Keep the zram fallback until its replacement is installed

zram-generator creates no device at all when nothing configures one, so the
/etc copy is the only thing holding up swap until the vendor drop-in lands.
Removing it early costs a machine its zram entirely, not just its tuning.

The update pipeline installs packages before it runs migrations, so a packaged
machine always has the drop-in by then. A dev checkout does not: omarchy-update-dev
pulls migrations from a release the installed package has never seen, and no
ordering of the pipeline can produce a file that has not been built yet.
Checking for the drop-in is what makes the removal safe rather than well
sequenced.

The tests pinned the drop-in path to a fixture as well. Left at the real path
they would pass or fail on whether the machine running them happened to carry
the packaged copy.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

migrations/1785013000.sh

@@ -1,6 +1,7 @@
 echo "Move zram tuning to a vendor drop-in"
 
 zram_conf="${OMARCHY_ZRAM_CONF:-/etc/systemd/zram-generator.conf}"
+zram_dropin="${OMARCHY_ZRAM_DROPIN:-/usr/lib/systemd/zram-generator.conf.d/90-omarchy.conf}"
 
 # The tuning ships as /usr/lib/systemd/zram-generator.conf.d/90-omarchy.conf.
 # Drop-ins outrank the main config file, so a leftover /etc copy decides nothing
@@ -8,6 +9,13 @@ zram_conf="${OMARCHY_ZRAM_CONF:-/etc/systemd/zram-generator.conf}"
 
 [[ -f $zram_conf ]] || exit 0
 
+# Only once the replacement is on disk. zram-generator makes no device at all
+# when nothing configures one, so until the drop-in lands the /etc copy is the
+# only thing standing between this machine and no zram swap. The update pipeline
+# installs packages before it runs migrations, but a dev checkout carries
+# migrations from a release the installed package does not have yet.
+[[ -f $zram_dropin ]] || exit 0
+
 # Package-owned copies go away with their package on upgrade.
 pacman -Qo "$zram_conf" &>/dev/null && exit 0
 

test/shell.d/zram-migration-test.sh

@@ -26,11 +26,17 @@ STUB
 
 chmod +x "$stub_bin/pacman" "$stub_bin/sudo"
 
+# The migration removes the /etc copy only once the drop-in that replaces it is
+# installed. Point that at a fixture so the result does not depend on whether
+# the machine running the tests happens to carry the real one.
+dropin="$TMPDIR/90-omarchy.conf"
+: >"$dropin"
+
 # omarchy-migrate runs each migration with `bash -euo pipefail` and stops the
 # whole chain on a non-zero exit, so match that invocation exactly.
 run_migration() {
   local conf="$1"
-  PATH="$stub_bin:$PATH" OMARCHY_ZRAM_CONF="$conf" \
+  PATH="$stub_bin:$PATH" OMARCHY_ZRAM_CONF="$conf" OMARCHY_ZRAM_DROPIN="$dropin" \
     bash -euo pipefail "$migration" >/dev/null ||
     fail "migration exits clean for $(basename "$conf")"
 }
@@ -74,7 +80,7 @@ pass "migration keeps a locally edited config"
 # them.
 conf="$TMPDIR/owned.conf"
 printf '[zram0]\ncompression-algorithm = zstd\n' >"$conf"
-PATH="$stub_bin:$PATH" PACMAN_OWNS=1 OMARCHY_ZRAM_CONF="$conf" \
+PATH="$stub_bin:$PATH" PACMAN_OWNS=1 OMARCHY_ZRAM_CONF="$conf" OMARCHY_ZRAM_DROPIN="$dropin" \
   bash -euo pipefail "$migration" >/dev/null ||
   fail "migration exits clean for a package-owned config"
 [[ -f $conf ]] || fail "migration keeps a package-owned config"
@@ -85,3 +91,14 @@ conf="$TMPDIR/absent.conf"
 run_migration "$conf"
 run_migration "$conf"
 pass "migration no-ops when the config is already gone"
+
+# Without the drop-in installed, the /etc copy is the only thing configuring
+# zram at all. Removing it would leave the machine with no zram device, so the
+# migration has to leave it alone and stay clean doing it.
+conf="$TMPDIR/no-dropin.conf"
+printf '[zram0]\ncompression-algorithm = zstd\n' >"$conf"
+PATH="$stub_bin:$PATH" OMARCHY_ZRAM_CONF="$conf" OMARCHY_ZRAM_DROPIN="$TMPDIR/absent-dropin.conf" \
+  bash -euo pipefail "$migration" >/dev/null ||
+  fail "migration exits clean when the drop-in is missing"
+[[ -f $conf ]] || fail "migration keeps the config when the drop-in is missing"
+pass "migration keeps the config until the drop-in is installed"