fix(accept-invite): dynamic encryptionVersion, Firestore TTL on attempt docs, wipe recoveryPhrase on accept

firestore.indexes.json

@@ -1,4 +1,11 @@
 {
   "indexes": [],
-  "fieldOverrides": []
+  "fieldOverrides": [
+    {
+      "collectionGroup": "invite_attempts",
+      "fieldPath": "expiresAt",
+      "ttl": true,
+      "indexes": []
+    }
+  ]
 }

functions/dist/couples/acceptInviteCallable.js

@@ -62,6 +62,7 @@ const admin = __importStar(require("firebase-admin"));
  */
 const ACCEPT_RATE_LIMIT_WINDOW_MS = 60 * 60 * 1000; // 1 hour
 const ACCEPT_RATE_LIMIT_MAX = 10; // 10 attempts per hour per user
+const ACCEPT_ATTEMPT_TTL_MS = 25 * 60 * 60 * 1000; // 25h: rate window + 1h buffer; Firestore TTL cleans up after
 exports.acceptInviteCallable = functions.https.onCall(async (data, context) => {
     var _a, _b, _c;
     const callerId = (_a = context.auth) === null || _a === void 0 ? void 0 : _a.uid;
@@ -85,8 +86,11 @@ exports.acceptInviteCallable = functions.https.onCall(async (data, context) => {
         throw new functions.https.HttpsError('resource-exhausted', 'Too many code attempts. Try again later.');
     }
     // Record this attempt before doing any work, so failures also count.
+    // expiresAt is the Firestore TTL field — see firestore.indexes.json fieldOverrides.
+    const attemptExpiresAt = admin.firestore.Timestamp.fromMillis(admin.firestore.Timestamp.now().toMillis() + ACCEPT_ATTEMPT_TTL_MS);
     await db.collection('users').doc(callerId).collection('invite_attempts').add({
         attemptedAt: admin.firestore.FieldValue.serverTimestamp(),
+        expiresAt: attemptExpiresAt,
         code,
     });
     // Caller must not already be paired.
@@ -122,6 +126,15 @@ exports.acceptInviteCallable = functions.https.onCall(async (data, context) => {
     }
     const coupleId = db.collection('couples').doc().id;
     const coupleRef = db.collection('couples').doc(coupleId);
+    // Derive encryption version from E2EE field presence.
+    // encryptionVersion must stay in sync with EncryptionVersion.kt:
+    //   0 = plaintext (no couple key; iOS MVP path)
+    //   1 = legacy migration (mixed)
+    //   2 = strict E2EE (all new Android couples)
+    // Hardcoding 2 when wrappedCoupleKey is null creates a broken couple state
+    // where the client expects a key that does not exist.
+    const hasE2EE = wrappedCoupleKey != null && kdfSalt != null && kdfParams != null;
+    const encryptionVersion = hasE2EE ? 2 : 0;
     const batch = db.batch();
     batch.set(coupleRef, {
         id: coupleId,
@@ -129,22 +142,22 @@ exports.acceptInviteCallable = functions.https.onCall(async (data, context) => {
         inviteCode: code,
         createdAt: admin.firestore.FieldValue.serverTimestamp(),
         streakCount: 0,
-        // encryptionVersion must stay in sync with Android's
-        // app/src/main/java/app/closer/crypto/EncryptionVersion.kt.
-        // v0 = plaintext (iOS MVP, no E2EE); v1 = legacy migration;
-        // v2 = strict E2EE — the default for all new Android couples.
-        encryptionVersion: 2,
+        encryptionVersion,
         wrappedCoupleKey: wrappedCoupleKey !== null && wrappedCoupleKey !== void 0 ? wrappedCoupleKey : null,
         kdfSalt: kdfSalt !== null && kdfSalt !== void 0 ? kdfSalt : null,
         kdfParams: kdfParams !== null && kdfParams !== void 0 ? kdfParams : null,
     });
     batch.update(db.collection('users').doc(inviterUserId), { coupleId });
     batch.update(db.collection('users').doc(callerId), { coupleId });
+    // Wipe the recovery phrase from the invite doc on acceptance.
+    // It served its purpose (returned to the acceptor above); leaving key material
+    // in a document that stays in Firestore for 24h is unnecessary exposure.
     batch.update(inviteRef, {
         status: 'accepted',
         acceptedByUserId: callerId,
         acceptedAt: admin.firestore.FieldValue.serverTimestamp(),
         coupleId,
+        recoveryPhrase: admin.firestore.FieldValue.delete(),
     });
     await batch.commit();
     console.log(`[acceptInviteCallable] ${callerId} accepted invite ${code}; created couple ${coupleId}`);

