Add support for tmux control mode (#3656) #18928

joexue · 2025-05-20T00:19:08Z

Summary of the Pull Request

Let WT supports tmux control mode

References and Relevant Issues

#3656

Detailed Description of the Pull Request / Additional comments

Support:

Create/attach tmux session
Split pane vertical/horizontal
Window/panes size change
Remove pane/tab if remote pane exit or window exit

Improvements may do:

Merge the tmux menus/button with existing menu/button
Add the keyboard accelerators for tmux menus
Unicode support(the VTParser just pass part of characters in DCS mode
When attached a session, focus on the same focused tab/pane when detaching(backend is done, need to do some work frontend)
Test code

Tested by using tmux 3.4:
ssh to a machine has tmux or use wsl, then run
"tmux -CC" or "tmux -CC a"

Validation Steps Performed

PR Checklist

[x ] Closes Add support for tmux Control Mode #3656
Tests added/passed
Documentation updated
- If checked, please file a pull request on our docs repo and link it here: #xxx
Schema updated (if necessary)

joexue · 2025-05-20T00:29:08Z

@microsoft-github-policy-service agree

DHowett · 2025-05-20T02:59:52Z

whoa

iDarshan · 2025-05-20T23:22:17Z

This is a long-awaited feature! Thanks @joexue!

BinaryShrub · 2025-05-20T23:58:21Z

DHowett · 2025-05-23T00:03:41Z

FYI: I am working with reduced staffing at the moment, so reviews may be slow to come. I apologize for that.

iDarshan · 2025-06-03T20:38:07Z

Is there a nightly build with this PR to test?

carlos-zamora · 2025-06-05T17:21:45Z

Is there a nightly build with this PR to test?

Your best bet is to build this locally. Once it merges, it will be available on the Canary channel though.

iDarshan · 2025-06-06T02:15:22Z

Is there a nightly build with this PR to test?

Your best bet is to build this locally. Once it merges, it will be available on the Canary channel though.

I tried to find the build guide, but couldn't find one. Do you have the link handy?

joexue · 2025-06-06T13:13:42Z

Is there a nightly build with this PR to test?

Your best bet is to build this locally. Once it merges, it will be available on the Canary channel though.

I tried to find the build guide, but couldn't find one. Do you have the link handy?

README.md ->Developer Guidance @iDarshan

carlos-zamora · 2025-06-10T22:22:01Z

Hi @joexue! Thanks for doing this! I published a build for the team to test internally and we've got a few notes we want to share with you 😊

Notes/Reactions:
- Settings menu item is gone from the dropdown
- It makes your existing window a special "tmux only" window; it disables the menu, but it doesn't disable the key bindings, so you can still split in non-tmux panes
- Scrollbars are gone? I guess scrolling is server side
Requested changes:
- [Bug] can't type in an older pane after splitting panes
- tmux tabs should not be draggable into a new window
- Add a setting to Profile > "Terminal Emulation" page that disables this (it should be disabled by default)
- Bug: Closing a tab/pane will not kill the instance on the server side
- Add a feature flag to features.xml (Guidance)
- [Architectural notes] We should see if we can't just model a tmux pane as a connection so we don't need to pump output into the terminal from the App layer

Overall, this is a really exciting feature and we're excited to see it land! Let us know if you need any guidance or additional comments on any of the thoughts above. 😊

CC @DHowett @lhecker @zadjii-msft

joexue · 2025-06-12T02:54:13Z

Hi @joexue! Thanks for doing this! I published a build for the team to test internally and we've got a few notes we want to share with you 😊

Notes/Reactions:

Settings menu item is gone from the dropdown

It makes your existing window a special "tmux only" window; it disables the menu, but it doesn't disable the key bindings, so you can still split in non-tmux panes

Scrollbars are gone? I guess scrolling is server side

Scrollbars are gone is by design, I put the comment in the code, since we want to make local panes size match remote(tmux) panes size, but each split, tmux just lost 1 character to use it as separator, if we have side scrollbars, we cannot make two side's size match. To meet this, the padding size is changed too.

As the menu, it is because I tried to touch as less code as I can to do the job. So give the tmux a separate UI system. I described in the PR, this could be improved and should integrated into the present UI/menu system.
But, I think we can skip this ugly stage, directly change the code to make the tmux control mode work with present UI/menu system. I will address this, those +button/flyout splitting menus specifically for tmux will be gone.

