diff --git a/justfile b/justfile
index 90585a8..8a640ee 100644
--- a/justfile
+++ b/justfile
@@ -28,14 +28,15 @@ build:
 # The test gate: the suite, no cache, the coverage floor.
 test:
     #!/usr/bin/env perl
-    system(q{go}, q{test}, q{-count=1}, q{-timeout}, q{10m},
+    my @fence = qw{systemd-run --user --scope -p MemoryMax=4G -p MemorySwapMax=0};
+    system(@fence, q{go}, q{test}, q{-count=1}, q{-timeout}, q{10m},
       q{-coverprofile}, q{coverage.out}, qw({{packages}})) == 0
       or die qq{the test suite failed\n};
     # The packages outside the coverage set carry tests of their own: the CLI's
     # exit codes and manual-page guard, and the debugger's architecture-neutral
     # units.  They run without a profile, because a thin main and a ptrace-bound
     # package would drag the floor down rather than measure the product.
-    system(q{go}, q{test}, q{-count=1}, q{-timeout}, q{10m},
+    system(@fence, q{go}, q{test}, q{-count=1}, q{-timeout}, q{10m},
       q{./cmd/...}, q{./debug/...}) == 0
       or die qq{the tests outside the coverage set failed\n};
     open(my $c, q{-|}, q{go}, q{tool}, q{cover}, q{-func=coverage.out}) or die qq{cover: $!};
@@ -48,15 +49,18 @@ test:
 
 # The same suite under the race detector. The expensive one.
 race:
-    go test -race -count=1 -timeout 10m {{packages}}
+    # Ceiling 16G, not the default 4G: with every package in parallel the race
+    # footprint peaks over 8G (8G died in the parser package, 16G passed,
+    # measured 2026-10-02), and the wide machine at the keyboard can carry it.
+    systemd-run --user --scope -p MemoryMax=16G -p MemorySwapMax=0 go test -race -count=1 -timeout 10m {{packages}}
 
 # Fast scoped run for iterating. This is the one that runs after every edit.
 unit pkgs=packages run=".*":
-    go test {{pkgs}} -run '{{run}}'
+    systemd-run --user --scope -p MemoryMax=4G -p MemorySwapMax=0 go test {{pkgs}} -run '{{run}}'
 
 # Time-boxed fuzz of one target in one package. The package is required; never a gate.
 fuzz target pkg fuzztime="60s":
-    go test -run '^$' -fuzz '{{target}}' -fuzztime={{fuzztime}} {{pkg}}
+    systemd-run --user --scope -p MemoryMax=4G -p MemorySwapMax=0 go test -run '^$' -fuzz '{{target}}' -fuzztime={{fuzztime}} {{pkg}}
 
 # Benchmarks. On an idle machine only.
 bench pkgs=packages: