diff --git a/config/dot/quickshell/displays-harness.qml b/config/dot/quickshell/displays-harness.qml
index 780580f..9095478 100644
--- a/config/dot/quickshell/displays-harness.qml
+++ b/config/dot/quickshell/displays-harness.qml
@@ -6,6 +6,10 @@ import qs.config
 import qs.services
 
 ShellRoot {
+    // The isolated screen model begins with both fixture outputs so changing
+    // it below exercises the same reactive topology path as a real hotplug.
+    Component.onCompleted: Displays.screenOverride = ["DP-2", "HDMI-A-1"]
+
     IpcHandler {
         target: "displays-test"
 
@@ -42,6 +46,7 @@ ShellRoot {
         function transactionStatus(): string {
             return JSON.stringify({
                 layout: Displays.currentLayout(),
+                primaryFirst: Displays.primaryFirstMonitors.map(monitor => monitor.name),
                 pending: Displays.pendingRequestedLayout,
                 previous: Displays.pendingPreviousLayout,
                 reverting: Displays.revertExpectedLayout,
@@ -141,5 +146,8 @@ ShellRoot {
             if (monitor) Displays.forget(monitor.name);
         }
         function refresh(): void { Displays.refresh(); }
+        function setScreenModel(names: string): void {
+            Displays.screenOverride = JSON.parse(names);
+        }
     }
 }
diff --git a/config/dot/quickshell/modules/settings/DisplaysPage.qml b/config/dot/quickshell/modules/settings/DisplaysPage.qml
index 0f9987e..7164491 100644
--- a/config/dot/quickshell/modules/settings/DisplaysPage.qml
+++ b/config/dot/quickshell/modules/settings/DisplaysPage.qml
@@ -22,7 +22,7 @@ SettingsPage {
 
     property string selectedOutput: ""
     readonly property var monitor: Displays.monitorNamed(root.selectedOutput)
-        ?? (Displays.monitors.length > 0 ? Displays.monitors[0] : null)
+        ?? (Displays.primaryFirstMonitors.length > 0 ? Displays.primaryFirstMonitors[0] : null)
     readonly property string currentMode: root.monitor
         ? root.monitor.mode
         : ""
@@ -38,7 +38,8 @@ SettingsPage {
 
     function syncSelectedOutput(): void {
         if (!Displays.monitorNamed(root.selectedOutput))
-            root.selectedOutput = Displays.monitors.length > 0 ? Displays.monitors[0].name : "";
+            root.selectedOutput = Displays.primaryFirstMonitors.length > 0
+                ? Displays.primaryFirstMonitors[0].name : "";
     }
 
     // Probing I2C for DDC-capable monitors takes on the order of a second, so
@@ -137,7 +138,7 @@ SettingsPage {
         ChoiceGrid {
             width: parent.width
             label: "Display"
-            options: Displays.monitors.map(monitor => ({
+            options: Displays.primaryFirstMonitors.map(monitor => ({
                 value: monitor.name,
                 label: monitor.description || monitor.name
             }))
diff --git a/config/dot/quickshell/modules/settings/WallpaperControls.qml b/config/dot/quickshell/modules/settings/WallpaperControls.qml
index a3eaf10..e33aa65 100644
--- a/config/dot/quickshell/modules/settings/WallpaperControls.qml
+++ b/config/dot/quickshell/modules/settings/WallpaperControls.qml
@@ -18,6 +18,13 @@ Column {
     width: parent ? parent.width : 620
     spacing: 4
 
+    onOutputsChanged: root.syncSelectedOutput()
+
+    function syncSelectedOutput(): void {
+        if (!root.outputs.includes(root.selectedOutput))
+            root.selectedOutput = root.outputs.length > 0 ? root.outputs[0] : "";
+    }
+
     ChoiceGrid {
         width: parent.width
         label: "Wallpaper mode"
diff --git a/config/dot/quickshell/scripts/panama-lock b/config/dot/quickshell/scripts/panama-lock
index 4d4a837..ed62d1a 100755
--- a/config/dot/quickshell/scripts/panama-lock
+++ b/config/dot/quickshell/scripts/panama-lock
@@ -17,8 +17,10 @@ status_file="$state_dir/hyprlock-status.json"
 fallback="$config_home/hypr/hyprlock.conf"
 temporary="$generated.tmp.$$"
 status_temporary="$status_file.tmp.$$"
+shipped_wallpaper="$HOME/Pictures/Wallpapers/faroe_islands.jpg"
 
