refactor(chat): tool display cleanup — split ChatBubble.kt god file, drop dead code (#762)

* refactor(chat): extract tool display subsystem from ChatBubble.kt

ChatBubble.kt was a 2578-line god file. Split it into four files in the
same package (zero import churn, no behavior change):

- ChatBubble.kt: user/assistant/system bubbles + dispatch + shared
  helpers (formatTimestamp, buildHighlightedString, InlineAttachment)
- ParsedToolData.kt: the parsed tool payload model
- ToolResultParser.kt: parseToolOutput + per-tool formatters + the
  Gson-compat JSON shims and tolerant exit_code parser
- ToolBubble.kt: ToolBubble + ExpandedToolContent + HeaderRow +
  SecurityRiskChip + CopyButton

formatTimestamp became internal (shared with ToolBubble.kt).
Verified: ktlintCheck + testDebugUnitTest green locally.

* refactor(chat): drop dead ParsedToolData fields and unused shim

Verified via grep: parsed.args / parsed.result / parsed.stderr /
parsed.isRunning / parsed.toolName had zero readers across app/src
(main + test + androidTest). toolName + isRunning are asserted by
ToolBubbleParsingTest, so they stay; args/result/stderr were built by
every formatter (21 construction sites) and never read — removing them
also kills a JSON.stringify-per-tool-complete wasted map build.

keySet() shim had no call sites. formatTodoToolOutput's args param
became unused with the field removal — dropped it too.

Verified: ktlintCheck + testDebugUnitTest green locally.

* refactor(chat): drop unused lastSessionId and ToolBubble isDarkTheme param

ChatScrollController.lastSessionId: introduced in #683, never read or
written since (namefreq scan + git log -S confirm single occurrence at
declaration). Session-change detection moved to lastTailKey/
lastMessageCount.

ToolBubble.isDarkTheme: never read in the body (MaterialTheme +
statusColors do the theming); single call site updated.

Verified: ktlintCheck + compileDebugKotlin green locally.

---------

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

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

@@ -0,0 +1,20 @@
+package com.m57.hermescontrol.ui.chat
+
+/**
+ * Cleanly parsed representation of a tool call, extracted from the
+ * tool.complete JSON payload (which contains both args and result).
+ */
+data class ParsedToolData(
+    val toolName: String = "",
+    val isTerminal: Boolean = false,
+    val stdout: String? = null,
+    val exitCode: Int? = null,
+    val error: String? = null,
+    val summaryText: String? = null,
+    val durationSec: Double? = null,
+    val mainOutput: String? = null,
+    val extraFields: Map<String, String> = emptyMap(),
+    val isRunning: Boolean = false,
+    val diffOutput: String? = null,
+    val diffPath: String? = null,
+)

