ci: cargo -j1 to keep peak memory under host budget; retrigger moongreet

Run 108 hit a verified global OOM (constraint=CONSTRAINT_NONE) when cargo -j2 ran two parallel rustc workers on a host with 1.6 GiB available. -j1 halves the peak. 4 GiB swapfile added on host as additional buffer; this changes the build pipeline as the second layer.

.gitea/workflows/build-and-publish.yaml

@@ -53,13 +53,18 @@ jobs:
               sudo pacman -S --needed --noconfirm $MAKEDEPS
             fi
 
-            # Parallel build with two cargo jobs. Previous single-threaded
-            # throttling was based on an unverified OOM assumption (run 86
-            # on 2026-04-23 stalled; no dmesg/journalctl evidence of
-            # OOMKiller was ever captured). If a real OOM happens, capture
-            # `dmesg | grep -i "killed process"` first before re-throttling.
-            export CARGO_BUILD_JOBS=2
-            export MAKEFLAGS="-j2"
+            # Single-threaded build to keep memory peak below the 8 GiB
+            # host budget. Run 108 (2026-04-28) hit a verified global OOM
+            # (constraint=CONSTRAINT_NONE in journalctl, rustc killed at
+            # 1.7 GiB RSS while host was already at 6.2 GiB used / 1.6 GiB
+            # available). Two parallel rustc workers blow that reserve.
+            # Container-side mem_limit doesn't help because the kill is
+            # global, not cgroup. -j1 halves the peak; act_runner blkio
+            # cap (30 MB/s) protects I/O. Do NOT raise without a wider
+            # memory plan (more host RAM, per-container caps, or larger
+            # swap headroom).
+            export CARGO_BUILD_JOBS=1
+            export MAKEFLAGS="-j1"
             makepkg -sfd --noconfirm
 
             # makepkg can emit multiple artifacts per build (main + -debug

moongreet-git/PKGBUILD

@@ -6,7 +6,7 @@
 pkgname=moongreet-git
 epoch=1
 pkgver=0.8.3.r3.gb9b6f50
-pkgrel=6
+pkgrel=7
 pkgdesc="A greetd greeter for Wayland with GTK4 and Layer Shell"
 arch=('x86_64')
 url="https://gitea.moonarch.de/nevaforget/greetd-moongreet"