diff --git a/app/src/main/java/app/closer/domain/MemoryCapsuleGenerator.kt b/app/src/main/java/app/closer/domain/MemoryCapsuleGenerator.kt
index 7d1193c1..6357b764 100644
--- a/app/src/main/java/app/closer/domain/MemoryCapsuleGenerator.kt
+++ b/app/src/main/java/app/closer/domain/MemoryCapsuleGenerator.kt
@@ -23,6 +23,10 @@ import java.time.temporal.ChronoUnit
  * - Reveal-derived titles use only category metadata and the fact that a reveal happened.
  * - Manual notes are accepted as already-encrypted ciphertext; this object does not encrypt.
  * - Tags are built from category, source type, and date context only.
+ *
+ * Determinism: every factory takes an injectable `createdAtMillis` (defaulting to the wall clock)
+ * so that, given identical inputs, the produced capsule is identical. Tests pin it; production omits
+ * it to stamp the real creation time.
  */
 object MemoryCapsuleGenerator {
 
@@ -67,7 +71,8 @@ object MemoryCapsuleGenerator {
         event: MemoryDateIdeaEvent,
         noteCiphertext: String? = null,
         photoStoragePath: String? = null,
-        now: LocalDate = LocalDate.now()
+        now: LocalDate = LocalDate.now(),
+        createdAtMillis: Long = System.currentTimeMillis()
     ): MemoryCapsule {
         val date = event.scheduledDate ?: now
         val displayCategory = event.category.takeIf { it.isNotBlank() } ?: DATE_CATEGORY
@@ -92,7 +97,7 @@ object MemoryCapsuleGenerator {
             ),
             source = MemoryCapsuleSource.DATE_IDEA,
             sourceRefId = event.dateIdeaId,
-            createdAt = System.currentTimeMillis()
+            createdAt = createdAtMillis
         )
     }
 
@@ -106,7 +111,8 @@ object MemoryCapsuleGenerator {
         authorId: String,
         event: MemoryRevealEvent,
         noteCiphertext: String? = null,
-        photoStoragePath: String? = null
+        photoStoragePath: String? = null,
+        createdAtMillis: Long = System.currentTimeMillis()
     ): MemoryCapsule {
         val displayCategory = event.categoryId?.takeIf { it.isNotBlank() } ?: REVEAL_CATEGORY
         val title = "A moment we revealed together${categoryFragment(displayCategory)}"
@@ -127,7 +133,7 @@ object MemoryCapsuleGenerator {
             ),
             source = MemoryCapsuleSource.REVEAL,
             sourceRefId = event.questionId,
-            createdAt = System.currentTimeMillis()
+            createdAt = createdAtMillis
         )
     }
 
@@ -139,7 +145,8 @@ object MemoryCapsuleGenerator {
         authorId: String,
         event: MemoryRecapEvent,
         noteCiphertext: String? = null,
-        photoStoragePath: String? = null
+        photoStoragePath: String? = null,
+        createdAtMillis: Long = System.currentTimeMillis()
     ): MemoryCapsule {
         val displayCategory = event.favoriteCategory?.takeIf { it.isNotBlank() } ?: RECAP_CATEGORY
         val weekNumber = weekNumberLabel(event.weekStart, event.weekEnd)
@@ -162,7 +169,7 @@ object MemoryCapsuleGenerator {
             ),
             source = MemoryCapsuleSource.WEEKLY_RECAP,
             sourceRefId = event.recapId,
-            createdAt = System.currentTimeMillis()
+            createdAt = createdAtMillis
         )
     }
 
@@ -174,7 +181,8 @@ object MemoryCapsuleGenerator {
         authorId: String,
         event: MemoryChallengeEvent,
         noteCiphertext: String? = null,
-        photoStoragePath: String? = null
+        photoStoragePath: String? = null,
+        createdAtMillis: Long = System.currentTimeMillis()
     ): MemoryCapsule {
         val displayCategory = event.challengeCategory?.takeIf { it.isNotBlank() } ?: CHALLENGE_CATEGORY
         val title = "Challenge completed${categoryFragment(displayCategory)}"
@@ -195,7 +203,7 @@ object MemoryCapsuleGenerator {
             ),
             source = MemoryCapsuleSource.CHALLENGE,
             sourceRefId = event.challengeId,
-            createdAt = System.currentTimeMillis()
+            createdAt = createdAtMillis
         )
     }
 
@@ -209,7 +217,8 @@ object MemoryCapsuleGenerator {
         coupleId: String,
         authorId: String,
         input: MemoryManualInput,
-        now: LocalDate = LocalDate.now()
+        now: LocalDate = LocalDate.now(),
+        createdAtMillis: Long = System.currentTimeMillis()
     ): MemoryCapsule {
         val displayCategory = input.category.takeIf { it.isNotBlank() } ?: DEFAULT_CATEGORY
         val title = input.title.takeIf { it.isNotBlank() }
@@ -231,7 +240,7 @@ object MemoryCapsuleGenerator {
                 now = now
             ),
             source = MemoryCapsuleSource.MANUAL,
-            createdAt = System.currentTimeMillis()
+            createdAt = createdAtMillis
         )
     }
 
diff --git a/app/src/test/java/app/closer/domain/MemoryCapsuleGeneratorTest.kt b/app/src/test/java/app/closer/domain/MemoryCapsuleGeneratorTest.kt
index f9bf4a6c..a642cbeb 100644
--- a/app/src/test/java/app/closer/domain/MemoryCapsuleGeneratorTest.kt
+++ b/app/src/test/java/app/closer/domain/MemoryCapsuleGeneratorTest.kt
@@ -425,8 +425,11 @@ class MemoryCapsuleGeneratorTest {
             scheduledDate = today
         )
 
-        val first = MemoryCapsuleGenerator.fromDateIdea(coupleId, authorId, event, now = today)
-        val second = MemoryCapsuleGenerator.fromDateIdea(coupleId, authorId, event, now = today)
+        // Pin the clock: the generator documents itself as pure/deterministic, so identical inputs
+        // (including createdAtMillis) must yield identical capsules. Without an injected clock the
+        // createdAt timestamp made this flaky across millisecond boundaries.
+        val first = MemoryCapsuleGenerator.fromDateIdea(coupleId, authorId, event, now = today, createdAtMillis = 1_700_000_000_000L)
+        val second = MemoryCapsuleGenerator.fromDateIdea(coupleId, authorId, event, now = today, createdAtMillis = 1_700_000_000_000L)
 
         assertEquals(first, second)
     }