Incorrect grouping of search results between "Extensions" and "Other Matches"

Background

In https://github.com/php/phd/pull/154, we resolved the issue of missing pages in the search index. However, now that these pages are visible in search results, a long-standing bug in result grouping has become apparent.

Issue

Some search results are incorrectly categorized between the "Extensions" and "Other Matches" groups.

Example:

Query: security

As shown:

1. "Security (PHP Manual)" appears in the "Extensions" group, although it is not a PHP extension.
2. "Security consideration" (from the win32service extension) is incorrectly placed in the "Other Matches" group.

Cause

The client-side search code groups results based on types, including Function, Variable, Class, Exception, Extension, and Other Matches (general). These types are assigned according to the XML element tags in the manual's source.

Issue 1: Incorrect grouping in "Extensions"

The first issue occurs in this section of the code:

https://github.com/php/web-php/blob/27fbef13e912547b4086793a5dd2e04fc0fcf684/js/search.js#L130-L134

The code assumes that any entry with the element tag <book>, <set>, or <reference> is related to extensions, which is inaccurate. Many entries, though using these elements, do not belong to extensions.

Example data:

id	ldesc	element
getting-started	Getting Started	book
install	Installation and Configuration	book
...	...	...
reserved.variables	Predefined Variables	reference
wrappers	Supported Protocols and Wrappers	reference
...	...	...

SELECT "docbook_id", "ldesc", "element"
FROM "ids" 
WHERE "element" IN ('book','set','reference')

Issue 2: Incorrect grouping in "Other Matches"

The second issue is due to an assumption in the following code:

https://github.com/php/web-php/blob/27fbef13e912547b4086793a5dd2e04fc0fcf684/js/search.js#L136-L141

The code assumes that entries with the tags <section>, <chapter>, <appendix>, or <article> do not belong to an extension. While this is not as bad, there are many pages that are part of an extension but are currently placed in the "Other Matches" group:

id	ldesc	element
...	...	...
apcu.installation	Installation	section
apcu.configuration	Runtime Configuration	section
...	...	...
pdo.setup	Installing/Configuring	chapter
pdo.constants	Predefined Constants	appendix
pdo.connections	Connections and Connection management	chapter
...	...	...

SELECT "docbook_id", "ldesc", "element"
FROM "ids" 
WHERE "element" IN ('section','chapter','appendix','article')

PHP Manual index dump

For convenience, here is the dump from the PHD SQLite index for the PHP Manual: php-manual-index_2024-10-08.sql.gz

Notes

• This will continue to be relevant even after #1084 is merged, as it uses the same logic for displaying the result type.
• The screenshot has the upcoming fix for https://github.com/php/phd/issues/159 applied.

Start in js/search.js at the grouping logic around lines 130-141, then compare its element-based assumptions with the provided PHP Manual SQLite index dump and the listed examples. Determine how the result type should distinguish extension pages from general manual pages, and verify that the Security, apcu, pdo, and similar results appear in the correct groups.