diff --git a/spruce/brick/fnkey_watchdog.sh b/spruce/brick/fnkey_watchdog.sh
new file mode 100755
index 000000000..b2d2d33f6
--- /dev/null
+++ b/spruce/brick/fnkey_watchdog.sh
@@ -0,0 +1,63 @@
+#!/bin/sh
+# Dispatch the Brick's two Fn keys by running the action the user picked in the
+# "Fn Key and Switch Settings" editor.
+#
+# On stock firmware the TrimUI keymon daemon reads the editor's per-key mapping
+# and runs the chosen action on each Fn press. spruce deliberately does not run
+# keymon (it replaced keymon everywhere with its own getevent watchdogs), so the
+# Fn keys did nothing. This watchdog is the spruce-native replacement for that
+# one job: watch the input node, and on an Fn key-down run the mapped action.
+#
+# Data model (all owned by the editor, /usr/trimui/apps/fn_editor/fneditor):
+#   /usr/trimui/fnkeys/f1key_launch  - one line, absolute path to the left  Fn action
+#   /usr/trimui/fnkeys/f2key_launch  - one line, absolute path to the right Fn action
+# The launch files are re-read on every press, so remapping in the editor takes
+# effect immediately with no restart. An unmapped key has no launch file and is
+# simply ignored.
+#
+# The action scripts are stateless togglers invoked with no argument (e.g.
+# com.trimui.toggle.ledc.sh flips the LED, com.trimui.switch.backlight.sh cycles
+# brightness), so this watchdog just executes the launch path as-is, exactly as
+# keymon did.
+#
+# Key codes: on the Brick the left/right Fn keys report as $B_L3 (1 317) and
+# $B_R3 (1 318) on $EVENT_PATH_READ_INPUTS_SPRUCE (event3). The Brick has no
+# analog sticks, so 317/318 are exclusively the Fn keys here (the B_L3/B_R3
+# naming is inherited from the shared TrimUI config). The node is read
+# non-exclusively, alongside the home/buttons watchdogs that already read it.
+
+. /mnt/SDCARD/spruce/scripts/helperFunctions.sh
+
+F1_LAUNCH="/usr/trimui/fnkeys/f1key_launch"
+F2_LAUNCH="/usr/trimui/fnkeys/f2key_launch"
+
+# Run the action named in a *key_launch file, if it points at a runnable script.
+# Backgrounded so a slow action never blocks the next keypress.
+run_fnkey() {
+    launch_file="$1"
+    which_key="$2"
+    [ -r "$launch_file" ] || return 0            # key unmapped: nothing to do
+    action=$(cat "$launch_file" 2>/dev/null)
+    [ -n "$action" ] || return 0                 # empty mapping
+    if [ ! -x "$action" ]; then
+        log_message "fnkey_watchdog.sh: $which_key Fn action not executable: $action"
+        return 0
+    fi
+    log_message "fnkey_watchdog.sh: $which_key Fn -> $action"
+    "$action" &
+}
+
+log_message "fnkey_watchdog.sh: Started up."
+
+# Outer loop restarts the reader if the getevent pipe ever exits, so the
+# watchdog stays durable like its siblings. -pid $$ makes getevent exit with us.
+while true; do
+    getevent -pid $$ "$EVENT_PATH_READ_INPUTS_SPRUCE" | while read line; do
+        case $line in
+            *"key $B_L3 1"*) run_fnkey "$F1_LAUNCH" left ;;
+            *"key $B_R3 1"*) run_fnkey "$F2_LAUNCH" right ;;
+        esac
+    done
+    log_message "fnkey_watchdog.sh: getevent pipe exited, restarting..."
+    sleep 1
+done
diff --git a/spruce/scripts/platform/device_functions/Brick.sh b/spruce/scripts/platform/device_functions/Brick.sh
index adfc3ffc9..095a8d178 100644
--- a/spruce/scripts/platform/device_functions/Brick.sh
+++ b/spruce/scripts/platform/device_functions/Brick.sh
@@ -36,4 +36,15 @@ device_init() {
         cp /mnt/SDCARD/spruce/smartpro/bin/bash /bin/bash
         chmod +x /bin/bash
     fi
+}
+
+launch_startup_watchdogs() {
+    launch_common_startup_watchdogs_v2
+
+    # Dispatch the Brick's Fn keys (spruce does not run the stock keymon that
+    # would otherwise do this). Launched here so it lives alongside the other
+    # durable watchdogs and survives the early-boot churn; pinned like them.
+    /mnt/SDCARD/spruce/brick/fnkey_watchdog.sh &
+    SYSTEM_CPU=${DEVICE_MAX_CORES_ONLINE%"${DEVICE_MAX_CORES_ONLINE#?}"}
+    pin_cpu "$SYSTEM_CPU" -n fnkey_watchdog.sh &
 }
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