = maxToolCallsPerTurn)
-                                            }
-                                        }
-                                    }
-                                    firstProseSeen = true
-                                    entryIndex++
-                                }
 
-                                is AgentEntry.ToolRow -> {
+                        is ChatTurn.Agent -> {
-                                    val toolMessage = entry.message
+                            var firstProseSeen = false
-                                    val milestone = toolMilestones[entryIndex]
+                            // Reasoning hoist: the turn's reasoning renders at the
-                                    item(key = "tool-${toolMessage.id}") {
+                            // TOP of the turn — above tool rows — so thinking
-                                        Column(modifier = Modifier.padding(bottom = 6.dp)) {
+                            // leads, then the tool work, then the answer. The
-                                            FullBleedToolRow(toolMessage)
+                            // matching prose entry renders without its own card.
-                                            milestone?.let { count ->
+                            val turnReasoning =
-                                                ToolCallDivider(count = count, maxPerTurn = maxToolCallsPerTurn)
+                                turn.entries
-                                            }
+                                    .filterIsInstance<AgentEntry.Prose>()
-                                        }
+                                    .firstOrNull { it.message.reasoningText.isNotBlank() }
+                            if (turnReasoning != null) {
+                                val reasoning = turnReasoning.message
+                                item(key = "reasoning-${reasoning.id}") {
+                                    Column(modifier = Modifier.padding(bottom = 6.dp)) {
+                                        // Lead the turn with the assistant identity
+                                        // and timestamp, then the thinking block.
+                                        AssistantTurnHeader(timestamp = reasoning.timestamp)
+                                        ReasoningCard(
+                                            reasoningText = reasoning.reasoningText,
+                                            isStreaming = reasoning.isStreaming,
+                                        )
                                     }
-                                    entryIndex++
                                 }
-
+                            }
-                                is AgentEntry.SystemEvent -> {
+                            turn.entries.forEach { entry ->
-                                    val sysMessage = entry.message
+                                when (entry) {
-                                    item(key = "sys-${sysMessage.id}") {
+                                    is AgentEntry.Prose -> {
-                                        Column(modifier = Modifier.padding(bottom = 6.dp)) {
+                                        val proseMessage = entry.message
-                                            if (sysMessage.displayKind != null) {
+                                        val showTurnHeader = !firstProseSeen && turnReasoning == null
-                                                // Timeline marker (issue #904):
+                                        val hoistedReasoning =
-                                                // model/personality switches and
+                                            turnReasoning != null &&
-                                                // auto-continues render as a chip.
+                                                proseMessage.id == turnReasoning.message.id
-                                                TimelineMarkerChip(message = sysMessage)
+                                        val milestone = toolMilestones[entryIndex]
-                                            } else {
+                                        item(key = "prose-${proseMessage.id}") {
-                                                FullBleedSystemEvent(
+                                            Column(modifier = Modifier.padding(bottom = 12.dp)) {
-                                                    message = sysMessage,
+                                                if (proseMessage.isStreaming && typingEffectEnabled) {
-                                                    onRespondApproval = viewModel::respondToApproval,
+                                                    StreamingFullBleedWithTypingEffect(
-                                                )
+                                                        streaming = proseMessage,
+                                                        typingDelayMs = typingEffectDelayMs,
+                                                        isDark = isDark,
+                                                        showTurnHeader = showTurnHeader,
+                                                        showReasoning = !hoistedReasoning,
+                                                    )
+                                                } else {
+                                                    FullBleedAgentMessage(
+                                                        message = proseMessage,
+                                                        showTurnHeader = showTurnHeader,
+                                                        isDarkTheme = isDark,
+                                                        // Highlight only bubbles that actually contain a match —
+                                                        // the rest skip the highlight scan entirely.
+                                                        searchQuery =
+                                                            if (searchState.isActive &&
+                                                                proseMessage.id in searchState.matchedIds
+                                                            ) {
+                                                                searchState.query
+                                                            } else {
+                                                                ""
+                                                            },
+                                                        isCurrentMatch =
+                                                            searchState.currentMatchId != null &&
+                                                                searchState.currentMatchId == proseMessage.id,
+                                                        showReasoning = !hoistedReasoning,
+                                                        onOpenAttachment = viewModel::openAttachment,
+                                                        onSaveAttachment = onSaveAttachment,
+                                                        savingAttachmentPath = savingAttachmentPath,
+                                                        openingAttachmentPath = openingAttachmentPath,
+                                                        canSaveAttachment = savingAttachmentPath == null,
+                                                        onImageClick = onImageClick,
+                                                    )
+                                                }
+                                                milestone?.let { count ->
+                                                    ToolCallDivider(count = count, maxPerTurn = maxToolCallsPerTurn)
+                                                }
                                             }
                                         }
+                                        firstProseSeen = true
+                                        entryIndex++
+                                    }
+
+                                    is AgentEntry.ToolRow -> {
+                                        val toolMessage = entry.message
+                                        val milestone = toolMilestones[entryIndex]
+                                        item(key = "tool-${toolMessage.id}") {
+                                            Column(modifier = Modifier.padding(bottom = 6.dp)) {
+                                                FullBleedToolRow(toolMessage)
+                                                milestone?.let { count ->
+                                                    ToolCallDivider(count = count, maxPerTurn = maxToolCallsPerTurn)
+                                                }
+                                            }
+                                        }
+                                        entryIndex++
+                                    }
+
+                                    is AgentEntry.SystemEvent -> {
+                                        val sysMessage = entry.message
+                                        item(key = "sys-${sysMessage.id}") {
+                                            Column(modifier = Modifier.padding(bottom = 6.dp)) {
+                                                if (sysMessage.displayKind != null) {
+                                                    // Timeline marker (issue #904):
+                                                    // model/personality switches and
+                                                    // auto-continues render as a chip.
+                                                    TimelineMarkerChip(message = sysMessage)
+                                                } else {
+                                                    FullBleedSystemEvent(
+                                                        message = sysMessage,
+                                                        onRespondApproval = viewModel::respondToApproval,
+                                                    )
+                                                }
+                                            }
+                                        }
+                                        entryIndex++
                                     }
-                                    entryIndex++
                                 }
                             }
                         }
                     }
                 }
-            }
 
