fix(auth): make a profile write unable to unpair a couple (C-AUTH-001 hardening)

The previous commit fixed the path that reached the hazard. This removes the
hazard: createUser was a whole-document set() of every field, so any caller
holding a partially-loaded User wrote coupleId = null over a paired user and
dropped coupleId/partnerId. The User that does this is not exotic — for ~200ms
after every sign-in, users/{uid} exists with no fields on it at all. Getting a
read slightly wrong should cost a no-op, not a relationship's history.

createUser now merges, and UserProfileWrite omits every null or blank value, so a
field is only ever written with a real value and a hollow User produces an empty
map. For a document that doesn't exist yet — the only case callers actually intend
— the result is byte-identical to before. Clearing a field stays the job of the
targeted update* methods, where the call site says so. It also carries the same
locked-placeholder require()s the targeted writers already had.

plan is deliberately no longer written: User.plan defaults to "free", so merging it
would silently downgrade a paying user whose document we read while it was hollow.
The server owns that field (RevenueCat), reads already default a missing plan to
"free", and no gate reads it — entitlements live in the server-only subdoc. Checked
against firestore.rules: create requires no fields, and update's hasOnly allowlist
still covers everything written.

Correcting my last commit message while I'm here: it claimed CreateProfile submit
calls createUser and overwrites the name. Only half true — it uses targeted merges
when it sees an existing doc, and only calls createUser when it reads null. The
path that actually reached the sharp edge was Google sign-in: mergeGoogleProfile
decided "new account" from runCatching { getUser(uid) }.getOrNull(), which is null
for a failed read as much as for a missing document — C-AUTH-001's conflation, in a
place that then wrote a whole document. It also existed as two verbatim copies, in
LoginViewModel and SignUpViewModel, so the same bug was there twice. Now one
GoogleProfileMerger: it does nothing on a failed read, and won't seed a name over a
stub (which would overwrite a returning user's real name with their Google one).
Both view models drop userRepository entirely as a result.

User.isSignInStub is now shared rather than private to OnboardingViewModel, since
two callers need the same question answered.

UserProfileWriteTest pins the rule; mutation-checked by reverting the omit rule,
which fails 3 of them. Full unit suite green. Sign-in verified live on the throwaway.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/main/java/app/closer/data/remote/FirestoreUserDataSource.kt

@@ -95,21 +95,35 @@ class FirestoreUserDataSource @Inject constructor(
         awaitClose { listener.remove() }
     }
 
+    /**
+     * Write a user's profile without ever erasing what is already there.
+     *
+     * This was a whole-document `set()` of every field, which made it destructive by construction:
+     * any caller holding a partially-loaded [User] — or the field-less document that exists for
+     * ~200ms after sign-in (C-AUTH-001) — would write `coupleId = null` over a paired user, dropping
+     * `coupleId`/`partnerId` and unpairing the couple, plus overwriting their name. That is far too
+     * sharp an edge for a function every auth path calls: getting a read slightly wrong should cost
+     * a no-op, not a relationship's history.
+     *
+     * So it merges, and [UserProfileWrite] omits anything null or blank — a field is only ever
+     * written with a real value. For a document that doesn't exist yet (the only case callers
+     * actually intend) the result is identical to before. Clearing a field stays the job of the
+     * targeted `update*` methods, which say so at the call site.
+     */
     suspend fun createUser(user: User) {
-        userRef(user.id).set(
+        // Same guard the targeted writers carry: never persist the "locked" UI string as a value.
-            mapOf(
+        require(user.displayName != FieldEncryptor.LOCKED_PLACEHOLDER) {
-                "email" to user.email,
+            "Refusing to persist the locked placeholder as displayName"
-                "displayName" to encryptProfileField(user.displayName, user.coupleId),
+        }
-                "photoUrl" to user.photoUrl,
+        require(user.sex != FieldEncryptor.LOCKED_PLACEHOLDER) {
-                "sex" to encryptProfileField(user.sex, user.coupleId),
+            "Refusing to persist the locked placeholder as sex"
-                "partnerId" to user.partnerId,
+        }
-                "coupleId" to user.coupleId,
+        val fields = UserProfileWrite.fields(
-                "plan" to user.plan,
+            user,
-                "birthDate" to user.birthDate,
+            displayName = encryptProfileField(user.displayName, user.coupleId),
-                "createdAt" to user.createdAt,
+            sex = encryptProfileField(user.sex, user.coupleId)
-                "lastActiveAt" to user.lastActiveAt
+        )
-            )
+        userRef(user.id).set(fields, SetOptions.merge()).await()
-        ).await()
     }
 