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

@@ -0,0 +1,528 @@
+package com.m57.hermescontrol.ui.chat
+
+import android.content.ClipData
+import android.text.format.DateFormat
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.animateContentSize
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.scaleIn
+import androidx.compose.animation.scaleOut
+import androidx.compose.foundation.clickable
+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.offset
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.text.selection.SelectionContainer
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Build
+import androidx.compose.material.icons.filled.CheckCircle
+import androidx.compose.material.icons.filled.ContentCopy
+import androidx.compose.material.icons.filled.Error
+import androidx.compose.material3.Card
+import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.ClipEntry
+import androidx.compose.ui.platform.LocalClipboard
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.testTag
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.Role
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextDecoration
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import com.m57.hermescontrol.R
+import com.m57.hermescontrol.theme.HermesStatusColors
+import com.m57.hermescontrol.theme.LocalHermesStatusColors
+import com.m57.hermescontrol.ui.chat.components.DiffViewCard
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+
+@Composable
+private fun ExpandedToolContent(
+    parsed: ParsedToolData,
+    contentColor: Color,
+    statusColors: HermesStatusColors,
+) {
+    Column(verticalArrangement = Arrangement.spacedBy(4.dp)) {
+        // Summary line at top of expanded view
+        if (parsed.summaryText != null) {
+            Text(
+                text = parsed.summaryText,
+                style =
+                    MaterialTheme.typography.bodySmall.copy(
+                        color = contentColor.copy(alpha = 0.7f),
+                        fontFamily = FontFamily.Monospace,
+                        fontSize = 11.sp,
+                    ),
+            )
+            Spacer(modifier = Modifier.height(2.dp))
+        }
+
+        if (parsed.isTerminal) {
+            // ── Terminal output ──
+            parsed.stdout?.let {
+                Text(
+                    text = it,
+                    style =
+                        MaterialTheme.typography.bodySmall.copy(
+                            color = contentColor.copy(alpha = 0.9f),
+                            fontFamily = FontFamily.Monospace,
+                            fontSize = 11.sp,
+                        ),
+                )
+            }
+            parsed.error?.let {
+                Text(
+                    text = stringResource(R.string.chat_tool_execution_error, it),
+                    style =
+                        MaterialTheme.typography.bodySmall.copy(
+                            color = statusColors.error,
+                            fontWeight = FontWeight.Bold,
+                            fontFamily = FontFamily.Monospace,
+                            fontSize = 11.sp,
+                        ),
+                )
+            }
+            parsed.exitCode?.let { code ->
+                if (code != 0) {
+                    Text(
+                        text = stringResource(R.string.chat_tool_exit_code, code),
+                        style =
+                            MaterialTheme.typography.labelSmall.copy(
+                                color = statusColors.error,
+                                fontWeight = FontWeight.Medium,
+                            ),
+                    )
+                }
+            }
+
+            // Duration footer for terminal
+            parsed.durationSec?.let { dur ->
+                Text(
+                    text = "Duration: ${"%.1f".format(dur)}s",
+                    style =
+                        MaterialTheme.typography.labelSmall.copy(
+                            color = contentColor.copy(alpha = 0.5f),
+                        ),
+                )
+            }
+        } else {
+            // ── Generic tool output / Diff view ──
+            if (parsed.diffOutput != null) {
+                DiffViewCard(
+                    diffText = parsed.diffOutput,
+                    filePath = parsed.diffPath,
+                )
+            } else {
+                parsed.mainOutput?.let {
+                    Text(
+                        text = it,
+                        style =
+                            MaterialTheme.typography.bodySmall.copy(
+                                color = contentColor.copy(alpha = 0.9f),
+                                fontSize = 12.sp,
+                            ),
+                    )
+                }
+                parsed.extraFields.forEach { (key, value) ->
+                    Row(
+                        modifier = Modifier.fillMaxWidth(),
+                        horizontalArrangement = Arrangement.spacedBy(4.dp),
+                    ) {
+                        Text(
+                            text = "$key:",
+                            style =
+                                MaterialTheme.typography.labelSmall.copy(
+                                    color = contentColor.copy(alpha = 0.6f),
+                                    fontWeight = FontWeight.Bold,
+                                ),
+                        )
+                        Text(
+                            text = value,
+                            style =
+                                MaterialTheme.typography.bodySmall.copy(
+                                    color = contentColor.copy(alpha = 0.9f),
+                                    fontSize = 11.sp,
+                                ),
+                        )
+                    }
+                }
+            }
+        }
+        // Duration footer
+        parsed.durationSec?.let { dur ->
+            Text(
+                text = "Duration: ${"%.1f".format(dur)}s",
+                style =
+                    MaterialTheme.typography.labelSmall.copy(
+                        color = contentColor.copy(alpha = 0.5f),
+                    ),
+            )
+        }
+    }
+}
+
+@Composable
+internal fun ToolBubble(
+    message: ChatMessage,
+    modifier: Modifier = Modifier,
+) {
+    var expanded by remember { mutableStateOf(false) }
+    var showRawJson by remember { mutableStateOf(false) }
+    val chipColor = MaterialTheme.colorScheme.surfaceContainerHigh
+    val contentColor = MaterialTheme.colorScheme.onSurfaceVariant
+    val statusColors = LocalHermesStatusColors.current
+
+    val parsed =
+        remember(message.content, message.toolName, message.toolStatus) {