-            // Clarify bubble — rendered at the very bottom
+                // Clarify bubble — rendered at the very bottom
-            if (clarifyRequest != null) {
+                if (clarifyRequest != null) {
-                item(key = "clarify_bubble") {
+                    item(key = "clarify_bubble") {
-                    ClarifyBubble(
+                        ClarifyBubble(
-                        text = clarifyRequest.text,
+                            text = clarifyRequest.text,
-                        options = clarifyRequest.options,
+                            options = clarifyRequest.options,
-                        onOptionSelected = { option -> onRespondClarify?.invoke(option) },
+                            onOptionSelected = { option -> onRespondClarify?.invoke(option) },
-                        onDismiss = { onDismissClarify?.invoke() },
+                            onDismiss = { onDismissClarify?.invoke() },
-                    )
+                        )
+                    }
                 }
             }
         }

app/src/main/java/com/m57/hermescontrol/ui/settings/SettingsSubPages.kt

@@ -191,6 +191,8 @@ internal fun SettingsChatPage(
                 onTypingEffectEnabledChange = viewModel::onTypingEffectEnabledChange,
                 typingEffectDelayMs = state.typingEffectDelayMs,
                 onTypingEffectDelayMsChange = viewModel::onTypingEffectDelayMsChange,
+                chatFontScale = state.chatFontScale,
+                onChatFontScaleChange = viewModel::onChatFontScaleChange,
             )
         }
     }

