diff --git a/README.md b/README.md
index 3334a21..d05f41d 100755
--- a/README.md
+++ b/README.md
@@ -162,4 +162,64 @@ Gitea Actions runs two workflows on every push to `main` and on pull requests:
 
 Production runs as a single Docker image (multi-stage build — the frontend is built to static files and served directly by the backend), deployed via Portainer behind Nginx Proxy Manager, with authentik forward-auth gating `/admin`. That infrastructure is homelab-specific and documented separately outside this repo.
 
-The container applies pending migrations before starting the server, so deployed code can never be ahead of the database schema. A failed migration stops the container rather than letting it serve against a schema it doesn't match — check `docker logs` on the app container if it doesn't come up.
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+The container applies pending migrations before starting the server, so deployed code can never be ahead of the database schema. A failed migration stops the container rather than letting it serve against a schema it doesn't match — check `docker logs` on the app container if it doesn't come up.
+
+## QA environment
+
+`docker-compose.qa.yml` defines a disposable QA stack for reviewing merged-but-undeployed changes online. It runs alongside production on the same NAS with its own containers, database, volumes, and host port, and is started only when a review is needed.
+
+It differs from production deliberately: `DEMO_MODE=true` with no PayPal credentials (so checkout is exercisable but cannot reach live PayPal), no SMTP configuration (so it cannot email anyone), and `restart: "no"` (so a NAS reboot doesn't quietly bring it back up).
+
+### One-time setup on the NAS
+
+Create the directory structure. These paths are deliberately **not** under `/volume1/configs/redefined-designs` — sharing production's Postgres directory would mean QA writing into production's database files.
+
+```bash
+sudo mkdir -p /volume1/configs/redefined-designs-qa/postgres
+sudo mkdir -p /volume1/configs/redefined-designs-qa/uploads
+
+# The official postgres image runs as uid/gid 999. Without this the DB
+# container exits immediately with a data-directory permissions error.
+sudo chown -R 999:999 /volume1/configs/redefined-designs-qa/postgres
+sudo chmod 700 /volume1/configs/redefined-designs-qa/postgres
+
+# Uploads are written by the app container, which runs as root.
+sudo chown -R root:root /volume1/configs/redefined-designs-qa/uploads
+sudo chmod 755 /volume1/configs/redefined-designs-qa/uploads
+
+# Confirm the two environments are separate before going further.
+ls -la /volume1/configs/redefined-designs-qa/
+ls -la /volume1/configs/redefined-designs/
+```
+
+Then, in Portainer, create a stack **named `redefined-designs-qa`** from `docker-compose.qa.yml`, with one environment variable `QA_DB_PASSWORD`. The stack name matters: it becomes the compose project name, and reusing production's name would make compose reconcile the two stacks against each other and remove the production containers.
+
+Finally, add an Nginx Proxy Manager host for `qa-redefined-designs` pointing at the NAS on port `32751`, with authentik forward-auth on `location /` — the whole site, not just `/admin`, so nothing unreleased is publicly reachable.
+
+### Reviewing a change
+
+```bash
+cd /volume1/docker/redefined-designs
+gitc() { sudo docker run --rm -it -v /volume1/docker/redefined-designs:/repo -v ~/.gitconfig-docker/.gitconfig:/root/.gitconfig -w /repo alpine/git "$@"; }
+gitc pull origin main
+gitc log --oneline -3
+
+sudo docker build --no-cache -t redefined-designs:qa /volume1/docker/redefined-designs
+# start the redefined-designs-qa stack in Portainer
+
+# Migrations run as the container starts — confirm before reviewing.
+sudo docker logs redefined-designs-qa-syn | head -30
+```
+
+Stop the stack in Portainer when finished.
+
+### Resetting QA data
+
+QA data is disposable. To start from an empty database, stop the stack first, then:
+
+```bash
+# Check the path before running this. It must contain -qa.