 settings_valid=false
+wallpaper_warning=""
 
 cleanup() {
     rm -f "$temporary" "$status_temporary" 2>/dev/null || true
@@ -76,7 +78,23 @@ read_object() {
 }
 
 valid_path() {
-    [[ "$1" == /* && "$1" != *","* && "$1" != *$'\n'* ]]
+    [[ "$1" == /* && "$1" != *","* && "$1" != *$'\n'* && -f "$1" && -r "$1" ]]
+}
+
+resolve_wallpaper_path() {
+    local candidate="$1"
+    if valid_path "$candidate"; then
+        resolved_wallpaper="$candidate"
+        return
+    fi
+    if [[ -n "$candidate" ]]; then
+        wallpaper_warning="One or more lock-screen wallpapers were unavailable; a safe fallback is in use."
+    fi
+    if valid_path "$shipped_wallpaper"; then
+        resolved_wallpaper="$shipped_wallpaper"
+    else
+        resolved_wallpaper="screenshot"
+    fi
 }
 
 # Same 8 named accents as config/Theme.qml's `accents` map (kept in sync by
@@ -134,10 +152,9 @@ load_preferences() {
     wallpaper_mode="$(read_string wallpaperMode single)"
     [[ "$wallpaper_mode" == single || "$wallpaper_mode" == slideshow || "$wallpaper_mode" == per-monitor ]] \
         || wallpaper_mode=single
-    wallpaper_path="$(read_string wallpaperPath '')"
-    if ! valid_path "$wallpaper_path"; then
-        wallpaper_path="$HOME/Pictures/Wallpapers/faroe_islands.jpg"
-    fi
+    wallpaper_warning=""
+    resolve_wallpaper_path "$(read_string wallpaperPath '')"
+    wallpaper_path="$resolved_wallpaper"
     wallpaper_assignments="$(read_object wallpaperPerMonitor)"
 
     case "$blur_level" in
@@ -218,8 +235,9 @@ emit_backgrounds() {
                     candidate="$(jq -r --arg output "$output" \
                         'if has($output) and (.[$output] | type) == "string" then .[$output] else "" end' \
                         <<<"$wallpaper_assignments" 2>/dev/null || true)"
-                    if valid_path "$candidate"; then
-                        assigned="$candidate"
+                    if [[ -n "$candidate" ]]; then
+                        resolve_wallpaper_path "$candidate"
+                        assigned="$resolved_wallpaper"
                     fi
                 fi
                 emit_background "$output" "$assigned"
@@ -344,7 +362,7 @@ generate() {
         write_status false "$fallback" true "The lock-screen configuration could not be generated."
         return 1
     fi
-    write_status true "$generated" false ""
+    write_status true "$generated" false "$wallpaper_warning"
 }
 
 status() {
diff --git a/config/dot/quickshell/scripts/panama-wallpaper-scan b/config/dot/quickshell/scripts/panama-wallpaper-scan
new file mode 100755
index 0000000..9097287
--- /dev/null
+++ b/config/dot/quickshell/scripts/panama-wallpaper-scan
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+# Finds wallpaper candidates from fixed roots passed as separate arguments.
+# Keeping paths as argv values avoids shell interpolation for names containing
+# quotes, spaces, or other shell syntax.
+
+set -euo pipefail
+
+find "$@" -maxdepth 2 -type f \
+    \( -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.png' -o -iname '*.webp' \) \
+    -printf '%T@ %p\n' 2>/dev/null \
+    | sort -rn \
+    | cut -d' ' -f2- \
+    | head -60
diff --git a/config/dot/quickshell/services/Displays.qml b/config/dot/quickshell/services/Displays.qml
index a094af1..ef2fd2f 100644
--- a/config/dot/quickshell/services/Displays.qml
+++ b/config/dot/quickshell/services/Displays.qml
@@ -29,8 +29,24 @@ Singleton {
     // [{ name, description, width, height, refreshRate, scale, transform,
     //    modes: [{ label, mode, width, height, refresh }] }]
     property var monitors: []
+    // Quickshell.screens is the topology authority. The override is only the
+    // isolated harness model; normal sessions always observe Quickshell.
+    property var screenOverride: null
     property string lastError: ""
 
