fix: mount memory-backed emptyDir at /dev/shm for Electron apps

Instead of disabling shared memory usage, mount a proper tmpfs at
/dev/shm so Antigravity (and Chrome) have real shared memory available.
Removes --disable-dev-shm-usage; keeps --no-sandbox (separate issue).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

chart/Chart.yaml

@@ -2,5 +2,5 @@ apiVersion: v2
 name: devcontainer
 description: Antigravity Dev Container with Happy Coder AI assistant
 type: application
-version: 0.1.6
+version: 0.1.9
 appVersion: "latest"

chart/templates/deployment.yaml

@@ -71,6 +71,8 @@ spec:
               mountPath: /home
             - name: workspace
               mountPath: /workspace
+            - name: shm
+              mountPath: /dev/shm
           {{- if ne (.Values.ide | default "vscode") "none" }}
           livenessProbe:
             httpGet:
@@ -99,6 +101,10 @@ spec:
       volumes:
         - name: workspace
           emptyDir: {}
+        - name: shm
+          emptyDir:
+            medium: Memory
+            sizeLimit: {{ .Values.shm.sizeLimit }}
         - name: userhome
           persistentVolumeClaim:
             claimName: {{ include "antigravity.pvcName" . }}

chart/values.yaml

@@ -41,6 +41,11 @@ storage:
   size: 32Gi
   className: ceph-filesystem
 
+# Shared memory size — mounted at /dev/shm as a memory-backed emptyDir.
+# Electron apps (Antigravity, Chrome) use /dev/shm for GPU/IPC buffers.
+shm:
+  sizeLimit: 2Gi
+
 resources:
   requests:
     memory: "2Gi"

scripts/startapp.sh

@@ -21,7 +21,8 @@ echo "Workspace: $WORKSPACE_DIR"
 case "$IDE" in
     antigravity)
         echo "Opening Google Antigravity in: $WORKSPACE_DIR"
-        exec antigravity --new-window --wait "$WORKSPACE_DIR"
+        # --no-sandbox is required for Electron apps in Docker (no kernel sandbox available)
+        exec antigravity --no-sandbox --new-window --wait "$WORKSPACE_DIR"
         ;;
     none)
         echo "IDE=none: no IDE launched, keeping container alive."