feat(desktop): add classifyPreviewLink classifier

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

desktop/src/lib/previewLinkRouter.test.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from 'vitest'
+import { classifyPreviewLink } from './previewLinkRouter'
+
+describe('classifyPreviewLink', () => {
+  it('classifies loopback urls as browser-localhost', () => {
+    expect(classifyPreviewLink('http://localhost:5173/').kind).toBe('browser-localhost')
+    expect(classifyPreviewLink('http://127.0.0.1:8080/x').kind).toBe('browser-localhost')
+  })
+  it('classifies html file paths as browser-file', () => {
+    expect(classifyPreviewLink('file:///Users/x/index.html').kind).toBe('browser-file')
+    expect(classifyPreviewLink('/Users/x/page.htm').kind).toBe('browser-file')
+    expect(classifyPreviewLink('./out/index.html').kind).toBe('browser-file')
+  })
+  it('classifies relative previewable docs as file-preview', () => {
+    expect(classifyPreviewLink('docs/report.md').kind).toBe('file-preview')
+    expect(classifyPreviewLink('src/app.ts').kind).toBe('file-preview')
+  })
+  it('classifies remote http(s) as remote', () => {
+    expect(classifyPreviewLink('https://example.com').kind).toBe('remote')
+  })
+  it('ignores anchors and empty', () => {
+    expect(classifyPreviewLink('#section').kind).toBe('ignored')
+    expect(classifyPreviewLink('').kind).toBe('ignored')
+  })
+  it('exposes a normalized path for file kinds', () => {
+    expect(classifyPreviewLink('file:///Users/x/index.html').path).toBe('/Users/x/index.html')
+    expect(classifyPreviewLink('docs/report.md').path).toBe('docs/report.md')
+  })
+})

desktop/src/lib/previewLinkRouter.ts

@@ -0,0 +1,45 @@
+import { isLoopbackHostname } from './desktopRuntime'
+
+export type PreviewLinkKind =
+  | 'browser-localhost'
+  | 'browser-file'
+  | 'file-preview'
+  | 'remote'
+  | 'ignored'
+
+export type PreviewLinkClass = { kind: PreviewLinkKind; path?: string; url?: string }
+
+const PREVIEWABLE_EXT = new Set(['md', 'markdown', 'txt', 'ts', 'tsx', 'js', 'jsx', 'json', 'css', 'py', 'rs', 'go', 'java', 'sh', 'yml', 'yaml', 'png', 'jpg', 'jpeg', 'gif', 'svg'])
+
+function extOf(p: string): string {
+  const m = /\.([a-z0-9]+)(?:[?#].*)?$/i.exec(p)
+  const g = m?.[1]
+  return g ? g.toLowerCase() : ''
+}
+
+export function classifyPreviewLink(href: string): PreviewLinkClass {
+  const raw = href.trim()
+  if (!raw || raw.startsWith('#')) return { kind: 'ignored' }
+
+  try {
+    const u = new URL(raw)
+    if (u.protocol === 'http:' || u.protocol === 'https:') {
+      return isLoopbackHostname(u.hostname)
+        ? { kind: 'browser-localhost', url: u.toString() }
+        : { kind: 'remote', url: u.toString() }
+    }
+    if (u.protocol === 'file:') {
+      return { kind: 'browser-file', path: decodeURIComponent(u.pathname) }
+    }
+    return { kind: 'ignored' }
+  } catch {
+    // not an absolute URL → treat as a path
+  }
+
+  const ext = extOf(raw)
+  if (ext === 'html' || ext === 'htm') return { kind: 'browser-file', path: raw }
+  if (PREVIEWABLE_EXT.has(ext)) {
+    return raw.startsWith('/') ? { kind: 'browser-file', path: raw } : { kind: 'file-preview', path: raw }
+  }
+  return { kind: 'ignored' }
+}