Python: Run Selection/Line in Python Terminal drops blank lines inside triple-quoted strings

[Ma-XX-oN]

Type: Bug

Behaviour

When I use Python: Run Selection/Line in Python Terminal on code that
contains a triple-quoted string with a blank line “sandwiched” between two
non-blank lines, that blank line is removed in the version of the code that
gets executed in the REPL.

Running the same code as a normal script (python file.py) preserves the blank
line. So the behaviour of the code depends on whether it is run as a script or
via Run Selection/Line in Python Terminal, which should not happen.

This breaks code that relies on the exact newline structure of the string, such
as regex-based parsing of multi-line documentation blocks.

Steps to reproduce:

1. Create a new file, e.g. test_blank_line.py, with exactly this content:

    text = """line 1
    line 2
   
    line 4
    """
   
    print(repr(text))
   

   Note: there is a blank line between line 2 and line 4 inside the
   triple-quoted string.

2. Run the file normally in the integrated terminal:

    python test_blank_line.py
   

3. Observe the output:

    'line 1\nline 2\n\nline 4\n'
   

   There are two \n characters between line 2 and line 4, as expected.

4. Now select the entire code in test_blank_line.py and run:

   • Command Palette → Python: Run Selection/Line in Python Terminal, or
   • Right click → Run Selection/Line in Python Terminal.

5. Observe the output printed in the Python REPL in the integrated terminal:

    'line 1\nline 2\nline 4\n'
   

   The blank line between line 2 and line 4 is now missing (only a
   single \n remains). This shows that the text sent to the REPL by
   Run Selection/Line in Python Terminal does not faithfully match the text in
   the editor.

---

Diagnostic data

Output for Python in the Output panel (View→Output, change the drop-down in the upper-right of the Output panel to Python)

>>> text = """line 1
... line 2
... line 4
... """
>>>
>>> print(repr(text))
'line 1\nline 2\nline 4\n'
>>>

Extension version: 2025.20.1
VS Code version: Code 1.107.1 (994fd12f8d3a5aa16f17d42c041e5809167e845a, 2025-12-17T14:15:14.850Z)
OS version: Windows_NT x64 10.0.26200
Modes:

• Python version (& distribution if applicable, e.g. Anaconda): 3.12.12
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): Venv
• Value of the python.languageServer setting: Default

User Settings

languageServer: "Pylance"

Installed Extensions

Extension Name	Extension Id	Version
autodocstring	njp	0.6.1
cmake-highlight	zch	0.0.2
cmake-tools	ms-	1.21.36
code-spell-checker	str	4.4.0
code-spell-checker-british-english	str	1.4.34
code-spell-checker-canadian-english	str	1.1.29
copilot-chat	Git	0.35.2
cpptools	ms-	1.30.0
cpptools-extension-pack	ms-	1.3.1
cpptools-themes	ms-	2.0.0
debugpy	ms-	2025.18.0
graphviz-interactive-preview	tin	0.3.5
hexeditor	ms-	1.11.1
htmlplay	bia	0.0.10
js-debug	ms-	1.105.0
js-debug-companion	ms-	1.1.3
openscad-language-support	Lea	2.0.1
overtype	DrM	0.5.0
powershell	ms-	2025.4.0
prettier-plus	Shu	3.0.0
project-manager	ale	13.0.1
python	ms-	2025.20.1
remote-containers	ms-	0.434.0
text-power-tools	qcz	1.51.0
vscode-autohotkey-debug	zer	1.11.1
vscode-autohotkey-plus-plus	mar	6.7.1
vscode-containers	ms-	2.3.0
vscode-js-profile-table	ms-	1.0.10
vscode-pylance	ms-	2025.10.4
vscode-python-envs	ms-	1.14.0
vscode-texttoolbox	car	2.29.0

System Info

Item	Value
CPUs	AMD Ryzen 7 5700U with Radeon Graphics (16 x 1797)
GPU Status	2d_canvas: enabled 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 webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	7.38GB (0.77GB free)
Process Argv	--crash-reporter-id 1cf35118-2bd4-4544-b0e1-09535383293d
Screen Reader	yes
VM	0%

A/B Experiments

vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31436602
aj953862:31281341
nes-set-on:31351930
6abeh943:31336334
envsdeactivate2:31353495
cloudbuttont:31379625
todos-1:31405332
3efgi100_wstrepl:31403338
use-responses-api:31390855
6j29d282:31407606
2a0ce269:31428710
ec5jj548:31422691
terminalsuggestenabled:31431119
cmp-ext-treat:31426748
cp_cls_c_966_ss:31435507
copilot6169-t2000-control:31440805
a9239246:31437220
c0683394:31419495
478ah919:31426797
ge8j1254_inline_auto_hint_haiku:31427726
nes-autoexp-off:31439334
a5gib710:31434435
38bie571_auto:31426784
no_request_with_suggest:31435826
rename_enabled:31436409
7a04d226_do_not_restore_last_panel_session:31438103
anthropic_thinking_t:31432745
p_e9cf0154:31434513
h0hdh950:31428394
cp_cls_c_1081:31433293
copilot-nes-callisto-trt:31434412
nowdiget:31438323

[eleanorjboyd]

Are you using the Python Environments extension? You can use it with python.useEnvironmentsExtension: true and see if that changes it- just trying to figure out which codebase it is in

[github-actions]

Because we have not heard back with the information we requested, we are closing this issue for now. If you are able to provide the info later on, then we will be happy to re-open this issue to pick up where we left off.

Happy Coding!