Add internal session foundation

backend/prisma/migrations/20260627190000_milestone1171_internal_session_foundation/migration.sql

@@ -0,0 +1,30 @@
+CREATE TYPE "AccountSessionStatus" AS ENUM ('ACTIVE', 'REVOKED', 'EXPIRED');
+
+CREATE TABLE "account_sessions" (
+  "id" UUID NOT NULL,
+  "user_id" UUID NOT NULL,
+  "refresh_token_hash" TEXT NOT NULL,
+  "status" "AccountSessionStatus" NOT NULL DEFAULT 'ACTIVE',
+  "access_token_version" INTEGER NOT NULL DEFAULT 1,
+  "expires_at" TIMESTAMP(3) NOT NULL,
+  "last_refreshed_at" TIMESTAMP(3),
+  "revoked_at" TIMESTAMP(3),
+  "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "updated_at" TIMESTAMP(3) NOT NULL,
+  CONSTRAINT "account_sessions_pkey" PRIMARY KEY ("id")
+);
+
+CREATE UNIQUE INDEX "account_sessions_refresh_token_hash_key"
+ON "account_sessions"("refresh_token_hash");
+
+CREATE INDEX "account_sessions_user_id_idx"
+ON "account_sessions"("user_id");
+
+CREATE INDEX "account_sessions_status_expires_at_idx"
+ON "account_sessions"("status", "expires_at");
+
+ALTER TABLE "account_sessions"
+ADD CONSTRAINT "account_sessions_user_id_fkey"
+FOREIGN KEY ("user_id") REFERENCES "users"("id")
+ON DELETE CASCADE
+ON UPDATE CASCADE;

backend/prisma/schema.prisma

@@ -33,6 +33,7 @@ model User {
   outgoingTransfers       OwnershipTransfer[]      @relation("OwnershipTransferFromUser")
   incomingTransfers       OwnershipTransfer[]      @relation("OwnershipTransferToUser")
   initiatedTransfers      OwnershipTransfer[]      @relation("OwnershipTransferRequestedByUser")
+  accountSessions         AccountSession[]
 
   @@map("users")
 }
@@ -282,6 +283,24 @@ model OwnershipTransfer {
   @@map("ownership_transfers")
 }
 
+model AccountSession {
+  id                 String               @id @default(uuid()) @db.Uuid
+  userId             String               @map("user_id") @db.Uuid
+  refreshTokenHash   String               @unique @map("refresh_token_hash")
+  status             AccountSessionStatus @default(ACTIVE)
+  accessTokenVersion Int                  @default(1) @map("access_token_version")
+  expiresAt          DateTime             @map("expires_at")
+  lastRefreshedAt    DateTime?            @map("last_refreshed_at")
+  revokedAt          DateTime?            @map("revoked_at")
+  createdAt          DateTime             @default(now()) @map("created_at")
+  updatedAt          DateTime             @updatedAt @map("updated_at")
+  user               User                 @relation(fields: [userId], references: [id], onDelete: Cascade, onUpdate: Cascade)
+
+  @@index([userId])
+  @@index([status, expiresAt])
+  @@map("account_sessions")
+}
+
 enum UserAccountKind {
   LEGACY_DEFAULT
   GUEST
@@ -294,6 +313,12 @@ enum UserAccountStatus {
   DELETED
 }
 
+enum AccountSessionStatus {
+  ACTIVE
+  REVOKED
+  EXPIRED
+}
+
 enum DevicePlatform {
   MACOS
   IPHONE