diff --git a/src/post-type/render.php b/src/post-type/render.php
index 95cc5d1..2fb2b73 100644
--- a/src/post-type/render.php
+++ b/src/post-type/render.php
@@ -10,7 +10,13 @@
 $display_type = $attributes['displayType'] ?? 'select';
 $layout_direction = $attributes['layoutDirection'] ?? 'vertical';
 
-if ( $block->context['query']['inherit'] ) {
+// The query block's own attribute default carries `inherit`, but markup that
+// names a `query` object without it (hand written patterns, third party query
+// blocks) reaches render with the key absent. Read it as "not inherited"
+// rather than warning about an undefined index.
+$inherit = ! empty( $block->context['query']['inherit'] );
+
+if ( $inherit ) {
 	$query_var = 'query-post_type';
 	$page_var = 'page';
 	$base_url = str_replace( '/page/' . get_query_var( 'paged' ), '', remove_query_arg( [ $query_var, $page_var ] ) );
@@ -29,7 +35,7 @@
 }
 
 // Fill in inherited query types.
-if ( $block->context['query']['inherit'] ) {
+if ( $inherit ) {
 	$inherited_post_types = $wp_query->get( 'query-filter-post_type' ) === 'any'
 		? get_post_types( [ 'public' => true, 'exclude_from_search' => false ] )
 		: (array) $wp_query->get( 'query-filter-post_type' );
diff --git a/tests/e2e/README.md b/tests/e2e/README.md
index 0092745..83b3186 100644
--- a/tests/e2e/README.md
+++ b/tests/e2e/README.md
@@ -31,7 +31,10 @@ run and `npm run playground:start`:
 3. Activates this plugin, mounted from the working tree.
 4. Copies `tests/mu-plugins/register-test-content.php` into `mu-plugins`, which
    registers the post types and taxonomies the tests filter against — including
-   deliberately private ones.
+   deliberately private ones. It also records any PHP notice raised from this
+   plugin's files and prints it into the page as a `qf-php-error:` comment,
+   followed by a `qf-php-errors-checked` marker, so a spec can assert a page
+   rendered cleanly without depending on `display_errors`.
 5. Runs `tests/seed.php`, which creates the fixture terms, posts and the demo
    pages the specs visit.
 
@@ -44,6 +47,7 @@ Seeding is idempotent, guarded by the `query_filter_e2e_seeded` option.
 | `/taxonomy-filter/` | 1 | Taxonomy filter (select) |
 | `/taxonomy-checkboxes/` | 2 | Taxonomy filter (checkboxes) |
 | `/post-type-filter/` | 3 | Post type filter and core search block |
+| `/no-inherit-context/` | 4 | Both filters, in a query loop whose `query` context omits `inherit` |
 | `/search-pagination/` | 5 | Core search block and pagination, two posts to a page |
 
