refactor dotenv parsing to improve caching logic and ensure readability; update health endpoint to reflect key match status

common.php

@@ -16,22 +16,25 @@ function qdb_env_file_path(): string {
 }
 
 /**
- * Parse a dotenv file (cached per path). Does not use getenv/putenv.
+ * Parse a dotenv file. Does not use getenv/putenv.
+ * Not cached when unreadable (FPM workers can start before .env exists).
  *
  * @return array<string, string>
  */
 function qdb_parse_env_file(string $path): array {
     static $cache = [];
-    if (isset($cache[$path])) {
-        return $cache[$path];
+    $mtime = @filemtime($path) ?: 0;
+    $cacheKey = $path . "\0" . $mtime;
+    if ($mtime > 0 && isset($cache[$cacheKey])) {
+        return $cache[$cacheKey];
     }
     $out = [];
     if (!is_readable($path)) {
-        return $cache[$path] = $out;
+        return $out;
     }
     $lines = file($path, FILE_IGNORE_NEW_LINES);
     if ($lines === false) {
-        return $cache[$path] = $out;
+        return $out;
     }
     foreach ($lines as $line) {
         $line = trim($line);
@@ -56,7 +59,10 @@ function qdb_parse_env_file(string $path): array {
         }
         $out[$name] = $value;
     }
-    return $cache[$path] = $out;
+    if ($mtime > 0) {
+        $cache[$cacheKey] = $out;
+    }
+    return $out;
 }
 
 /**
@@ -70,6 +76,11 @@ function qdb_env_get(string $name): ?string {
     if (isset($GLOBALS['qdb_dotenv'][$name]) && $GLOBALS['qdb_dotenv'][$name] !== '') {
         return $GLOBALS['qdb_dotenv'][$name];
     }
+    // Do not use getenv() for QDB_MASTER_KEY — FPM can retain a stale system value
+    // when .env was missing on the worker's first request.
+    if ($name === 'QDB_MASTER_KEY') {
+        return null;
+    }
     $v = getenv($name);
     if ($v !== false && $v !== '') {
         return $v;