Xdebug extension not enabled on PHP 8.3 suffix 6 (Debian 13/trixie) images

Bug Report

What happened

When using PHP 8.3 with xdebug: "debug,develop,trace" in .lando.yml, Xdebug is not loaded into PHP, but Lando still sets the XDEBUG_CONFIG environment variable (including log=/tmp/xdebug.log). This results in startup warnings:

Xdebug: [Log Files] File '/tmp/xdebug.log' could not be opened.
Xdebug: [Log Files] File '/tmp/xdebug.log' could not be opened.

And php -v confirms Xdebug is not loaded:

PHP 8.3.30 (cli) (built: Feb 24 2026 19:14:59) (NTS)
Copyright (c) The PHP Group
Zend Engine v4.3.30, Copyright (c) Zend Technologies
    with Zend OPcache v8.3.30, Copyright (c), by Zend Technologies

Root cause

The xdebug.so file is present at /usr/local/lib/php/extensions/no-debug-non-zts-20230831/xdebug.so, but no docker-php-ext-xdebug.ini file is created in /usr/local/etc/php/conf.d/. All other extensions (apcu, bcmath, redis, etc.) do have their ini files.

Meanwhile, xxx-lando-default.ini does configure Xdebug settings (xdebug.mode, xdebug.start_with_request, etc.) and XDEBUG_CONFIG is set in the environment — but the extension itself is never loaded via zend_extension=xdebug.so.

Environment

• Lando: v3.26.2
• PHP: 8.3.30
• Image base: Debian 13 (trixie) — suffix 6
• Xdebug .so: exists at /usr/local/lib/php/extensions/no-debug-non-zts-20230831/xdebug.so
• docker-php-ext-xdebug.ini: missing

Comparison

The same .lando.yml config with xdebug: "debug,develop,trace" on PHP 8.2 (Debian 12 / suffix 5 image) works correctly — Xdebug is loaded and no warnings appear.

.lando.yml

name: myapp
recipe: wordpress
config:
  php: "8.3"
  via: nginx
  webroot: web
  xdebug: "debug,develop,trace"

Related

This may be related to #92 — both issues stem from Lando's Xdebug configuration not aligning with the actual state of the extension in the container.

Inspect the PHP 8.3 Debian 13/trixie suffix 6 image configuration that should create /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini, and compare it with the working PHP 8.2 suffix 5 image. Verify that the Xdebug extension is loaded by php -v and that the startup warnings disappear when xdebug is enabled through .lando.yml.