fix(#1): address PR review — split upsert into insert/update, add @Transaction, runBlocking seed, trailing newline

Per review on PR #8 (#8):

- Split @Upsert into @Insert(OnConflictStrategy.REPLACE) + @Update in all 3 DAOs.
  @Upsert returns -1 on the update path, so callers wanting the row ID would
  get a junk value. Interactors now call insert vs update based on id == 0.
  UpsertCategory returns category.id explicitly for the id != 0 branch.
- Add @Transaction to the 3 @Relation queries (ExpenseDao.subscribeAll,
  ExpenseDao.subscribeByDateRange, RecurringExpenseDao.subscribeAll). This
  silences the KSP warnings the PR body mentioned and makes the intent
  explicit.
- Switch MainApplication seeding from a fire-and-forget CoroutineScope to
  runBlocking(Dispatchers.IO). A fast first-tap on HomeScreen could otherwise
  call GetCategories.awaitDefault() before seeding completed and crash.
- Add documenting comment on CategoryDao.getDefault() noting that the
  'only one isDefault = 1' invariant is maintained at the interactor layer
  (partial unique index would be a v2 migration).
- Add trailing newline to app/build.gradle.kts.
- File follow-up issue #9 for flipping exportSchema to true before any v2
  migration lands.

app/src/main/java/dev/achmad/ledgerr/data/local/dao/CategoryDao.kt

@@ -1,8 +1,10 @@
 package dev.achmad.ledgerr.data.local.dao
 
 import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
 import androidx.room.Query
-import androidx.room.Upsert
+import androidx.room.Update
 import dev.achmad.ledgerr.data.local.entity.CategoryEntity
 import kotlinx.coroutines.flow.Flow
 
@@ -18,16 +20,27 @@ interface CategoryDao {
     @Query("SELECT * FROM categories WHERE id = :id")
     suspend fun getById(id: Long): CategoryEntity?
 
+    /**
+     * Returns the single category marked as the system default. The "Uncategorized"
+     * category is seeded as the only default on first launch. There is no
+     * DB-level uniqueness constraint on `isDefault = 1` (a partial unique index
+     * would be a v2 migration); the invariant is maintained by `SeedDefaultCategories`
+     * and `UpsertCategory` at the interactor layer. If multiple defaults ever
+     * sneak in, this returns an arbitrary one.
+     */
     @Query("SELECT * FROM categories WHERE isDefault = 1 LIMIT 1")
     suspend fun getDefault(): CategoryEntity?
 
     @Query("SELECT COUNT(*) FROM categories")
     suspend fun count(): Int
 
-    @Upsert
-    suspend fun upsert(category: CategoryEntity): Long
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insert(category: CategoryEntity): Long
 
-    @Upsert
+    @Update
+    suspend fun update(category: CategoryEntity)
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
     suspend fun upsertAll(categories: List<CategoryEntity>)
 
     @Query("DELETE FROM categories WHERE id = :id")

app/src/main/java/dev/achmad/ledgerr/data/local/dao/ExpenseDao.kt

@@ -3,9 +3,11 @@ package dev.achmad.ledgerr.data.local.dao
 import androidx.room.Dao
 import androidx.room.Embedded
 import androidx.room.Insert
+import androidx.room.OnConflictStrategy
 import androidx.room.Query
 import androidx.room.Relation
-import androidx.room.Upsert
+import androidx.room.Transaction
+import androidx.room.Update
 import dev.achmad.ledgerr.data.local.entity.CategoryEntity
 import dev.achmad.ledgerr.data.local.entity.ExpenseEntity
 import kotlinx.coroutines.flow.Flow
@@ -22,9 +24,11 @@ data class ExpenseWithCategoryRow(
 @Dao
 interface ExpenseDao {
 
+    @Transaction
     @Query("SELECT * FROM expenses ORDER BY date DESC, createdAt DESC")
     fun subscribeAll(): Flow<List<ExpenseWithCategoryRow>>
 
