Razor formatting fails with overlapping changes

Type: Bug

## Issue Description ##
## Steps to Reproduce ##

## Expected Behavior ##

## Actual Behavior ##

Extension version: 2.140.9
VS Code version: Code 1.136.1 (a44adf7f53e00964ab890f9f8758a334f1fc15bc, 2026-09-03T05:06:41Z)
OS version: Windows_NT x64 10.0.26200
Modes:

### Logs ###

### C# log ###

```
2026-09-04 13:50:09.901 [info] Locating .NET runtime version 10.0.5
2026-09-04 13:50:09.995 [info] Dotnet path: C:\Program Files\dotnet\dotnet.exe
2026-09-04 13:50:09.995 [info] Activating C# + C# Dev Kit...
2026-09-04 13:50:10.225 [info] info: Program[0]
2026-09-04 13:50:10.225 [info] Server started with process ID 33380
2026-09-04 13:50:11.008 [info] [Program] Language server initialized
2026-09-04 13:50:11.009 [info] [Program] Monitoring client process 17020 for exit
2026-09-04 13:50:11.466 [info] [initialized] [Microsoft.CodeAnalysis.LanguageServer.FileBasedPrograms.FileBasedProgramsEntryPointDiscovery] Finished discovery in 'd:\WorkStation\mr-logistics' in 14 milliseconds
2026-09-04 13:50:14.870 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\WorkStation\mr-logistics\Repository\Repository.csproj loaded by C# Dev Kit
2026-09-04 13:50:14.910 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\WorkStation\mr-logistics\Domain\Domain.csproj loaded by C# Dev Kit
2026-09-04 13:50:14.914 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\WorkStation\mr-logistics\Application\Application.csproj loaded by C# Dev Kit
2026-09-04 13:50:14.916 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\WorkStation\mr-logistics\Application.Test\Application.Test.csproj loaded by C# Dev Kit
2026-09-04 13:50:14.921 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\WorkStation\mr-logistics\Common.Library\Common.Library.csproj loaded by C# Dev Kit
2026-09-04 13:50:14.922 [info] [serviceBroker/connect] [WorkspaceProjectFactoryService] Project D:\WorkStation\mr-logistics\Web\Web.csproj loaded by C# Dev Kit
2026-09-04 14:29:18.544 [error] Request textDocument/formatting failed.
Message: The changes must not overlap. (Parameter 'changes')
Code: -32000
[object Object]
2026-09-04 14:29:35.611 [error] Request textDocument/formatting failed.
Message: The changes must not overlap. (Parameter 'changes')
Code: -32000
[object Object]

```

### C# LSP Trace Logs log ###

```

```

## Environment Information ##
**VSCode version**: 1.136.1
**C# Extension**: 2.140.9
**Using OmniSharp**: false

Dotnet Information
.NET SDK:
Version: 10.0.400
Commit: 14fbf8d527
Workload version: 10.0.400-manifests.b0ae88bd
MSBuild version: 18.9.6+14fbf8d52

Runtime Environment:
OS Name: Windows
OS Version: 10.0.26200
OS Platform: Windows
RID: win-x64
Base Path: C:\Program Files\dotnet\sdk\10.0.400\

.NET workloads installed:
There are no installed workloads to display.
Configured to use workload sets when installing new manifests.
No workload sets are installed. Run "dotnet workload restore" to install a workload set.

Host:
Version: 10.0.11
Architecture: x64
Commit: e2f47b0110

.NET SDKs installed:
2.2.207 [C:\Program Files\dotnet\sdk]
6.0.428 [C:\Program Files\dotnet\sdk]
8.0.424 [C:\Program Files\dotnet\sdk]
10.0.400 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
Microsoft.AspNetCore.All 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 8.0.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 10.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 8.0.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 10.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 6.0.36 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 8.0.30 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 10.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
x86 [C:\Program Files (x86)\dotnet]
registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
DOTNET_CLI_UI_LANGUAGE [en-US]

