diff --git a/README.md b/README.md
index 051c0e7..3ea3b45 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,7 @@ docker compose -f docker-compose.dev.yml up --build
 ```
 
 Frontend runs on http://localhost:5173 and the backend on http://localhost:8000.
+The backend media index is persisted in a Docker volume (`backend_cache`) so rebuilds and container restarts do not force a full re-index.
 
 ### Manual backend/frontend development
 
diff --git a/backend/README.md b/backend/README.md
index 446a4a6..99c32fe 100644
--- a/backend/README.md
+++ b/backend/README.md
@@ -100,6 +100,7 @@ API docs available at: http://localhost:8000/docs
 ## Docker
 
 The repository root includes a production `docker-compose.yml` and a development `docker-compose.dev.yml`.
+The backend media index is stored in the `backend_cache` Docker volume so it survives container restarts and image rebuilds.
 
 ## API Endpoints
 
diff --git a/docker-compose.dev.yml b/docker-compose.dev.yml
index 74573b0..2357279 100644
--- a/docker-compose.dev.yml
+++ b/docker-compose.dev.yml
@@ -16,6 +16,7 @@ services:
     volumes:
       - ./backend:/app/backend
       - ${SSH_KEY_HOST_DIR}:/root/.ssh:ro
+      - backend_cache:/app/backend/.cache
     restart: unless-stopped
 
   frontend:
@@ -39,3 +40,4 @@ services:
 
 volumes:
   frontend_node_modules:
+  backend_cache:
diff --git a/docker-compose.yml b/docker-compose.yml
index fc8a063..1f9c427 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -11,6 +11,7 @@ services:
       SSH_KEY_NAME: ${SSH_KEY_NAME}
     volumes:
       - ${SSH_KEY_HOST_DIR}:/root/.ssh:ro
+      - backend_cache:/app/backend/.cache
     restart: unless-stopped
     networks:
       - web
@@ -64,6 +65,9 @@ services:
       - "8080:80"
     restart: unless-stopped
 
+volumes:
+  backend_cache:
+
 networks:
   web:
     external: true
diff --git a/docs/REQUIREMENTS.md b/docs/REQUIREMENTS.md
index 631758e..a0f2abc 100644
--- a/docs/REQUIREMENTS.md
+++ b/docs/REQUIREMENTS.md
@@ -128,6 +128,7 @@ Phase 1: Jellyfin media index, SSH-based remote filesystem inspection, server mo
 - Provide Docker Compose deployment files at the repository root for production and local development.
 - Backend Docker deployment should mount a private SSH key and a known_hosts file into the container rather than baking them into the image.
 - Production compose should also pass the root `.env` into the backend container so runtime auth settings like `OIDC_ISSUER_URL` are available there, not just at compose interpolation time.
+- The backend media index should persist in a Docker volume so a container restart or image rebuild does not force a new full index build.
 - The SSH key configuration should support separate directory/name inputs so Docker Compose can mount an arbitrary host SSH directory into `/root/.ssh` while the app assembles the full key path.
 - Show Jellyfin media counts for movies, series, and series episodes on the dashboard.
 - Show dashboard session activity from Jellyfin, including both currently playing sessions and logged-in idle sessions.