feat: add workspace tenant foundations

backend/alembic/env.py

@@ -30,6 +30,7 @@ import app.models.report  # noqa: E402, F401
 import app.models.setting  # noqa: E402, F401
 import app.models.user  # noqa: E402, F401
 import app.models.webhook  # noqa: E402, F401
+import app.models.workspace  # noqa: E402, F401
 
 # Import all models so that autogenerate can detect them
 from app.core.database import Base  # noqa: E402

backend/alembic/versions/2c3d4e5f6a7b_add_workspace_foundations.py

@@ -0,0 +1,129 @@
+"""add workspace foundations
+
+Revision ID: 2c3d4e5f6a7b
+Revises: 1b2c3d4e5f6a
+Create Date: 2026-05-23 18:58:00.000000
+"""
+
+from datetime import datetime
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "2c3d4e5f6a7b"
+down_revision = "1b2c3d4e5f6a"
+branch_labels = None
+depends_on = None
+
+
+def _default_workspace_id_sql() -> str:
+    return "(SELECT id FROM workspaces WHERE slug = 'default')"
+
+
+def upgrade() -> None:
+    """Create workspaces and attach existing single-tenant rows to default."""
+    op.create_table(
+        "workspaces",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("slug", sa.String(), nullable=False),
+        sa.Column("name", sa.String(), nullable=False),
+        sa.Column("description", sa.Text(), nullable=True),
+        sa.Column("active", sa.Boolean(), nullable=False),
+        sa.Column("created_at", sa.DateTime(), nullable=True),
+        sa.Column("updated_at", sa.DateTime(), nullable=True),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint("slug"),
+    )
+    op.create_index(op.f("ix_workspaces_id"), "workspaces", ["id"])
+    op.create_index(op.f("ix_workspaces_slug"), "workspaces", ["slug"])
+    op.create_index(op.f("ix_workspaces_active"), "workspaces", ["active"])
+    op.create_index(op.f("ix_workspaces_created_at"), "workspaces", ["created_at"])
+    op.create_index("ix_workspaces_active_slug", "workspaces", ["active", "slug"])
+
+    now = datetime.utcnow()
+    workspaces = sa.table(
+        "workspaces",
+        sa.column("slug", sa.String()),
+        sa.column("name", sa.String()),
+        sa.column("description", sa.Text()),
+        sa.column("active", sa.Boolean()),
+        sa.column("created_at", sa.DateTime()),
+        sa.column("updated_at", sa.DateTime()),
+    )
+    op.bulk_insert(
+        workspaces,
+        [
+            {
+                "slug": "default",
+                "name": "Default Workspace",
+                "description": "Automatically created for existing single-tenant installs.",
+                "active": True,
+                "created_at": now,
+                "updated_at": now,
+            }
+        ],
+    )
+
+    with op.batch_alter_table("domains") as batch_op:
+        batch_op.add_column(sa.Column("workspace_id", sa.Integer(), nullable=True))
+        batch_op.create_foreign_key(
+            "fk_domains_workspace_id_workspaces",
+            "workspaces",
+            ["workspace_id"],
+            ["id"],
+        )
+        batch_op.create_index(op.f("ix_domains_workspace_id"), ["workspace_id"])
+        batch_op.create_index("ix_domains_workspace_name", ["workspace_id", "name"])
+
+    with op.batch_alter_table("mail_sources") as batch_op:
+        batch_op.add_column(sa.Column("workspace_id", sa.Integer(), nullable=True))
+        batch_op.create_foreign_key(
+            "fk_mail_sources_workspace_id_workspaces",
+            "workspaces",
+            ["workspace_id"],
+            ["id"],
+        )
+        batch_op.create_index(op.f("ix_mail_sources_workspace_id"), ["workspace_id"])
+        batch_op.create_index("ix_mail_sources_workspace_enabled", ["workspace_id", "enabled"])
+
+    with op.batch_alter_table("users") as batch_op:
+        batch_op.add_column(sa.Column("workspace_id", sa.Integer(), nullable=True))
+        batch_op.create_foreign_key(
+            "fk_users_workspace_id_workspaces",
+            "workspaces",
+            ["workspace_id"],
+            ["id"],
+        )
+        batch_op.create_index(op.f("ix_users_workspace_id"), ["workspace_id"])
+
+    op.execute(f"UPDATE domains SET workspace_id = {_default_workspace_id_sql()}")
+    op.execute(f"UPDATE mail_sources SET workspace_id = {_default_workspace_id_sql()}")
+    op.execute(f"UPDATE users SET workspace_id = {_default_workspace_id_sql()}")
+
+
+def downgrade() -> None:
+    """Remove workspace ownership columns and table."""
+    with op.batch_alter_table("users") as batch_op:
+        batch_op.drop_index(op.f("ix_users_workspace_id"))
+        batch_op.drop_constraint("fk_users_workspace_id_workspaces", type_="foreignkey")
+        batch_op.drop_column("workspace_id")
+
+    with op.batch_alter_table("mail_sources") as batch_op:
+        batch_op.drop_index("ix_mail_sources_workspace_enabled")
+        batch_op.drop_index(op.f("ix_mail_sources_workspace_id"))
+        batch_op.drop_constraint("fk_mail_sources_workspace_id_workspaces", type_="foreignkey")
+        batch_op.drop_column("workspace_id")
+
+    with op.batch_alter_table("domains") as batch_op:
+        batch_op.drop_index("ix_domains_workspace_name")
+        batch_op.drop_index(op.f("ix_domains_workspace_id"))
+        batch_op.drop_constraint("fk_domains_workspace_id_workspaces", type_="foreignkey")
+        batch_op.drop_column("workspace_id")
+
+    op.drop_index("ix_workspaces_active_slug", table_name="workspaces")
+    op.drop_index(op.f("ix_workspaces_created_at"), table_name="workspaces")
+    op.drop_index(op.f("ix_workspaces_active"), table_name="workspaces")
+    op.drop_index(op.f("ix_workspaces_slug"), table_name="workspaces")
+    op.drop_index(op.f("ix_workspaces_id"), table_name="workspaces")
+    op.drop_table("workspaces")