app/src/main/java/com/m57/hermescontrol/ui/settings/SettingsViewModel.kt

@@ -36,6 +36,7 @@ data class SettingsUiState(
     val isSaved: Boolean = false,
     val typingEffectEnabled: Boolean = false,
     val typingEffectDelayMs: Int = 30,
+    val chatFontScale: Float = 1.0f,
     val profiles: List<ConnectionProfile> = emptyList(),
     val selectedProfileId: String? = null,
     val renameProfileName: String = "",
@@ -76,6 +77,7 @@ class SettingsViewModel(
         val themePreset = AuthManager.getThemePreset()
         val typingEffectEnabled = AuthManager.isTypingEffectEnabled()
         val typingEffectDelayMs = AuthManager.getTypingEffectDelayMs()
+        val chatFontScale = AuthManager.getChatFontScale()
         val profiles = AuthManager.getConnectionProfiles()
         val appLanguage = AuthManager.getAppLanguage()
         val renameProfileName =
@@ -95,6 +97,7 @@ class SettingsViewModel(
                 themePreset = themePreset,
                 typingEffectEnabled = typingEffectEnabled,
                 typingEffectDelayMs = typingEffectDelayMs,
+                chatFontScale = chatFontScale,
                 profiles = profiles,
                 selectedProfileId = selectedId,
                 renameProfileName = renameProfileName,
@@ -310,6 +313,11 @@ class SettingsViewModel(
         AuthManager.setTypingEffectDelayMs(delayMs)
     }
 
+    fun onChatFontScaleChange(scale: Float) {
+        _uiState.update { it.copy(chatFontScale = scale, isSaved = false) }
+        AuthManager.setChatFontScale(scale)
+    }
+
     /** Clear all auth credentials — logs out and returns to landing screen. */
     fun logout() {
         AuthManager.setToken(null)

app/src/main/java/com/m57/hermescontrol/ui/settings/components/AppearanceSection.kt

@@ -10,6 +10,7 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.MaterialTheme
@@ -18,22 +19,29 @@ import androidx.compose.material3.SegmentedButton
 import androidx.compose.material3.SegmentedButtonDefaults
 import androidx.compose.material3.SingleChoiceSegmentedButtonRow
 import androidx.compose.material3.Slider
+import androidx.compose.material3.Surface
 import androidx.compose.material3.Switch
 import androidx.compose.material3.SwitchDefaults
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.dp
 import com.m57.hermescontrol.R
 import com.m57.hermescontrol.theme.ThemePreference
 import com.m57.hermescontrol.theme.ThemePreset
 import com.m57.hermescontrol.ui.settings.SectionCard
+import kotlin.math.abs
+import kotlin.math.roundToInt
 
