fix(web): re-apply main's round-10 markdown fixes inside the factory

Four behavior fixes from main's inline-renderer architecture, re-expressed
in the branch's extracted ChatMarkdown factory where the rebase could not
carry them:

- #7741: file-link tooltips show the full target path, not the shortened
  display form the chip already shows
- #7856: ordered-list marker gutters size by marker width (string starts,
  negative markers, first-vs-last width) instead of digit count alone
- #6439: link-href extraction uses the shared spaced-path-aware helper,
  so command-clicking 'my folder/file.ts' links works
- #8098: file links only default to the in-app browser for browser-native
  documents; agent file links open in the file viewer again

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: juliusmarminge

apps/web/src/components/ChatMarkdown.tsx

@@ -99,6 +99,8 @@ import {
 } from "../markdown-clipboard";
 import { remarkNormalizeListItemIndentation } from "../markdown-list-indentation";
 import {
+  shouldOpenMarkdownFileLinkInBrowserByDefault,
+  extractMarkdownLinkHrefs,
   normalizeMarkdownLinkDestination,
   resolveInlineCodeFileLinkMeta,
   resolveMarkdownFileLinkMeta,
@@ -250,13 +252,15 @@ function findTaskListMarkerOffset(markdown: string, listItemStart: number): numb
  */
 export function orderedListGutterStyle(
   itemCount: number,
-  start: number | undefined,
+  start: unknown,
 ): { "--list-gutter": string } | undefined {
-  const firstNumber = typeof start === "number" && Number.isFinite(start) ? start : 1;
+  const parsedStart = Number.parseInt(String(start ?? 1), 10);
+  const firstNumber = Number.isNaN(parsedStart) ? 1 : parsedStart;
   const lastNumber = firstNumber + Math.max(itemCount - 1, 0);
-  const digits = String(Math.abs(lastNumber)).length;
-  if (digits <= 2) return undefined;
-  return { "--list-gutter": `${digits + 1}ch` };
+  // The width includes a negative marker's minus sign (#7856).
+  const markerWidth = Math.max(String(firstNumber).length, String(lastNumber).length);
+  if (markerWidth <= 2) return undefined;
+  return { "--list-gutter": `${markerWidth + 1}ch` };
 }
 
 const CHAT_MARKDOWN_SANITIZE_SCHEMA = {
@@ -908,7 +912,6 @@ interface MarkdownFileLinkProps {
   className?: string | undefined;
 }
 
-const MARKDOWN_LINK_HREF_PATTERN = /\[[^\]]*]\(([^)\s]+)(?:\s+["'][^"']*["'])?\)/g;
 const MARKDOWN_FILE_LINK_CLASS_NAME =
   "chat-markdown-file-link cursor-pointer transition-colors hover:bg-accent/70";
 
@@ -987,16 +990,6 @@ function extractInlineCodeSpans(text: string): string[] {
   return spans;
 }
 
-function extractMarkdownLinkHrefs(text: string): string[] {
-  const hrefs: string[] = [];
-  for (const match of text.matchAll(MARKDOWN_LINK_HREF_PATTERN)) {
-    const href = match[1]?.trim();
-    if (!href) continue;
-    hrefs.push(href);
-  }
-  return hrefs;
-}
-
 function normalizeMarkdownLinkHrefKey(href: string): string {
   const normalizedHref = normalizeMarkdownLinkDestination(href);
   return rewriteMarkdownFileUriHref(normalizedHref) ?? normalizedHref;
@@ -1394,7 +1387,7 @@ const MarkdownFileLink = memo(function MarkdownFileLink({
             onClick={(event) => {
               event.preventDefault();
               event.stopPropagation();
-              if (onOpenInBrowser) {
+              if (onOpenInBrowser && shouldOpenMarkdownFileLinkInBrowserByDefault(iconPath)) {
                 handleOpenInBrowser();
                 return;
               }
@@ -1411,7 +1404,9 @@ const MarkdownFileLink = memo(function MarkdownFileLink({
         className="max-w-[min(40rem,calc(100vw-2rem))] font-mono text-[11px] leading-tight"
       >
         <div className="overflow-x-auto whitespace-nowrap [scrollbar-color:color-mix(in_srgb,var(--border)_78%,transparent)_transparent] [scrollbar-width:thin] [&::-webkit-scrollbar]:h-1.5 [&::-webkit-scrollbar-thumb]:rounded-full [&::-webkit-scrollbar-thumb]:bg-[color-mix(in_srgb,var(--border)_78%,transparent)] [&::-webkit-scrollbar-track]:bg-transparent">
-          {displayPath}
+          {/* The full path: the chip already shows the shortened form, and a link
+              to the workspace root collapses to a bare label that repeats it. */}
+          {targetPath}
         </div>
       </TooltipPopup>
     </Tooltip>