deploy(S4): Blender headless pipeline + WebAR client + backend fixes

Dockerfile

@@ -45,12 +45,36 @@ RUN apt-get update && apt-get install -y \
 # ── S4: Blender 4.5 LTS headless (official Linux x64 tarball, URL verified 2026-07-17).
 # Geometry processing + GLB export only — no rendering → CPU hardware is sufficient.
 ARG BLENDER_VERSION=4.5.3
+# BLENDER IS OPTIONAL AND MUST NOT BE ABLE TO TAKE THE BACKEND DOWN.
+#
+# This step used to be fatal. On 2026-08-08 download.blender.org began answering
+# HuggingFace's build IPs with 403 — the file is still published (verified 200
+# with the same URL and the same curl User-Agent from a normal network), so this
+# is the CDN refusing the builder, not a bad version pin. The whole Space failed
+# to build and the API, the assistant and the PC relay all went offline because a
+# 377 MB download for the 3D geometry pipeline was refused by a third party.
+#
+# The core backend does not need Blender; only the model/GLB pipeline does. So
+# the download is now best-effort with a mirror fallback and a soft exit, and
+# blender_available() at runtime decides whether that one feature is offered.
+# An optional dependency of one subsystem should degrade that subsystem, never
+# the server.
 RUN mkdir -p /opt/blender && \
-    curl -fsSL "https://download.blender.org/release/Blender4.5/blender-${BLENDER_VERSION}-linux-x64.tar.xz" \
-      -o /tmp/blender.tar.xz && \
-    tar -xJf /tmp/blender.tar.xz -C /opt/blender --strip-components=1 && \
-    rm /tmp/blender.tar.xz && \
-    /opt/blender/blender --version
+    ( curl -fsSL --retry 3 --retry-delay 2 \
+        -A "Mozilla/5.0 (X11; Linux x86_64) omega-build" \
+        "https://download.blender.org/release/Blender4.5/blender-${BLENDER_VERSION}-linux-x64.tar.xz" \
+        -o /tmp/blender.tar.xz \
+      || curl -fsSL --retry 2 --retry-delay 2 \
+        -A "Mozilla/5.0 (X11; Linux x86_64) omega-build" \
+        "https://mirrors.ocf.berkeley.edu/blender/release/Blender4.5/blender-${BLENDER_VERSION}-linux-x64.tar.xz" \
+        -o /tmp/blender.tar.xz \
+      || echo "BLENDER DOWNLOAD UNAVAILABLE — continuing without it" ) && \
+    ( test -s /tmp/blender.tar.xz \
+      && tar -xJf /tmp/blender.tar.xz -C /opt/blender --strip-components=1 \
+      && rm -f /tmp/blender.tar.xz \
+      && /opt/blender/blender --version \
+      || echo "Blender not installed; 3D geometry features will report unavailable" ) && \
+    true
 
 # Set up a new user named "user" with user ID 1000
 RUN useradd -m -u 1000 user

dist/app-release.apk

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:3768e22e18bbcc3cb6721d89727731626d6a1c675e227383dca5197d37915519
+oid sha256:a3905dc8e7e13df42584f11579773098ec39330e80884ae6272082136c2cdffe
 size 116538395