functions/src/couples/acceptInviteCallable.ts

@@ -25,8 +25,9 @@ import * as admin from 'firebase-admin'
  *  6. Update both user documents with the new coupleId.
  *  7. Mark the invite as accepted.
  */
-const ACCEPT_RATE_LIMIT_WINDOW_MS = 60 * 60 * 1000 // 1 hour
-const ACCEPT_RATE_LIMIT_MAX = 10                     // 10 attempts per hour per user
+const ACCEPT_RATE_LIMIT_WINDOW_MS = 60 * 60 * 1000       // 1 hour
+const ACCEPT_RATE_LIMIT_MAX = 10                          // 10 attempts per hour per user
+const ACCEPT_ATTEMPT_TTL_MS = 25 * 60 * 60 * 1000        // 25h: rate window + 1h buffer; Firestore TTL cleans up after
 
 export const acceptInviteCallable = functions.https.onCall(async (data: any, context) => {
   const callerId = context.auth?.uid
@@ -55,8 +56,13 @@ export const acceptInviteCallable = functions.https.onCall(async (data: any, con
     throw new functions.https.HttpsError('resource-exhausted', 'Too many code attempts. Try again later.')
   }
   // Record this attempt before doing any work, so failures also count.
+  // expiresAt is the Firestore TTL field — see firestore.indexes.json fieldOverrides.
+  const attemptExpiresAt = admin.firestore.Timestamp.fromMillis(
+    admin.firestore.Timestamp.now().toMillis() + ACCEPT_ATTEMPT_TTL_MS
+  )
   await db.collection('users').doc(callerId).collection('invite_attempts').add({
     attemptedAt: admin.firestore.FieldValue.serverTimestamp(),
+    expiresAt: attemptExpiresAt,
     code,
   })
 
@@ -102,6 +108,16 @@ export const acceptInviteCallable = functions.https.onCall(async (data: any, con
   const coupleId = db.collection('couples').doc().id
   const coupleRef = db.collection('couples').doc(coupleId)
 
+  // Derive encryption version from E2EE field presence.
+  // encryptionVersion must stay in sync with EncryptionVersion.kt:
+  //   0 = plaintext (no couple key; iOS MVP path)
+  //   1 = legacy migration (mixed)
+  //   2 = strict E2EE (all new Android couples)
+  // Hardcoding 2 when wrappedCoupleKey is null creates a broken couple state
+  // where the client expects a key that does not exist.
+  const hasE2EE = wrappedCoupleKey != null && kdfSalt != null && kdfParams != null
+  const encryptionVersion = hasE2EE ? 2 : 0
+
   const batch = db.batch()
 
   batch.set(coupleRef, {
@@ -110,11 +126,7 @@ export const acceptInviteCallable = functions.https.onCall(async (data: any, con
     inviteCode: code,
     createdAt: admin.firestore.FieldValue.serverTimestamp(),
     streakCount: 0,
-    // encryptionVersion must stay in sync with Android's
-    // app/src/main/java/app/closer/crypto/EncryptionVersion.kt.
-    // v0 = plaintext (iOS MVP, no E2EE); v1 = legacy migration;
-    // v2 = strict E2EE — the default for all new Android couples.
-    encryptionVersion: 2,
+    encryptionVersion,
     wrappedCoupleKey: wrappedCoupleKey ?? null,
     kdfSalt: kdfSalt ?? null,
     kdfParams: kdfParams ?? null,
@@ -123,11 +135,15 @@ export const acceptInviteCallable = functions.https.onCall(async (data: any, con
   batch.update(db.collection('users').doc(inviterUserId), { coupleId })
   batch.update(db.collection('users').doc(callerId), { coupleId })
 
+  // Wipe the recovery phrase from the invite doc on acceptance.
+  // It served its purpose (returned to the acceptor above); leaving key material
+  // in a document that stays in Firestore for 24h is unnecessary exposure.
   batch.update(inviteRef, {
     status: 'accepted',
     acceptedByUserId: callerId,
     acceptedAt: admin.firestore.FieldValue.serverTimestamp(),
     coupleId,
+    recoveryPhrase: admin.firestore.FieldValue.delete(),
   })
 
   await batch.commit()