+            parseToolOutput(message.content, message.toolName, message.toolStatus == ToolStatus.RUNNING)
+        }
+    val config = ToolSchemaRegistry.getDisplayConfig(message.toolName)
+
+    val clipboard = LocalClipboard.current
+    val scope = rememberCoroutineScope()
+    var showCopyButton by remember { mutableStateOf(false) }
+
+    // Auto-dismiss copy button after 4 seconds
+    LaunchedEffect(showCopyButton) {
+        if (showCopyButton) {
+            delay(4000)
+            showCopyButton = false
+        }
+    }
+
+    Box(
+        modifier =
+            modifier
+                .fillMaxWidth()
+                .padding(horizontal = 8.dp, vertical = 1.dp),
+        contentAlignment = Alignment.CenterStart,
+    ) {
+        Card(
+            onClick = { expanded = !expanded },
+            colors = CardDefaults.cardColors(containerColor = chipColor),
+            shape = RoundedCornerShape(8.dp),
+        ) {
+            Column(
+                modifier =
+                    Modifier
+                        .animateContentSize()
+                        .padding(horizontal = 10.dp, vertical = 6.dp),
+            ) {
+                // ── Header row: icon + tool name ──
+                HeaderRow(message, config, contentColor, statusColors)
+
+                // ── Tool progress preview (tool.progress) ──
+                if (message.toolStatus == ToolStatus.RUNNING && !message.progressPreview.isNullOrEmpty()) {
+                    Text(
+                        text = message.progressPreview,
+                        style =
+                            MaterialTheme.typography.bodySmall.copy(
+                                color = contentColor.copy(alpha = 0.7f),
+                                fontFamily = FontFamily.Monospace,
+                                fontSize = 11.sp,
+                            ),
+                        maxLines = 1,
+                        overflow = TextOverflow.Ellipsis,
+                        modifier = Modifier.padding(top = 4.dp, start = 22.dp),
+                    )
+                }
+
+                // ── Security risk chip (tool.output_risk) ──
+                val riskData = message.toolOutputRiskData
+                if (riskData != null && (riskData.risk == "medium" || riskData.risk == "high" || riskData.redacted)) {
+                    SecurityRiskChip(riskData, contentColor)
+                }
+
+                // ── Summary line (always visible when collapsed) ──
+                if (!expanded && parsed?.summaryText != null) {
+                    Text(
+                        text = parsed.summaryText,
+                        style =
+                            MaterialTheme.typography.bodySmall.copy(
+                                color = contentColor.copy(alpha = 0.7f),
+                                fontFamily = FontFamily.Monospace,
+                                fontSize = 11.sp,
+                            ),
+                        maxLines = 1,
+                        overflow = TextOverflow.Ellipsis,
+                        modifier = Modifier.padding(top = 4.dp, start = 22.dp),
+                    )
+                }
+
+                // ── Expanded content ──
+                if (expanded) {
+                    Spacer(modifier = Modifier.height(6.dp))
+
+                    if (showRawJson) {
+                        // Raw JSON view — selectable + copy button
+                        Box {
+                            SelectionContainer {
+                                Text(
+                                    text = message.content,
+                                    style =
+                                        MaterialTheme.typography.bodySmall.copy(
+                                            color = contentColor.copy(alpha = 0.8f),
+                                            fontFamily = FontFamily.Monospace,
+                                            fontSize = 11.sp,
+                                        ),
+                                )
+                            }
+                            CopyButton(
+                                visible = showCopyButton,
+                                textToCopy = message.content,
+                                onCopy = { showCopyButton = false },
+                                modifier =
+                                    Modifier
+                                        .align(Alignment.TopEnd)
+                                        .offset(x = 8.dp, y = (-8).dp),
+                            )
+                        }
+
+                        Spacer(modifier = Modifier.height(8.dp))
+                        Text(
+                            text = stringResource(R.string.chat_tool_show_parsed),
+                            style =
+                                MaterialTheme.typography.labelSmall.copy(
+                                    color = MaterialTheme.colorScheme.primary,
+                                    textDecoration = TextDecoration.Underline,
+                                ),
+                            modifier =
+                                Modifier
+                                    .testTag("chat_tool_show_parsed")
+                                    .clickable(role = Role.Button) { showRawJson = false },
+                        )
+                    } else if (parsed != null) {
+                        // Clean structured expanded view
+                        Box {
+                            SelectionContainer {
+                                ExpandedToolContent(parsed, contentColor, statusColors)
+                            }
+                            CopyButton(
+                                visible = showCopyButton,
+                                textToCopy = message.content,
+                                onCopy = { showCopyButton = false },
+                                modifier =
+                                    Modifier
+                                        .align(Alignment.TopEnd)
+                                        .offset(x = 8.dp, y = (-8).dp),
+                            )
+                        }
+
+                        Spacer(modifier = Modifier.height(8.dp))
+                        Text(
+                            text = stringResource(R.string.chat_tool_show_raw),
+                            style =
+                                MaterialTheme.typography.labelSmall.copy(
+                                    color = MaterialTheme.colorScheme.primary,
+                                    textDecoration = TextDecoration.Underline,
+                                ),
+                            modifier =
+                                Modifier
