diff --git a/zygisk/module/action.sh b/zygisk/module/action.sh
index c3ea8c1a34..58b7d206d4 100644
--- a/zygisk/module/action.sh
+++ b/zygisk/module/action.sh
@@ -1,4 +1,15 @@
 MANAGER_PACKAGE_NAME="@MANAGER_PACKAGE_NAME@"
 INJECTED_PACKAGE_NAME="@INJECTED_PACKAGE_NAME@"
 
+# The manager also ships inside this module as manager.apk and may have been
+# installed as a regular package. When it has, launching its activity directly
+# is more reliable than the injection path below, which needs
+# ${INJECTED_PACKAGE_NAME} to start a 2D activity at all and to receive the
+# injected manager dex -- neither holds in every environment (some systems
+# never let the shell host an activity, and dynamic code loading restrictions
+# can block the dex the way GrapheneOS does, see #805).
+if pm path "$MANAGER_PACKAGE_NAME" >/dev/null 2>&1; then
+  am start -n "$MANAGER_PACKAGE_NAME/.ui.MainActivity" >/dev/null 2>&1 && exit 0
+fi
+
 am start -c "${MANAGER_PACKAGE_NAME}.LAUNCH_MANAGER" "${INJECTED_PACKAGE_NAME}/.BugreportWarningActivity"
diff --git a/zygisk/module/daemon b/zygisk/module/daemon
index 3b1dec4a5f..8cc8fb4f5d 100644
--- a/zygisk/module/daemon
+++ b/zygisk/module/daemon
@@ -26,8 +26,11 @@ if [ "$debug" = "true" ]; then
 fi
 
 # Mount an empty temporary file system over /data/resource-cache to avoid possible overlay conflicts.
-# Note that this script runs inside an isolated mount namespace (via unshare).
-mount tmpfs -t tmpfs /data/resource-cache
+# Only when service.sh has established a mount namespace that cannot propagate this mount back to the
+# host: without one it would hide the real resource cache from every process on the device.
+if [ "${VECTOR_MOUNTNS_ISOLATED:-0}" = 1 ]; then
+  mount tmpfs -t tmpfs /data/resource-cache
+fi
 
 # Wait for Zygote socket using a polling loop
 if [ ! -S "/dev/socket/zygote" ]; then
diff --git a/zygisk/module/service.sh b/zygisk/module/service.sh
index e49f8859b2..c726aa5970 100644
--- a/zygisk/module/service.sh
+++ b/zygisk/module/service.sh
@@ -1,6 +1,78 @@
-# Extract the directory path and change directory 
+# Extract the directory path and change directory
 MODDIR="${0%/*}"
 cd "$MODDIR" || exit 1
 
-# Start the daemon directly in the background within a private mount namespace
-unshare --propagation slave -m "$MODDIR/daemon" --system-server-max-retry=3 "$@" &
+# The service stage has no console, and the daemon cannot log anything before it
+# exists, so a start that fails is invisible by construction. Keep one line per
+# boot, and mirror it to logcat when log is around as well.
+TRACE_LOG=/data/local/tmp/vector-service.log
+trace() {
+  printf '%s %s\n' "$(date '+%Y-%m-%d %H:%M:%S' 2>/dev/null)" "$*" >>"$TRACE_LOG" 2>/dev/null
+  command -v log >/dev/null 2>&1 && log -p i -t VectorService "$*" >/dev/null 2>&1
+}
+
+# A replayed service stage (KernelSU's emulated soft reboot) leaves the old
+# daemon alive, and tryLock() in the daemon does not reliably turn the second
+# one away (#878): the two then claim the same proxy service and break
+# injection. The survivor handles a system_server restart through its binder
+# death recipient, so leaving it alone is the repair; a second daemon is what
+# breaks injection.
+daemon_running() {
+  command -v pgrep >/dev/null 2>&1 && pgrep -f '^vectord' >/dev/null 2>&1 && return 0
+  command -v pidof >/dev/null 2>&1 && pidof vectord >/dev/null 2>&1 && return 0
+  return 1
+}
+
+if daemon_running; then
+  trace "vectord already running, not starting a second one"
+  exit 0
+fi
+
+# toybox builds that implement only a subset of util-linux reject
+# --propagation outright, which leaves the daemon dead with nothing anywhere to
+# say so. The root solution usually ships a fuller busybox, so prefer its
+# unshare, then the system one, and only then a namespace whose propagation
+# type cannot be set.
+find_busybox() {
+  for bb in "${MAGISKTMP:-/nonexistent}/busybox" \
+    "${MAGISKTMP:-/nonexistent}/.magisk/busybox" \
+    /data/adb/ksu/bin/busybox \
+    /data/adb/magisk/busybox \
+    /data/adb/ap/bin/busybox \
+    /system/xbin/busybox; do
+    [ -f "$bb" ] && [ -x "$bb" ] && { printf '%s\n' "$bb"; return 0; }
+  done
+  bb="$(command -v busybox 2>/dev/null)" && [ -f "$bb" ] && [ -x "$bb" ] && printf '%s\n' "$bb"
+}
+BB="$(find_busybox)"
+DAEMON="$MODDIR/daemon"
+
+# The daemon mounts a tmpfs over /data/resource-cache, which is only safe when
+# this namespace cannot propagate mounts back to the host.
+# VECTOR_MOUNTNS_ISOLATED records that service.sh has established exactly that.
+if [ -n "$BB" ] && "$BB" unshare --propagation slave -m true >/dev/null 2>&1; then
+  trace "starting vectord with $BB unshare --propagation slave -m"
+  VECTOR_MOUNTNS_ISOLATED=1 "$BB" unshare --propagation slave -m "$DAEMON" --system-server-max-retry=3 "$@" &
+elif unshare --propagation slave -m true >/dev/null 2>&1; then
+  trace "starting vectord with unshare --propagation slave -m"
+  VECTOR_MOUNTNS_ISOLATED=1 unshare --propagation slave -m "$DAEMON" --system-server-max-retry=3 "$@" &
+elif unshare -m /system/bin/sh -c '
+    mount --make-rprivate / 2>/dev/null || mount --make-rslave / 2>/dev/null || exit 1
+    ! grep -q " shared:" /proc/self/mountinfo
+  ' >/dev/null 2>&1; then
+  trace "starting vectord with unshare -m and a private mount tree"
+  unshare -m /system/bin/sh -c '
+    if mount --make-rprivate / 2>/dev/null || mount --make-rslave / 2>/dev/null; then
+      if ! grep -q " shared:" /proc/self/mountinfo; then
+        export VECTOR_MOUNTNS_ISOLATED=1
+      fi
+    fi
+    exec "$0" "$@"
+  ' "$DAEMON" --system-server-max-retry=3 "$@" &
+elif unshare -m true >/dev/null 2>&1; then
+  trace "starting vectord with unshare -m (propagation unchanged, mount skipped)"
+  unshare -m "$DAEMON" --system-server-max-retry=3 "$@" &
+else
+  trace "starting vectord without a mount namespace (resource-cache mount skipped)"
+  "$DAEMON" --system-server-max-retry=3 "$@" &
+fi