fix: updates_xml_build preserves existing channel entries

When building a dev release, the CLI was overwriting the entire
updates.xml with only the dev entry, wiping the stable channel.
Now reads existing entries and preserves channels not being updated.

Authored-by: Moko Consulting
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cli/updates_xml_build.php

@@ -316,6 +316,32 @@ for ($i = 0; $i <= $stabilityIndex; $i++) {
 	);
 }
 
+// -- Preserve existing entries for channels not being updated -----------------
+$dest = $outputFile ?? "{$root}/updates.xml";
+$preservedEntries = [];
+
+if (file_exists($dest)) {
+	$existingXml = @simplexml_load_file($dest);
+	if ($existingXml) {
+		// Channels we're writing — don't preserve these
+		$writtenChannels = [];
+		for ($i = 0; $i <= $stabilityIndex; $i++) {
+			$writtenChannels[] = $allChannels[$i];
+		}
+
+		foreach ($existingXml->update as $existingUpdate) {
+			$existingTag = '';
+			if (isset($existingUpdate->tags->tag)) {
+				$existingTag = (string) $existingUpdate->tags->tag;
+			}
+			// Keep entries for channels we're NOT overwriting
+			if (!empty($existingTag) && !in_array($existingTag, $writtenChannels, true)) {
+				$preservedEntries[] = '  ' . trim($existingUpdate->asXML());
+			}
+		}
+	}
+}
+
 // -- Write updates.xml --------------------------------------------------------
 $year = date('Y');
 $output = <<<XML
@@ -327,7 +353,8 @@ $output = <<<XML
 
 <updates>
 XML;
-$output .= "\n" . implode("\n", $entries) . "\n</updates>\n";
+$allEntries = array_merge($preservedEntries, $entries);
+$output .= "\n" . implode("\n", $allEntries) . "\n</updates>\n";
 
 $dest = $outputFile ?? "{$root}/updates.xml";
 file_put_contents($dest, $output);