Add landing page feature flag

[reakaleek]

cursorful-video-landing-page-1741101919376.mp4

[Copilot]

PR Overview

This PR introduces a landing page feature flag and related UI adjustments while refactoring hx attribute generation across several views.

• Introduces a new feature flag for landing page rendering in FeatureFlags.cs.
• Updates Htmx helper methods and associated templates to use consolidated hx attribute generation.
• Adjusts DOM element selectors and minor refactoring in assets and layout views.

Reviewed Changes

File	Description
src/Elastic.Markdown/IO/Configuration/FeatureFlags.cs	Adds support for a landing page feature flag with environment variable overrides.
src/Elastic.Markdown/Helpers/Htmx.cs	Updates hx attribute helper methods with a new condition in GetHxSelectOob.
docs/_docset.yml	Updates feature flag defaults to enable primary-nav and landing-page.
src/Elastic.Markdown/Assets/copybutton.ts	Changes default SVG icon for the copy button and updates the element selector.
src/Elastic.Markdown/Slices/HtmlWriter.cs	Removes an unused using directive for Configuration.
src/Elastic.Markdown/Slices/_Layout.cshtml	Adds conditional rendering for the landing page and assigns element IDs.
src/Elastic.Markdown/Slices/Layout/_Header.cshtml	Refactors hx attribute application by using a consolidated helper call.
src/Elastic.Markdown/Slices/Layout/_Breadcrumbs.cshtml	Refactors hx attributes in breadcrumbs and updates meta tag position calculation.

Copilot reviewed 13 out of 13 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (4)

src/Elastic.Markdown/Helpers/Htmx.cs:15

• Consider validating that currentUrl has sufficient length before slicing with currentUrl[startIndex..] to guard against potential runtime errors.

if (currentUrl[startIndex..] == "/")

src/Elastic.Markdown/Assets/copybutton.ts:151

• [nitpick] Confirm that the updated COPYBUTTON_SELECTOR without the '.markdown-content' qualifier is intentional and matches the intended DOM structure.

const COPYBUTTON_SELECTOR = 'div.highlight pre';

src/Elastic.Markdown/Slices/Layout/_Breadcrumbs.cshtml:25

• [nitpick] Verify that using @(index+2) for the breadcrumb position accurately reflects the hierarchy, ensuring there is no off-by-one error in the metadata.

<meta itemprop="position" content="@(index+2)">

src/Elastic.Markdown/IO/Configuration/FeatureFlags.cs:18

• [nitpick] Clarify the decision to treat non-boolean environment variable values as 'enabled' by adding more detailed comments or unit tests to document this behavior.

// if the env var is set but not a bool, we treat it as enabled

[reakaleek]

Suggested change

	primary-nav: true
	landing-page: true
	primary-nav: false
	landing-page: false

[florent-leborgne]

First round of review!

[florent-leborgne]

A note suggesting to move this to the header next to troubleshoot & co link

[florent-leborgne]

We should remove this, this is visually connected to "Elastic documentation" while it's not related. The button also exists already in the header.

[florent-leborgne]

Suggested change

	<p class="mt-2">Lorem ipsum dolor sit amet, consectetur adipiscing elitLorem ipsum dolor sit amet, consectetur adipiscing elit</p>
	<p class="mt-2">Learn about Elasticsearch, the components at the heart of the Elastic Search AI Platform, and the solutions it powers.</p>

To give a better idea of what's behind the link. Should link to the get-started main page.

[florent-leborgne]

@reakaleek this is outdated since you modified these lines according to the Gdoc in between. But I think it's still valid

[reakaleek]

Sorry, for pushing changes!

I will consider this and other cases!

[florent-leborgne]

Suggested change

	<div class="lg:basis-[50%] rounded-xl border-1 border-grey-20 p-6">
	<p>Elastic architecture</p>
	<p class="mt-2">Lorem ipsum dolor sit amet, consectetur adipiscing elitLorem ipsum dolor sit amet, consectetur adipiscing elit</p>
	</div>

I think we need only 1 path to keep things simple and clear for readers

[florent-leborgne]

@reakaleek this is outdated since you modified these lines according to the Gdoc in between. But I think it's still valid

[reakaleek]

This looks a bit odd. I think we need more fitting design for this.

[Copilot]

PR Overview

This PR introduces a feature flag for the landing page and updates various components to support conditional rendering and behavior based on this flag. Key changes include modifying feature flag evaluation and error handling, adjusting layout and navigation rendering for the landing page, and updating related documentation and assets.

Reviewed Changes

File	Description
src/Elastic.Markdown/IO/Configuration/FeatureFlags.cs	Adds a landing page flag and adjusts environment variable evaluation for feature flags.
src/Elastic.Markdown/Helpers/Htmx.cs	Updates the hx-select-oob logic to handle landing page rendering and changes how target selectors are constructed.
src/Elastic.Markdown/Slices/_ViewModels.cs	Introduces a new IsLandingPage property based on the landing page flag.
docs/_docset.yml	Enables primary-nav and landing-page features for documentation previews.
src/Elastic.Markdown/Assets/copybutton.ts	Updates the copy button icon SVG and adjusts the code cell selector.
src/Elastic.Markdown/Assets/pages-nav.ts	Modifies viewport checking logic to incorporate the parent element and update scrolling behavior.
src/Elastic.Markdown/Slices/HtmlWriter.cs	Removes an unused using directive for configuration.
src/Elastic.Markdown/Slices/_Layout.cshtml	Incorporates conditional layout logic for landing page rendering.
src/Elastic.Markdown/Slices/Layout/_SecondaryNav.cshtml	Conditionally renders nav elements based on landing page state.
src/Elastic.Markdown/Slices/Layout/_PrimaryNavDropdownItem.cshtml	Tweaks CSS classes for consistent spacing.
src/Elastic.Markdown/Slices/Layout/_Header.cshtml	Updates a navigation link from security to observability.
src/Elastic.Markdown/Slices/Layout/_Breadcrumbs.cshtml	Adjusts breadcrumb rendering and hx attributes for improved navigation behavior.

Copilot reviewed 17 out of 17 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

src/Elastic.Markdown/Helpers/Htmx.cs:26

• selectTargets is a string rather than a collection; using string.Join will split the string into individual characters. Consider returning the string directly instead of using string.Join.

return string.Join(',', selectTargets);