docs: record user-1001.slice memory limit fix (MemoryHigh instead of MemoryMax, swap enabled)

notes/bf-41xv.md

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+# Fix for user-1001.slice Memory Limits
+
+## Problem
+The user-1001.slice had:
+- `MemoryMax=32G` (hard cap - OOM kill at limit)
+- `MemorySwapMax=0` (swap disabled)
+
+This caused hard process kills when memory hit 32G instead of allowing the kernel to reclaim memory gracefully or use swap.
+
+## Solution
+Changed to:
+- `MemoryHigh=32G` (soft cap - kernel applies pressure and reclaims)
+- `MemoryMax=infinity` (no hard kill)
+- `MemorySwapMax=infinity` (can use system swap)
+
+## Configuration Files
+Persistent configs in `/etc/systemd/system.control/user-1001.slice.d/`:
+- `50-MemoryHigh.conf`: `MemoryHigh=34359738368` (32G)
+- `50-MemoryMax.conf`: `MemoryMax=infinity`
+- `50-MemorySwapMax.conf`: `MemorySwapMax=infinity`
+
+## Verification
+```bash
+# Current cgroup values
+cat /sys/fs/cgroup/user.slice/user-1001.slice/memory.high     # 34359738368 (32G)
+cat /sys/fs/cgroup/user.slice/user-1001.slice/memory.max      # max (unlimited)
+cat /sys/fs/cgroup/user.slice/user-1001.slice/memory.swap.max # max (unlimited)
+
+# systemd properties
+systemctl show user-1001.slice | grep -E "MemoryMax|MemoryHigh|MemorySwapMax"
+```
+
+## How It Was Done
+```bash
+sudo systemctl set-property -- user-1001.slice MemoryMax=infinity MemorySwapMax=infinity MemoryHigh=32G
+```
+
+The `systemctl set-property` command without `--runtime` makes the changes persistent across reboots by creating drop-in files in `/etc/systemd/system.control/`.