diff --git a/echolot-app/app/src/main/kotlin/app/echo_lot/app/SettingsScreen.kt b/echolot-app/app/src/main/kotlin/app/echo_lot/app/SettingsScreen.kt
index 5d59bac..f82bb00 100644
--- a/echolot-app/app/src/main/kotlin/app/echo_lot/app/SettingsScreen.kt
+++ b/echolot-app/app/src/main/kotlin/app/echo_lot/app/SettingsScreen.kt
@@ -16,6 +16,7 @@ import androidx.compose.foundation.verticalScroll
 import androidx.compose.material3.Button
 import androidx.compose.material3.Card
 import androidx.compose.material3.FilterChip
+import androidx.compose.material3.LocalContentColor
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Switch
@@ -130,12 +131,21 @@ fun SettingsScreen(
                 }
                 Text(privacyExplanation(privacy), style = MaterialTheme.typography.bodySmall)
 
+                // At FULL nothing is pseudonymized, so a salt has nothing to act on. Shown
+                // disabled rather than hidden: the setting is still stored and still applies the
+                // moment the level changes, and a control that vanishes hides that fact.
                 Toggle(
                     label = "Stable pseudonyms across runs",
-                    detail = "Lets you compare uploaded runs over time (same SSID reads the same " +
-                        "each time). It also links your uploads together, so leave it off on a " +
-                        "server you don't run yourself.",
-                    checked = stableSalt,
+                    detail = if (privacy == PrivacyLevel.FULL) {
+                        "Not used at this level — nothing is pseudonymized, so there is nothing " +
+                            "to keep stable. Choose balanced or strict to use this."
+                    } else {
+                        "Lets you compare uploaded runs over time (same SSID reads the same " +
+                            "each time). It also links your uploads together, so leave it off on " +
+                            "a server you don't run yourself."
+                    },
+                    checked = stableSalt && privacy != PrivacyLevel.FULL,
+                    enabled = privacy != PrivacyLevel.FULL,
                 ) { stableSalt = it; settings.stableSalt = it }
 
                 TextButton(onClick = onPreviewUpload) { Text("Preview what an upload would send") }
@@ -237,13 +247,22 @@ private fun privacyExplanation(level: PrivacyLevel): String = when (level) {
 }
 
 @Composable
-private fun Toggle(label: String, detail: String, checked: Boolean, onChange: (Boolean) -> Unit) {
+private fun Toggle(
+    label: String,
+    detail: String,
+    checked: Boolean,
+    enabled: Boolean = true,
+    onChange: (Boolean) -> Unit,
+) {
     Row(Modifier.fillMaxWidth(), verticalAlignment = Alignment.Top) {
         Column(Modifier.weight(1f)) {
-            Text(label, style = MaterialTheme.typography.bodyMedium)
-            Text(detail, style = MaterialTheme.typography.bodySmall)
+            // Dimmed together with the switch, so "this does nothing right now" reads at a glance
+            // instead of only on close inspection.
+            val alpha = if (enabled) 1f else 0.5f
+            Text(label, style = MaterialTheme.typography.bodyMedium, color = LocalContentColor.current.copy(alpha = alpha))
+            Text(detail, style = MaterialTheme.typography.bodySmall, color = LocalContentColor.current.copy(alpha = alpha))
         }
-        Switch(checked = checked, onCheckedChange = onChange)
+        Switch(checked = checked, onCheckedChange = onChange, enabled = enabled)
     }
 }