Copilot chat pane not rendering final response, yet shown in debugger

### Description

After asking Copilot to do nearly anything, it appears to stop early. Upon reviewing logs in the Chat Debug tool, it shows a final `panel/editAgent` call that never rendered.

EDIT: this appears to be linked to the _Creating n todos_ functionality. I'm not seeing final responses when Copilot says todos are created.

### Issue Details

Item|Value
---|---
Issue Category|Bug
Target|Visual Studio Code - Insiders
VS Code Version|Code - Insiders 1.128.0-insider (86df0e5dc86a78298b5ffce1c6f6793ad79c3e93, 2026-07-06T05:12:47Z)
OS Version|Windows_NT x64 10.0.26200

System Info

Item|Value
---|---
VS Code Version|Code - Insiders 1.128.0-insider (86df0e5dc86a78298b5ffce1c6f6793ad79c3e93, 2026-07-06T05:12:47Z)
OS Version|Windows_NT x64 10.0.26200
CPUs|AMD EPYC 7763 64-Core Processor (16 x 2445)
GPU Status|2d_canvas: unavailable_software
GPU0: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VENDOR=Microsoft, DRIVER_VERSION=10.0.26100.8521 *ACTIVE*
GPU1: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8521
GPU2: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.26100.8521
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: disabled_software
multiple_raster_threads: enabled_on
opengl: disabled_off
rasterization: disabled_software
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: disabled_software
video_encode: disabled_software
webgl: unavailable_software
webgpu: unavailable_software
webnn: unavailable_software
Load (avg)|
Memory (System)|63.95GB (36.22GB free)
Process Argv|--crash-reporter-id c2c48aec-a00f-4ee9-b93d-73b09ff4908e
Screen Reader|no
VM|0%
User Agent|Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Code-Insiders/1.128.0-insider Chrome/148.0.7778.271 Electron/42.5.0 Safari/537.36
Installation pure|true

Extensions (13, internal removed from list)

Name|Identifier|Author|Version
---|---|---|---
Mermaid|mermaidchart.vscode-mermaid-chart|MermaidChart|2.7.1
Azure Pipelines|ms-azure-devops.azure-pipelines|ms-azure-devops|1.261.1
Container Tools|ms-azuretools.vscode-containers|ms-azuretools|2.4.5
C# Dev Kit|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
PowerShell|ms-vscode.powershell|ms-vscode|2025.4.0
Chat Customizations Evaluations|ms-vscode.vscode-chat-customizations-evaluations|ms-vscode|1.0.8

Theme extensions: 9

A/B Experiments

```
vsliv368:30146709
pythonvspyt551:31249597
nativeloc1:31118317
dwcopilot:31158714
dwoutputs:31242946
copilot_t_ci:31333650
g012b348:31231168
pythonrdcb7:31268811
pythonpcpt1cf:31399617
6518g693:31302842
b6b4d950:31327385
63221493:31336333
envsactivate1:31349248
editstats-enabled:31346256
cloudbuttont:31366566
3efgi100_wstrepl:31403338
bj468946:31457056
metis_rerank_treatment1:31411021
cp_cls_t_966_ss:31526232
4je02754:31455664
c3h7c220:31478652
ge8j1254_inline_auto_hint_haiku:31490507
cp_cls_t_1081:31454832
conptydll_true:31485575
ia-use-proxy-models-svc:31446143
core-renderer-profiling-on:31440366
e9c30283:31453065
test_treatment2:31471001
c9b86496:31447327
idci7584:31454084
e3e4d672:31454087
ei9d7968:31462942
nes-extended-on:31455475
89g7j272:31506658
7e884298:31462391
7e187181:31482583
i2gc6536:31472020
52612955:31508042
h08i8180_copy:31475366
ddid_c:31478205
hmra_i5g22:-9
bjc72774_agent_sandbox:31538428
7df3h592:31491241
cp_cls_t_1082:31535311
logging_enabled_new:31490725
jb_cp_cls_t_632:31543129
32d76977:31503652
ha629193:31508444
cdk-lw-on:31524445
f9bf7985:31541111
31fi7170_t:31517328
a1ije391_t:31533808
api_cot_ctrl:31509853
hgf2d445:31510900
41836166:31537719
prpt_lrg:31513637
jbcp_cls_pctr_t:31531130
3f904173:31522231
cp_intellij_t_nes:31533504
jf4hg949:31526829
hide-eh-duplicates:31543293
h561g132:31534507
j4c47577:31544219
hjji5903:31534458
f412h606:31543414
max-result-50:31544847
```