Fix broken markdown URL for static front page by TBarregren · Pull Request #6 · ProgressPlanner/markdown-alternate

TBarregren · 2026-02-14T12:07:48Z

Summary

Fixes #5.

When a static page is set as the front page, get_permalink() returns the site root URL (e.g. https://example.com/). The existing rtrim('/') . '.md' logic produces an invalid URL like https://example.com.md.
This fix detects the front page case and generates /index.md instead. The slug is filterable via a new markdown_alternate_front_page_slug filter (default: "index").
Three locations are fixed: AlternateLinkHandler::output_alternate_link(), RewriteHandler::handle_accept_negotiation(), and RewriteHandler::parse_markdown_url().

Test plan

Set a static page as the front page (Settings → Reading)
Visit the front page and inspect the HTML <head> — verify the <link rel="alternate"> points to /index.md (not example.com.md)
Visit /index.md directly — verify it serves the front page as markdown
Send a request with Accept: text/markdown to the front page — verify it redirects to /index.md
Verify existing .md URLs for regular posts/pages still work
Test the markdown_alternate_front_page_slug filter to change "index" to e.g. "home"

🤖 Generated with Claude Code

When a static page is set as the front page, get_permalink() returns the site root URL (e.g. https://example.com/). The existing code strips the trailing slash and appends .md, producing an invalid URL like https://example.com.md. This fix detects the front page case and uses /index.md instead. The slug is filterable via 'markdown_alternate_front_page_slug'. Affected locations: - AlternateLinkHandler: <link rel="alternate"> tag generation - RewriteHandler: Accept header content negotiation redirect - RewriteHandler: REQUEST_URI parsing for /index.md routing Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

jdevalk · 2026-02-15T22:25:41Z

@ilicfilip could you see if this or #8 is the better approach?

Copilot

Pull request overview

This PR fixes a bug where static front pages produce invalid markdown URLs (e.g., https://example.com.md instead of https://example.com/index.md). The issue occurs because get_permalink() returns the site root URL for the front page, and appending .md after stripping the trailing slash creates a malformed URL.

Changes:

Added front page detection logic using URL comparison in three locations
Introduced a new filterable slug markdown_alternate_front_page_slug (default: "index") for the front page markdown URL
Extracted URL building logic into a private method in AlternateLinkHandler

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 7 comments.

File	Description
src/Discovery/AlternateLinkHandler.php	Added `build_markdown_url()` method to detect front pages and generate appropriate markdown URLs
src/Router/RewriteHandler.php	Added front page detection in `parse_markdown_url()` to route `/index.md` to the front page, and in `handle_accept_negotiation()` to generate correct redirect URLs

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Copilot · 2026-02-15T22:31:07Z

src/Router/RewriteHandler.php

+        // Build markdown URL — detect front page to avoid invalid domain.md URL.
+        $site_url = trailingslashit(home_url());
+        if (trailingslashit($canonical) === $site_url) {
+            $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');


The coding style here is inconsistent with the rest of the RewriteHandler.php file. This file uses no spaces inside function call parentheses (e.g., line 157: apply_filters('markdown_alternate_supported_post_types', $default_types)), but this line has spaces. For consistency with the existing code in this file, this should be apply_filters('markdown_alternate_front_page_slug', 'index') without spaces.

Copilot · 2026-02-15T22:31:07Z

src/Router/RewriteHandler.php

        $slug = $matches[1];

+        // Check if this is the front page slug (default "index", filterable).
+        $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');


The filter output should be sanitized before use to prevent potential security issues. Consider using sanitize_title() or at minimum validating that the slug contains only safe URL characters. This prevents malicious or malformed slugs from being used in URL construction, even though the impact is limited since WordPress will ultimately handle the URL.

Suggested change

$front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');

$front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');

// Ensure the filtered slug is safe before using it in routing logic.

if (!is_string($front_slug)) {

$front_slug = 'index';

} elseif (!preg_match('/^[A-Za-z0-9\-._~\/]+$/', $front_slug)) {

// Fallback to a safe default if the slug contains unexpected characters.

$front_slug = 'index';

}

Copilot · 2026-02-15T22:31:07Z

src/Discovery/AlternateLinkHandler.php

+        // Detect if this is the static front page by comparing to site URL.
+        $site_url = trailingslashit( home_url() );
+        if ( trailingslashit( $permalink ) === $site_url ) {


Consider using a more direct approach to detect the front page by comparing post IDs instead of URLs. This would be more reliable and clearer. For example: if ((int) get_option('page_on_front') === $post->ID && get_option('show_on_front') === 'page'). This approach avoids potential edge cases with URL formatting and is more explicit about checking the WordPress front page setting.

Suggested change

// Detect if this is the static front page by comparing to site URL.

$site_url = trailingslashit( home_url() );

if ( trailingslashit( $permalink ) === $site_url ) {

// Detect if this is the static front page using WordPress front page settings.

