fix: add input sanitization across date plan forms and repository

app/src/main/java/app/closer/data/repository/DatePlanRepositoryImpl.kt

@@ -77,18 +77,16 @@ class DatePlanRepositoryImpl @Inject constructor(
     }
 
     override suspend fun savePlan(plan: DatePlan) {
-        // Store in Room for local-first access
-        val entity = plan.toEntity()
-        
-        if (plan.id.isEmpty()) {
-            // Create new plan - let Firestore generate the ID
-            val newId = planDataSource.createPlan(plan.coupleId, plan)
+        val sanitized = plan.sanitized()
+        val entity = sanitized.toEntity()
+
+        if (sanitized.id.isEmpty()) {
+            val newId = planDataSource.createPlan(sanitized.coupleId, sanitized)
             val updatedEntity = entity.copy(id = newId)
             planDao.insert(updatedEntity)
         } else {
-            // Update existing plan
             planDao.insert(entity)
-            planDataSource.updatePlan(plan.coupleId, plan)
+            planDataSource.updatePlan(sanitized.coupleId, sanitized)
         }
     }
 
@@ -135,8 +133,29 @@ class DatePlanRepositoryImpl @Inject constructor(
         )
     }
 
+    // ─── Sanitization ────────────────────────────────────────────────────────
+
+    private fun DatePlan.sanitized(): DatePlan = copy(
+        scheduledTime = scheduledTime.take(MAX_TIME_LENGTH),
+        duration = duration.take(MAX_DURATION_LENGTH),
+        activity = activity.take(MAX_TEXT_LENGTH),
+        food = food.take(MAX_TEXT_LENGTH),
+        conversationPrompts = conversationPrompts
+            .take(MAX_PROMPTS)
+            .map { it.take(MAX_PROMPT_LENGTH) },
+        optionalChallenge = optionalChallenge?.take(MAX_TEXT_LENGTH)
+    )
+
     // ─── Mappers ─────────────────────────────────────────────────────────────
 
+    private companion object {
+        const val MAX_TIME_LENGTH = 20
+        const val MAX_DURATION_LENGTH = 50
+        const val MAX_TEXT_LENGTH = 500
+        const val MAX_PROMPT_LENGTH = 1_000
+        const val MAX_PROMPTS = 20
+    }
+
     private fun DatePlanPreferenceEntity.toDomain(): DatePlanPreference = DatePlanPreference(
         id = id,
         coupleId = coupleId,

app/src/main/java/app/closer/ui/dates/BucketListViewModel.kt

@@ -45,8 +45,8 @@ class BucketListViewModel @Inject constructor(
 
         val newItem = BucketListItem(
             coupleId = coupleId,
-            title = title,
-            description = description,
+            title = title.take(MAX_TITLE_LENGTH),
+            description = description.take(MAX_DESCRIPTION_LENGTH),
             category = category,
             addedBy = "currentUser",
             addedAt = System.currentTimeMillis()
@@ -100,6 +100,11 @@ class BucketListViewModel @Inject constructor(
     fun clear() {
         _uiState.update { BucketListUiState() }
     }
+
+    private companion object {
+        const val MAX_TITLE_LENGTH = 100
+        const val MAX_DESCRIPTION_LENGTH = 500
+    }
 }
 
 data class BucketListUiState(

app/src/main/java/app/closer/ui/dates/DateBuilderViewModel.kt

@@ -47,9 +47,9 @@ class DateBuilderViewModel @Inject constructor(
         val preference = DatePlanPreference(
             dateIdeaId = state.dateIdeaId,
             preferredDate = state.scheduledDate,
-            preferredTime = state.scheduledTime,
+            preferredTime = state.scheduledTime.take(MAX_TIME_LENGTH),
             budget = state.budget,
-            duration = state.duration
+            duration = state.duration.take(MAX_DURATION_LENGTH)
         )
 
         viewModelScope.launch {
@@ -60,6 +60,11 @@ class DateBuilderViewModel @Inject constructor(
     fun clear() {
         _uiState.update { DateBuilderUiState() }
     }
+
+    private companion object {
+        const val MAX_TIME_LENGTH = 20
+        const val MAX_DURATION_LENGTH = 50
+    }
 }
 
 data class DateBuilderUiState(