+sudo rm -rf /volume1/configs/redefined-designs-qa/postgres/pgdata
+```
+
+Restarting the stack recreates the database and re-runs every migration from scratch.
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diff --git a/docker-compose.qa.yml b/docker-compose.qa.yml
new file mode 100644
index 0000000..be79894
--- /dev/null
+++ b/docker-compose.qa.yml
@@ -0,0 +1,83 @@
+# QA stack — a disposable copy of the app for reviewing merged-but-undeployed
+# changes online. See issue #25.
+#
+# Deployed as its own Portainer stack, separate from production. Every value
+# that could collide with production has been changed: container names, host
+# port, volume paths, database name, and image tag. Do not copy a path or port
+# back from the production stack — a shared Postgres data directory would mean
+# QA writing into production's database files.
+#
+# Name the Portainer stack `redefined-designs-qa`, NOT `redefined-designs`.
+# The stack name becomes the compose project name. Reusing production's name
+# would make compose treat this as the same project and reconcile the two
+# against each other — it would happily remove the production containers
+# because they are not declared in this file.
+#
+# Required stack environment variable:
+#   QA_DB_PASSWORD  — deliberately not named DB_PASSWORD, so pasting the
+#                     production stack's variables here does nothing silently.
+#
+# Build the image on the NAS before starting the stack:
+#   sudo docker build --no-cache -t redefined-designs:qa /volume1/docker/redefined-designs
+
+services:
+  redefined-designs-qa:
+    image: redefined-designs:qa
+    container_name: redefined-designs-qa-syn
+    environment:
+      - TZ=America/Chicago
+      - PORT=3000
+      - PGHOST=redefined-designs-qa-db-syn
+      - PGPORT=5432
+      - PGUSER=redefined_qa
+      - PGPASSWORD=${QA_DB_PASSWORD}
+      - PGDATABASE=redefined_qa
+
+      # No PayPal credentials at all. DEMO_MODE lets the full cart and checkout
+      # flow run without them, so QA can exercise the whole purchase path with
+      # no way to reach live PayPal. Never set PAYPAL_ENV=live here. To test a
+      # real PayPal integration change, add sandbox credentials and set
+      # PAYPAL_ENV=sandbox — never the live ones.
+      - DEMO_MODE=true
+
+      # No SMTP configuration either. The mailer degrades gracefully when
+      # unconfigured: it logs a warning and skips sending. That is the desired
+      # behaviour here — a QA run must not be able to email real customers if
+      # a fixture ever contains a real address.
+      - SITE_CURRENCY=USD
+      - RESERVATION_MINUTES=15
+      - PUBLIC_URL=https://qa-redefined-designs.bermudalamb.synology.me
+    volumes:
+      # Separate uploads directory. Sharing production's would let a QA run
+      # write into, and a QA teardown delete, real product images.
+      - /volume1/configs/redefined-designs-qa/uploads:/app/uploads
+    ports:
+      # 32751, not production's 32750.
+      - 32751:3000
+    depends_on:
+      redefined-designs-qa-db-syn:
+        condition: service_healthy
+    # Not `unless-stopped`: QA is meant to be up only while a review is
+    # happening. `unless-stopped` would silently bring it back after every NAS
+    # reboot and leave it running indefinitely.
+    restart: "no"
+
+  redefined-designs-qa-db-syn:
+    image: postgres:16
+    container_name: redefined-designs-qa-db-syn
+    environment:
+      - POSTGRES_USER=redefined_qa
+      - POSTGRES_PASSWORD=${QA_DB_PASSWORD}
+      - POSTGRES_DB=redefined_qa
+      - PGDATA=/var/lib/postgresql/data/pgdata
+    volumes:
+      # Distinct data directory from production's
+      # /volume1/configs/redefined-designs/postgres. This is the single most
+      # important difference in this file.
+      - /volume1/configs/redefined-designs-qa/postgres:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U redefined_qa -d redefined_qa"]
+      interval: 10s
+      timeout: 5s
+      retries: 10
+    restart: "no"