 @Composable
 internal fun AppearanceSection(
@@ -194,10 +202,172 @@ internal fun ChatSection(
     onTypingEffectEnabledChange: (Boolean) -> Unit,
     typingEffectDelayMs: Int,
     onTypingEffectDelayMsChange: (Int) -> Unit,
+    chatFontScale: Float = 1.0f,
+    onChatFontScaleChange: (Float) -> Unit = {},
 ) {
+    val fontScaleOptions = listOf(0.85f, 1.0f, 1.15f, 1.30f, 1.50f)
+    val currentIndex =
+        fontScaleOptions.indexOfFirst { abs(it - chatFontScale) < 0.05f }
+            .takeIf { it >= 0 } ?: 1
+
     SectionCard {
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceBetween,
+            verticalAlignment = Alignment.CenterVertically,
+        ) {
+            Column(modifier = Modifier.weight(1f)) {
+                Text(
+                    text = stringResource(R.string.settings_item_chat_font_size),
+                    style = MaterialTheme.typography.bodyLarge,
+                )
+                Text(
+                    text = stringResource(R.string.settings_desc_chat_font_size),
+                    style =
+                        MaterialTheme.typography.bodySmall.copy(
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        ),
+                )
+            }
+            val scaleLabel =
+                when (currentIndex) {
+                    0 -> stringResource(R.string.settings_font_scale_small)
+                    1 -> stringResource(R.string.settings_font_scale_default)
+                    2 -> stringResource(R.string.settings_font_scale_large)
+                    3 -> stringResource(R.string.settings_font_scale_xlarge)
+                    else -> stringResource(R.string.settings_font_scale_huge)
+                }
+            Text(
+                text = scaleLabel,
+                style =
+                    MaterialTheme.typography.labelMedium.copy(
+                        color = MaterialTheme.colorScheme.primary,
+                        fontWeight = FontWeight.SemiBold,
+                    ),
+            )
+        }
+
+        Spacer(modifier = Modifier.height(8.dp))
+
+        Slider(
+            value = currentIndex.toFloat(),
+            onValueChange = { onChatFontScaleChange(fontScaleOptions[it.roundToInt()]) },
+            valueRange = 0f..(fontScaleOptions.size - 1).toFloat(),
+            steps = fontScaleOptions.size - 2,
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceBetween,
+        ) {
+            Text(
+                text = "0.85×",
+                style =
+                    MaterialTheme.typography.labelSmall.copy(
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    ),
+            )
+            Text(
+                text = "1.0×",
+                style =
+                    MaterialTheme.typography.labelSmall.copy(
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    ),
+            )
+            Text(
+                text = "1.5×",
+                style =
+                    MaterialTheme.typography.labelSmall.copy(
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    ),
+            )
+        }
+
         Spacer(modifier = Modifier.height(16.dp))
 
+        Text(
+            text = stringResource(R.string.settings_chat_preview_title),
+            style =
+                MaterialTheme.typography.labelMedium.copy(
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                ),
+        )
+
+        Spacer(modifier = Modifier.height(8.dp))
+
+        val currentDensity = LocalDensity.current
+        val previewDensity =
+            remember(currentDensity, chatFontScale) {
+                Density(
+                    density = currentDensity.density,
+                    fontScale = currentDensity.fontScale * chatFontScale,
+                )
+            }
+
+        CompositionLocalProvider(LocalDensity provides previewDensity) {
+            Surface(
+                modifier = Modifier.fillMaxWidth(),
+                shape = RoundedCornerShape(12.dp),
+                color = MaterialTheme.colorScheme.surfaceContainer,
+            ) {
+                Column(
+                    modifier = Modifier.padding(12.dp),
+                    verticalArrangement = Arrangement.spacedBy(8.dp),
+                ) {
+                    // User bubble preview
+                    Row(
+                        modifier = Modifier.fillMaxWidth(),
+                        horizontalArrangement = Arrangement.End,
+                    ) {
+                        Surface(
+                            shape =
+                                RoundedCornerShape(
+                                    topStart = 14.dp,
+                                    topEnd = 14.dp,
+                                    bottomStart = 14.dp,
+                                    bottomEnd = 4.dp,
+                                ),
+                            color = MaterialTheme.colorScheme.primary,
+                        ) {
+                            Text(
+                                text = stringResource(R.string.settings_chat_preview_user),
+                                style = MaterialTheme.typography.bodyMedium,
+                                color = MaterialTheme.colorScheme.onPrimary,
+                                modifier = Modifier.padding(horizontal = 10.dp, vertical = 6.dp),
+                            )
+                        }
+                    }
+
+                    // Assistant bubble preview
+                    Row(
+                        modifier = Modifier.fillMaxWidth(),
+                        horizontalArrangement = Arrangement.Start,
+                    ) {
+                        Surface(
+                            shape =
+                                RoundedCornerShape(
+                                    topStart = 14.dp,
+                                    topEnd = 14.dp,
+                                    bottomStart = 4.dp,
+                                    bottomEnd = 14.dp,
+                                ),
+                            color = MaterialTheme.colorScheme.surfaceContainerHigh,
+                        ) {
+                            Text(
+                                text = stringResource(R.string.settings_chat_preview_agent),
+                                style = MaterialTheme.typography.bodyMedium,
+                                color = MaterialTheme.colorScheme.onSurface,
+                                modifier = Modifier.padding(horizontal = 10.dp, vertical = 6.dp),
+                            )
+                        }
+                    }
+                }
+            }
+        }
+
+        Spacer(modifier = Modifier.height(20.dp))
+
         Row(
             modifier = Modifier.fillMaxWidth(),
             horizontalArrangement = Arrangement.SpaceBetween,

