fix: add Tink dependency, release key cleanup, rules hardening (batch v1.0.17)

app/build.gradle.kts

@@ -19,13 +19,12 @@ android {
         versionCode = 1
         versionName = "0.1.0"
 
-        // RevenueCat API key is supplied via local.properties (RC_API_KEY) and never committed.
+        // RevenueCat API key. Set RC_API_KEY in local.properties (never committed).
-        // TODO: Replace the PLACEHOLDER_RC_API_KEY fallback with a real key in local.properties before release.
+        // Debug builds fall back to a placeholder; release builds abort — see task guard below.
-        // The app will not process purchases correctly while the placeholder is active.
         buildConfigField(
             "String",
             "RC_API_KEY",
-            "\"${properties["RC_API_KEY"]?.toString() ?: "PLACEHOLDER_RC_API_KEY"}\""
+            "\"${properties["RC_API_KEY"]?.toString() ?: System.getenv("RC_API_KEY") ?: "PLACEHOLDER_RC_API_KEY"}\""
         )
     }
 
@@ -67,6 +66,22 @@ android {
 
 }
 
+// Abort any release assemble/bundle task when RC_API_KEY is absent or is the placeholder.
+// This runs at execution time so debug builds are never affected.
+tasks.matching { it.name.let { n ->
+    (n.startsWith("assemble") || n.startsWith("bundle")) && n.contains("Release", ignoreCase = true)
+}}.configureEach {
+    doFirst {
+        val key = (findProperty("RC_API_KEY") as? String)?.takeIf { it.isNotBlank() }
+            ?: System.getenv("RC_API_KEY")?.takeIf { it.isNotBlank() }
+        if (key == null || key == "PLACEHOLDER_RC_API_KEY") {
+            throw GradleException(
+                "RC_API_KEY is not set. Add it to local.properties or export RC_API_KEY before running a release build."
+            )
+        }
+    }
+}
+
 ksp {
     arg("room.schemaLocation", "$projectDir/schemas")
 }

app/src/main/java/app/closer/crypto/SealedRevealManager.kt

@@ -89,7 +89,11 @@ class SealedRevealManager @Inject constructor(
             recipientUserId = userId
         ) ?: return null
 
-        val myPrivateKey = userKeyManager.getOrCreatePrivateKey()
+        // loadPrivateKey — NOT getOrCreatePrivateKey. On a second device there is no local
+        // private key; generating a fresh one here would mismatch the published public key that
+        // the partner encrypted to, making unwrap fail silently or produce garbage. Returning
+        // null lets the caller surface LOST_LOCAL_KEY / WAITING_FOR_PARTNER correctly.
+        val myPrivateKey = userKeyManager.loadPrivateKey() ?: return null
         val oneTimeKey = releaseKeyEncryptor.unwrapFromSender(
             keyboxB64 = keybox,
             recipientPrivateKey = myPrivateKey,
@@ -158,7 +162,7 @@ class SealedRevealManager @Inject constructor(
             recipientUserId = userId
         ) ?: return null
 
-        val myPrivateKey = userKeyManager.getOrCreatePrivateKey()
+        val myPrivateKey = userKeyManager.loadPrivateKey() ?: return null
         val oneTimeKey = releaseKeyEncryptor.unwrapFromSender(
             keyboxB64 = keybox,
             recipientPrivateKey = myPrivateKey,

firestore.rules

@@ -391,12 +391,17 @@ service cloud.firestore {
                   && isEncryptedAnswerPayload(request.resource.data))
             );
 
-          // One-time key release for sealed thread answers (same pattern as daily answer release keys).
+          // One-time key release for sealed thread answers (same guards as daily answer release keys).
           match /releaseKeys/{recipientId} {
             allow read: if isCouplesMember(coupleId) && request.auth.uid == recipientId;
             allow create: if isCouplesMember(coupleId)
               && request.auth.uid == userId
+              && recipientId != userId
+              && recipientId in get(/databases/$(database)/documents/couples/$(coupleId)).data.userIds
+              // Both answers must exist before either key can be released — prevents early single-sided release.
+              && exists(/databases/$(database)/documents/couples/$(coupleId)/question_threads/$(threadId)/answers/$(recipientId))
               && isKeybox(request.resource.data.encryptedAnswerKey)
+              && request.resource.data.recipientUserId == recipientId
               && request.resource.data.keys().hasOnly(['recipientUserId', 'encryptedAnswerKey', 'releasedAt']);
             allow update, delete: if false;
           }
@@ -539,6 +544,10 @@ service cloud.firestore {
           && request.resource.data.userId == request.auth.uid
           && request.resource.data.questionId is string
           && request.resource.data.answerType is string
+          // answerDate must match the path segment — prevents a client writing a doc
+          // whose metadata disagrees with the path it lands in.
+          && request.resource.data.answerDate is string
+          && request.resource.data.answerDate == date
           && (
                // schemaVersion 3: partner-proof sealed answer.
                isSealedAnswerCreate(request.resource.data)