     /** Age-gate DOB (O-AGE-001). Set once when a Google/legacy user has no birthDate yet. */

app/src/main/java/app/closer/data/remote/UserProfileWrite.kt

@@ -0,0 +1,49 @@
+package app.closer.data.remote
+
+import app.closer.domain.model.User
+
+/**
+ * The field map [FirestoreUserDataSource.createUser] writes.
+ *
+ * Split out from the data source so the one rule that matters can be pinned by a JVM test, with no
+ * Firestore in the way: **a null or blank value is never written.** The map is merged into a document
+ * that may already hold a real, paired profile, so anything hollow in the [User] has to be left alone
+ * rather than written as an erasure.
+ *
+ * This exists because the write used to be a whole-document `set()`, which put every caller one bad
+ * read away from unpairing a couple: a partially-loaded `User` — or the field-less document that
+ * exists for ~200ms after sign-in (C-AUTH-001) — carries `coupleId = null`, and writing that over a
+ * paired user drops `coupleId`/`partnerId` and overwrites their name. Clearing a field is the job of
+ * the targeted `update*` methods, where the call site says so out loud.
+ */
+internal object UserProfileWrite {
+
+    /**
+     * [displayName] and [sex] are passed in already encrypted — the data source owns the couple key.
+     *
+     * `plan` is deliberately absent: it is a billing fact the server owns (RevenueCat writes it), and
+     * [User.plan] defaults to `"free"`, so merging it would silently downgrade a paying user whose
+     * document we read while it was still hollow. Reads already treat a missing `plan` as `"free"`,
+     * so not writing it is the same thing for a new user and harmless for everyone else.
+     */
+    fun fields(user: User, displayName: String, sex: String): Map<String, Any> = buildMap {
+        putIfReal("email", user.email)
+        putIfReal("displayName", displayName)
+        putIfReal("photoUrl", user.photoUrl)
+        putIfReal("sex", sex)
+        putIfReal("partnerId", user.partnerId)
+        putIfReal("coupleId", user.coupleId)
+        putIfReal("birthDate", user.birthDate)
+        // Epoch millis: 0 is "unset" (the hollow document), never a real timestamp.
+        putIfReal("createdAt", user.createdAt.takeIf { it > 0L })
+        putIfReal("lastActiveAt", user.lastActiveAt.takeIf { it > 0L })
+    }
+
+    private fun MutableMap<String, Any>.putIfReal(key: String, value: Any?) {
+        when (value) {
+            null -> Unit
+            is String -> if (value.isNotBlank()) put(key, value)
+            else -> put(key, value)
+        }
+    }
+}

app/src/main/java/app/closer/domain/model/User.kt

@@ -16,3 +16,15 @@ data class User(
     val createdAt: Long = System.currentTimeMillis(),
     val lastActiveAt: Long = System.currentTimeMillis()
 )
+
+/**
+ * True when nothing has been written to this person's document yet — as opposed to "this person has
+ * no profile", which looks identical field-by-field and means the opposite (C-AUTH-001).
+ *
+ * Signing in registers an FCM token, and that merge-write materialises `users/{uid}` before the
+ * profile has synced: for roughly the first 200ms every read returns a document that exists and has
+ * no identity on it. Every path that creates a real user writes [email] and [createdAt] first, so
+ * their absence means "too early to tell", never "new user". Read it again rather than acting on it.
+ */
+val User.isSignInStub: Boolean
+    get() = email.isBlank() && createdAt == 0L && coupleId == null

