The new native "Agents Window" (`Ctrl+Shift+A`) does not respect the workspace or file encoding configured in VS Code settings (e.g., Windows-1252, ISO-8859-1). This is a regression in experience compared to the standard GitHub Copilot chat extension, which respects file encoding perfectly.

Type: Bug

### Steps to Reproduce
1. Configure a workspace or a file with a non-UTF-8 encoding (e.g., `"files.encoding": "windows-1252"`).
2. Create or open a file containing special characters (e.g., "configuración", "año").
3. Open the Agents Window using `Ctrl+Shift+A`.
4. Ask the agent to analyze or make an edit to that file.
5. Notice that the agent reads incorrect characters or saves the file back with corrupted text, ignoring the active encoding configuration.

VS Code version: Code 1.135.0 (08d4889f9ec4a1685d257b9b95de036c8e1ce1e5, 2026-08-25T14:26:52Z)
OS version: Windows_NT x64 10.0.26200
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i7-9700 CPU @ 3.00GHz (8 x 3000)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x8086, DEVICE=0x3e98 [Intel(R) UHD Graphics 630], DRIVER_VENDOR=Intel, DRIVER_VERSION=30.0.101.1631 *ACTIVE*
GPU1: VENDOR= 0x8086, DEVICE=0x3e98 [Intel(R) UHD Graphics 630], DRIVER_VERSION=30.0.101.1631
GPU2: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8875
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)|31.78GB (11.13GB free)|
|Process Argv|--crash-reporter-id de3d37c7-31e9-49d7-9265-ee45636c8f0e|
|Screen Reader|no|
|VM|0%|
Extensions (17)

Name|Identifier|Author|Version
---|---|---|---
Informix 4GL|cristianrengifo.informix4gl|CristianRengifo|0.12.0
Copilot Usage|emagin8.copilot-usage|emagin8|0.1.3
Rainbow CSV|mechatroner.rainbow-csv|mechatroner|3.24.1
Spanish Language Pack for Visual Studio Code|ms-ceintl.vscode-language-pack-es|MS-CEINTL|1.131.2026082318
Kit de desarrollo de C#|ms-dotnettools.csdevkit|ms-dotnettools|3.20.199
C#|ms-dotnettools.csharp|ms-dotnettools|2.140.9
.NET Install Tool|ms-dotnettools.vscode-dotnet-runtime|ms-dotnettools|3.1.0
Python Debugger|ms-python.debugpy|ms-python|2026.6.0
Python|ms-python.python|ms-python|2026.4.0
Pylance|ms-python.vscode-pylance|ms-python|2026.3.1
Python Environments|ms-python.vscode-python-envs|ms-python|1.36.0
Remote - SSH|ms-vscode-remote.remote-ssh|ms-vscode-remote|0.128.0
PowerShell|ms-vscode.powershell|ms-vscode|2025.4.0
Chat Customizations Evaluations|ms-vscode.vscode-chat-customizations-evaluations|ms-vscode|1.0.8
Beyond Compare|scootersoftware.bcompare-vscode|ScooterSoftware|1.0.7
Office to Markdown Converter|testany.office-to-markdown|Testany|0.1.5
Chat Wizard|veverke.chatwizard|Veverke|1.6.0

A/B Experiments

```
vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31463988
aj953862:31281341
envsactivate1:31551504
cloudbuttont:31379625
3efgi100_wstrepl:31403338
ec5jj548:31422691
diffpatch-lysithea-0014-prod-ctrl:31574142
cp_cls_t_966_ss:31526232
4je02754:31466945
c3h7c220:31478652
ge8j1254_inline_auto_hint_haiku:31490510
cp_cls_t_1081:31454832
conptydll_true:31498968
e9c30283:31461165
c9b86496:31447327
ei9d7968:31496641
nes-extended-on:31455476
chat:31457767
8hig5102:31480529
89g7j272:31518289
i2gc6536:31499202
52612955:31516516
h08i8180_copy:31475368
ddid_t:31478206
hmra_i5g22:31518061
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
jh5f2457_c:31540921
jbcp_cls_pctr_t:31531130
61138546:31518536
cp_intellij_t_nes:31548657
jf4hg949:31526829
ahp-both-windows:31556933
sessions_3:31532893
ihg5j128:31534457
f412h606:31551416
7g2b5551:31542111
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
switchtoauto:31559321
0c1h4866:31566224
vrbsty_tr:31561058
session-mark-done:31558131
5b8j3302:31564601
mangle-name-treatment:31572634
lunaclean:31573760
permission_prompt_treatment:1332566
ccr_pr_nudge_control:1319470
vsc_wsm_t:1340632
eh853263:1355661

```