fix: preserve windows markdown link fragments (#4261)

src/renderer/src/components/editor/markdown-internal-links.test.ts

@@ -55,6 +55,20 @@ describe('resolveMarkdownLinkTarget', () => {
     })
   })
 
+  it('extracts hash line anchors from Windows drive-letter absolute .md links', () => {
+    const r = resolveMarkdownLinkTarget(
+      'C:\\repo\\docs\\guide.md#L10',
+      'C:\\repo\\docs\\note.md',
+      'C:\\repo'
+    )
+    expect(r).toMatchObject({
+      kind: 'markdown',
+      absolutePath: 'C:/repo/docs/guide.md',
+      relativePath: 'docs/guide.md',
+      line: 10
+    })
+  })
+
   it('extracts line from #L10', () => {
     const r = resolveMarkdownLinkTarget('./guide.md#L10', SOURCE, ROOT)
     expect(r).toMatchObject({ kind: 'markdown', line: 10, column: undefined })

src/renderer/src/components/editor/markdown-internal-links.ts

@@ -1,4 +1,8 @@
-import { filesystemPathToFileUri, fileUriToFilesystemPath } from '../../../../shared/file-uri-path'
+import {
+  filesystemPathHrefToFileUri,
+  filesystemPathToFileUri,
+  fileUriToFilesystemPath
+} from '../../../../shared/file-uri-path'
 import { isWindowsAbsolutePathLike } from '../../../../shared/cross-platform-path'
 
 // Pure classifier for markdown link targets. Called by the link-activation
@@ -112,7 +116,7 @@ function resolveRelativeToSource(rawHref: string, sourceFilePath: string): URL |
     if (isWindowsAbsolutePathLike(rawHref)) {
       // Why: URL treats `C:\...` as a custom `c:` scheme unless the Windows
       // absolute path is first converted to the file URL form used downstream.
-      return new URL(filesystemPathToFileUri(rawHref))
+      return new URL(filesystemPathHrefToFileUri(rawHref))
     }
     return new URL(rawHref, toFileUrl(sourceFilePath))
   } catch {

src/renderer/src/components/editor/markdown-preview-links.test.ts

@@ -16,6 +16,12 @@ describe('getMarkdownPreviewLinkTarget', () => {
     )
   })
 
+  it('preserves hash fragments on Windows drive-letter absolute links', () => {
+    expect(
+      getMarkdownPreviewLinkTarget('C:\\repo\\docs\\guide.md#L10', '/repo/docs/README.md')
+    ).toBe('file:///C:/repo/docs/guide.md#L10')
+  })
+
   it('preserves external links', () => {
     expect(getMarkdownPreviewLinkTarget('https://example.com/docs', '/repo/docs/README.md')).toBe(
       'https://example.com/docs'

src/renderer/src/components/editor/markdown-preview-links.ts

@@ -1,4 +1,8 @@
-import { filesystemPathToFileUri, fileUriToFilesystemPath } from '../../../../shared/file-uri-path'
+import {
+  filesystemPathHrefToFileUri,
+  filesystemPathToFileUri,
+  fileUriToFilesystemPath
+} from '../../../../shared/file-uri-path'
 import { isWindowsAbsolutePathLike } from '../../../../shared/cross-platform-path'
 
 function toFileUrl(filePath: string): string {
@@ -14,7 +18,7 @@ export function resolveMarkdownPreviewHref(rawUrl: string, filePath: string): UR
     if (isWindowsAbsolutePathLike(rawUrl)) {
       // Why: URL treats `C:\...` as a custom `c:` scheme unless we first
       // normalize the drive path into the file URL form markdown previews use.
-      return new URL(filesystemPathToFileUri(rawUrl))
+      return new URL(filesystemPathHrefToFileUri(rawUrl))
     }
     return new URL(rawUrl, toFileUrl(filePath))
   } catch {

src/shared/file-uri-path.ts

@@ -28,6 +28,30 @@ export function filesystemPathToFileUri(filePath: string): string {
   return normalizedPath.startsWith('/') ? `file://${encodedPath}` : `file:///${encodedPath}`
 }
 
+export function filesystemPathHrefToFileUri(filePathHref: string): string {
+  const suffixIndex = filePathHref.search(/[?#]/)
+  if (suffixIndex === -1) {
+    return filesystemPathToFileUri(filePathHref)
+  }
+
+  const pathPart = filePathHref.slice(0, suffixIndex)
+  const suffix = filePathHref.slice(suffixIndex)
+  const url = new URL(filesystemPathToFileUri(pathPart))
+  if (suffix.startsWith('#')) {
+    // Why: markdown href fragments like `#L10` should stay URL fragments,
+    // not become `%23L10` inside the Windows filesystem path.
+    url.hash = suffix
+    return url.toString()
+  }
+
+  const hashIndex = suffix.indexOf('#')
+  url.search = hashIndex === -1 ? suffix : suffix.slice(0, hashIndex)
+  if (hashIndex !== -1) {
+    url.hash = suffix.slice(hashIndex)
+  }
+  return url.toString()
+}
+
 export function fileUriToFilesystemPath(url: URL): string | null {
   if (url.protocol !== 'file:') {
     return null