+    readonly property var screenModel: Array.isArray(root.screenOverride)
+        ? root.screenOverride : Quickshell.screens
+    readonly property string screenSignature: root.screenModel
+        .map(screen => typeof screen === "string" ? screen : screen.name)
+        .filter(name => !!name)
+        .sort()
+        .join("|")
+    readonly property var primaryFirstMonitors: root.monitors.slice().sort((left, right) => {
+        if (left.primary !== right.primary)
+            return left.primary ? -1 : 1;
+        return left.name.localeCompare(right.name);
+    })
+
     // Set while a change is applied but not yet confirmed.
     property var pendingPreviousLayout: null
     property var pendingRequestedLayout: null
@@ -113,6 +129,17 @@ Singleton {
 
     Component.onCompleted: root.refresh()
 
+    onScreenSignatureChanged: root.reconcileTopology()
+
+    // A hotplug can invalidate the unconfirmed layout while the confirmation
+    // is visible. Read the current compositor layout first; the normal queued
+    // rollback then filters out any output that has disappeared.
+    function reconcileTopology(): void {
+        root.refresh();
+        if (root.awaitingConfirmation)
+            root.revertWithMessage("A display was connected or disconnected, so Panama restored the previous setting.");
+    }
+
     function refresh(): bool {
         if (!query.running) {
             query.generation = root.operationGeneration;
diff --git a/config/dot/quickshell/services/Wallpaper.qml b/config/dot/quickshell/services/Wallpaper.qml
index e68db62..ec4f15e 100644
--- a/config/dot/quickshell/services/Wallpaper.qml
+++ b/config/dot/quickshell/services/Wallpaper.qml
@@ -45,9 +45,10 @@ Singleton {
     readonly property string outputSignature: root.outputNames().slice().sort().join("|")
 
     property var outputNames: function() {
-        if (Array.isArray(root.outputOverride))
-            return root.outputOverride.slice();
-        return Quickshell.screens.map(screen => screen.name).filter(name => !!name);
+        const outputs = Array.isArray(root.outputOverride)
+            ? root.outputOverride.slice()
+            : Quickshell.screens.map(screen => screen.name).filter(name => !!name);
+        return root.primaryFirstOutputs(outputs);
     }
 
     readonly property var searchRoots: [
@@ -59,10 +60,8 @@ Singleton {
 
     Process {
         id: scan
-        command: ["bash", "-lc",
-            "find " + root.searchRoots.map(dir => `'${dir}'`).join(" ")
-            + " -maxdepth 2 -type f \\( -iname '*.jpg' -o -iname '*.jpeg' -o -iname '*.png' -o -iname '*.webp' \\)"
-            + " -printf '%T@ %p\\n' 2>/dev/null | sort -rn | cut -d' ' -f2- | head -60"]
+        command: [Quickshell.shellDir + "/scripts/panama-wallpaper-scan"]
+            .concat(root.searchRoots)
         stdout: StdioCollector {
             onStreamFinished: {
                 root.available = this.text.split("\n")
@@ -164,6 +163,18 @@ Singleton {
             activeQuery.running = true;
     }
 
+    // The saved primary role anchors Panama's per-monitor choices. Keep the
+    // compositor's remaining order stable so a reconnect does not reshuffle
+    // the rest of the picker unnecessarily.
+    function primaryFirstOutputs(outputs: var): var {
+        const stored = DesktopPreferences.get("displays");
+        const layouts = stored && typeof stored === "object" ? stored : {};
+        const primary = outputs.find(output => layouts[output]?.primary === true);
+        return primary === undefined
+            ? outputs
+            : [primary].concat(outputs.filter(output => output !== primary));
+    }
+
     function candidates(extra: var): var {
         const result = [];
         const discovered = Array.isArray(root.candidateOverride)
diff --git a/config/dot/quickshell/wallpaper-service-harness.qml b/config/dot/quickshell/wallpaper-service-harness.qml
index 57ef178..6fe92a8 100644
--- a/config/dot/quickshell/wallpaper-service-harness.qml
+++ b/config/dot/quickshell/wallpaper-service-harness.qml
@@ -7,7 +7,7 @@ import qs.services
 
