Improve Markdown file preview readability (#3240)

* feat(app): improve markdown file previews

Keep rendered documents on the chat reading rail, surface YAML front matter as readable metadata, and make shared Markdown links retain the chat accent and hover treatment.

* fix(app): preserve unsafe frontmatter source

* test(app): cover markdown link behavior

packages/app/src/assistant-file-links/link.tsx

@@ -1,16 +1,9 @@
-import { useMemo, useState, type CSSProperties, type MouseEvent, type ReactNode } from "react";
-import {
-  Platform,
-  Pressable,
-  Text,
-  View,
-  type StyleProp,
-  type TextStyle,
-  type ViewStyle,
-} from "react-native";
+import { useMemo, type CSSProperties, type MouseEvent, type ReactNode } from "react";
+import { Platform, Text, View, type StyleProp, type TextStyle, type ViewStyle } from "react-native";
 import { StyleSheet } from "react-native-unistyles";
 import { isNative, isWeb } from "@/constants/platform";
 import { MarkdownTextSpan } from "@/components/markdown-text";
+import { MarkdownLinkText } from "@/components/markdown/link-text";
 import { AssistantLinkPressProvider, type AssistantLinkPress } from "./link-press-context";
 import { Shortcut } from "@/components/ui/shortcut";
 import { Tooltip, TooltipContent, TooltipTrigger } from "@/components/ui/tooltip";
@@ -39,7 +32,6 @@ export function AssistantMarkdownLink({
   monoSurface,
   children,
 }: AssistantMarkdownLinkProps) {
-  const [hovered, setHovered] = useState(false);
   const { target, onHoverIn, onPress, onAuxPress } = useFileLink(source);
   const { configRef } = useAssistantFileLinkResolverContext();
   const workspaceRoot = configRef.current.workspaceRoot;
@@ -55,15 +47,6 @@ export function AssistantMarkdownLink({
     event.stopPropagation();
     onAuxPress();
   });
-  const handleHoverIn = useStableEvent(() => {
-    setHovered(true);
-    onHoverIn();
-  });
-  const handleHoverOut = useStableEvent(() => setHovered(false));
-  const hoveredTextStyle = useMemo<StyleProp<TextStyle>>(
-    () => [style, hovered && { textDecorationLine: "underline" as const }],
-    [style, hovered],
-  );
   const linkPress = useMemo<AssistantLinkPress>(
     () => ({ onPress, accessibilityRole: "link" }),
     [onPress],
@@ -114,19 +97,14 @@ export function AssistantMarkdownLink({
       onAuxClickCapture={preventAnchorNavigation}
       style={LINK_ANCHOR_STYLE}
     >
-      <Pressable
-        accessibilityRole="link"
+      <MarkdownLinkText
+        dataSet={monoSurface ? MARKDOWN_CODE_LINK_DATASET : undefined}
+        style={style}
         onPress={onPress}
-        onHoverIn={handleHoverIn}
-        onHoverOut={handleHoverOut}
+        onHoverIn={onHoverIn}
       >
-        <Text
-          dataSet={monoSurface ? MARKDOWN_CODE_LINK_DATASET : undefined}
-          style={hoveredTextStyle}
-        >
-          {children}
-        </Text>
-      </Pressable>
+        {children}
+      </MarkdownLinkText>
     </a>
   );