backend/app/api/api_v1/endpoints/domains.py

@@ -36,6 +36,10 @@ from app.services.report_persistence import (
     hydrate_report_store_from_db,
 )
 from app.services.report_store import ReportStore
+from app.services.workspaces import (
+    assign_default_workspace_to_unscoped_rows,
+    workspace_domain_query,
+)
 from app.utils.domain_validator import validate_domain_config
 
 logger = logging.getLogger(__name__)
@@ -417,22 +421,35 @@ def _normalize_domain_name(name: str) -> str:
     return name.strip().strip(".").lower()
 
 
-def _domain_names_for_summary(db: Session, store: ReportStore) -> List[str]:
+def _domain_names_for_summary(db: Session, store: ReportStore, workspace=None) -> List[str]:
     report_domains = store.get_domains()
-    stored_domains = [
+    stored_query = db.query(Domain.name).filter(Domain.active == True)  # noqa: E712
-        name
+    if workspace is not None:
-        for (name,) in db.query(Domain.name)
+        stored_query = stored_query.filter(Domain.workspace_id == workspace.id)
-        .filter(Domain.active == True)  # noqa: E712
+    stored_domains = [name for (name,) in stored_query.order_by(Domain.name).all()]
-        .order_by(Domain.name)
+
+    if workspace is None:
+        scoped_report_domains = report_domains
+    else:
+        stored_scope = {
+            name: workspace_id
+            for name, workspace_id in db.query(Domain.name, Domain.workspace_id)
+            .filter(Domain.name.in_(report_domains))
             .all()
+        }
+        scoped_report_domains = [
+            name
+            for name in report_domains
+            if name not in stored_scope or stored_scope[name] == workspace.id
         ]
-    return list(dict.fromkeys(stored_domains + report_domains))
+    return list(dict.fromkeys(stored_domains + scoped_report_domains))
 
 
-def _domain_exists(db: Session, store: ReportStore, domain_name: str) -> bool:
+def _domain_exists(db: Session, store: ReportStore, domain_name: str, workspace=None) -> bool:
-    return domain_name in store.get_domains() or bool(
+    row = db.query(Domain.id, Domain.workspace_id).filter(Domain.name == domain_name).first()
-        db.query(Domain.id).filter(Domain.name == domain_name).first()
+    if row:
-    )
+        return workspace is None or row.workspace_id == workspace.id
+    return domain_name in store.get_domains()
 
 
 def _record_evidence(
@@ -1070,10 +1087,12 @@ async def read_domains(db: Session = Depends(get_db)):
     """
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    domains = _domain_names_for_summary(db, store)
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    domains = _domain_names_for_summary(db, store, workspace)
     summaries = store.get_all_domain_summaries()
     stored = {
-        domain.name: domain for domain in db.query(Domain).filter(Domain.name.in_(domains)).all()
+        domain.name: domain
+        for domain in workspace_domain_query(db, workspace).filter(Domain.name.in_(domains)).all()
     }
 
     result = []
@@ -1104,6 +1123,7 @@ async def create_domain(
     _auth: dict = Depends(require_admin_auth),
 ):
     """Create a monitored domain before any DMARC reports have arrived."""
+    workspace = assign_default_workspace_to_unscoped_rows(db)
     name = _normalize_domain_name(payload.name)
     validation = validate_domain_config({"name": name, "description": payload.description or ""})
     if not validation["valid"]:
@@ -1111,7 +1131,7 @@ async def create_domain(
             status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
             detail=validation["errors"],
         )
-    existing = db.query(Domain).filter(Domain.name == name).first()
+    existing = workspace_domain_query(db, workspace).filter(Domain.name == name).first()
     if existing:
         raise HTTPException(
             status_code=status.HTTP_409_CONFLICT,
@@ -1124,6 +1144,7 @@ async def create_domain(
         if selector and selector.strip()
     )
     domain = Domain(
+        workspace_id=workspace.id,
         name=name,
         description=payload.description,
         dkim_selectors=selectors or None,
@@ -1155,7 +1176,8 @@ async def read_domain(domain_name: str, db: Session = Depends(get_db)):
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
     domains = store.get_domains()
-    stored_domain = db.query(Domain).filter(Domain.name == domain_name).first()
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    stored_domain = workspace_domain_query(db, workspace).filter(Domain.name == domain_name).first()
 
     if domain_name not in domains and stored_domain is None:
         raise HTTPException(
@@ -1230,8 +1252,9 @@ async def get_domain_dns_records(
     """
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
+    workspace = assign_default_workspace_to_unscoped_rows(db)
 
