Target Xdebug at loopback, not host.docker.internal

host.docker.internal only works when the IDE and the workspace share a
Docker host — true for local docker-compose, false for Coder, where the
workspace runs on a remote deployment and the IDE lives on the
developer's laptop.

JetBrains Gateway and VS Code Remote set up reverse SSH tunnels to the
workspace container, so the IDE's debug listener is reachable at
127.0.0.1:9003 from inside the container. Point client_host there and
pin client_port=9003. Keep discover_client_host=true for web-request
flows where REMOTE_ADDR identifies the caller.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: chapterjason

scripts/php/xdebug.ini

@@ -7,11 +7,14 @@
 ;   XDEBUG_MODE=debug php …
 ; or per-request with the XDEBUG_TRIGGER cookie / GET / POST / env var.
 ;
-; client_host=host.docker.internal targets the Docker host running the
-; workspace container; discover_client_host finds the right IP if the
-; IDE is elsewhere on the network.
+; client_host=127.0.0.1 targets the IDE via the reverse SSH tunnel that
+; JetBrains Gateway / VS Code Remote set up when connecting to a Coder
+; workspace — the IDE's debug listener is reachable inside the container
+; at loopback. discover_client_host covers web-request debugging where
+; REMOTE_ADDR / X-Forwarded-For reveals the caller.
 xdebug.mode = off
-xdebug.client_host = host.docker.internal
+xdebug.client_host = 127.0.0.1
+xdebug.client_port = 9003
 xdebug.start_with_request = trigger
 xdebug.discover_client_host = true
 xdebug.log_level = 0