Requested changes:

[Bug] can't type in an older pane after splitting panes

I did not see this bug, to help me to reproduce it here, could you describe your env? how do you connect to tmux server? what is the tmux version?

tmux tabs should not be draggable into a new window

Sure, let me fix it.

Add a setting to Profile > "Terminal Emulation" page that disables this (it should be disabled by default)

Sure, let me look it.

Bug: Closing a tab/pane will not kill the instance on the server side

This is by design, remote pane should close by quit it's app. but this is arguable, if we think close local pane should close remote pane too, it is easy and feasible.

Add a feature flag to features.xml (Guidance)

Sure. Fair enough.

[Architectural notes] We should see if we can't just model a tmux pane as a connection so we don't need to pump output into the terminal from the App layer

Please provide the idea, I can try to implement it.

Overall, this is a really exciting feature and we're excited to see it land! Let us know if you need any guidance or additional comments on any of the thoughts above. 😊

CC @DHowett @lhecker @zadjii-msft

Thanks!

Since this PR is a bit big, another option is we split it into two or three parts to make it easy to review and integrate. Such as
part 1: infra libs(parser, TermControl, Terminal, ControlCore)
part 2: TmuxControl
part 3: integrating and UI/Menu

What do you think, split it or just keep as it is?

joexue · 2025-06-17T03:19:59Z

@carlos-zamora @DHowett @lhecker @zadjii-msft
All comments are addressed, please try again.

Thanks

lhecker · 2025-12-15T20:27:24Z

I have now pushed my changes and would love to hear your opinion. You don't have to filter yourself obviously. I don't believe my changes are technically correct, but I think it works as least as well as it did before. I tried fixing all bugs and issues that I could find and left notes for anything else.

src/cascadia/TerminalApp/TmuxControl.cpp

DHowett

Review comments for @lhecker - 42/67 files completed!

DHowett · 2025-12-16T20:33:10Z

src/cascadia/TerminalApp/Resources/en-US/Resources.resw

  </data>
-</root>
+  <data name="TmuxControlInfo" xml:space="preserve">
+    <value>Running in tmux control mode; Press 'q' to detach:</value>


We may need to {Lock...} the word tmux in some of these. We also historically made the q an insert from another resource (so that in German for example the Azure Connection can say "Enter Ja/nein [J/n]"

DHowett · 2025-12-16T20:34:44Z

src/cascadia/TerminalApp/TmuxControl.cpp

+        const auto newTabClickRevoker = std::move(_newTabClickRevoker);
+        auto& page = _page;
+
+        {


hmm... can you *this={} somehow?

src/cascadia/TerminalConnection/TmuxConnection.cpp

src/common.build.pre.props

src/features.xml

src/cascadia/TerminalSettingsEditor/Profiles_Terminal.xaml

src/cascadia/TerminalSettingsEditor/ProfileViewModel.cpp

DHowett · 2025-12-16T20:44:59Z

src/cascadia/TerminalSettingsEditor/PreviewConnection.cpp

-        TerminalOutput.raise(fmt::format(PreviewText, _displayPowerlineGlyphs ? PromptTextPowerline : PromptTextPlain));
+        const auto prompt = _displayPowerlineGlyphs ? PromptTextPowerline : PromptTextPlain;
+        const auto text = fmt::format(FMT_COMPILE(PreviewText), prompt);
+        TerminalOutput.raise(winrt_wstring_to_array_view(text));


well that's unfortunate that one of these functions became throwing

fmt::format can throw though. Marking it as noexcept is akschually technically incorrect. 🤓

DHowett · 2025-12-16T20:46:10Z

src/cascadia/TerminalControl/TermControl.cpp

        {
            // Do we ever get here (= uninitialized terminal)? If so: How?
-            assert(false);
+            // Yes, we can get here, when do Pane._Split, it need to call _SetupEntranceAnimation^M


you have some trailing ^Ms here!

DHowett · 2025-12-16T20:47:44Z

src/cascadia/TerminalApp/TmuxControl.cpp

+                if (_control)
+                {
+                    _responseBuffer.append(L"\r\n");
+                    _control.InjectTextAtCursor(_responseBuffer);


This should go through the Connection, shouldn't it? If not, document why not

I feel like if we successfully route everything through the connection, we don't need InjectTextAtCursor

but also I understand that we need a way to put the "Press Q" message into the originating control...