 Posts: `Alpha One` and `Alpha Two` in the `alpha` category, `Beta One` in
diff --git a/tests/e2e/query-context.spec.js b/tests/e2e/query-context.spec.js
new file mode 100644
index 0000000..c8c8348
--- /dev/null
+++ b/tests/e2e/query-context.spec.js
@@ -0,0 +1,30 @@
+const { test, expect, POSTS } = require( './fixtures' );
+
+test.describe( 'Query context without inherit', () => {
+	test( 'the filters render without a PHP notice', async ( {
+		page,
+		loop,
+	} ) => {
+		await page.goto( '/no-inherit-context/' );
+		await loop.expectTitles( POSTS.all );
+
+		await expect( loop.postTypeSelect() ).toBeVisible();
+		await expect( loop.taxonomySelect() ).toBeVisible();
+
+		// The test mu-plugin collects anything this plugin's files raise and
+		// prints it as an HTML comment, so the assertion does not depend on
+		// how the environment is configured to display errors.
+		const html = await page.content();
+		expect( html ).toContain( 'qf-php-errors-checked' );
+		expect( html ).not.toContain( 'qf-php-error:' );
+	} );
+
+	test( 'the filters still narrow the loop', async ( { page, loop } ) => {
+		await page.goto( '/no-inherit-context/' );
+
+		await loop.taxonomySelect().selectOption( { label: 'Alpha' } );
+
+		await page.waitForURL( /query-4-category=alpha/ );
+		await loop.expectTitles( POSTS.alpha );
+	} );
+} );
diff --git a/tests/mu-plugins/register-test-content.php b/tests/mu-plugins/register-test-content.php
index d2fc39b..caa8015 100644
--- a/tests/mu-plugins/register-test-content.php
+++ b/tests/mu-plugins/register-test-content.php
@@ -48,3 +48,55 @@ function register_test_content() : void {
 		'hierarchical' => false,
 	] );
 }
+
+/**
+ * PHP notices raised from inside this plugin during the current request.
+ *
+ * @var string[]
+ */
+$GLOBALS['query_filter_php_errors'] = [];
+
+set_error_handler( __NAMESPACE__ . '\\record_plugin_php_error', E_ALL );
+add_action( 'wp_footer', __NAMESPACE__ . '\\print_plugin_php_errors', 1000 );
+
+/**
+ * Record diagnostics raised from this plugin's own files.
+ *
+ * A PHP warning only reaches the response when the server is configured to
+ * display errors, which is not something a test can rely on. Collecting them
+ * here instead means a spec can assert that a page rendered cleanly whatever
+ * the environment does with `display_errors`.
+ *
+ * Returns false so PHP's own handler still runs and the debug log is unchanged.
+ *
+ * @param int    $errno   Level of the error raised.
+ * @param string $errstr  Error message.
+ * @param string $errfile File the error was raised in.
+ * @param int    $errline Line the error was raised on.
+ * @return bool False, so the standard error handler also runs.
+ */
+function record_plugin_php_error( int $errno, string $errstr, string $errfile = '', int $errline = 0 ) : bool {
+	if ( strpos( $errfile, '/query-filter/' ) !== false ) {
+		$GLOBALS['query_filter_php_errors'][] = sprintf(
+			'%s in %s:%d',
+			$errstr,
+			basename( dirname( $errfile ) ) . '/' . basename( $errfile ),
+			$errline
+		);
+	}
+
+	return false;
+}
+
+/**
+ * Print the recorded notices, and a marker proving the handler was installed.
+ *
+ * @return void
+ */
+function print_plugin_php_errors() : void {
+	foreach ( array_unique( $GLOBALS['query_filter_php_errors'] ) as $error ) {
+		printf( "<!-- qf-php-error: %s -->\n", esc_html( $error ) );
+	}
+
+	echo "<!-- qf-php-errors-checked -->\n";
+}
diff --git a/tests/seed.php b/tests/seed.php
index 8252022..7d88d7d 100644
--- a/tests/seed.php
+++ b/tests/seed.php
@@ -146,6 +146,24 @@ function query_loop_markup( int $query_id, string $filters ) : string {
 	),
 ] );
 
+// Page 4: a query loop whose `query` context omits `inherit` altogether, as
+// hand written pattern markup and third party query blocks do. The filters
+// must render without warning about the missing key.
+seed_post( 'No Inherit Context', 'page', [
+	'post_name' => 'no-inherit-context',
+	'post_content' => <<<HTML
+<!-- wp:query {"queryId":4,"query":{"perPage":10,"postType":"post","order":"asc","orderBy":"title"}} -->
+<div class="wp-block-query">
+<!-- wp:query-filter/post-type /-->
+<!-- wp:query-filter/taxonomy {"taxonomy":"category"} /-->
+<!-- wp:post-template -->
+<!-- wp:post-title /-->
+<!-- /wp:post-template -->
+</div>
+<!-- /wp:query -->
+HTML,
+] );
+
 // Page 5: a paginated loop with a search block, two posts to a page, so a
 // search can be started from a page the results do not reach.
 seed_post( 'Search Pagination', 'page', [