fix: symlink 探测有界并发 + UNC 标记平台中性化（回应 CR/自审）

- fs-tree: symlink 目标 stat 从串行改为 32 并发工作池（readdir 流关闭后统一
  探测），symlink 密集/网络目标目录不再累加延迟；顺序与分类语义不变
- html-route: 解码不再重建反斜杠 UNC，统一重建为平台中性的 //server/share/...
  前斜杠形态（win32/POSIX 均正确 resolve），从而删除 windowsPathStyle 平台信号
  与 client isWindowsStylePath 助手；同时解决无 cwd 时正斜杠 UNC 的往返盲点
- 测试/文档同步；移除未使用的 isPosix

tests/fs-tree-symlink.spec.ts

@@ -86,4 +86,28 @@ describe.skipIf(!canSymlink)('fs-tree symlink listing', () => {
       rmSync(dir, { recursive: true, force: true })
     }
   })
+
+  it('classifies every row correctly across a symlink-heavy level (bounded probe)', async () => {
+    const dir = mkdtempSync(join(tmpdir(), 'dsh-sidebar-symlink-many-'))
+    mkdirSync(join(dir, 'real-dir'))
+    writeFileSync(join(dir, 'real-file.txt'), 'content')
+    try {
+      // More links than the probe concurrency cap exercises the worker pool;
+      // every directory link must still classify as a directory and every
+      // file link as a file (order is already checked by the sort assertion).
+      for (let index = 0; index < 48; index += 1) {
+        symlinkSync(join(dir, 'real-dir'), join(dir, `dir-link-${index}`))
+        symlinkSync(join(dir, 'real-file.txt'), join(dir, `file-link-${index}`))
+      }
+      const listing = await listDirectory(dir)
+      for (let index = 0; index < 48; index += 1) {
+        expect(listing.entries.find(entry => entry.name === `dir-link-${index}`))
+          .toMatchObject({ isDir: true, isSymlink: true, broken: false })
+        expect(listing.entries.find(entry => entry.name === `file-link-${index}`))
+          .toMatchObject({ isDir: false, isSymlink: true, broken: false })
+      }
+    } finally {
+      rmSync(dir, { recursive: true, force: true })
+    }
+  })
 })

tests/fs-tree.spec.ts

@@ -1,7 +1,7 @@
 import { describe, expect, it } from 'vitest'
 import { resolve } from 'node:path'
 import { compareEntries, isWithin, parentOf, requireAbsolute, rootLabel } from '../src/fs-tree.ts'
-import { isPosix, isWin32 } from './platform.ts'
+import { isWin32 } from './platform.ts'
 
 describe('fs-tree', () => {
   it('sorts directories first, then names case-insensitively', () => {

tests/html-route.spec.ts

@@ -21,22 +21,19 @@ describe('encodeHtmlUrl', () => {
       .toBe('/sidebar/html/sess-1/C%3A/Users/me/a.html')
   })
 
-  it('encodes a Windows UNC path with the // marker only for Windows-style sessions', () => {
-    // Backslash UNC is unambiguous: the marker is emitted whenever the
-    // caller declares the session Windows-style.
-    expect(encodeHtmlUrl('sess-1', '\\\\server\\share\\proj\\a.html', true))
+  it('encodes a UNC path with the // marker (backslash and forward-slash forms)', () => {
+    expect(encodeHtmlUrl('sess-1', '\\\\server\\share\\proj\\a.html'))
       .toBe('/sidebar/html/sess-1//server/share/proj/a.html')
-    // Forward-slash UNC needs the same marker on a Windows-style session.
-    expect(encodeHtmlUrl('sess-1', '//server/share/proj/a.html', true))
+    expect(encodeHtmlUrl('sess-1', '//server/share/proj/a.html'))
       .toBe('/sidebar/html/sess-1//server/share/proj/a.html')
   })
 
-  it('keeps a POSIX // path marker-free (the platform guard)', () => {
-    // A leading // is a legitimate POSIX absolute path: without the
-    // Windows-style flag it must NOT be marked as UNC, or the host would
-    // decode it back into a backslash form it then rejects.
+  it('keeps a POSIX // path marker-encoded (the marker is platform-neutral)', () => {
+    // The decoder rebuilds '//server/share/...', which node:path resolves to
+    // '/server/share/...' on POSIX and '\\server\share\...' on win32 — so the
+    // leading double slash round-trips without any platform signal.
     expect(encodeHtmlUrl('s-1', '//server/share/a.html'))
-      .toBe('/sidebar/html/s-1/server/share/a.html')
+      .toBe('/sidebar/html/s-1//server/share/a.html')
   })
 
   it('percent-encodes special characters in segments', () => {
@@ -74,19 +71,21 @@ describe('decodeHtmlUrl', () => {
     expect(resolve('C:/Users/me/a.html')).toBe('C:\\Users\\me\\a.html')
   })
 