$is_static_front_page = (

get_option( 'show_on_front' ) === 'page'

&& (int) get_option( 'page_on_front' ) === (int) $post->ID

);

if ( $is_static_front_page ) {

$site_url = trailingslashit( home_url() );

Copilot · 2026-02-15T22:31:07Z

src/Router/RewriteHandler.php

+        // Build markdown URL — detect front page to avoid invalid domain.md URL.
+        $site_url = trailingslashit(home_url());
+        if (trailingslashit($canonical) === $site_url) {
+            $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');
+            $md_url = $site_url . $front_slug . '.md';
+        } else {
+            $md_url = rtrim($canonical, '/') . '.md';
+        }


Consider using a more direct approach to detect the front page. Since this code runs during template_redirect (when WordPress query is available), you could use is_front_page() to check if the current page is the front page, which would be clearer and more reliable than URL comparison. This would also be consistent with WordPress conventions for front page detection.

Copilot · 2026-02-15T22:31:07Z

src/Discovery/AlternateLinkHandler.php

+        // Detect if this is the static front page by comparing to site URL.
+        $site_url = trailingslashit( home_url() );
+        if ( trailingslashit( $permalink ) === $site_url ) {
+            $front_slug = apply_filters( 'markdown_alternate_front_page_slug', 'index' );


The filter output should be sanitized before use in URL construction. Consider using sanitize_title() to ensure the slug contains only safe URL characters. This prevents potential security issues from malicious filter values and ensures the generated URL is well-formed.

Suggested change

$front_slug = apply_filters( 'markdown_alternate_front_page_slug', 'index' );

$front_slug = apply_filters( 'markdown_alternate_front_page_slug', 'index' );

$front_slug = sanitize_title( (string) $front_slug );

if ( $front_slug === '' ) {

$front_slug = 'index';

}

Copilot · 2026-02-15T22:31:08Z

src/Router/RewriteHandler.php

+        // Build markdown URL — detect front page to avoid invalid domain.md URL.
+        $site_url = trailingslashit(home_url());
+        if (trailingslashit($canonical) === $site_url) {
+            $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');


The filter output should be sanitized before use in URL construction. Consider using sanitize_title() to ensure the slug contains only safe URL characters. This prevents potential security issues from malicious filter values and ensures the generated URL is well-formed.

Suggested change

$front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');

$front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');

$front_slug = sanitize_title($front_slug);

Copilot · 2026-02-15T22:31:08Z

src/Router/RewriteHandler.php

        $slug = $matches[1];

+        // Check if this is the front page slug (default "index", filterable).
+        $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');


The coding style here is inconsistent with the rest of the RewriteHandler.php file. This file uses no spaces inside function call parentheses (e.g., line 157: apply_filters('markdown_alternate_supported_post_types', $default_types)), but this line has spaces. For consistency with the existing code in this file, this should be apply_filters('markdown_alternate_front_page_slug', 'index') without spaces.

jdevalk · 2026-02-17T09:57:30Z

Thanks for this fix — this appears superseded by #8 (same static front-page markdown URL area) and is currently conflicting with main. Closing to reduce overlap and keep one active path for this fix.

jdevalk requested review from Copilot and ilicfilip February 15, 2026 22:25

Copilot started reviewing on behalf of jdevalk February 15, 2026 22:26 View session

Copilot AI reviewed Feb 15, 2026

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jdevalk closed this Feb 17, 2026

jdevalk mentioned this pull request Feb 17, 2026

fix: resolve static front page .md URL generation (#5) #8

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Fix broken markdown URL for static front page#6

Fix broken markdown URL for static front page#6
TBarregren wants to merge 1 commit intoProgressPlanner:mainfrom
TBarregren:fix/front-page-markdown-url

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-        $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');
+        $front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');
+        // Ensure the filtered slug is safe before using it in routing logic.
+        if (!is_string($front_slug)) {
+            $front_slug = 'index';
+        } elseif (!preg_match('/^[A-Za-z0-9\-._~\/]+$/', $front_slug)) {
+            // Fallback to a safe default if the slug contains unexpected characters.
+            $front_slug = 'index';
+        }

-        // Detect if this is the static front page by comparing to site URL.
-        $site_url = trailingslashit( home_url() );
-        if ( trailingslashit( $permalink ) === $site_url ) {
+        // Detect if this is the static front page using WordPress front page settings.
+        $is_static_front_page = (
+            get_option( 'show_on_front' ) === 'page'
+            && (int) get_option( 'page_on_front' ) === (int) $post->ID
+        );
+        if ( $is_static_front_page ) {
+            $site_url   = trailingslashit( home_url() );

	$front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');
	$front_slug = apply_filters('markdown_alternate_front_page_slug', 'index');
	$front_slug = sanitize_title($front_slug);

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TBarregren commented Feb 14, 2026

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