app/src/main/java/app/closer/domain/usecase/GoogleProfileMerger.kt

@@ -0,0 +1,73 @@
+package app.closer.domain.usecase
+
+import android.util.Log
+import app.closer.domain.model.GoogleSignInResult
+import app.closer.domain.model.User
+import app.closer.domain.model.isSignInStub
+import app.closer.domain.repository.UserRepository
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * Seeds a user's profile from what Google already knows (name, photo) at sign-in.
+ *
+ * Best-effort by design: it fills gaps for a new account and otherwise stays out of the way. It ran
+ * as identical copies inside both `LoginViewModel` and `SignUpViewModel`, which is how the same bug
+ * came to exist twice.
+ *
+ * The bug: it decided "this is a new account" from `runCatching { getUser(uid) }.getOrNull()`, which
+ * returns null both when the user genuinely has no document *and* when the read simply failed. On the
+ * second reading it created the profile from scratch, overwriting a real one. That is the same
+ * conflation as C-AUTH-001, and the same rule applies — a read you don't trust decides nothing.
+ */
+@Singleton
+class GoogleProfileMerger @Inject constructor(
+    private val userRepository: UserRepository
+) {
+    suspend fun merge(result: GoogleSignInResult) {
+        val uid = result.uid
+        if (uid.isBlank()) return
+
+        val read = runCatching { userRepository.getUser(uid) }
+        if (read.isFailure) {
+            // Can't tell a new account from an unreadable one. Writing either way risks overwriting a
+            // real profile, and the only thing at stake here is a pre-filled name — so do nothing.
+            Log.w(TAG, "Couldn't read the profile at Google sign-in; leaving it untouched", read.exceptionOrNull())
+            return
+        }
+        val existing = read.getOrNull()
+
+        if (existing == null) {
+            userRepository.createUser(
+                User(
+                    id = uid,
+                    email = result.email,
+                    displayName = result.displayName,
+                    photoUrl = result.photoUrl,
+                    createdAt = System.currentTimeMillis(),
+                    lastActiveAt = System.currentTimeMillis()
+                )
+            )
+            return
+        }
+
+        // A document with nothing written to it yet looks exactly like a brand-new account: every
+        // field blank. Filling it in from Google would overwrite the real name of a returning user
+        // whose profile simply hadn't synced yet. Their name is already set — leave it alone.
+        if (existing.isSignInStub) {
+            Log.w(TAG, "Profile not synced yet at Google sign-in; not seeding name/photo over it")
+            return
+        }
+
+        if (existing.displayName.isBlank() && result.displayName.isNotBlank()) {
+            userRepository.updateDisplayName(uid, result.displayName)
+        }
+        if (existing.photoUrl.isBlank() && result.photoUrl.isNotBlank()) {
+            userRepository.updatePhotoUrl(uid, result.photoUrl)
+        }
+    }
+
+    private companion object {
+        const val TAG = "GoogleProfileMerger"
+    }
+}

app/src/main/java/app/closer/ui/auth/LoginViewModel.kt

@@ -2,10 +2,8 @@ package app.closer.ui.auth
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
-import app.closer.domain.model.GoogleSignInResult
-import app.closer.domain.model.User
 import app.closer.domain.repository.AuthRepository
-import app.closer.domain.repository.UserRepository
+import app.closer.domain.usecase.GoogleProfileMerger
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -26,7 +24,7 @@ data class LoginUiState(
 @HiltViewModel
 class LoginViewModel @Inject constructor(
     private val authRepository: AuthRepository,
-    private val userRepository: UserRepository
+    private val googleProfileMerger: GoogleProfileMerger
 ) : ViewModel() {
 
     private val _uiState = MutableStateFlow(LoginUiState())
@@ -51,7 +49,7 @@ class LoginViewModel @Inject constructor(
         viewModelScope.launch {
             authRepository.signInWithGoogle(idToken)
                 .onSuccess { result ->
-                    mergeGoogleProfile(result)
+                    googleProfileMerger.merge(result)
                     _uiState.update { it.copy(isLoading = false, success = true) }
                 }
                 .onFailure { e -> _uiState.update { it.copy(isLoading = false, error = friendlyError(e)) } }
@@ -69,30 +67,6 @@ class LoginViewModel @Inject constructor(
         }
     }
 
