Fix icon theme not updating on reload after Dark/Light mode switch

[Copilot]

RevitThemeDetector stores the detected Revit UI theme in static fields, so after switching themes mid-session the stale value persists for the process lifetime — a full Revit restart was required to see correct icons.

Change

Clear the theme cache at the start of each LoadSession() so the active theme is re-queried on every reload:

// SessionManagerService.LoadSession()
_extensionManager?.ClearParserCaches();
RevitThemeDetector.ClearCache();   // ← added

The cache is repopulated on the first IsDarkTheme() call within that same load, so there is no performance regression. After this change, a pyRevit reload is sufficient to pick up a Dark ↔ Light mode switch.

[devloai]

Unable to trigger custom agent "Code Reviewer". You have run out of credits 😔
Please upgrade your plan or buy additional credits from the subscription page.

[jmcouffin]

Fixes #3361

[jmcouffin]

@romangolev @Wurschdhaud @tay0thman what are you thoughts on this? Shall we leave it as is and document it in the reload button tooltip or adjust the behavior following this PR?

[Wurschdhaud]

Copilot claims there is no overhead, so why not? 😄
But the bug report claims he did restart anyway, so this shouldn't be the root cause. I don't have 2027 installed to verify.

[romangolev]

@jmcouffin to fully cover the issue #3361 we need to implement the event listener that would identify the theme switch and adjust the UI accordingly. With current copilot implementation user is going to be stuck in the same situation without being able to see the difference after he or she changes the theme.

The proper implementation should include the event listener like this and also should prompt user to restar pyRevit to properly propagate changes.

private void OnThemeChanged(object sender, ThemeChangedEventArgs e)
{
    if (e.ThemeChangedType == ThemeType.UITheme)
    {
        // Ribbon/UI theme changed
    }
}

@jmcouffin fancy implementing this one? or I could take this over if you don't mind

[jmcouffin]

Please, go ahead!
@romangolev

[romangolev]

@jmcouffin much better now 😄 tested locally with Revit 2027

[jmcouffin]

Inception time: asked copilot review

[Copilot]

Pull request overview

This PR aims to ensure pyRevit picks up Revit Dark/Light theme changes without requiring a full Revit restart, primarily so ribbon icons update correctly after a mid-session theme switch.

Changes:

• Clear RevitThemeDetector’s static cache at the beginning of each SessionManagerService.LoadSession() so theme is re-detected on reload.
• Add a RevitThemeChangeMonitor that listens for Revit theme changes and prompts the user to reload pyRevit, then triggers reload on the next Idling.
• Add unit tests covering theme-change detection, de-duping, readiness deferral, and disposal behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
dev/pyRevitLoader/Source/PyRevitLoaderApplication.cs	Wires in theme-change monitoring and schedules a reload via Idling after user confirmation.
dev/pyRevitLoader/pyRevitAssemblyBuilder/UIManager/SessionManagerService.cs	Clears the theme detector cache at the start of each session load/reload.
dev/pyRevitLoader/pyRevitAssemblyBuilder/SessionManager/RevitThemeChangeMonitor.cs	Introduces a monitor + reflection-based theme source to detect theme transitions and request UI refresh.
dev/pyRevitLoader/pyRevitExtensionParserTester/RevitThemeChangeMonitorTests.cs	Adds coverage for monitor behavior (transition, duplicates, startup deferral, disposal, idempotent start, reflection forwarding).
dev/pyRevitLoader/pyRevitExtensionParserTester/pyRevitExtensionParserTest.csproj	Includes the new test file in the test project build.
dev/pyRevitLoader/pyRevitAssemblyBuilder/pyRevitAssemblyBuilder.csproj	Broadens the .NET Core reference condition to TargetFrameworkIdentifier == .NETCoreApp.

[Wurschdhaud]

Did you test against older versions that didn't have themes?

[romangolev]

Did you test against older versions that didn't have themes?

I've just gave it a spin with Revit 2022, no issues detected

[sanzoghenzo]

Changes look good, but I'm wondering if this should be done automatically instead of asking the user to restart or not.

I don't believe this is a frequent enough operation to justify more work on it, though!

[romangolev]

@sanzoghenzo yeah, that's going to be so much better UI

I've made changes for the Icons to update automatically. Please, take a look again 👀