diff --git a/Dockerfile b/Dockerfile
index e4e3d78..0ee0fe2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,8 +10,9 @@
 # changes — so the two drift apart silently. They did: the IMU-less calib fix
 # was in this tree but not in the base's binary, and every Gemini episode
 # aborted (SIGABRT, surfacing as rc=-6) in a Space whose source had the fix.
-# Compiling from the deployed tree costs ~10 s and makes the binary match the
-# source by construction.
+# The base was rebuilt (:2026-10-20, now :latest) and matches the source again,
+# but nothing keeps it that way. Compiling from the deployed tree costs ~10 s
+# and makes the binary match the source by construction.
 FROM pollenrobotics/grabette-vslam
 
 USER root
diff --git a/grabette-postprocess/README.md b/grabette-postprocess/README.md
index 1d6f750..814ec05 100644
--- a/grabette-postprocess/README.md
+++ b/grabette-postprocess/README.md
@@ -51,13 +51,18 @@ The SLAM step requires Docker. The image is published, so pull it:
 docker pull pollenrobotics/grabette-vslam
 ```
 
-Pin `:2026-07-22` instead of `:latest` when a result has to stay comparable.
+It is multi-arch (amd64 + arm64), so it runs natively on Apple Silicon.
+Pin `:2026-10-20` instead of `:latest` when a result has to stay comparable
+(`:2026-07-22` predates IMU-less camera support and aborts on Gemini episodes).
 To build it yourself (Dockerfile + `offline_vslam.cpp` are both in the repo):
 
 ```bash
 docker build -t pollenrobotics/grabette-vslam docker/vslam/
 ```
 
+Add `--build-arg BUILD_JOBS=4` if the RTAB-Map compile runs out of memory
+(e.g. in Docker Desktop's default 8 GB VM).
+
 ## Quick start
 
 The pipeline expects `-i` to point at a **dataset directory** containing one or
diff --git a/grabette-postprocess/docker/vslam/Dockerfile b/grabette-postprocess/docker/vslam/Dockerfile
index 2ffbaab..38c040e 100644
--- a/grabette-postprocess/docker/vslam/Dockerfile
+++ b/grabette-postprocess/docker/vslam/Dockerfile
@@ -17,6 +17,9 @@ RUN apt-get update \
  && rm -rf /var/lib/apt/lists/*
 
 ARG RTABMAP_VERSION=0.23.1
+# Parallel compile jobs (default: all cores). Each job can take >1 GB, so lower
+# it on a small VM, e.g. --build-arg BUILD_JOBS=4 in an 8 GB Docker Desktop.
+ARG BUILD_JOBS
 RUN git clone --depth 1 --branch ${RTABMAP_VERSION} \
         https://github.com/introlab/rtabmap.git /tmp/rtabmap \
  && cmake -S /tmp/rtabmap -B /tmp/rtabmap/build \
@@ -24,7 +27,7 @@ RUN git clone --depth 1 --branch ${RTABMAP_VERSION} \
         -DBUILD_APP=OFF \
         -DBUILD_EXAMPLES=OFF \
         -DBUILD_TOOLS=OFF \
- && cmake --build /tmp/rtabmap/build --parallel $(nproc) \
+ && cmake --build /tmp/rtabmap/build --parallel ${BUILD_JOBS:-$(nproc)} \
  && cmake --install /tmp/rtabmap/build \
  && ldconfig \
  && rm -rf /tmp/rtabmap