+                                    .testTag("chat_tool_show_raw")
+                                    .clickable(role = Role.Button) { showRawJson = true },
+                        )
+                    } else {
+                        // Unparseable content — show raw JSON, selectable
+                        Box {
+                            SelectionContainer {
+                                Text(
+                                    text = message.content,
+                                    style =
+                                        MaterialTheme.typography.bodySmall.copy(
+                                            color = contentColor.copy(alpha = 0.8f),
+                                            fontFamily = FontFamily.Monospace,
+                                            fontSize = 11.sp,
+                                        ),
+                                )
+                            }
+                            CopyButton(
+                                visible = showCopyButton,
+                                textToCopy = message.content,
+                                onCopy = { showCopyButton = false },
+                                modifier =
+                                    Modifier
+                                        .align(Alignment.TopEnd)
+                                        .offset(x = 8.dp, y = (-8).dp),
+                            )
+                        }
+                    }
+                }
+
+                // ── Timestamp ──
+                Text(
+                    text = formatTimestamp(message.timestamp, DateFormat.is24HourFormat(LocalContext.current)),
+                    color = contentColor.copy(alpha = 0.5f),
+                    style = MaterialTheme.typography.labelSmall,
+                    modifier = Modifier.align(Alignment.End).padding(top = 4.dp),
+                )
+            }
+        }
+    }
+}
+
+@Composable
+private fun HeaderRow(
+    message: ChatMessage,
+    config: ToolDisplayConfig,
+    contentColor: Color,
+    statusColors: HermesStatusColors,
+) {
+    Row(
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(8.dp),
+    ) {
+        // Status icon or spinner
+        if (message.toolStatus == ToolStatus.RUNNING) {
+            CircularProgressIndicator(
+                modifier = Modifier.size(14.dp),
+                strokeWidth = 2.dp,
+                color = MaterialTheme.colorScheme.secondary,
+            )
+        } else {
+            val icon =
+                when (message.toolStatus) {
+                    ToolStatus.COMPLETED -> Icons.Filled.CheckCircle
+                    ToolStatus.FAILED -> Icons.Filled.Error
+                    else -> Icons.Filled.Build
+                }
+            val tint =
+                when (message.toolStatus) {
+                    ToolStatus.COMPLETED -> statusColors.success
+                    ToolStatus.FAILED -> statusColors.error
+                    else -> contentColor.copy(alpha = 0.6f)
+                }
+            Icon(
+                imageVector = icon,
+                contentDescription = null,
+                modifier = Modifier.size(14.dp),
+                tint = tint,
+            )
+        }
+
+        Text(
+            text = message.toolName ?: stringResource(R.string.chat_tool_fallback),
+            style =
+                MaterialTheme.typography.labelMedium.copy(
+                    color = contentColor,
+                    fontFamily = FontFamily.Monospace,
+                ),
+        )
+    }
+}
+
+/**
+ * Security risk chip for [tool.output_risk] events.
+ *
+ * Shows a compact ⚠ badge when the backend flagged tool output as risky.
+ * Renders in the tool card between the header row and the summary line.
+ */
+@Composable
+private fun SecurityRiskChip(
+    riskData: ToolOutputRiskData,
+    contentColor: Color,
+    modifier: Modifier = Modifier,
+) {
+    val statusColors = LocalHermesStatusColors.current
+    val (chipColor, label) =
+        when {
+            riskData.risk == "high" -> statusColors.error to "Risky output"
+            riskData.risk == "medium" -> statusColors.warning to "Caution"
+            else -> statusColors.warning to "Redacted"
+        }
+
+    Row(
+        modifier =
+            modifier
+                .padding(top = 4.dp, start = 22.dp),
+        verticalAlignment = Alignment.CenterVertically,
+        horizontalArrangement = Arrangement.spacedBy(4.dp),
+    ) {
+        Text(
+            text = "⚠",
+            style = MaterialTheme.typography.labelSmall,
+            color = chipColor,
+        )
+        Text(
+            text = label,
+            style =
+                MaterialTheme.typography.labelSmall.copy(
+                    fontWeight = FontWeight.Medium,
+                ),
+            color = chipColor,
+        )
+        if (riskData.redacted && (riskData.risk == "high" || riskData.risk == "medium")) {
+            Text(
+                text = "· redacted",
+                style = MaterialTheme.typography.labelSmall,
+                color = chipColor.copy(alpha = 0.7f),
+            )
+        }
+    }
+}
+
+@Composable
+private fun CopyButton(
+    visible: Boolean,
+    textToCopy: String,
+    onCopy: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    val clipboard = LocalClipboard.current
+    val scope = rememberCoroutineScope()
+    AnimatedVisibility(
+        visible = visible,
+        enter = fadeIn() + scaleIn(),
+        exit = fadeOut() + scaleOut(),
+        modifier = modifier,
+    ) {
+        Surface(
+            shape = RoundedCornerShape(50),
+            color = MaterialTheme.colorScheme.surface.copy(alpha = 0.95f),
+            shadowElevation = 6.dp,
+        ) {
+            IconButton(
+                onClick = {
+                    scope.launch {
+                        clipboard.setClipEntry(ClipEntry(ClipData.newPlainText(null, textToCopy)))
+                    }
+                    onCopy()
+                },
+                modifier = Modifier.size(32.dp),
+            ) {
+                Icon(
+                    Icons.Filled.ContentCopy,
+                    contentDescription = stringResource(R.string.content_desc_copy),
+                    modifier = Modifier.size(16.dp),
+                    tint = MaterialTheme.colorScheme.onSurface,
+                )
+            }
+        }
+    }
+}

app/src/main/java/com/m57/hermescontrol/ui/chat/components/ChatScrollController.kt

@@ -54,7 +54,6 @@ class ChatScrollController(
     var pendingCount by mutableStateOf(0)
         private set
 
-    private var lastSessionId: String? = null
     private var lastTailKey: Any? = null
     private var lastMessageCount: Int = 0