Setup aborts at Phase 5/11 (Full) because SearchHighlightOff cannot write the protected SearchSettings key on Windows build 28000

从 steps/registry-taskbar-search.ps1 开始，将 SearchHighlightOff 与相邻的 WidgetServiceOff 步骤进行比较，后者已经处理受保护的 Windows 设置。在 Windows 11 build 28000 上运行 Full setup 操作，或者如果仓库提供了相应测试，则添加一个有针对性的回归测试。当这个受保护的注册表值不再中止 setup 且后续阶段继续执行时，即表示完成。

Summary

On Windows 11 build 28000, the Full action aborts at Phase 5/11 because the SearchHighlightOff tweak cannot write HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\SearchSettings\IsDynamicSearchBoxEnabled. Windows blocks value writes to that key at the kernel level, even for an elevated administrator.

Because the SearchHighlightOff step is not marked BestEffort (unlike the adjacent WidgetServiceOff step), this single un-writable cosmetic setting terminates the entire run, so Phases 6–11 (Edge, fonts, Terminal, PowerShell profile, Copilot, WSL) never execute.

Environment

Steps to reproduce

1. On Windows 11 build 28000, run irm https://aka.ms/devconfig/full/setup.ps1 | iex from an elevated PowerShell 7 session.
2. Let setup complete Phases 1–4 and the first four steps of Phase 5.

Actual result

Phase 5/11 -- Taskbar, search & start tweaks
  ...
  -> Disable Show search highlights...

Calm OS setup stopped early.
  Windows blocked changing HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion\SearchSettings\IsDynamicSearchBoxEnabled. Administrator access or Windows policy may restrict this setting.
  (_registry.ps1 line 50)
  Nothing already applied was undone -- running this again picks up where it left off.

The underlying exception is an UnauthorizedAccessException ("Attempted to perform an unauthorized operation./ 未经授权操作") raised by New-ItemProperty at steps/_registry.ps1:48, caught and rethrown with the friendly message at steps/_registry.ps1:50-52.

Re-running simply reproduces the identical failure, so Full can never advance past Phase 5 on this build.

Root cause

Windows on this build protects the SearchSettings key against value writes, independent of ACLs. The key is owned by the user and its ACL grants the user, SYSTEM and Administrators KEY_ALL_ACCESS (KA), with no Deny ACE — yet every value write is refused.

Note the key carries an explicit ACE for a MicrosoftWindows.Client.CBS AppContainer SID (S-1-15-3-1024-1086922356-207614091-3724853071-841836187-4018695103-34218837-3164163255-155871754), which is the search/taskbar package (SearchHost.exe runs from MicrosoftWindows.Client.CBS_cw5n1h2txyewy).

Methods attempted, all failing

SearchSettings has no policy mirror on this build (HKLM\SOFTWARE\Policies\Microsoft\Windows\CurrentVersion\SearchSettings does not exist), so there is no supported policy-based way to set this value either.

Expected result

Either of:

1. SearchHighlightOff should be marked BestEffort = $true, like the WidgetServiceOff step in the very same file, so a platform-protected cosmetic setting cannot abort the whole run; or
2. If the value is genuinely un-writable on current builds, the step should be removed or its apply-path changed to a supported API.

Suggested fix

In windows-dev-config/steps/registry-taskbar-search.ps1, the file already acknowledges this exact class of problem for Widgets:

# Windows may protect the Widgets policy even from an administrator.
@{
    Name        = 'WidgetServiceOff'
    KeyPath     = 'HKLM\SOFTWARE\Policies\Microsoft\Dsh'
    ValueName   = 'AllowNewsAndInterests'
    Value       = 0
    Description = 'Disable Widgets'
    BestEffort  = $true
}

The SearchHighlightOff tweak immediately above it has the same exposure but lacks the flag:

@{
    Name        = 'SearchHighlightOff'
    KeyPath     = 'HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\SearchSettings'
    ValueName   = 'IsDynamicSearchBoxEnabled'
    Value       = 0
    Description = 'Disable Show search highlights'
}

Adding BestEffort = $true (or removing the tweak) would let Full continue on builds where Windows protects this key.

Additional notes

• Verified against the current main: steps/registry-taskbar-search.ps1 is byte-identical to the copy setup installed, so the issue is present in the latest code.
• Related prior report: #109 ("Disable Widget service errors on fresh Windows 11 PC") — the same class of failure, which is presumably why WidgetServiceOff was given BestEffort. SearchHighlightOff appears to have been missed.
• No existing issue appears to cover IsDynamicSearchBoxEnabled / SearchSettings specifically.