 ShellRoot {
     Component.onCompleted: {
-        Wallpaper.outputOverride = ["DP-2", "HDMI-A-1"];
+        Wallpaper.outputOverride = ["HDMI-A-1", "DP-2"];
         Wallpaper.candidateOverride = ["/images/a.jpg", "/images/b.jpg", "/images/c.jpg"];
         Wallpaper.startupRestoreEnabled = false;
         Wallpaper.slideshowIntervalOverrideMs = 60000;
@@ -63,7 +63,9 @@ ShellRoot {
                 assignments: DesktopPreferences.get("wallpaperPerMonitor"),
                 slideshowPath: Wallpaper.slideshowPath,
                 shuffleBag: Wallpaper.shuffleBag,
-                slideshowTimerRunning: Wallpaper.slideshowTimerRunning
+                slideshowTimerRunning: Wallpaper.slideshowTimerRunning,
+                scanning: Wallpaper.scanning,
+                available: Wallpaper.available
             });
         }
     }
diff --git a/config/dot/quickshell/wallpaper-settings-harness.qml b/config/dot/quickshell/wallpaper-settings-harness.qml
index 57fcd4a..21be75b 100644
--- a/config/dot/quickshell/wallpaper-settings-harness.qml
+++ b/config/dot/quickshell/wallpaper-settings-harness.qml
@@ -46,6 +46,16 @@ ShellRoot {
             return JSON.stringify(root.calls);
         }
 
+        function selectOutput(output: string): void {
+            controls.selectedOutput = output;
+        }
+
+        function updateOutputs(outputs: string): void {
+            controls.outputs = outputs === "" ? [] : outputs.split("|");
+        }
+
+        function selectedOutput(): string { return controls.selectedOutput; }
+
         function states(): string {
             picker.mode = "single";
             const single = {
diff --git a/tests/quickshell/display-transaction-contract b/tests/quickshell/display-transaction-contract
index d13cf57..9d6d657 100755
--- a/tests/quickshell/display-transaction-contract
+++ b/tests/quickshell/display-transaction-contract
@@ -223,16 +223,18 @@ failed_state="$(wait_for '.busy == false and .awaiting == false')"
 jq -e '.lastError | contains("rejected")' <<<"$failed_state" >/dev/null \
     || fail "failed apply did not retain a useful recovery message: $failed_state"
 
-# If an output disconnects while a change is pending, rollback sends one
-# transaction containing every output that is still connected.
+# If an output disconnects while a change is pending, the screen-model observer
+# refreshes topology and rolls back with only the still-connected output. This
+# intentionally does not call Displays.refresh() through the public harness API.
 [[ "$(run ipc --pid "$harness_pid" call displays-test applyLayoutFixture 3000 320)" == "true" ]] \
     || fail 'disconnect fixture could not start'
 wait_for '.canConfirm == true' >/dev/null
 jq '.[0:1]' "$monitor_state" >"$fixture/connected.json"
 mv "$fixture/connected.json" "$monitor_state"
-run ipc --pid "$harness_pid" call displays-test refresh >/dev/null
-wait_for '.layout | length == 1' >/dev/null
-run ipc --pid "$harness_pid" call displays-test revertChange >/dev/null
+run ipc --pid "$harness_pid" call displays-test setScreenModel '["DP-2"]' >/dev/null
+wait_for '(.layout | length == 1) and .awaiting == false and .busy == false' >/dev/null
+[[ "$(transaction_status | jq -c .primaryFirst)" == '["DP-2"]' ]] \
+    || fail "primary-first monitor list did not reconcile after hot-unplug: $(transaction_status)"
 wait_for '.busy == false and .awaiting == false' >/dev/null
 disconnect_payload="$(tail -1 "$eval_log")"
 [[ "$(rg -o 'hl\.monitor' <<<"$disconnect_payload" | wc -l)" == "1" ]] \
diff --git a/tests/quickshell/lock-screen-helper-contract b/tests/quickshell/lock-screen-helper-contract
index c705f36..4e8b11d 100755
--- a/tests/quickshell/lock-screen-helper-contract
+++ b/tests/quickshell/lock-screen-helper-contract
@@ -14,6 +14,9 @@ settings="$config_home/panama/settings.json"
 generated="$state_home/panama/hyprlock.conf"
 hyprlock_log="$fixture/hyprlock.log"
 theme_helper="$repo_dir/config/dot/quickshell/scripts/panama-theme-apps"
+shipped_wallpaper="$fixture_home/Pictures/Wallpapers/faroe_islands.jpg"
+global_wallpaper="$fixture_home/Pictures/Wallpapers/global.jpg"
+portrait_wallpaper="$fixture_home/Pictures/Wallpapers/portrait.jpg"
 
 fail() {
     printf 'lock screen helper contract: %s\n' "$1" >&2
@@ -28,6 +31,9 @@ trap cleanup EXIT
 
