diff --git a/README.md b/README.md
index 2b64e98..be660ab 100755
--- a/README.md
+++ b/README.md
@@ -118,7 +118,9 @@ mkdir -p /tmp/redefined-uploads
 
 `PUBLIC_URL` is required only alongside SMTP because its only job is building links in email; an environment that cannot send mail does not need it. `UPLOADS_DIR` has no such reprieve — its fallback of `/app/uploads` is correct inside the container and wrong everywhere else.
 
-**Adding to the required list has reach beyond this repository.** A variable added to `ALWAYS_REQUIRED` must also be set in every environment that deploys, and there are two of those. `docker-compose.qa.yml` is checked automatically — `backend/tests/unit/composeEnvironment.test.ts` reads the validator's own list and fails if the compose file does not set something on it, which is what #107 existed to prevent from recurring. Production runs from a Portainer stack **outside this repository**, so nothing can check it: that one has to be updated by hand, before the deploy rather than during it.
+**Adding to the required list has reach beyond this repository.** A variable added to `ALWAYS_REQUIRED` must also be set in every environment that deploys, and there are two of those. Both are checked automatically — `backend/tests/unit/composeEnvironment.test.ts` reads the validator's own list and fails if a compose file does not set something on it, which is what #107 existed to prevent from recurring. It runs over every deployment file in the repository and hands each one's entries to `validateEnv` itself, so a file is checked against exactly what the container checks at boot.
+
+Production was outside that net until #118. It ran from a stack that existed only in Portainer's web editor, which no test could read — and on 2026-08-23 it refused to boot because `UPLOADS_DIR` had no line in it, while being set in Portainer's stack variables. `docker-compose.prod.yml` is now in the repository and covered like QA's, which is also why it must be deployed as a **git repository stack** rather than pasted into the web editor: a pasted copy drifts from the checked one and the guard goes back to being decorative.
 
 Note also that setting a variable in Portainer's stack environment is not the same as giving it to the container. Stack variables are interpolated into the compose file as `${VAR}`; a service receives exactly what its own `environment:` block lists. A variable with no line there never arrives, however carefully it was set in the UI.
 
diff --git a/docker-compose.prod.yml b/docker-compose.prod.yml
index 4b9723c..f51f123 100644
--- a/docker-compose.prod.yml
+++ b/docker-compose.prod.yml
@@ -20,10 +20,30 @@
 #   Reference:    refs/heads/main
 #   Compose path: docker-compose.prod.yml
 #
-# `pull_policy: build` matters. Without it the stack reuses whatever is already
-# tagged redefined-designs:latest, which is how a redeploy can appear to succeed
-# while still running old code. Leave any Portainer option that re-pulls images
-# turned OFF — there is no registry to pull this image from.
+# THIS STACK DOES NOT BUILD. It runs the image tagged redefined-designs:latest,
+# which has to already exist on the NAS before the stack starts. A first deploy,
+# or a NAS that has pruned images, fails with "image not found" rather than
+# quietly building one — see #146.
+#
+# That is deliberate. QA builds from this repository and is reviewed; production
+# then runs the image that was reviewed, promoted by hand:
+#
+#   docker tag redefined-designs:qa redefined-designs:latest
+#
+# Building here instead would look simpler and would ship something else. The
+# Dockerfile copies package.json without package-lock.json and installs with
+# `npm install`, so two builds of the same commit can resolve different
+# transitive dependencies. "Same git ref" is therefore not "same image", and the
+# reviewed bytes are the only thing that is.
+#
+# The promotion is load-bearing, not a convenience. Forgetting it means a
+# redeploy that reuses the previous redefined-designs:latest and appears to
+# succeed while running old code — the same failure `pull_policy: build` guards
+# against in QA, arriving by a different route. State which image is being
+# promoted as part of the deploy.
+#
+# Leave any Portainer option that re-pulls images turned OFF — there is no
+# registry to pull this image from.
 #
 # WHY MOST VALUES ARE HARDCODED HERE RATHER THAN INTERPOLATED
 #
@@ -59,14 +79,9 @@
 
 services:
   redefined-designs:
-    # Built from this repository by Portainer rather than pulled. The same
-    # Dockerfile QA uses, so the two images differ only in configuration.
-    build:
-      context: .
-      dockerfile: Dockerfile
+    # No `build:` — see the note at the top of this file. This tag is produced
+    # by promoting the image QA was reviewed against, not by rebuilding here.
     image: redefined-designs:latest
-    # Always build; never reuse the existing tag.
-    pull_policy: build
     container_name: redefined-designs-syn
     environment:
       - TZ=America/Chicago