diff --git a/migrations/1784809452.sh b/migrations/1784809452.sh
new file mode 100644
index 00000000..e32da36b
--- /dev/null
+++ b/migrations/1784809452.sh
@@ -0,0 +1,43 @@
+echo "Remove Snapper timeline snapshots leaked by earlier defaults"
+
+SNAPPER_CONFIG_PATH="${OMARCHY_SNAPPER_CONFIG_PATH:-/etc/snapper/configs/root}"
+
+as_root() {
+  if (( EUID == 0 )); then
+    "$@"
+  else
+    sudo "$@"
+  fi
+}
+
+command -v snapper >/dev/null || exit 0
+[[ -f $SNAPPER_CONFIG_PATH ]] || exit 0
+
+# Only clean up when timeline snapshotting is off, as Omarchy configures it.
+# Anyone who deliberately turned it back on keeps their snapshots.
+grep -qFx 'TIMELINE_CREATE="no"' "$SNAPPER_CONFIG_PATH" || exit 0
+
+# Earlier installs ran hourly timeline snapshots. Later configs stopped
+# creating them but never deleted the existing ones, and number cleanup
+# skips snapshots marked Cleanup=timeline, so they pile up forever:
+# hundreds of snapshots pinning 100+ GB of extents on long-running machines.
+leaked=$(as_root snapper -c root --csvout list --columns number,cleanup 2>/dev/null | awk -F, '$2 == "timeline" { print $1 }' || true)
+[[ -n $leaked ]] || exit 0
+
+echo "Deleting $(wc -w <<<"$leaked") leaked timeline snapshots (disk space is reclaimed in the background)"
+
+# Delete in small batches; one big delete can die on a DBus timeout partway.
+# A failed batch must not take the rest of the migration run down with it, so
+# the drain is best effort: whatever survives is picked up by the next run.
+batch=()
+for number in $leaked; do
+  batch+=("$number")
+  if (( ${#batch[@]} == 20 )); then
+    as_root snapper -c root delete "${batch[@]}" || true
+    batch=()
+  fi
+done
+
+if (( ${#batch[@]} > 0 )); then
+  as_root snapper -c root delete "${batch[@]}" || true
+fi
diff --git a/test/shell.d/snapper-timeline-leak-test.sh b/test/shell.d/snapper-timeline-leak-test.sh
new file mode 100644
index 00000000..a5adb84f
--- /dev/null
+++ b/test/shell.d/snapper-timeline-leak-test.sh
@@ -0,0 +1,104 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+leak_migration=$(grep -rl 'timeline snapshots leaked by earlier defaults' "$ROOT/migrations" | head -n 1 || true)
+[[ -n $leak_migration ]] || fail "Snapper timeline leak migration exists"
+
+test_tmp=$(mktemp -d)
+trap 'rm -rf "$test_tmp"' EXIT
+
+fake_bin="$test_tmp/bin"
+mkdir -p "$fake_bin"
+
+cat >"$fake_bin/sudo" <<'STUB'
+#!/bin/bash
+exec "$@"
+STUB
+chmod +x "$fake_bin/sudo"
+
+cat >"$fake_bin/snapper" <<'STUB'
+#!/bin/bash
+printf 'snapper %s\n' "$*" >>"$TEST_LOG"
+if [[ "$*" == *"--csvout list"* ]]; then
+  echo "number,cleanup"
+  for i in $(seq 1 45); do
+    echo "$i,timeline"
+  done
+  echo "100,number"
+  echo "101,"
+fi
+STUB
+chmod +x "$fake_bin/snapper"
+
+snapper_config="$test_tmp/root"
+printf '%s\n' 'TIMELINE_CREATE="no"' 'NUMBER_CLEANUP="yes"' >"$snapper_config"
+
+TEST_LOG="$test_tmp/calls.log" \
+PATH="$fake_bin:$PATH" \
+OMARCHY_SNAPPER_CONFIG_PATH="$snapper_config" \
+  bash -euo pipefail "$leak_migration" >/dev/null
+
+deletes=$(grep -c '^snapper -c root delete ' "$test_tmp/calls.log" || true)
+[[ $deletes -eq 3 ]] || fail "leak migration deletes snapshots in batches" "expected 3 delete calls, got $deletes"
+
+first_batch=$(grep -m1 '^snapper -c root delete ' "$test_tmp/calls.log")
+[[ $first_batch == "snapper -c root delete $(seq -s ' ' 1 20)" ]] || fail "leak migration caps delete batches at 20 snapshots" "$first_batch"
+
+last_batch=$(grep '^snapper -c root delete ' "$test_tmp/calls.log" | tail -n 1)
+[[ $last_batch == "snapper -c root delete $(seq -s ' ' 41 45)" ]] || fail "leak migration deletes the final partial batch" "$last_batch"
+
+! grep -E '^snapper -c root delete .*\b(100|101)\b' "$test_tmp/calls.log" || fail "leak migration only deletes timeline snapshots"
+pass "leak migration removes leaked timeline snapshots in batches and keeps the rest"
+
+# omarchy-migrate runs under set -e, so a batch that dies on a DBus timeout
+# would otherwise abort the run and skip every migration queued behind it.
+: >"$test_tmp/calls.log"
+printf '%s\n' 'TIMELINE_CREATE="no"' 'NUMBER_CLEANUP="yes"' >"$snapper_config"
+
+cat >"$fake_bin/snapper" <<'STUB'
+#!/bin/bash
+printf 'snapper %s\n' "$*" >>"$TEST_LOG"
+if [[ "$*" == *"--csvout list"* ]]; then
+  echo "number,cleanup"
+  for i in $(seq 1 45); do
+    echo "$i,timeline"
+  done
+  exit 0
+fi
+echo "failure: dbus timeout" >&2
+exit 1
+STUB
+
+TEST_LOG="$test_tmp/calls.log" \
+PATH="$fake_bin:$PATH" \
+OMARCHY_SNAPPER_CONFIG_PATH="$snapper_config" \
+  bash -euo pipefail "$leak_migration" >/dev/null 2>&1 ||
+  fail "leak migration survives a failed delete batch"
+
+deletes=$(grep -c '^snapper -c root delete ' "$test_tmp/calls.log" || true)
+[[ $deletes -eq 3 ]] || fail "leak migration keeps draining after a failed batch" "expected 3 delete calls, got $deletes"
+pass "leak migration tolerates a batch that fails partway"
+
+: >"$test_tmp/calls.log"
+printf '%s\n' 'TIMELINE_CREATE="yes"' >"$snapper_config"
+
+TEST_LOG="$test_tmp/calls.log" \
+PATH="$fake_bin:$PATH" \
+OMARCHY_SNAPPER_CONFIG_PATH="$snapper_config" \
+  bash -euo pipefail "$leak_migration" >/dev/null
+
+[[ ! -s $test_tmp/calls.log ]] || fail "leak migration leaves deliberate timeline setups alone"
+pass "leak migration skips systems where timeline snapshots are intentional"
+
+: >"$test_tmp/calls.log"
+
+TEST_LOG="$test_tmp/calls.log" \
+PATH="$fake_bin:$PATH" \
+OMARCHY_SNAPPER_CONFIG_PATH="$test_tmp/missing" \
+  bash -euo pipefail "$leak_migration" >/dev/null
+
+[[ ! -s $test_tmp/calls.log ]] || fail "leak migration skips systems without a Snapper root config"
+pass "leak migration is a no-op without Snapper configured"