 mkdir -p "$fixture_home/Pictures/Wallpapers" "$config_home/panama" \
     "$config_home/hypr" "$state_home" "$test_bin"
+printf 'shipped wallpaper\n' >"$shipped_wallpaper"
+printf 'global wallpaper\n' >"$global_wallpaper"
+printf 'portrait wallpaper\n' >"$portrait_wallpaper"
 cp "$repo_dir/config/dot/hypr/hyprlock.conf.template" \
     "$config_home/hypr/hyprlock.conf.template"
 HOME="$fixture_home" XDG_CONFIG_HOME="$config_home" \
@@ -131,19 +137,38 @@ write_settings '{"accentName":"not-a-real-accent","colorScheme":"dark"}'
 run_helper generate
 rg -Fq 'outer_color = rgba(130, 170, 255, 0.9)' "$generated" || fail 'an unknown accent name did not fall back to blue'
 
-write_settings '{
-  "lockBackgroundMode":"wallpaper",
-  "wallpaperMode":"per-monitor",
-  "wallpaperPath":"/images/global.jpg",
-  "wallpaperPerMonitor":{"DP-2":"/images/portrait.jpg"}
-}'
+write_settings "$(jq -n \
+    --arg global "$global_wallpaper" \
+    --arg portrait "$portrait_wallpaper" \
+    '{lockBackgroundMode:"wallpaper",wallpaperMode:"per-monitor",wallpaperPath:$global,wallpaperPerMonitor:{"DP-2":$portrait}}')"
 run_helper generate
 [[ "$(rg -c '^background \{' "$generated")" -eq 2 ]] || fail 'wallpaper mode did not create one block per output'
-awk '/^background \{/{block++} block==1 && /monitor = DP-2/{monitor=1} block==1 && /path = \/images\/portrait.jpg/{path=1} END{exit !(monitor && path)}' "$generated" \
+awk -v path="$portrait_wallpaper" '/^background \{/{block++} block==1 && /monitor = DP-2/{monitor=1} block==1 && index($0, "path = " path){path_seen=1} END{exit !(monitor && path_seen)}' "$generated" \
     || fail 'per-monitor wallpaper was not used for DP-2'
-awk '/^background \{/{block++} block==2 && /monitor = HDMI-A-1/{monitor=1} block==2 && /path = \/images\/global.jpg/{path=1} END{exit !(monitor && path)}' "$generated" \
+awk -v path="$global_wallpaper" '/^background \{/{block++} block==2 && /monitor = HDMI-A-1/{monitor=1} block==2 && index($0, "path = " path){path_seen=1} END{exit !(monitor && path_seen)}' "$generated" \
     || fail 'missing monitor assignment did not fall back to the global wallpaper'
 
+# A selected but unreadable image never reaches hyprlock. One bounded warning
+# covers both missing global and per-monitor choices while the shipped image is
+# still readable.
+write_settings "$(jq -n \
+    --arg missing "$fixture/missing.jpg" \
+    '{lockBackgroundMode:"wallpaper",wallpaperMode:"per-monitor",wallpaperPath:$missing,wallpaperPerMonitor:{"DP-2":$missing}}')"
+run_helper generate
+[[ "$(rg -c "path = $shipped_wallpaper" "$generated")" -eq 2 ]] \
+    || fail 'missing selected wallpapers did not fall back to the readable shipped image'
+jq -e '.generated == true and .fallback == false
+    and .error == "One or more lock-screen wallpapers were unavailable; a safe fallback is in use."' \
+    <<<"$(run_helper status)" >/dev/null \
+    || fail 'missing wallpaper fallback did not report one bounded warning'
+
+# If no image is readable, screenshot is the only background source that
+# hyprlock can still render safely.
+rm -f "$shipped_wallpaper"
+run_helper generate
+[[ "$(rg -c 'path = screenshot' "$generated")" -eq 2 ]] \
+    || fail 'missing wallpapers without the shipped image did not fall back to screenshots'
+
 write_settings '{"lockBackgroundMode":"screenshot","lockShowClock":true,"lockShowDate":false,"lockShowUser":false,"use24Hour":true}'
 run_helper generate
 rg -Fq 'text = cmd[update:1000] date +"%H:%M"' "$generated" || fail '24-hour clock setting was ignored'
diff --git a/tests/quickshell/wallpaper-service-contract b/tests/quickshell/wallpaper-service-contract
index 769ce4f..187316a 100755
--- a/tests/quickshell/wallpaper-service-contract
+++ b/tests/quickshell/wallpaper-service-contract
@@ -15,6 +15,8 @@ active_state="$fixture/active.json"
 control="$fixture/control"
 shell_log="$fixture/quickshell.log"
 harness_pid=""
+quoted_home="$fixture/home's"
+quoted_wallpaper="$quoted_home/Pictures/Wallpapers/quoted.jpg"
 
 fail() {
     printf 'wallpaper service contract: %s\n' "$1" >&2
@@ -46,9 +48,18 @@ cleanup() {
 }
 trap cleanup EXIT
 
