diff --git a/src/EntryPoints/REST/ValidateSubjectApi.php b/src/EntryPoints/REST/ValidateSubjectApi.php
index 73d543e8..5adc60f6 100644
--- a/src/EntryPoints/REST/ValidateSubjectApi.php
+++ b/src/EntryPoints/REST/ValidateSubjectApi.php
@@ -63,7 +63,7 @@ public function getBodyParamSettings(): array {
 				self::PARAM_SOURCE => 'body',
 				ParamValidator::PARAM_TYPE => 'array',
 				ParamValidator::PARAM_REQUIRED => true,
-				self::PARAM_DESCRIPTION => 'Proposed Statements (property/value pairs). Shape matches docs/SubjectFormat.md.',
+				self::PARAM_DESCRIPTION => 'Proposed Statements (property/value pairs). Shape matches docs/api/subject-format.md.',
 			],
 		];
 	}
diff --git a/src/EntryPoints/REST/ValidateSubjectUpdateApi.php b/src/EntryPoints/REST/ValidateSubjectUpdateApi.php
index 42289d45..a6396866 100644
--- a/src/EntryPoints/REST/ValidateSubjectUpdateApi.php
+++ b/src/EntryPoints/REST/ValidateSubjectUpdateApi.php
@@ -68,7 +68,7 @@ public function getBodyParamSettings(): array {
 				self::PARAM_SOURCE => 'body',
 				ParamValidator::PARAM_TYPE => 'array',
 				ParamValidator::PARAM_REQUIRED => true,
-				self::PARAM_DESCRIPTION => 'Proposed Statements (property/value pairs) for the proposed update. Shape matches docs/SubjectFormat.md.',
+				self::PARAM_DESCRIPTION => 'Proposed Statements (property/value pairs) for the proposed update. Shape matches docs/api/subject-format.md.',
 			],
 			'comment' => [
 				self::PARAM_SOURCE => 'body',
diff --git a/tests/phpunit/DocsPathReferencesTest.php b/tests/phpunit/DocsPathReferencesTest.php
new file mode 100644
index 00000000..3db9a2b0
--- /dev/null
+++ b/tests/phpunit/DocsPathReferencesTest.php
@@ -0,0 +1,96 @@
+<?php
+
+declare( strict_types = 1 );
+
+namespace ProfessionalWiki\NeoWiki\Tests;
+
+use PHPUnit\Framework\TestCase;
+use RecursiveDirectoryIterator;
+use RecursiveIteratorIterator;
+use SplFileInfo;
+
+/**
+ * Guards the docs paths cited in production code against the docs tree.
+ *
+ * Several REST param descriptions point readers at a documentation file. Those strings are
+ * user-facing: they are served in the generated OpenAPI spec. Nothing else checks them, so a
+ * doc rename silently turns them into dead references.
+ *
+ * When this fails, either the doc moved (update the citing string) or the path was never right.
+ *
+ * @coversNothing
+ */
+class DocsPathReferencesTest extends TestCase {
+
+	public function testEveryDocsPathCitedInSourceCodeExists(): void {
+		$this->assertSame(
+			[],
+			$this->danglingDocsReferences(),
+			'These src/ files cite a docs file that does not exist. Point them at the current path.'
+		);
+	}
+
+	/**
+	 * @return list<string> e.g. "src/EntryPoints/REST/ValidateSubjectApi.php:66 cites docs/Foo.md"
+	 */
+	private function danglingDocsReferences(): array {
+		$dangling = [];
+
+		foreach ( $this->sourceFiles() as $file ) {
+			foreach ( $this->citedDocsPaths( $file ) as $line => $paths ) {
+				foreach ( $paths as $path ) {
+					if ( !file_exists( $this->extensionRoot() . '/' . $path ) ) {
+						$relativeFile = substr( $file, strlen( $this->extensionRoot() ) + 1 );
+						$dangling[] = "$relativeFile:$line cites $path";
+					}
+				}
+			}
+		}
+
+		return $dangling;
+	}
+
+	/**
+	 * @return list<string> absolute paths of every PHP file under src/.
+	 */
+	private function sourceFiles(): array {
+		$files = [];
+
+		$directory = new RecursiveDirectoryIterator( $this->extensionRoot() . '/src' );
+		/** @var SplFileInfo $file */
+		foreach ( new RecursiveIteratorIterator( $directory ) as $file ) {
+			if ( $file->isFile() && $file->getExtension() === 'php' ) {
+				$files[] = $file->getPathname();
+			}
+		}
+
+		sort( $files );
+
+		return $files;
+	}
+
+	/**
+	 * @return array<int, list<string>> docs paths cited in the file, keyed by line number.
+	 */
+	private function citedDocsPaths( string $file ): array {
+		$contents = file_get_contents( $file );
+		$this->assertNotFalse( $contents, "Could not read $file" );
+
+		$cited = [];
+
+		foreach ( explode( "\n", $contents ) as $index => $line ) {
+			preg_match_all( '#\bdocs/[A-Za-z0-9._/-]+\.md#', $line, $matches );
+
+			if ( $matches[0] !== [] ) {
+				$cited[$index + 1] = $matches[0];
+			}
+		}
+
+		return $cited;
+	}
+
+	private function extensionRoot(): string {
+		return dirname( __DIR__, 2 );
+	}
+
+}