-  it('decodes a UNC round-trip back to the network path', () => {
-    const url = encodeHtmlUrl('sess-1', '\\\\server\\share\\proj\\a.html', true)
+  it('decodes a UNC round-trip back to the platform-neutral forward-slash form', () => {
+    const url = encodeHtmlUrl('sess-1', '\\\\server\\share\\proj\\a.html')
     expect(decodeHtmlUrl(url)).toEqual({
       ok: true,
-      ref: { sessionId: 'sess-1', path: '\\\\server\\share\\proj\\a.html' },
+      ref: { sessionId: 'sess-1', path: '//server/share/proj/a.html' },
     })
+    // The host's requireAbsolute resolves that form per-platform:
+    // '\\server\share\proj\a.html' on win32, '/server/share/proj/a.html' on POSIX.
   })
 
-  it('decodes a marker-free POSIX // path as a plain absolute path', () => {
+  it('round-trips a POSIX // path through the same marker', () => {
     const url = encodeHtmlUrl('s-1', '//server/share/a.html')
     expect(decodeHtmlUrl(url)).toEqual({
       ok: true,
-      ref: { sessionId: 's-1', path: '/server/share/a.html' },
+      ref: { sessionId: 's-1', path: '//server/share/a.html' },
     })
   })
 
@@ -167,12 +166,12 @@ describe('relative asset resolution stays in-route', () => {
   it('relative assets of a UNC document stay inside the same route', () => {
     // The WHATWG URL preserves the '//' marker during relative resolution,
     // so ./style.css lands back on the route with the UNC prefix intact.
-    const doc = `http://h${encodeHtmlUrl('s', '\\\\server\\share\\proj\\index.html', true)}`
+    const doc = `http://h${encodeHtmlUrl('s', '\\\\server\\share\\proj\\index.html')}`
     expect(new URL('./style.css', doc).pathname)
       .toBe('/sidebar/html/s//server/share/proj/style.css')
     expect(decodeHtmlUrl(new URL('./style.css', doc).pathname)).toEqual({
       ok: true,
-      ref: { sessionId: 's', path: '\\\\server\\share\\proj\\style.css' },
+      ref: { sessionId: 's', path: '//server/share/proj/style.css' },
     })
   })
 })

tests/paths.spec.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { isAbsolutePath, isWindowsStylePath, relativeTo } from '../src/client/paths.ts'
+import { isAbsolutePath, relativeTo } from '../src/client/paths.ts'
 import { resolveSidebarPath } from '../src/client/produced-files.ts'
 import { htmlUrl } from '../src/client/api.ts'
 
@@ -56,33 +56,13 @@ describe('path helpers', () => {
     expect(isAbsolutePath('rel/x.ts')).toBe(false)
   })
 
-  it('detects windows-style session paths (platform signal for the html route)', () => {
-    expect(isWindowsStylePath('C:\\work\\proj')).toBe(true)
-    expect(isWindowsStylePath('C:/work/proj')).toBe(true)
-    expect(isWindowsStylePath('\\\\server\\share\\proj')).toBe(true)
-    expect(isWindowsStylePath('//server/share/proj')).toBe(false) // ambiguous form needs the drive/backslash signal
-    expect(isWindowsStylePath('/Users/me/code')).toBe(false)
-  })
-
-  it('htmlUrl marks UNC paths from the file path itself (cwd-independent signal)', () => {
-    // cwd not hydrated yet: the unambiguous backslash UNC path must still
-    // keep its '//' marker, or win32 would decode /server/... against the
-    // current drive and the isWithin fence would reject the preview (403).
+  it('htmlUrl always marks UNC paths (platform-neutral marker)', () => {
+    // The marker is platform-neutral now: the host resolves the decoded
+    // '//server/share/...' form per-platform, so no cwd/OS signal is needed.
     expect(htmlUrl({ sessionId: 's' }, '\\\\server\\share\\proj\\a.html'))
       .toBe('/sidebar/html/s//server/share/proj/a.html')
-    // A forward-slash-form cwd (still Windows) does not mask the backslash path.
-    expect(htmlUrl({ sessionId: 's', cwd: '//server/share/proj' }, '\\\\server\\share\\proj\\a.html'))
-      .toBe('/sidebar/html/s//server/share/proj/a.html')
-    // Both cwd and path in the forward-slash UNC form: the '//' path matches
-    // the '//' cwd, so it is UNC and keeps the marker (win32 round-trips).
-    expect(htmlUrl({ sessionId: 's', cwd: '//server/share/proj' }, '//server/share/proj/a.html'))
-      .toBe('/sidebar/html/s//server/share/proj/a.html')
-    // A Windows drive cwd marks forward-slash UNC paths.
-    expect(htmlUrl({ sessionId: 's', cwd: 'C:\\work' }, '//server/share/proj/a.html'))
-      .toBe('/sidebar/html/s//server/share/proj/a.html')
-    // A POSIX session keeps forward-slash paths marker-free.
     expect(htmlUrl({ sessionId: 's', cwd: '/home/me' }, '//server/share/a.html'))
-      .toBe('/sidebar/html/s/server/share/a.html')
+      .toBe('/sidebar/html/s//server/share/a.html')
     expect(htmlUrl({ sessionId: 's', cwd: '/home/me' }, '/home/me/index.html'))
       .toBe('/sidebar/html/s/home/me/index.html')
   })

tests/platform.ts

@@ -8,6 +8,3 @@
 
 /** True when running on Windows (drive letters / UNC path semantics apply). */
 export const isWin32 = process.platform === 'win32'
-
-/** True on every non-Windows host (POSIX path semantics). */
-export const isPosix = !isWin32