diff --git a/backend/src/config/secret-bundle.ts b/backend/src/config/secret-bundle.ts
index 3da8e6fb..da3ffbae 100644
--- a/backend/src/config/secret-bundle.ts
+++ b/backend/src/config/secret-bundle.ts
@@ -30,6 +30,8 @@ const MAX_LINE_BYTES = 16 * 1024;
 export interface SecretBundleConfig {
   secretsFile?: string;
   secretFiles?: Readonly<Record<string, string | undefined>>;
+  /** Accepted for callers that pass the raw process environment. */
+  THT_SECRETS_FILE?: string;
 }
 
 function unavailable(): Error { return new Error("secret bundle is unavailable"); }
@@ -89,12 +91,18 @@ export function loadSecretBundle(file: string): ReadonlyMap<string, string> {
 
 /** Resolve a value from the bundle, with the pre-bundle *_SECRET_FILE fallback. */
 export function secretValue(config: SecretBundleConfig, key: string): string | undefined {
-  if (config.secretsFile) {
-    const found = loadSecretBundle(config.secretsFile).get(key);
+  const bundlePath = config.secretsFile ?? config.THT_SECRETS_FILE;
+  if (bundlePath) {
+    const found = loadSecretBundle(bundlePath).get(key);
     if (found !== undefined) return found;
   }
   const legacyName = LEGACY_FILES[key];
-  const legacyPath = legacyName ? config.secretFiles?.[legacyName] : undefined;
+  const legacyPath = legacyName
+    ? config.secretFiles?.[legacyName] ?? (() => {
+      const raw = (config as unknown as Record<string, unknown>)[legacyName];
+      return typeof raw === "string" ? raw : undefined;
+    })()
+    : undefined;
   if (!legacyPath) return undefined;
   const value = readSecure(legacyPath);
   if (!value || /\s/.test(value)) throw unavailable();