diff --git a/backend/alembic/versions/1490781700bc_backfill_default_tree_author_id_to_.py b/backend/alembic/versions/1490781700bc_backfill_default_tree_author_id_to_.py
index 8d42e44c..8b093f14 100644
--- a/backend/alembic/versions/1490781700bc_backfill_default_tree_author_id_to_.py
+++ b/backend/alembic/versions/1490781700bc_backfill_default_tree_author_id_to_.py
@@ -13,7 +13,6 @@ from typing import Sequence, Union
 
 from alembic import op
 import sqlalchemy as sa
-from sqlalchemy.dialects.postgresql import UUID as PG_UUID
 import uuid
 
 
@@ -25,18 +24,40 @@ depends_on: Union[str, Sequence[str], None] = None
 
 SERVICE_ACCOUNT_EMAIL = "noreply@resolutionflow.com"
 SERVICE_ACCOUNT_NAME = "ResolutionFlow"
+SYSTEM_ACCOUNT_NAME = "ResolutionFlow System"
+SYSTEM_ACCOUNT_DISPLAY_CODE = "RF-SYS-1"
 
 
 def upgrade() -> None:
     conn = op.get_bind()
 
-    # Ensure service account exists
+    # Check if service user already exists
     row = conn.execute(
-        sa.text("SELECT id FROM users WHERE email = :email"),
+        sa.text("SELECT id, account_id FROM users WHERE email = :email"),
         {"email": SERVICE_ACCOUNT_EMAIL},
     ).fetchone()
 
-    if row is None:
+    if row is not None:
+        service_id = str(row[0])
+    else:
+        # Ensure a system account exists for the service user
+        acct_row = conn.execute(
+            sa.text("SELECT id FROM accounts WHERE display_code = :code"),
+            {"code": SYSTEM_ACCOUNT_DISPLAY_CODE},
+        ).fetchone()
+
+        if acct_row is None:
+            account_id = str(uuid.uuid4())
+            conn.execute(
+                sa.text("""
+                    INSERT INTO accounts (id, name, display_code, created_at, updated_at)
+                    VALUES (:id, :name, :code, NOW(), NOW())
+                """),
+                {"id": account_id, "name": SYSTEM_ACCOUNT_NAME, "code": SYSTEM_ACCOUNT_DISPLAY_CODE},
+            )
+        else:
+            account_id = str(acct_row[0])
+
         service_id = str(uuid.uuid4())
         conn.execute(
             sa.text("""
@@ -44,12 +65,12 @@ def upgrade() -> None:
                     id, email, name, password_hash, role,
                     is_super_admin, is_team_admin, is_active,
                     is_service_account, must_change_password,
-                    account_role, created_at
+                    account_id, account_role, created_at
                 ) VALUES (
                     :id, :email, :name, :password_hash, 'engineer',
                     false, false, true,
                     true, false,
-                    'engineer', NOW()
+                    :account_id, 'engineer', NOW()
                 )
             """),
             {
@@ -57,10 +78,9 @@ def upgrade() -> None:
                 "email": SERVICE_ACCOUNT_EMAIL,
                 "name": SERVICE_ACCOUNT_NAME,
                 "password_hash": "!service-account-no-login",
+                "account_id": account_id,
             },
         )
-    else:
-        service_id = str(row[0])
 
     # Backfill is_default trees that have no author
     result = conn.execute(
@@ -75,7 +95,6 @@ def upgrade() -> None:
 
 
 def downgrade() -> None:
-    # Restore NULL on trees that were authored by the service account and are default
     conn = op.get_bind()
     row = conn.execute(
         sa.text("SELECT id FROM users WHERE email = :email"),
diff --git a/backend/app/core/service_account.py b/backend/app/core/service_account.py
index d16e91c8..a2175981 100644
--- a/backend/app/core/service_account.py
+++ b/backend/app/core/service_account.py
@@ -18,6 +18,31 @@ logger = logging.getLogger(__name__)
 
 SERVICE_ACCOUNT_EMAIL = "noreply@resolutionflow.com"
 SERVICE_ACCOUNT_NAME = "ResolutionFlow"
+SYSTEM_ACCOUNT_NAME = "ResolutionFlow System"
+SYSTEM_ACCOUNT_DISPLAY_CODE = "RF-SYS-1"
+
+
+async def _ensure_system_account(db: AsyncSession) -> uuid.UUID:
+    """Get or create the ResolutionFlow system account. Returns its ID."""
+    from app.models.account import Account
+    from sqlalchemy import text
+
+    result = await db.execute(
+        select(Account).where(Account.display_code == SYSTEM_ACCOUNT_DISPLAY_CODE)
+    )
+    account = result.scalar_one_or_none()
+    if account is not None:
+        return account.id
+
+    new_account = Account(
+        id=uuid.uuid4(),
+        name=SYSTEM_ACCOUNT_NAME,
+        display_code=SYSTEM_ACCOUNT_DISPLAY_CODE,
+    )
+    db.add(new_account)
+    await db.flush()
+    logger.info(f"[service_account] Created system account (id={new_account.id})")
+    return new_account.id
 
 
 async def ensure_service_account(db: AsyncSession) -> uuid.UUID:
@@ -40,7 +65,8 @@ async def ensure_service_account(db: AsyncSession) -> uuid.UUID:
             await db.commit()
         return user.id
 
-    # Create the service account with a random, unusable password hash
+    account_id = await _ensure_system_account(db)
+
     new_user = User(
         id=uuid.uuid4(),
         email=SERVICE_ACCOUNT_EMAIL,
@@ -52,6 +78,7 @@ async def ensure_service_account(db: AsyncSession) -> uuid.UUID:
         is_active=True,
         is_service_account=True,
         must_change_password=False,
+        account_id=account_id,
         account_role="engineer",
     )
     db.add(new_user)