diff --git a/stage-airplanes/06-firstboot/00-run.sh b/stage-airplanes/06-firstboot/00-run.sh
index 3f358f27e2..9de3dd3ba3 100755
--- a/stage-airplanes/06-firstboot/00-run.sh
+++ b/stage-airplanes/06-firstboot/00-run.sh
@@ -54,6 +54,19 @@ printf '%s\n' "${AIRPLANES_FEED_UPDATE_CHANNEL}" \
 	> "${ROOTFS_DIR}/etc/airplanes/release-channel"
 chmod 0644 "${ROOTFS_DIR}/etc/airplanes/release-channel"
 
+# Image-install provenance marker. Its presence tells the feed daemons this is
+# an overlay-image feeder, distinguishing it from a standalone feed install
+# (which has neither marker nor binary) and from a legacy image (detected
+# instead by the baked /usr/bin/airplanes-feeder binary the marker post-dates).
+# Only presence is contractual: feed reads it with `-f` and never sources it,
+# so the body is a shell-safe comment for anyone who cats the file. Baked here
+# rather than delivered by the runtime overlay so the flag stays permanent
+# across overlay updates, rollbacks, or removal — the same reason
+# release-channel is baked.
+printf '%s\n' '# airplanes.live image-install marker; presence signals an overlay-image feeder.' \
+	> "${ROOTFS_DIR}/etc/airplanes/image-install"
+chmod 0644 "${ROOTFS_DIR}/etc/airplanes/image-install"
+
 # pi-gen's export-image stage copies ${ROOTFS_DIR}/boot/firmware/* onto the
 # FAT partition during image assembly, so writing the template here lands it
 # on partition 1 where SD-card editors can reach it.
diff --git a/test/overlay-smoke-inner.sh b/test/overlay-smoke-inner.sh
index c22b2bd3fa..25ae0f2544 100755
--- a/test/overlay-smoke-inner.sh
+++ b/test/overlay-smoke-inner.sh
@@ -78,11 +78,12 @@ echo "==> contract assertions"
 fail() { echo "FAIL: $*" >&2; exit 1; }
 # Stage 01 is setup-only now (service account + state dirs). Feed artifacts
 # (feed-airplanes binary, apl-feed CLI, daemon wrappers, systemd units, runtime
-# libs, mlat-client venv, feed.env, image-install marker, enable links) arrive
-# through the runtime overlay at stage 02 (managed_paths + migrations), which
-# this fast smoke does NOT run. Assertions below cover only what stages 00 + 01
-# + 06 produce, not the overlay-delivered feed surface. The full image build +
-# boot-smoke cover the feed overlay path end to end.
+# libs, mlat-client venv, feed.env, enable links) arrive through the runtime
+# overlay at stage 02 (managed_paths + migrations), which this fast smoke does
+# NOT run. Assertions below cover only what stages 00 + 01 + 06 produce, not the
+# overlay-delivered feed surface. The full image build + boot-smoke cover the
+# feed overlay path end to end. (The /etc/airplanes/image-install provenance
+# marker is baked by stage 06, not the overlay, so it IS asserted below.)
 [[ -d /etc/airplanes ]] || fail "/etc/airplanes dir missing (stage 01 chroot)"
 id -u airplanes-feed >/dev/null 2>&1 || fail "airplanes-feed user missing (stage 01 chroot)"
 getent group airplanes-feed >/dev/null 2>&1 || fail "airplanes-feed group missing (stage 01 chroot)"
@@ -264,6 +265,14 @@ esac
 [[ "$release_channel_content" == "$AIRPLANES_FEED_UPDATE_CHANNEL" ]] \
     || fail "release-channel content '$release_channel_content' does not match AIRPLANES_FEED_UPDATE_CHANNEL='$AIRPLANES_FEED_UPDATE_CHANNEL'"
 
+# image-install marker: stage 06 bakes it so the feed daemons detect an
+# overlay-image feeder (airplanes-feed.sh sets IMAGE_INSTALL=1 on presence).
+# Baked into /etc rather than overlay-delivered so it survives overlay updates,
+# rollbacks, or removal.
+[[ -f /etc/airplanes/image-install ]] || fail "image-install marker missing"
+[[ "$(stat -c %a /etc/airplanes/image-install)" == "644" ]] \
+    || fail "image-install marker mode != 0644"
+
 # Build-manifest sentinel written by stage 00.
 [[ -s /etc/airplanes/.build-pi-gen-sha ]] || fail ".build-pi-gen-sha missing or empty"