Add "micaAlt" as a value for the useMica theme option

[Jay Patel (JayPatel095)]

Summary of the Pull Request

Adds a "micaAlt" option to useMica using a string enum rather than a boolean (like the old system). Backward compat is maintained with the boolean values which is limited to using or not using mica w/o micaAlt.

References and Relevant Issues

Closes #17650

Detailed Description of the Pull Request / Additional comments

The old useMica was a boolean mapping to DWMSBT_MAINWINDOW or DWMSBT_NONE. This adds a third state for DWMSBT_TABBEDWINDOW, doing the same thing as CloseOnExitMode and bellStyle (boolean to enum).

To do this, the new MicaStyle enum was added in Theme.idl, a JSON_ENUM_WRAPPER for MicaStyle was added to TerminalSettingsSerializationHelpers.h with an override for booleans, various refactoring changes from boolean->enum, and some tests. Doc repo has ready-to-merge PR as well, mirroring the changes to closeOnExit rather than bellStyle, MicrosoftDocs/terminal#969.

No settings UI added, stays JSON-only.

Validation Steps Performed

Compiled on 25H2 Pro VM but transparent effects don't render over RDP -> sideloaded onto VMWare with 3D effects enabled -> took images below.

PR Checklist

• Closes Mica Alt #17650
• Tests added/passed
• Documentation updated
  • If checked, please file a pull request on our docs repo and link it here: Update useMica options for micaAlt and enum changes MicrosoftDocs/terminal#969.
• Schema updated (if necessary)

old, false (no mica)

old, true (mica)

new, "none" (no mica)

new, "mica" (mica)

new, "micaAlt" (micaAlt)

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Jay Patel (JayPatel095)]

@microsoft-github-policy-service agree

[azure-pipelines]

Azure Pipelines:
There may be pipelines that require an authorized user to comment /azp run to run.

[Jay Patel (JayPatel095)]

Mike Griese (@zadjii-msft) Mind starting CI?

[Jay Patel (JayPatel095)]

/azp

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[Jay Patel (JayPatel095)]

/azp run

[azure-pipelines]

Commenter does not have sufficient privileges for PR 20464 in repo microsoft/terminal

[Dustin L. Howett (DHowett)]

Jay Patel (@JayPatel095) we mind starting CI before doing a review, yes, because the purpose of delaying CI is to prevent people from modifying the pipeline and compromising the build agent.

I see that you tried two times to interact with the azure pipelines bot, over the weekend when nobody would be around to watch. Should we be concerned?

[Jay Patel (JayPatel095)]

Jay Patel (@JayPatel095) we mind starting CI before doing a review, yes, because the purpose of delaying CI is to prevent people from modifying the pipeline and compromising the build agent.

I'm a bit confused, since I only interacted with the bot 3 hours ago, as in this morning, specifically after 9. Otherwise it was just basic lint and the policy agreement. As in my only direct attempt to start CI was today, and otherwise it was a request to someone experienced enough to tell me if I was missing something or needed to wait, like how I now know you guys aren't CI-first. So, I don't really think there is an issue here.

[Dustin L. Howett (DHowett)]

ah, misread :)

[Dustin L. Howett (DHowett)]

/azp run

[azure-pipelines]

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

[Jay Patel (JayPatel095)]

Believe I'm using a too new clang-format that comes w/ VS 2026. Will take a look soon. I was just trying to format master... Fixed now.

[Dustin L. Howett (DHowett)]

/azp run

[azure-pipelines]

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

[Jay Patel (JayPatel095)]

Dustin L. Howett (@DHowett) Any next steps regarding review?

[Jay Patel (JayPatel095)]

Dustin L. Howett (@DHowett) Mike Griese (@zadjii-msft) Hate to ping you guys on repeat but its been a while since CI passed