-    private suspend fun mergeGoogleProfile(result: GoogleSignInResult) {
-        val uid = result.uid
-        if (uid.isBlank()) return
-        val existing = runCatching { userRepository.getUser(uid) }.getOrNull()
-        if (existing == null) {
-            userRepository.createUser(
-                User(
-                    id = uid,
-                    email = result.email,
-                    displayName = result.displayName,
-                    photoUrl = result.photoUrl,
-                    createdAt = System.currentTimeMillis(),
-                    lastActiveAt = System.currentTimeMillis()
-                )
-            )
-        } else {
-            if (existing.displayName.isBlank() && result.displayName.isNotBlank()) {
-                userRepository.updateDisplayName(uid, result.displayName)
-            }
-            if (existing.photoUrl.isBlank() && result.photoUrl.isNotBlank()) {
-                userRepository.updatePhotoUrl(uid, result.photoUrl)
-            }
-        }
-    }
 
     private fun friendlyError(e: Throwable): String = when {
         e.message?.contains("no user record") == true -> "No account found with that email."

app/src/main/java/app/closer/ui/auth/SignUpViewModel.kt

@@ -5,10 +5,8 @@ import androidx.lifecycle.viewModelScope
 import app.closer.domain.AgeGate
 import app.closer.domain.SignupHandoff
 import app.closer.ui.brand.CloserCopy
-import app.closer.domain.model.GoogleSignInResult
-import app.closer.domain.model.User
 import app.closer.domain.repository.AuthRepository
-import app.closer.domain.repository.UserRepository
+import app.closer.domain.usecase.GoogleProfileMerger
 import dagger.hilt.android.lifecycle.HiltViewModel
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -35,7 +33,7 @@ data class SignUpUiState(
 @HiltViewModel
 class SignUpViewModel @Inject constructor(
     private val authRepository: AuthRepository,
-    private val userRepository: UserRepository,
+    private val googleProfileMerger: GoogleProfileMerger,
     private val signupHandoff: SignupHandoff
 ) : ViewModel() {
 
@@ -89,7 +87,7 @@ class SignUpViewModel @Inject constructor(
         viewModelScope.launch {
             authRepository.signInWithGoogle(idToken)
                 .onSuccess { result ->
-                    mergeGoogleProfile(result)
+                    googleProfileMerger.merge(result)
                     _uiState.update { it.copy(isLoading = false, googleSuccess = true) }
                 }
                 .onFailure { e -> _uiState.update { it.copy(isLoading = false, error = friendlyError(e)) } }
@@ -98,30 +96,6 @@ class SignUpViewModel @Inject constructor(
 
     fun reportError(message: String) = _uiState.update { it.copy(error = message) }
 
-    private suspend fun mergeGoogleProfile(result: GoogleSignInResult) {
-        val uid = result.uid
-        if (uid.isBlank()) return
-        val existing = runCatching { userRepository.getUser(uid) }.getOrNull()
-        if (existing == null) {
-            userRepository.createUser(
-                User(
-                    id = uid,
-                    email = result.email,
-                    displayName = result.displayName,
-                    photoUrl = result.photoUrl,
-                    createdAt = System.currentTimeMillis(),
-                    lastActiveAt = System.currentTimeMillis()
-                )
-            )
-        } else {
-            if (existing.displayName.isBlank() && result.displayName.isNotBlank()) {
-                userRepository.updateDisplayName(uid, result.displayName)
-            }
-            if (existing.photoUrl.isBlank() && result.photoUrl.isNotBlank()) {
-                userRepository.updatePhotoUrl(uid, result.photoUrl)
-            }
-        }
-    }
 
     private fun friendlyError(e: Throwable): String = when {
         e.message?.contains("email address is already") == true -> "An account with this email already exists."