+    @Transaction
     @Query(
         "SELECT * FROM expenses " +
             "WHERE date BETWEEN :startDay AND :endDay " +
@@ -50,8 +54,11 @@ interface ExpenseDao {
     )
     suspend fun getByDateRange(startDay: Long, endDay: Long): List<ExpenseEntity>
 
-    @Upsert
-    suspend fun upsert(expense: ExpenseEntity): Long
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insert(expense: ExpenseEntity): Long
+
+    @Update
+    suspend fun update(expense: ExpenseEntity)
 
     @Insert
     suspend fun insertAll(expenses: List<ExpenseEntity>)

app/src/main/java/dev/achmad/ledgerr/data/local/dao/RecurringExpenseDao.kt

@@ -2,9 +2,12 @@ package dev.achmad.ledgerr.data.local.dao
 
 import androidx.room.Dao
 import androidx.room.Embedded
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
 import androidx.room.Query
 import androidx.room.Relation
-import androidx.room.Upsert
+import androidx.room.Transaction
+import androidx.room.Update
 import dev.achmad.ledgerr.data.local.entity.CategoryEntity
 import dev.achmad.ledgerr.data.local.entity.RecurringExpenseEntity
 import kotlinx.coroutines.flow.Flow
@@ -21,6 +24,7 @@ data class RecurringExpenseWithCategoryRow(
 @Dao
 interface RecurringExpenseDao {
 
+    @Transaction
     @Query("SELECT * FROM recurring_expenses ORDER BY nextDueDate ASC")
     fun subscribeAll(): Flow<List<RecurringExpenseWithCategoryRow>>
 
@@ -30,8 +34,11 @@ interface RecurringExpenseDao {
     @Query("SELECT * FROM recurring_expenses WHERE isActive = 1 AND nextDueDate <= :today")
     suspend fun getDue(today: Long): List<RecurringExpenseEntity>
 
-    @Upsert
-    suspend fun upsert(recurring: RecurringExpenseEntity): Long
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insert(recurring: RecurringExpenseEntity): Long
+
+    @Update
+    suspend fun update(recurring: RecurringExpenseEntity)
 
     @Query("DELETE FROM recurring_expenses WHERE id = :id")
     suspend fun deleteById(id: Long)

app/src/main/java/dev/achmad/ledgerr/domain/category/interactor/UpsertCategory.kt

@@ -9,7 +9,7 @@ class UpsertCategory(
 ) {
     suspend fun await(category: Category): Long {
         if (category.id == 0L) {
-            return dao.upsert(category.toEntity())
+            return dao.insert(category.toEntity())
         }
         val existing = dao.getById(category.id)
         val resolved = if (existing != null && category.isDefault && !existing.isDefault) {
@@ -17,6 +17,7 @@ class UpsertCategory(
         } else {
             category
         }
-        return dao.upsert(resolved.toEntity())
+        dao.update(resolved.toEntity())
+        return category.id
     }
 }

app/src/main/java/dev/achmad/ledgerr/ui/base/MainApplication.kt

@@ -7,9 +7,8 @@ import dev.achmad.ledgerr.di.domainModule
 import dev.achmad.ledgerr.di.preferenceModule
 import dev.achmad.ledgerr.di.util.inject
 import dev.achmad.ledgerr.domain.category.interactor.SeedDefaultCategories
-import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
 import org.koin.android.ext.koin.androidContext
 import org.koin.android.ext.koin.androidLogger
 import org.koin.core.context.startKoin
@@ -23,7 +22,7 @@ class MainApplication : Application() {
             androidContext(this@MainApplication)
             modules(coreModule, dataModule, domainModule, preferenceModule)
         }
-        CoroutineScope(Dispatchers.IO).launch {
+        runBlocking(Dispatchers.IO) {
             inject<SeedDefaultCategories>().await()
         }
     }