-mkdir -p "$config_home/panama" "$state_home" "$test_bin"
+mkdir -p "$config_home/panama" "$state_home" "$test_bin" \
+    "$quoted_home/Pictures/Wallpapers"
 cp -a "$repo_dir/config/dot/quickshell" "$config_path"
-printf '%s\n' '{}' >"$config_home/panama/settings.json"
+printf 'quoted wallpaper\n' >"$quoted_wallpaper"
+cat >"$config_home/panama/settings.json" <<'JSON'
+{
+  "displays": {
+    "DP-2": {"mode":"4500x3000@60.00","scale":1.5,"transform":0,"x":0,"y":0,"primary":true},
+    "HDMI-A-1": {"mode":"2560x1440@60.00","scale":1,"transform":0,"x":3000,"y":0,"primary":false}
+  }
+}
+JSON
 printf '%s\n' '{}' >"$active_state"
 : >"$command_log"
 : >"$control"
@@ -92,6 +103,7 @@ qs_for_harness() {
         XDG_CONFIG_HOME="$config_home"
         XDG_STATE_HOME="$state_home"
         PATH="$test_bin:$PATH"
+        HOME="$quoted_home"
         PANAMA_WALLPAPER_COMMAND_LOG="$command_log"
         PANAMA_WALLPAPER_ACTIVE_STATE="$active_state"
         PANAMA_WALLPAPER_CONTROL="$control"
@@ -113,6 +125,18 @@ wait_idle() {
     fail "wallpaper transaction did not settle: $status"
 }
 
+wait_for_scan() {
+    local status=""
+    for _ in $(seq 1 80); do
+        status="$(qs_for_harness ipc call wallpaper-service-test status)"
+        jq -e --arg path "$quoted_wallpaper" \
+            '.scanning == false and (.available | index($path) != null)' \
+            <<<"$status" >/dev/null && return
+        sleep 0.1
+    done
+    fail "argument-safe wallpaper scan did not discover the quoted HOME image: $status"
+}
+
 qs_for_harness --daemonize >"$shell_log" 2>&1 || fail 'isolated service harness did not launch'
 for _ in $(seq 1 60); do
     harness_pid="$(instances_for_harness | head -1)"
@@ -123,6 +147,7 @@ for _ in $(seq 1 60); do
     sleep 0.1
 done
 [[ "$harness_pid" =~ ^[0-9]+$ ]] || fail 'isolated service harness process did not start'
+wait_for_scan
 wait_idle >/dev/null
 
 : >"$command_log"
diff --git a/tests/quickshell/wallpaper-settings-contract b/tests/quickshell/wallpaper-settings-contract
index 657122a..53cd3c7 100755
--- a/tests/quickshell/wallpaper-settings-contract
+++ b/tests/quickshell/wallpaper-settings-contract
@@ -68,6 +68,15 @@ done
 [[ "$(qs_for_harness ipc call wallpaper-settings-test activate per-monitor /images/c.jpg)" \
     == '["assign:DP-2:/images/c.jpg"]' ]] || fail 'Per-display mode did not assign the selected output'
 
+qs_for_harness ipc call wallpaper-settings-test selectOutput HDMI-A-1 >/dev/null
+qs_for_harness ipc call wallpaper-settings-test updateOutputs 'DP-2|HDMI-A-1' >/dev/null
+[[ "$(qs_for_harness ipc call wallpaper-settings-test selectedOutput)" == 'HDMI-A-1' ]] \
+    || fail 'a valid per-monitor selection was reset during topology reconciliation'
+qs_for_harness ipc call wallpaper-settings-test updateOutputs 'DP-2' >/dev/null
+selected_after_disconnect="$(qs_for_harness ipc call wallpaper-settings-test selectedOutput)"
+[[ "$selected_after_disconnect" == 'DP-2' ]] \
+    || fail "a disconnected per-monitor selection did not fall back to the primary output: $selected_after_disconnect"
+
 states="$(qs_for_harness ipc call wallpaper-settings-test states)"
 jq -e '.selectedOutput == "DP-2"
     and .single == {"current":true,"selected":true}