app/src/main/res/values-ko/strings.xml

@@ -187,6 +187,17 @@
     <string name="settings_item_typing_delay">지연: %1$d ms</string>
     <string name="settings_delay_10ms">10 ms</string>
     <string name="settings_delay_100ms">100 ms</string>
+    <string name="settings_item_chat_font_size">채팅 글꼴 크기</string>
+    <string name="settings_desc_chat_font_size">채팅 메시지의 텍스트 크기를 조절합니다</string>
+    <string name="settings_font_scale_value">글꼴 크기: %1$s</string>
+    <string name="settings_font_scale_small">작게 (0.85×)</string>
+    <string name="settings_font_scale_default">기본 (1.0×)</string>
+    <string name="settings_font_scale_large">크게 (1.15×)</string>
+    <string name="settings_font_scale_xlarge">아주 크게 (1.3×)</string>
+    <string name="settings_font_scale_huge">최대 (1.5×)</string>
+    <string name="settings_chat_preview_title">미리보기</string>
+    <string name="settings_chat_preview_user">채팅 텍스트 크기를 조절할 수 있나요?</string>
+    <string name="settings_chat_preview_agent">완료되었습니다! 여기에서 글꼴 크기를 조정할 수 있습니다.</string>
     <string name="settings_action_test_connection">연결 테스트</string>
     <string name="settings_sec_about">정보</string>
     <string name="settings_about_app_name">헤르메스 모바일</string>

app/src/main/res/values-zh/strings.xml

@@ -184,6 +184,17 @@
     <string name="settings_item_typing_delay">延迟：%1$d 毫秒</string>
     <string name="settings_delay_10ms">10 毫秒</string>
     <string name="settings_delay_100ms">100 毫秒</string>
+    <string name="settings_item_chat_font_size">聊天字体大小</string>
+    <string name="settings_desc_chat_font_size">缩放聊天消息文字大小</string>
+    <string name="settings_font_scale_value">字体大小：%1$s</string>
+    <string name="settings_font_scale_small">小 (0.85×)</string>
+    <string name="settings_font_scale_default">默认 (1.0×)</string>
+    <string name="settings_font_scale_large">大 (1.15×)</string>
+    <string name="settings_font_scale_xlarge">特大 (1.3×)</string>
+    <string name="settings_font_scale_huge">极大 (1.5×)</string>
+    <string name="settings_chat_preview_title">预览</string>
+    <string name="settings_chat_preview_user">可以调整聊天字体大小吗？</string>
+    <string name="settings_chat_preview_agent">已搞定！你可以在这里自定义字体缩放比例。</string>
     <string name="settings_action_test_connection">测试连接</string>
     <string name="settings_sec_about">关于</string>
     <string name="settings_sec_language">语言</string>

