Terminal no longer responds to escape sequence 6n

Type: Bug

On Windows, the terminal no longer correctly responds to escape sequence 6n with the current cursor position.

To reproduce, open a terminal (does not appear to matter what shell is used, but I tested on PowerShell 7.6.6 and Git Bash) and run python. In the Python shell, run

from contextlib import contextmanager
from ctypes import byref, windll, wintypes
import sys

@contextmanager
def disable_echo():
    stdin_handle = windll.kernel32.GetStdHandle(-10)
    old_stdin_mode = wintypes.DWORD()
    windll.kernel32.GetConsoleMode(stdin_handle, byref(old_stdin_mode))
    try:
        windll.kernel32.SetConsoleMode(stdin_handle, 0)
        yield
    finally:
        windll.kernel32.SetConsoleMode(stdin_handle, old_stdin_mode)

def get_cursor_pos() -> tuple[int, int]:
    with disable_echo():
        sys.stdout.write("\x1b[6n")
        sys.stdout.flush()
        result = ""
        while not result.endswith("R"):
            result += sys.stdin.read(1)
        row, _, col = result.removeprefix("\x1b[").removesuffix("R").partition(";")
        return (int(col) - 1, int(row) - 1)

get_cursor_pos()

This hangs inside the sys.stdin.read(1) call. If the same thing is run in Windows Terminal, it correctly returns a value such as

>>> get_cursor_pos()
(0, 29)

Checking the stdout mode on both VS Code's terminal and Windows terminal...

stdout_handle = windll.kernel32.GetStdHandle(-11)
stdout_mode = wintypes.DWORD()
windll.kernel32.GetConsoleMode(stdout_handle, byref(stdout_mode))
stdout_mode.value

...results in 7, which includes the 0x4 bit for ENABLE_VIRTUAL_TERMINAL_PROCESSING, so I would expect it to work in both. I previously tested a project which uses this code in VS Code's terminal, so I know this used to work in an earlier version of VS Code, but I don't know which version that was.

VS Code version: Code 1.138.0 (7debcd0e2acdea1c52de81bf9ee1620444407dda, 2026-09-15T07:24:32Z)
OS version: Windows_NT x64 10.0.26200
Modes:

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
ddidt:31399633
ec5jj548:31422691
cp_cls_t_966_ss:31526232
4je02754:31466945
8hhj4413:31478653
cp_cls_c_1081:31454833
conptydll_true:31498968
e9c30283:31461165
c9b86496:31447327
ei9d7968:31496641
chat:31457767
ddid_t:31478206
hmra_i5g22:31518061
7df3h592:31512476
cp_cls_t_1082:31535311
logging_enabled_new:31498466
j0d79568:31499440
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
36h42362:31564511
c7c27ce7:31554789
1h923230:31564177
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
0d8dfbc3:31570291
a1hcc538:31559322
0c1h4866:31566224
session-archive:31558132
5b8j3302:31564601
autotiers:31584978
mangle-name-control:31572633
allow-signed-out:31584137
intellij_nes_preview_t:31580086
39a5d156:31574986
2bfb8b39:31585911
outline:31581109
links-control:31586637
aw-autom-on:31583758
revealsession_control_7ed7e840:31582193
4ab0b639:31584543
codex-agent-host-stable-control:31585316
66c8a39e-e7a5-4b4c-a3c0-41b161c795c4:31586113
permission_prompt_treatment:1332566
ccr_pr_nudge_control:1319470
vsc_wsm_c:1340633
1g5a5742:1379227
3aced641:1389836

Start by running the supplied Python reproduction in VS Code's integrated terminal with PowerShell 7.6.6 and Git Bash, then compare the response with Windows Terminal. Trace the integrated terminal's Windows escape-sequence and console input handling. Done means escape sequence 6n returns the cursor position without hanging in sys.stdin.read(1).