refactoring

backend/prisma/migrations/20260218000001_remove_unique_project_id_from_ongoing_timers/migration.sql

@@ -0,0 +1,4 @@
+-- Remove the erroneous UNIQUE constraint on ongoing_timers.project_id.
+-- Multiple users must be able to have concurrent timers on the same project.
+-- The one-timer-per-user constraint is correctly enforced by the UNIQUE on user_id.
+DROP INDEX IF EXISTS "ongoing_timers_project_id_key";

backend/prisma/schema.prisma

@@ -51,7 +51,7 @@ model Project {
   client   Client @relation(fields: [clientId], references: [id], onDelete: Cascade)
 
   timeEntries  TimeEntry[]
-  ongoingTimer OngoingTimer?
+  ongoingTimers OngoingTimer[]
 
   @@index([userId])
   @@index([clientId])
@@ -85,7 +85,7 @@ model OngoingTimer {
 
   userId    String  @map("user_id") @db.VarChar(255) @unique
   user      User    @relation(fields: [userId], references: [id], onDelete: Cascade)
-  projectId String? @unique @map("project_id")
+  projectId String? @map("project_id")
   project   Project? @relation(fields: [projectId], references: [id], onDelete: SetNull)
 
   @@index([userId])