app/src/test/java/app/closer/data/remote/UserProfileWriteTest.kt

@@ -0,0 +1,105 @@
+package app.closer.data.remote
+
+import app.closer.domain.model.User
+import app.closer.domain.model.isSignInStub
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * These are about one thing: a profile write must never be able to erase a couple.
+ *
+ * `createUser` used to `set()` the whole document, so a caller holding a partially-loaded [User]
+ * would write `coupleId = null` over a paired user and unpair them (C-AUTH-001). The read that
+ * produces such a User is not exotic — for ~200ms after every sign-in, `users/{uid}` exists with no
+ * fields on it at all — so the write itself has to be incapable of the damage.
+ */
+class UserProfileWriteTest {
+
+    /** Exactly what a read returns in the first ~200ms after sign-in. */
+    private val signInStub = User(id = "u1", createdAt = 0L, lastActiveAt = 0L)
+
+    private val pairedUser = User(
+        id = "u1",
+        email = "ava@example.com",
+        displayName = "enc:v1:name",
+        photoUrl = "https://example.com/a.jpg",
+        sex = "enc:v1:sex",
+        partnerId = "ben",
+        coupleId = "couple1",
+        birthDate = 946_684_800_000L,
+        createdAt = 1_700_000_000_000L,
+        lastActiveAt = 1_700_000_001_000L
+    )
+
+    private fun fieldsOf(user: User) =
+        UserProfileWrite.fields(user, displayName = user.displayName, sex = user.sex)
+
+    @Test
+    fun aHollowUserCannotUnpairACouple() {
+        val fields = fieldsOf(signInStub)
+        // The whole bug in one assertion: merging this must not touch the pairing.
+        assertFalse("coupleId must not be written from a hollow user", fields.containsKey("coupleId"))
+        assertFalse("partnerId must not be written from a hollow user", fields.containsKey("partnerId"))
+    }
+
+    @Test
+    fun aHollowUserWritesNothingAtAll() {
+        // Not just the pairing: there is nothing real on this document, so nothing should be said
+        // about it. A merge of an empty map is a no-op, which is the correct outcome.
+        assertEquals(emptyMap<String, Any>(), fieldsOf(signInStub))
+    }
+
+    @Test
+    fun aRealUserStillWritesEveryField() {
+        // The non-destructive rule must not cost a genuine create anything.
+        val fields = fieldsOf(pairedUser)
+        assertEquals("ava@example.com", fields["email"])
+        assertEquals("enc:v1:name", fields["displayName"])
+        assertEquals("https://example.com/a.jpg", fields["photoUrl"])
+        assertEquals("enc:v1:sex", fields["sex"])
+        assertEquals("ben", fields["partnerId"])
+        assertEquals("couple1", fields["coupleId"])
+        assertEquals(946_684_800_000L, fields["birthDate"])
+        assertEquals(1_700_000_000_000L, fields["createdAt"])
+        assertEquals(1_700_000_001_000L, fields["lastActiveAt"])
+    }
+
+    @Test
+    fun blanksAreOmittedRatherThanWrittenAsErasures() {
+        val partial = pairedUser.copy(photoUrl = "", sex = "", birthDate = null)
+        val fields = fieldsOf(partial)
+        assertFalse("a blank photoUrl must not clear an existing one", fields.containsKey("photoUrl"))
+        assertFalse("a blank sex must not clear an existing one", fields.containsKey("sex"))
+        assertFalse("a null birthDate must not clear an existing one", fields.containsKey("birthDate"))
+        // ...while everything real about the same user is still written.
+        assertEquals("couple1", fields["coupleId"])
+    }
+
+    @Test
+    fun planIsNeverWritten() {
+        // User.plan defaults to "free", so writing it would downgrade a paying user whose document
+        // we happened to read while it was hollow. The server owns this field.
+        assertFalse(fieldsOf(pairedUser).containsKey("plan"))
+        assertFalse(fieldsOf(pairedUser.copy(plan = "premium")).containsKey("plan"))
+    }
+
+    @Test
+    fun unsetTimestampsAreNotWrittenAsZero() {
+        // 0 is "unset", and writing it would date a real account to 1970.
+        val fields = fieldsOf(pairedUser.copy(createdAt = 0L, lastActiveAt = 0L))
+        assertFalse(fields.containsKey("createdAt"))
+        assertFalse(fields.containsKey("lastActiveAt"))
+    }
+
+    @Test
+    fun theStubIsRecognisedAndARealUserIsNot() {
+        assertTrue("the post-sign-in document must read as a stub", signInStub.isSignInStub)
+        assertFalse("a paired user must never read as a stub", pairedUser.isSignInStub)
+        // A genuinely new account is NOT a stub: every create writes email + createdAt first, which
+        // is what keeps new users flowing to profile setup instead of being retried forever.
+        val brandNew = User(id = "u2", email = "new@example.com", createdAt = 1_700_000_000_000L)
+        assertFalse("a new account with identity on it is not a stub", brandNew.isSignInStub)
+    }
+}