global.json file:
Not found

Learn more:
https://aka.ms/dotnet/info

Download .NET:
https://aka.ms/dotnet/download

Visual Studio Code Extensions

|Extension|Author|Version|Folder Name|
|---|---|---|---|
|Angular2|johnpapa|22.0.0|johnpapa.angular2-22.0.0|
|csdevkit|ms-dotnettools|3.20.199|ms-dotnettools.csdevkit-3.20.199-win32-x64|
|csharp|ms-dotnettools|2.140.9|ms-dotnettools.csharp-2.140.9-win32-x64|
|debugpy|ms-python|2026.6.0|ms-python.debugpy-2026.6.0-win32-x64|
|es7-react-js-snippets|dsznajder|4.4.3|dsznajder.es7-react-js-snippets-4.4.3|
|material-icon-theme|PKief|5.38.1|pkief.material-icon-theme-5.38.1|
|ng-template|Angular|22.1.0|angular.ng-template-22.1.0|
|prettier-vscode|esbenp|12.4.0|esbenp.prettier-vscode-12.4.0|
|python|ms-python|2026.4.0|ms-python.python-2026.4.0-win32-x64|
|vscode-dotnet-runtime|ms-dotnettools|3.1.0|ms-dotnettools.vscode-dotnet-runtime-3.1.0|
|vscode-eslint|dbaeumer|3.0.34|dbaeumer.vscode-eslint-3.0.34|
|vscode-pylance|ms-python|2026.3.1|ms-python.vscode-pylance-2026.3.1|
|vscode-python-envs|ms-python|1.36.0|ms-python.vscode-python-envs-1.36.0-win32-x64|
|vscode-react-native|msjsdiag|1.13.0|msjsdiag.vscode-react-native-1.13.0|;

C# Settings

|Setting|Value|
|---|---|
|preferCSharpExtension|false|
|compilerDiagnosticScope|openFiles|
|analyzerDiagnosticScope|openFiles|
|enableXamlTools|true|
|useServerGC|true|;

System Info

|Item|Value|
|---|---|
|CPUs|12th Gen Intel(R) Core(TM) i5-12500H (16 x 3110)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x8086, DEVICE=0x46a6 [Intel(R) Iris(R) Xe Graphics], DRIVER_VENDOR=Intel, DRIVER_VERSION=31.0.101.4255 *ACTIVE*
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.9278
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|undefined|
|Memory (System)|23.70GB (4.94GB free)|
|Process Argv|--crash-reporter-id 13c236eb-63e4-46d5-b7c7-a7e5ab7efc29|
|Screen Reader|no|
|VM|40%|

A/B Experiments

```
vsliv368cf:30146710
pythonvspyt551cf:31249601
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31463988
aj953862:31281341
82j33506:31327384
envsactivate1:31551504
cloudbuttont:31379625
3efgi100_wstrepl:31403338
ec5jj548:31422691
diffpatch-lysithea-24-production:31578711
cp_cls_t_966_ss:31526232
4je02754:31466945
8hhj4413:31478653
ge8j1254_inline_auto_hint_haiku:31490510
cp_cls_t_1081:31454832
conptydll_true:31498968
e9c30283:31461165
46204921:31447328
control_6dc23131:31576178
ei9d7968:31496641
chat:31457767
8hig5102:31480529
89g7j272:31518289
i2gc6536:31499202
52612955:31516516
ddid_t:31478206
hmra_i5g22:31518061
ja75b849:31575055
7df3h592:31512476
cp_cls_t_1082:31535311
logging_enabled_new:31498466
db5d2638:31499441
jb_cp_cls_t_632:31543129
56dj4588:31512888
32d76977:31512328
ha629193:31508444
a1ije391_t:31540920
jbcp_cls_pctr_t:31531130
cp_intellij_t_nes:31548657
gf14b233:31526830
ahp-both-windows:31556933
ihg5j128:31534457
9gg7f176:31542112
enable_editor_pane_layout:31569726
allow-none:31555437
ac562147:31564510
c7c27ce7:31554789
1h923230:31564177
0dg73464:31554319
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
0d8dfbc3:31570291
a1hcc538:31559322
nemo-v2:31565334
0c1h4866:31566224
vrbsty_tr:31561058
session-mark-done:31558131
5b8j3302:31564601
mangle-name-control:31572633
multiv2:31574985
2bfb8b39:31576696
permission_prompt_treatment:1332566
ccr_pr_nudge_adoption:1319471
vsc_wsm_c:1340633
jidc7660:1370295
auto_mode_control:1367906

```

No source file, test, reproduction steps, or trace log is provided. Start by reproducing the Razor formatting request using the reported VS Code and C# extension versions, then trace the textDocument/formatting request that reports overlapping changes. Done means identifying the overlapping-change path and adding a regression test for the failing formatting case.

Written by the indexing model from the issue text.