Implement 5s timeout for ConPTY handoff embedding.

[Kuldeep2822k]

Add a timer in WindowEmperor to automatically exit after 5 seconds if no windows are created during a ConPTY handoff. The timer is cancelled as soon as a new window is created. This prevents the process from staying alive indefinitely if a handoff fails or is never received.

Summary of the Pull Request

I've implemented a 5-second timeout for the ConPTY handoff embedding in the Windows Terminal.

1. Added a SafeDispatcherTimer _handoffTimeoutTimer; member to the WindowEmperor class.
2. In HandleCommandlineArgs, when the application is launched with the -Embedding flag (ConPTY handoff), the timer is started with a 5-second interval.
3. If the timer ticks (indicating no window was created within 5 seconds), it calls _postQuitMessageIfNeeded() to attempt an application exit.
4. In CreateNewWindow, the timer is explicitly stopped to ensure that the application doesn't exit if a window is successfully created.

The implementation follows the existing codebase patterns using SafeDispatcherTimer and _postQuitMessageIfNeeded

References and Relevant Issues

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

PR Checklist

• Closes #xxx
• 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)

[Kuldeep2822k]

@Kuldeep2822k please read the following Contributor License Agreement(CLA). If you agree with the CLA, please reply with the following information.

@microsoft-github-policy-service agree [company="{your company}"]

Options:

• (default - no company specified) I have sole ownership of intellectual property rights to my Submissions and I am not making Submissions in the course of work for my employer.

@microsoft-github-policy-service agree

• (when company given) I am making Submissions in the course of work for my employer (or my employer has intellectual property rights in my Submissions by contract or applicable law). I have permission from my employer to make Submissions and enter into this Agreement on behalf of my employer. By signing below, the defined term “You” includes me and my employer.

@microsoft-github-policy-service agree company="Microsoft"

Contributor License Agreement

@microsoft-github-policy-service agree

[lhecker]

How did you test this?

[Kuldeep2822k]

How did you test this?

I tested this by launching wt.exe -Embedding without sending a handoff signal. The process (PID 18960) exited automatically after ~5 seconds, confirming the SafeDispatcherTimer fires and calls _postQuitMessageIfNeeded() correctly. Without this fix, the process would remain alive indefinitely.

[DHowett]

@lhecker honestly I'm not sure I hate this; it seems reasonable that we don't want to stick around, and we did leave a comment about that!

[lhecker]

@DHowett yep!

[DHowett]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).
1 pipeline(s) were filtered out due to trigger conditions.

[DHowett]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).
1 pipeline(s) were filtered out due to trigger conditions.

[DHowett]

did you fix the code format by eye or by using one of our code formatting scripts...

[DHowett]

(i ask since it failed again)

[Kuldeep2822k]

I fixed it by eye — I didn't use your code formatting scripts. Here's what I did:

Identified the CI failure: "Code Health Check Code Format failed"
Read your .clang-format configuration to understand the Microsoft style rules
Examined the code changes in WindowEmperor.cpp
Spotted the unnecessary blank lines before/after _handoffTimeoutTimer.Stop();
Manually edited the file to remove them

this was done because i use linux

[DHowett]

you know, clang-format runs on linux...

[DHowett]

as long as you don't munge the line endings :)

[Kuldeep2822k]

from what i understand it i ran curl.exe -s -S -L "https://raw.githubusercontent.com/check-spelling/check-spelling/cfb6f7e75bbfc89c71eaa30366d0c166f1bd9c8c/apply.pl" | perl - "https://github.com/microsoft/terminal/actions/runs/31035358696/attempts/1"
and commit it should fix it ?

[DHowett]

this is not a spelling check failure. that script will not help you.

[Kuldeep2822k]

you know, clang-format runs on linux...

oh sorry i missed that i was trying to run but it kept failing so i tried a general approach

[Kuldeep2822k]

i have resolved the spell check issue now it cleared without any issue can you check @DHowett

[DHowett]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).
1 pipeline(s) were filtered out due to trigger conditions.