refactor(entrypoint): improve privilege dropping and config initialization

- Updated entrypoint.sh to initialize the on-disk config only if it does not already exist, preserving user edits across restarts.
- Enhanced privilege dropping logic to ensure the container does not run as root if the privilege drop fails.
- Clarified comments in Dockerfile and entrypoint.sh for better understanding of the privilege management process.
- Updated README.md to include a note about persistent disks requiring a paid service on Render.
- Adjusted render.yaml to clarify the Docker command behavior and added a note regarding auto-deploy settings.

entrypoint.sh

@@ -3,26 +3,42 @@ dir="$HOME/.nanobot"
 
 # Render deploy path (see render.yaml + render-config.json). Gated on Render's
 # automatic RENDER=true env var so local Docker/podman usage is unaffected.
-# Copies the committed config template onto the mounted disk (wiring secrets via
-# ${VAR} env vars and keeping runtime data on the persistent disk), chowns the
-# root-owned mount, then drops to the non-root nanobot user. Logs each decision
-# so a failed start is diagnosable in Render's logs.
+# Initializes the on-disk config from the committed template (wiring secrets via
+# ${VAR} env vars, keeping runtime data on the persistent disk) and appends the
+# --config flag. Logs each decision so a failed start is diagnosable in Render's
+# logs. Privilege dropping is handled below, for every root start (not just here).
 if [ "$RENDER" = "true" ]; then
     echo "[entrypoint] Render deploy — starting as $(id)"
     mkdir -p "$dir" || echo "[entrypoint] warning: mkdir $dir failed"
     config="$dir/config.json"
-    cp /app/render-config.json "$config" || echo "[entrypoint] warning: cp config failed"
-    if [ "$(id -u)" = "0" ]; then
-        chown -R nanobot:nanobot "$dir" || echo "[entrypoint] warning: chown $dir failed"
-        if setpriv --reuid=nanobot --regid=nanobot --init-groups true 2>/dev/null; then
-            echo "[entrypoint] dropping privileges to nanobot via setpriv"
-            exec setpriv --reuid=nanobot --regid=nanobot --init-groups nanobot "$@" --config "$config"
-        fi
-        echo "[entrypoint] setpriv privilege-drop not permitted — running as root"
+    # Initialize config only when it does not already exist, so WebUI/provider
+    # settings edited at runtime survive restarts. The disk persists config.json
+    # across deploys; overwriting it every boot would discard those changes.
+    if [ ! -f "$config" ]; then
+        echo "[entrypoint] initializing $config from render-config.json"
+        cp /app/render-config.json "$config" || echo "[entrypoint] warning: cp config failed"
+    else
+        echo "[entrypoint] existing $config found — leaving it in place"
     fi
-    exec nanobot "$@" --config "$config"
+    set -- "$@" --config "$config"
 fi
 
+# Drop privileges whenever the container starts as root. Render mounts the
+# persistent disk root-owned, and a plain `docker run` also defaults to root now,
+# so this covers both. Chown the data dir so the non-root user can write it, then
+# re-exec as nanobot. Fail closed: if the privilege drop cannot be performed,
+# exit rather than run the agent as root.
+if [ "$(id -u)" = "0" ]; then
+    chown -R nanobot:nanobot "$dir" 2>/dev/null || echo "[entrypoint] warning: chown $dir failed"
+    if setpriv --reuid=nanobot --regid=nanobot --init-groups true 2>/dev/null; then
+        echo "[entrypoint] dropping privileges to nanobot via setpriv"
+        exec setpriv --reuid=nanobot --regid=nanobot --init-groups nanobot "$@"
+    fi
+    echo "[entrypoint] error: started as root but setpriv privilege drop failed — refusing to run as root" >&2
+    exit 1
+fi
+
+# Already non-root: make sure the data dir is writable before starting.
 if [ -d "$dir" ] && [ ! -w "$dir" ]; then
     owner_uid=$(stat -c %u "$dir" 2>/dev/null || stat -f %u "$dir" 2>/dev/null)
     cat >&2 <<EOF
@@ -35,4 +51,5 @@ Fix (pick one):
 EOF
     exit 1
 fi
+
 exec nanobot "$@"