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

@@ -207,6 +207,17 @@
     <string name="settings_item_typing_delay">Delay: %1$d ms</string>
     <string name="settings_delay_10ms">10 ms</string>
     <string name="settings_delay_100ms">100 ms</string>
+    <string name="settings_item_chat_font_size">Chat Font Size</string>
+    <string name="settings_desc_chat_font_size">Scale text size in chat messages</string>
+    <string name="settings_font_scale_value">Font Size: %1$s</string>
+    <string name="settings_font_scale_small">Small (0.85×)</string>
+    <string name="settings_font_scale_default">Default (1.0×)</string>
+    <string name="settings_font_scale_large">Large (1.15×)</string>
+    <string name="settings_font_scale_xlarge">Extra Large (1.3×)</string>
+    <string name="settings_font_scale_huge">Huge (1.5×)</string>
+    <string name="settings_chat_preview_title">Preview</string>
+    <string name="settings_chat_preview_user">Can you adjust the chat text size?</string>
+    <string name="settings_chat_preview_agent">Done! You can customize the font scale right here.</string>
     <string name="settings_action_test_connection">Test Connection</string>
     <string name="settings_sec_about">About</string>
     <string name="settings_sec_language">Language</string>

app/src/test/java/com/m57/hermescontrol/data/config/ServerStoreTest.kt

@@ -15,6 +15,7 @@ class ServerStoreTest {
         assertEquals(9119, state.port)
         assertTrue(state.autoReconnect)
         assertEquals("token", state.wsAuthParam)
+        assertEquals(1.0f, state.chatFontScale)
         assertTrue(state.connectionProfiles.isEmpty())
         assertNull(state.selectedProfileId)
     }

app/src/test/java/com/m57/hermescontrol/ui/settings/SettingsViewModelTest.kt

@@ -68,6 +68,7 @@ class SettingsViewModelTest {
         every { AuthManager.getThemePreset() } returns ThemePreset.DEFAULT
         every { AuthManager.isTypingEffectEnabled() } returns true
         every { AuthManager.getTypingEffectDelayMs() } returns 30
+        every { AuthManager.getChatFontScale() } returns 1.0f
         every { AuthManager.getConnectionProfiles() } returns emptyList()
         every { AuthManager.getSelectedProfileId() } answers { storedSelectedProfileId }
         every { AuthManager.baseUrl() } returns "http://127.0.0.1:9119/"
@@ -79,6 +80,7 @@ class SettingsViewModelTest {
         every { AuthManager.setThemePreset(any()) } returns Unit
         every { AuthManager.setTypingEffectEnabled(any()) } returns Unit
         every { AuthManager.setTypingEffectDelayMs(any()) } returns Unit
+        every { AuthManager.setChatFontScale(any()) } returns Unit
         every { AuthManager.setSelectedProfileId(any()) } answers {
             storedSelectedProfileId = firstArg()
         }
@@ -130,6 +132,7 @@ class SettingsViewModelTest {
             every { AuthManager.getThemePreset() } returns ThemePreset.CATPPUCCIN
             every { AuthManager.isTypingEffectEnabled() } returns false
             every { AuthManager.getTypingEffectDelayMs() } returns 15
+            every { AuthManager.getChatFontScale() } returns 1.30f
             every { AuthManager.getConnectionProfiles() } returns testProfiles
             every { AuthManager.getAppLanguage() } returns "fr"
 
@@ -146,12 +149,23 @@ class SettingsViewModelTest {
             assertEquals(ThemePreset.CATPPUCCIN, state.themePreset)
             assertEquals(false, state.typingEffectEnabled)
             assertEquals(15, state.typingEffectDelayMs)
+            assertEquals(1.30f, state.chatFontScale)
             assertEquals(testProfiles, state.profiles)
             assertEquals("prof-2", state.selectedProfileId)
             assertEquals("Home", state.renameProfileName)
             assertEquals("fr", state.appLanguage)
         }
 
+    @Test
+    fun testOnChatFontScaleChange_updatesStateAndAuthManager() {
+        val viewModel = createViewModel()
+
+        viewModel.onChatFontScaleChange(1.15f)
+
+        assertEquals(1.15f, viewModel.uiState.value.chatFontScale)
+        verify { AuthManager.setChatFontScale(1.15f) }
+    }
+
     @Test
     fun testLoadSettings_noSelectedProfile_renameEmpty() {
         every { AuthManager.getConnectionProfiles() } returns testProfiles