This should go through the Connection, shouldn't it? If not, document why not

The connection in this case is the OG tmux one. It's currently in the OSC state and so we can't inject text through the connection. It would just come back to us.

A way I used to consider is using delimiters to distinguish the text goes to tmux or local terminal, but in that case, performance is an issue. That why I used a weird callback to do so.
BTW, I saw a needs-author-feedback label on this PR, I’m not sure if that means me, if so, I’m on a trip, plus I have left the context for long time, please let @lhecker completely take over it. I like your change.👍

DHowett · 2025-12-18T22:40:00Z

@joexue Yep, don't worry about the Needs-Author-Feedback. Even if the PR gets automatically closed.

As long as you keep your fork up, and your branch open, we prefer to work on your PR like this.

That way, you get credit for doing the bulk of the work -- and we can thank you appropriately when it ships. We would literally not have started on this without you. :)

DHowett · 2025-12-18T22:40:08Z

/azp run

azure-pipelines · 2025-12-18T22:40:22Z

Azure Pipelines successfully started running 2 pipeline(s).

lhecker · 2026-01-06T17:54:54Z

/azp run

azure-pipelines · 2026-01-06T17:55:08Z

Azure Pipelines successfully started running 2 pipeline(s).

lhecker · 2026-01-06T20:14:26Z

/azp run

azure-pipelines · 2026-01-06T20:14:39Z

Azure Pipelines successfully started running 2 pipeline(s).

lhecker · 2026-01-13T15:14:44Z

/azp run

azure-pipelines · 2026-01-13T15:14:58Z

Azure Pipelines successfully started running 2 pipeline(s).

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joexue mentioned this pull request May 20, 2025

Add support for tmux Control Mode #3656

Open

carlos-zamora added a commit that referenced this pull request Jun 10, 2025

PRE-MERGE #18928 Add support for tmux control mode (#3656)

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joexue force-pushed the tmux_cc_pr branch from fed711a to 2bf4d08 Compare June 17, 2025 03:18

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joexue force-pushed the tmux_cc_pr branch from 2bf4d08 to b70dad2 Compare June 17, 2025 23:42

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DHowett mentioned this pull request Jun 18, 2025

VT mouse mode: no reaction to touch inputs #19039

Open

joexue force-pushed the tmux_cc_pr branch 2 times, most recently from 54c2bac to 4817698 Compare June 20, 2025 01:35

lhecker added 2 commits December 15, 2025 21:15

Merge remote-tracking branch 'origin/main' into tmux_cc_pr

c1c8672

Big, big refactor

8e3e19e

github-advanced-security bot found potential problems Dec 15, 2025

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Exclude from spell checking

0d466b6

DHowett requested changes Dec 16, 2025

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microsoft-github-policy-service bot added Needs-Author-Feedback The original author of the issue/PR needs to come back and respond to something and removed Needs-Author-Feedback The original author of the issue/PR needs to come back and respond to something labels Dec 16, 2025

lhecker added 2 commits December 18, 2025 20:32

Merge remote-tracking branch 'origin/main' into tmux_cc_pr

1aa4f17

Partially address feedback

76bd54f

lhecker added 2 commits January 6, 2026 18:20

Revert accidental change

7c05042

Address feedback

1b9e54e

Fix AuditMode nagging

71effe1

carlos-zamora added the zBugBash-Consider label Jan 12, 2026

Merge remote-tracking branch 'origin/main' into tmux_cc_pr

7ec5d91

carlos-zamora added a commit that referenced this pull request Jan 13, 2026

PRE-MERGE #18928 Add support for tmux control mode (#3656)

82487d0

lhecker added 4 commits January 14, 2026 18:54

Merge remote-tracking branch 'origin/main' into tmux_cc_pr

be3db4f

Fix a crash when dragging tabs / pressing +

e9ad3f4

Fix tmux setting not being respected

00cc0c3

Merge remote-tracking branch 'origin/main' into tmux_cc_pr

fe718b6

Add support for tmux control mode (#3656) #18928

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Summary of the Pull Request

References and Relevant Issues

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

PR Checklist

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joexue commented May 20, 2025

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DHowett commented Dec 18, 2025

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