docs/Engineering_Reference_Manual.md

@@ -1481,8 +1481,9 @@ OOB code = `truncate6(SHA-256(pubkey ‖ nonce))`.
 ### C-AUTH-001 - a `users/{uid}` read right after sign-in returns a field-less document
 **Symptom**: signing in on a *new device* with a fully set-up, paired account routed to `CREATE_PROFILE` ("What should your partner call you?", over a `🔒 Couldn't unlock on this device` value) instead of `RECOVERY`. Reproduced end to end on a throwaway emulator with a real paired account.
 **Cause**: for roughly the first 200ms after sign-in, `getUser(uid)` returns a document that **exists with no fields at all** - no `email`, no `displayName`, no `coupleId` - and the real document only lands afterwards. Sign-in registers the FCM token, and that `SetOptions.merge()` write materialises `users/{uid}` before the profile has synced. Measured on-device: two reads at t+0ms field-less, the real document at t+215ms. `Source.SERVER` does **not** dodge it, so "read from the server" is not the fix.
-**Why it was destructive**: `FirestoreUserDataSource.createUser` is a whole-document `set()`, not a merge, and `CreateProfileViewModel` submit calls it. Tapping through that mistakenly-shown screen overwrites the real `displayName` with the locked placeholder and drops `coupleId`/`partnerId`, unpairing the couple - and the user never reaches Recovery.
+**Why it was destructive**: the user never reaches Recovery, and the screen they get instead invites them to overwrite the profile it couldn't read. `CreateProfileViewModel` submit is only *partly* protected - it uses targeted merges when it sees an existing doc (and `updateDisplayName`/`updateSex` `require` the value isn't the locked placeholder), but it calls `createUser` when it reads `null`, and `createUser` was a whole-document `set()` of every field. Any caller holding a partially-loaded `User` therefore wrote `coupleId = null` over a paired user, dropping `coupleId`/`partnerId`. The Google path reached exactly that: `mergeGoogleProfile` decided "new account" from `runCatching { getUser(uid) }.getOrNull()`, which is `null` for a *failed read* as much as for a missing doc.
-**Fix (R30)**: `OnboardingViewModel.resolveDestination` treats a field-less document as "ask again", not as "new user": it retries (3x, 400ms backoff) until a document with real identity on it arrives, and only that decides. A read that never succeeds routes Home (non-destructive; Home routes to Recovery by itself when the couple key is missing). `UserRepository.getUserFromServer` (`Source.SERVER`) backs the decision so an offline read throws instead of guessing from cache.
+**Fix (R30)**: `OnboardingViewModel.resolveDestination` treats a field-less document as "ask again", not as "new user": it retries (3x, 400ms backoff) until a document with real identity on it arrives, and only that decides. A read that never succeeds routes Home (non-destructive; Home routes to Recovery by itself when the couple key is missing). `UserRepository.getUserFromServer` (`Source.SERVER`) backs the decision so an offline read throws instead of guessing from cache. `User.isSignInStub` is the shared predicate.
+**Hardening (R30)**: the primitive can no longer do the damage. `createUser` merges, and `UserProfileWrite` omits every null/blank value, so a hollow `User` produces an empty map - a no-op - instead of an erasure; it also carries the placeholder `require`s, and deliberately never writes `plan` (client default `"free"` would downgrade a paying user; the server owns it, reads default it). `mergeGoogleProfile` was duplicated verbatim in `LoginViewModel` and `SignUpViewModel` - the same bug twice - and is now one `GoogleProfileMerger` that does nothing on a failed read and won't seed over a stub. Pinned by `UserProfileWriteTest` (mutation-checked: reverting the omit rule fails 3 of them).
 **Re-introduction risk**: **any** one-shot `users/{uid}` read on a startup path that branches on a field being blank. `exists() == true` does not mean "populated". Blank fields this early mean "not synced yet", and `createUser`'s `set()` semantics make guessing wrong expensive. If you need "does this person have a profile", require identity (`email`/`createdAt`) to be present before believing the answer.
 
 ---