feat(pairing): solo sealed answers that unlock on pairing

Unpaired users could only reach a waiting-room dead end and could not answer
questions until a partner joined. Responses.couple_id is now nullable so a
solo user answers immediately and banks "sealed answers" (couple_id IS NULL).
Pairing claims both members' sealed answers and computes matches for every
question both have now answered. Invite copy and the unpaired push nudge
escalate with the sealed answer count.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/mobile/app/(app)/pairing.tsx

@@ -16,9 +16,10 @@ import { Ionicons } from "@expo/vector-icons";
 import { LinearGradient } from "expo-linear-gradient";
 import Animated, { FadeInDown } from "react-native-reanimated";
 import * as Clipboard from "expo-clipboard";
-import { useAuthStore } from "../../src/store";
+import { useAuthStore, useMatchStore } from "../../src/store";
 import { coupleApi } from "../../src/lib/coupleApi";
 import { getPairingError } from "../../src/lib/errors";
+import { buildInviteShareMessage } from "../../src/lib/inviteShareCopy";
 import { Events } from "../../src/lib/analytics";
 import { router, useLocalSearchParams } from "expo-router";
 import { GradientBackground, GlassCard, GlassButton } from "../../src/components/ui";
@@ -28,7 +29,7 @@ import { getPendingInviteCode, clearPendingInviteCode } from "../../src/lib/pend
 import { checkClipboardForInviteCode } from "../../src/lib/clipboardInviteOffer";
 
 export default function PairingScreen() {
-    const { fetchCouple, fetchUser, couple, partner, isLoading: isAuthLoading } = useAuthStore();
+    const { fetchCouple, fetchUser, couple, partner, sealedCount, isLoading: isAuthLoading } = useAuthStore();
     const params = useLocalSearchParams<{ code?: string }>();
     const [inviteCode, setInviteCode] = useState("");
     const [isSubmitting, setIsSubmitting] = useState(false);
@@ -36,9 +37,13 @@ export default function PairingScreen() {
     const [clipboardOfferCode, setClipboardOfferCode] = useState<string | null>(null);
     const [prefillAttempted, setPrefillAttempted] = useState(false);
 
-    // Redirect if already paired
+    // Redirect if already paired. Pairing claims both members' sealed answers and
+    // computes matches server-side, so the matches store must refetch here too:
+    // whichever partner lands on this redirect first would otherwise show stale,
+    // pre-pairing matches until some unrelated screen happened to refresh it.
     useEffect(() => {
         if (couple && partner) {
+            void useMatchStore.getState().fetchMatches(true);
             router.replace("/(app)");
         }
     }, [couple, partner]);
@@ -145,6 +150,9 @@ export default function PairingScreen() {
 
             await fetchUser(); // Refresh user to get couple_id
             await fetchCouple(); // Fetch couple data
+            // Joining claims both members' sealed answers and computes matches
+            // server-side, so the joiner needs a fresh matches list too.
+            void useMatchStore.getState().fetchMatches(true);
             Events.coupleJoined();
 
             Alert.alert("Success", "You are now paired!", [
@@ -171,7 +179,7 @@ export default function PairingScreen() {
     };
 
     const shareMessage = couple?.invite_code
-        ? `Join me on Sauci! Tap this link to pair up instantly: https://sauci.app/join/${couple.invite_code} (or enter code ${couple.invite_code} in the app)`
+        ? buildInviteShareMessage(couple.invite_code, sealedCount)
         : "";
 
     const shareCode = async () => {
@@ -279,6 +287,21 @@ export default function PairingScreen() {
                             </Text>
                         </Animated.View>
 
+                        {/* Earned value: sealed answers already banked while unpaired */}
+                        {sealedCount > 0 && (
+                            <Animated.View
+                                entering={FadeInDown.delay(250).duration(500)}
+                                style={styles.section}
+                            >
+                                <GlassCard variant="elevated">
+                                    <Text style={styles.sealedCountText} testID="pairing-sealed-count">
+                                        You have already answered {sealedCount} question{sealedCount === 1 ? "" : "s"} about us.
+                                        They will unlock the moment your partner joins.
+                                    </Text>
+                                </GlassCard>
+                            </Animated.View>
+                        )}
+
                         {/* Code Card */}
                         <Animated.View
                             entering={FadeInDown.delay(300).duration(500)}
@@ -645,6 +668,11 @@ const styles = StyleSheet.create({
         textAlign: "center",
         maxWidth: 280,
     },
+    sealedCountText: {
+        ...typography.body,
+        color: colors.text,
+        textAlign: "center",
+    },
     section: {
         marginBottom: spacing.md,
     },