diff --git a/.github/.codecov.yml b/.github/.codecov.yml
new file mode 100644
index 000000000..16a00ecce
--- /dev/null
+++ b/.github/.codecov.yml
@@ -0,0 +1,4 @@
+# Third-party code, excluded for the same reason phpcs.xml.dist and
+# phpstan.neon.dist exclude it. See includes/Vendor/AiClient/README.md.
+ignore:
+  - "includes/Vendor/**"
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 97cb05778..30ef073f4 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -22,6 +22,10 @@
 		<include>
 			<directory suffix=".php">includes</directory>
 		</include>
+		<!-- Vendored third-party code; see includes/Vendor/AiClient/README.md. -->
+		<exclude>
+			<directory suffix=".php">includes/Vendor</directory>
+		</exclude>
 		<report>
 			<clover outputFile="tests/_output/php-coverage.xml" />
 			<html outputDirectory="tests/_output/html" />