WorkspaceService.open() reloads full app even with { preserveWindow: true } – how to switch workspace without full reload?

[sumit140792]

Hi Theia team,

We are currently using Theia in a custom setup and trying to switch workspaces without reloading the entire app or losing the UI state.

await this.workspaceService.open(workspaceFilePath, { preserveWindow: true });

This avoids opening a new browser tab.

But the application still reloads, and we lose things like open editors, side panel state, etc.

Questions:
Is there a supported way to create a new project and open it as a workspace without reloading the full browser context?

Is the workspace switch API (workspaceService.open) designed to always trigger a reload?

Are there any workarounds to simulate a workspace switch more smoothly, e.g. by dynamically updating the workspace roots without triggering a hard reload?

We want a smooth UX where switching workspaces doesn't force a full browser reload or destroy state.

[msujew]

Hey @sumit140792,

I don't think this is possible. You will find that VSCode has the same issue. Note that the preserveWindow field is there to decide whether to use the existing window (i.e. reloading it) or to create a new window.

On a technical level, a lot of things have a dependency to the workspace. For example, the plugin host needs to be restarted when changing the workspace, etc. It is just much easier to reload the whole frontend than to ensure that every component can correctly deal with a changed workspace.

[sumit140792]

Thanks for the detailed response earlier.

Just to follow up — in our use case, each project needs to be a fully isolated workspace, with its own .theia folder, settings, launch configurations, etc. So unfortunately, we can't use multi-root workspaces because everything would get merged into a single .theia-workspace file, which breaks the separation between projects.

Our main goal is to allow the user to:

Create a new project (with a clean workspace)

Open that project using workspaceService.open(...)

Avoid a disruptive full reload or at least preserve editor and layout state

Since Theia triggers a full reload by design, could you please advise:

1. Is there any recommended pattern or API to preserve and restore layout/UI state across workspace switches?
2. Are there any hooks or lifecycle events we can use to inject state saving/restoration logic cleanly before and after workspaceService.open(...)?
3. Would a custom workspace switch mechanism (without workspaceService.open()) be advisable, or is that likely to break internal assumptions?
   We’d really appreciate any insights or best practices here, as this affects the core UX of our application.

Thanks again for your help!

[msujew]

Is there any recommended pattern or API to preserve and restore layout/UI state across workspace switches?

You could modify the ShellLayoutRestorer to not store the layout on a per-workspace basis but on a global level.

Are there any hooks or lifecycle events we can use to inject state saving/restoration logic cleanly before and after workspaceService.open(...)?

There are lifecycle hooks both on the FrontendApplicationContribution (onStart, onStop) and Widget (storeLayout, restoreLayout) level to use depending on your use case.

Would a custom workspace switch mechanism (without workspaceService.open()) be advisable, or is that likely to break internal assumptions?

It would very likely break the plugin support in case you're using that. I believe there are also a few other services that rely on the current behavior, but they aren't as noticeable.

[sumit140792]

Thanks a lot for the detailed and helpful reply!

Your suggestion to modify the ShellLayoutRestorer to store layout globally rather than per workspace sounds promising — we’ll explore that approach to help us preserve layout across workspace switches.

We’ll also look into implementing the necessary logic using the lifecycle hooks you mentioned (FrontendApplicationContribution.onStart/onStop and Widget.storeLayout/restoreLayout) to manage state saving and restoration around the call to workspaceService.open(...).

As for avoiding workspaceService.open(), your warning about breaking plugin support (and potentially other core services) is well noted. We'll stick to the supported flow and avoid custom workspace switching logic that could compromise stability or compatibility.

If you have any example implementations, tips, or community references for overriding ShellLayoutRestorer or restoring layout globally, that would be greatly appreciated.

Thanks again for your guidance!

[msujew]

The StorageService is in charge of prefixing the layout key (used by the ShellLayoutRestorer) for workspace-specific storage. You can override that service to ensure that the key is not prefixed with the current workspace path, thereby making it global:

theia/packages/core/src/browser/shell/shell-layout-restorer.ts

Line 123 in ab0ce56

protected storageKey = 'layout';

theia/packages/core/src/browser/storage-service.ts

Lines 86 to 92 in ab0ce56

	protected prefix(key: string): string {
	if (environment.electron.is()) {
	return `theia:${key}`;
	}
	const pathname = typeof window === 'undefined' ? '' : window.location.pathname;
	return `theia:${pathname}:${key}`;
	}