doc(Layout): improve load theme logic

[ArgoZhang]

Link issues

fixes #6597

Summary By Copilot

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Merge the latest code from the main branch

Summary by Sourcery

Improve theme load logic by asynchronously initializing theme through a JS module before rendering the base layout and unifying theme retrieval across modules.

Bug Fixes:

• Fix theme loading logic to address flickering and delayed theme application (feat(MeiliSearch): kbd style support dark mode #6596)

Enhancements:

• Load and initialize theme via a JS module in OnInitializedAsync before rendering layout
• Guard layout rendering with an initialization flag to wait for theme application
• Unify theme retrieval by removing getPreferredTheme and defaulting getTheme to use auto theme value
• Update related JS modules to replace getPreferredTheme with getTheme

[sourcery-ai]

Reviewer's Guide

This PR enhances the layout’s theme initialization by moving theme detection and application to a client-side JS module loaded during BaseLayout initialization, unifying the theme utility functions, and conditionally rendering the layout only after theme setup completes.

Sequence diagram for improved theme initialization in BaseLayout

sequenceDiagram
    participant BaseLayout
    participant JSRuntime
    participant ThemeModule
    participant Browser
    BaseLayout->>JSRuntime: Load JS module (BaseLayout.razor.js)
    JSRuntime->>ThemeModule: Call initTheme()
    ThemeModule->>Browser: getTheme() (from localStorage or attribute)
    ThemeModule->>Browser: setTheme(currentTheme, false)
    Note over BaseLayout: _init set to true, layout rendered

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Flow diagram for conditional layout rendering after theme initialization

flowchart TD
    A[Component Initialization] --> B{_init == false?}
    B -- Yes --> C[Do not render layout]
    B -- No --> D[Render Header and Body]
    D --> E[Layout visible with correct theme]

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File-Level Changes

Change	Details	Files
Add client-side theme initialization in BaseLayout	Inject IJSRuntime and IOptions Override OnInitializedAsync to load the JS module and call initTheme Introduce _init flag and render content only after initialization	BaseLayout.razor.cs BaseLayout.razor
Refactor theme utility functions to use a single getTheme	Remove getPreferredTheme export Extend getTheme to fallback to auto value Update Pre.razor.js and ThemeProvider.razor.js to import and call getTheme instead of getPreferredTheme	utility.js Pre.razor.js ThemeProvider.razor.js
Introduce BaseLayout.razor.js for theme setup	Create initTheme function to fetch current theme and apply it	BaseLayout.razor.js

Assessment against linked issues

Issue	Objective	Addressed	Explanation
#6596	Add dark mode styling support for keyboard (kbd) elements in MeiliSearch	❌	The PR only improves theme loading logic and does not add or modify any CSS or styling for kbd elements.
#6596	Introduce theme-aware CSS variables for kbd component styling	❌	No changes to CSS variables or kbd component styling are present in the PR diff.
#6596	Update documentation to reflect dark mode support for kbd elements	❌	The PR does not update documentation related to kbd elements or their dark mode support.

Possibly linked issues

• feat(MeiliSearch): kbd style support dark mode #6596: The PR refactors theme loading logic as described in the issue, explicitly linking to it.
• feat(MeiliSearch): kbd style support dark mode #6596: PR improves Layout theme loading, fixing dark mode issue with menu and footer.

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[sourcery-ai]

Hey @ArgoZhang - I've reviewed your changes - here's some feedback:

• Consider moving the JS interop theme initialization into OnAfterRenderAsync (with a first-render guard) to ensure the DOM is ready and avoid pre-render race conditions.
• Gating the entire layout behind the _init flag may produce a blank page if the module load fails or is slow—consider adding a simple loading skeleton or fallback to improve perceived performance.
• Wrap the module loading and initTheme invocation in a try/catch to gracefully handle JS interop failures and avoid the layout getting stuck uninitialized.

Prompt for AI Agents

Please address the comments from this code review:
## Overall Comments
- Consider moving the JS interop theme initialization into OnAfterRenderAsync (with a first-render guard) to ensure the DOM is ready and avoid pre-render race conditions.
- Gating the entire layout behind the _init flag may produce a blank page if the module load fails or is slow—consider adding a simple loading skeleton or fallback to improve perceived performance.
- Wrap the module loading and initTheme invocation in a try/catch to gracefully handle JS interop failures and avoid the layout getting stuck uninitialized.

## Individual Comments

### Comment 1
<location> `src/BootstrapBlazor.Server/Components/Layout/BaseLayout.razor:4` </location>
<code_context>
-    <main>
-        @Body
-    </main>
+    @if (_init)
+    {
+        <Header></Header>
+        <main>
+            @Body
+        </main>
</code_context>

<issue_to_address>
Delaying layout rendering until _init is true may impact perceived performance.

If initialization is asynchronous, users may experience a blank screen. Display a loading indicator or fallback UI during this period.
</issue_to_address>

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[sourcery-ai]

suggestion (performance): Delaying layout rendering until _init is true may impact perceived performance.

If initialization is asynchronous, users may experience a blank screen. Display a loading indicator or fallback UI during this period.