refactor: tighten tool call badge hover affordances

Move the open-file button inline after the summary text so the click
target sits next to what it acts on, and replace the tool icon with the
chevron on hover instead of showing a separate chevron at the row's end.
Hovering the icon slot keeps the tool icon visible for predictability.

packages/app/src/components/message.tsx

@@ -997,7 +997,8 @@ const expandableBadgeStylesheet = StyleSheet.create((theme) => ({
     opacity: 0.72,
   },
   secondaryLabel: {
-    flex: 1,
+    flexShrink: 1,
+    minWidth: 0,
     color: theme.colors.foregroundMuted,
     fontSize: theme.fontSize.base,
     fontWeight: theme.fontWeight.normal,
@@ -2064,7 +2065,7 @@ function ExpandableBadgeSecondaryLabel({
   onSecondaryLayout,
 }: ExpandableBadgeSecondaryLabelProps) {
   if (!secondaryLabel) {
-    return <View style={expandableBadgeStylesheet.spacer} />;
+    return null;
   }
   return (
     <Text
@@ -2125,6 +2126,11 @@ interface ExpandableBadgeLabelRowProps {
   onLabelRowLayout: (event: LayoutChangeEvent) => void;
   onLabelLayout: (event: LayoutChangeEvent) => void;
   onSecondaryLayout: (event: LayoutChangeEvent) => void;
+  showOpenFileButton: boolean;
+  isOpenFileHovered: boolean;
+  onOpenFilePress: (event: GestureResponderEvent) => void;
+  onOpenFileHoverIn: () => void;
+  onOpenFileHoverOut: () => void;
 }
 
 function ExpandableBadgeLabelRow({
@@ -2146,7 +2152,13 @@ function ExpandableBadgeLabelRow({
   onLabelRowLayout,
   onLabelLayout,
   onSecondaryLayout,
+  showOpenFileButton,
+  isOpenFileHovered,
+  onOpenFilePress,
+  onOpenFileHoverIn,
+  onOpenFileHoverOut,
 }: ExpandableBadgeLabelRowProps) {
+  const { theme } = useUnistyles();
   return (
     <View
       style={expandableBadgeStylesheet.labelRow}
@@ -2165,6 +2177,23 @@ function ExpandableBadgeLabelRow({
         shouldMeasureWebShimmer={shouldMeasureWebShimmer}
         onSecondaryLayout={onSecondaryLayout}
       />
+      {showOpenFileButton ? (
+        <Pressable
+          onPress={onOpenFilePress}
+          onHoverIn={onOpenFileHoverIn}
+          onHoverOut={onOpenFileHoverOut}
+          accessibilityRole="button"
+          accessibilityLabel="Open file"
+          testID="tool-call-open-file"
+          style={expandableBadgeStylesheet.openFileButton}
+          hitSlop={6}
+        >
+          <FileSymlink
+            size={14}
+            color={isOpenFileHovered ? theme.colors.foreground : theme.colors.foregroundMuted}
+          />
+        </Pressable>
+      ) : null}
       {isWebShimmer ? (
         <ExpandableBadgeWebShimmerOverlay
           label={label}
@@ -2221,6 +2250,23 @@ function renderExpandableBadgeIcon({
   return null;
 }
 
+function renderExpandableBadgeIconSlot({
+  showChevron,
+  chevronColor,
+  chevronStyle,
+  iconNode,
+}: {
+  showChevron: boolean;
+  chevronColor: string;
+  chevronStyle: StyleProp<ViewStyle>;
+  iconNode: ReactNode;
+}): ReactNode {
+  if (showChevron) {
+    return <ChevronRight size={14} color={chevronColor} style={chevronStyle} />;
+  }
+  return iconNode;
+}
+
 function computeShimmerMetrics(input: {
   label: string;
   secondaryLabel: string | undefined;
@@ -2343,6 +2389,7 @@ const ExpandableBadge = memo(function ExpandableBadge({
   const resolvedDisableOuterSpacing = useDisableOuterSpacing(disableOuterSpacing);
   const [isHovered, setIsHovered] = useState(false);
   const [isOpenFileHovered, setIsOpenFileHovered] = useState(false);
+  const [isIconHovered, setIsIconHovered] = useState(false);
   const [isPressed, setIsPressed] = useState(false);
   const isInteractive = Boolean(onToggle);
   const hasDetailContent = Boolean(renderDetails);
@@ -2371,6 +2418,8 @@ const ExpandableBadge = memo(function ExpandableBadge({
   );
   const handleOpenFileHoverIn = useCallback(() => setIsOpenFileHovered(true), []);
   const handleOpenFileHoverOut = useCallback(() => setIsOpenFileHovered(false), []);
+  const handleIconHoverIn = useCallback(() => setIsIconHovered(true), []);
+  const handleIconHoverOut = useCallback(() => setIsIconHovered(false), []);
 
   const nativeGradientIdRef = useRef(
     `shimmer-gradient-${Math.random().toString(36).substring(2, 9)}`,
@@ -2567,6 +2616,12 @@ const ExpandableBadge = memo(function ExpandableBadge({
 
   const iconColor = resolveExpandableBadgeIconColor({ isError, isActive, theme });
   const iconNode = renderExpandableBadgeIcon({ isError, iconColor, icon });
+  const iconSlotNode = renderExpandableBadgeIconSlot({
+    showChevron: isInteractive && isHovered && !isIconHovered,
+    chevronColor: theme.colors.foreground,
+    chevronStyle,
+    iconNode,
+  });
 
   const pressHandlers = isInteractive
     ? {
@@ -2591,7 +2646,13 @@ const ExpandableBadge = memo(function ExpandableBadge({
         style={pressableStyle}
       >
         <View style={expandableBadgeStylesheet.headerRow}>
-          <View style={expandableBadgeStylesheet.iconBadge}>{iconNode}</View>
+          <View
+            style={expandableBadgeStylesheet.iconBadge}
+            onPointerEnter={isWeb ? handleIconHoverIn : undefined}
+            onPointerLeave={isWeb ? handleIconHoverOut : undefined}
+          >
+            {iconSlotNode}
+          </View>
           <ExpandableBadgeLabelRow
             label={label}
             labelStyle={labelStyle}
@@ -2611,27 +2672,12 @@ const ExpandableBadge = memo(function ExpandableBadge({
             onLabelRowLayout={handleLabelRowLayout}
             onLabelLayout={handleLabelLayout}
             onSecondaryLayout={handleSecondaryLayout}
+            showOpenFileButton={Boolean(onOpenFile && isHovered)}
+            isOpenFileHovered={isOpenFileHovered}
+            onOpenFilePress={handleOpenFilePress}
+            onOpenFileHoverIn={handleOpenFileHoverIn}
+            onOpenFileHoverOut={handleOpenFileHoverOut}
           />
-          {onOpenFile && isHovered ? (
-            <Pressable
-              onPress={handleOpenFilePress}
-              onHoverIn={handleOpenFileHoverIn}
-              onHoverOut={handleOpenFileHoverOut}
-              accessibilityRole="button"
-              accessibilityLabel="Open file"
-              testID="tool-call-open-file"
-              style={expandableBadgeStylesheet.openFileButton}
-              hitSlop={6}
-            >
-              <FileSymlink
-                size={14}
-                color={isOpenFileHovered ? theme.colors.foreground : theme.colors.foregroundMuted}
-              />
-            </Pressable>
-          ) : null}
-          {isInteractive && isHovered ? (
-            <ChevronRight size={14} color={theme.colors.foreground} style={chevronStyle} />
-          ) : null}
         </View>
       </Pressable>
       {detailContent ? (