diff --git a/services/capture/src/capture-manager.js b/services/capture/src/capture-manager.js
index 89baa72..1f022a7 100644
--- a/services/capture/src/capture-manager.js
+++ b/services/capture/src/capture-manager.js
@@ -17,9 +17,9 @@ const PRE_ROLL_SECONDS = parseInt(process.env.PRE_ROLL_SECONDS || (_standbyMode
 // Growing-files mode: writes the master to a local SMB-backed share that the
 // editor can mount, instead of streaming to S3 in real time. The promotion
 // worker uploads the finalized file to S3 after the recording stops.
-// Toggled per-recorder via `GROWING_ENABLED=true` on the capture container
-// (see routes/recorders.js where the env is composed).
-const GROWING_ENABLED = process.env.GROWING_ENABLED === 'true';
+// Toggled per-recorder via `GROWING_ENABLED=true`, delivered per-session on
+// /capture/start (read fresh from process.env at record time in start(), NOT
+// cached here — standby sidecars boot with it false).
 const GROWING_PATH    = process.env.GROWING_PATH    || '/growing';
 
 // Approach A: when a CIFS source is supplied, this (privileged) container mounts
@@ -1001,8 +1001,14 @@ exit "$BMXRC"
     // Approach A: if a CIFS source is configured, mount it now. A mount failure
     // is non-fatal — we fall back to S3 streaming so the recording is never
     // lost.
-    let growingActive = GROWING_ENABLED;
-    if (growingActive && GROWING_SMB_MOUNT) {
+    // Read growing flags FRESH from env at record time — standby sidecars boot
+    // with GROWING_ENABLED=false and receive the real value per-session over
+    // /capture/start (capture.js sets process.env before this runs). The old
+    // module-level `const GROWING_ENABLED` / `GROWING_SMB_MOUNT` captured the
+    // empty boot values, so growing never engaged and every "growing" record
+    // silently produced HEVC/S3 instead of the XDCAM HD422 MXF.
+    let growingActive = process.env.GROWING_ENABLED === 'true';
+    if (growingActive && growingSmbConfig().mount) {
       if (!mountGrowingShare()) growingActive = false;  // fall back to S3
     }
     // Growing master is always MXF OP1a / XDCAM HD422 written by raw2bmx (the