-    if not _domain_exists(db, store, domain_id):
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1271,7 +1294,8 @@ async def get_domain_dns_health(
     """Return evidence-linked DNS health and enforcement readiness guidance."""
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    if not _domain_exists(db, store, domain_id):
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1289,7 +1313,8 @@ async def get_domain_posture_dashboard(
     """Return an evidence-first posture dashboard for a monitored domain."""
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    if not _domain_exists(db, store, domain_id):
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1309,7 +1334,8 @@ async def get_domain_mta_sts(
     """Return cached MTA-STS DNS and HTTPS policy posture for a domain."""
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    if not _domain_exists(db, store, domain_id):
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1345,7 +1371,8 @@ async def get_domain_bimi(
     """Return cached BIMI DNS posture for a domain."""
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    if not _domain_exists(db, store, domain_id):
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1461,8 +1488,9 @@ async def get_domain_reports(
     """
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
+    workspace = assign_default_workspace_to_unscoped_rows(db)
 
-    if not _domain_exists(db, store, domain_id):
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1513,8 +1541,9 @@ async def export_domain_reports(
 
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
+    workspace = assign_default_workspace_to_unscoped_rows(db)
 
-    if not _domain_exists(db, store, domain_id):
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1827,8 +1856,9 @@ async def get_domain_sources(
     """
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
+    workspace = assign_default_workspace_to_unscoped_rows(db)
 
-    if not _domain_exists(db, store, domain_id):
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1884,7 +1914,8 @@ async def get_domain_selectors(
     """
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    if not _domain_exists(db, store, domain_id):
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1910,7 +1941,8 @@ async def add_domain_selector(
     """
     store = ReportStore.get_instance()
     hydrate_report_store_from_db(db, store)
-    if domain_id not in store.get_domains():
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    if not _domain_exists(db, store, domain_id, workspace):
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,
             detail="Domain not found",
@@ -1923,9 +1955,9 @@ async def add_domain_selector(
             detail="Selector must not be empty",
         )
 
-    domain_db = db.query(Domain).filter(Domain.name == domain_id).first()
+    domain_db = workspace_domain_query(db, workspace).filter(Domain.name == domain_id).first()
     if not domain_db:
-        domain_db = Domain(name=domain_id)
+        domain_db = Domain(name=domain_id, workspace_id=workspace.id)
         db.add(domain_db)
 
     existing = [s.strip() for s in (domain_db.dkim_selectors or "").split(",") if s.strip()]
@@ -1944,7 +1976,8 @@ async def delete_domain_selector(
     db: Session = Depends(get_db),
 ):
     """Remove a manually configured DKIM selector from a domain."""
-    domain_db = db.query(Domain).filter(Domain.name == domain_id).first()
+    workspace = assign_default_workspace_to_unscoped_rows(db)
+    domain_db = workspace_domain_query(db, workspace).filter(Domain.name == domain_id).first()
     if not domain_db:
         raise HTTPException(
             status_code=status.HTTP_404_NOT_FOUND,

backend/app/main.py

@@ -20,6 +20,7 @@ import app.models.report  # noqa: F401 – ensure DMARCReport/ReportRecord table
 import app.models.setting  # noqa: F401 – ensure Setting table is registered
 import app.models.user  # noqa: F401 – ensure User table is registered
 import app.models.webhook  # noqa: F401 – ensure webhook tables are registered
+import app.models.workspace  # noqa: F401 – ensure workspace table is registered
 from app.api.api_v1.api import api_router
 from app.core.config import get_settings
 from app.core.database import Base, SessionLocal, engine

backend/app/models/domain.py

@@ -12,6 +12,7 @@ class Domain(Base):
     __tablename__ = "domains"
 
     id = Column(Integer, primary_key=True, index=True)
+    workspace_id = Column(Integer, ForeignKey("workspaces.id"), nullable=True, index=True)
     name = Column(String, unique=True, index=True, nullable=False)
     description = Column(Text, nullable=True)
     active = Column(Boolean, default=True, index=True)
@@ -30,6 +31,7 @@ class Domain(Base):
     updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
 
     # Relationships
+    workspace = relationship("Workspace", back_populates="domains")
     reports = relationship("DMARCReport", back_populates="domain", cascade="all, delete-orphan")
     forensic_reports = relationship(
         "ForensicReport", back_populates="domain", cascade="all, delete-orphan"
@@ -41,6 +43,8 @@ class Domain(Base):
     __table_args__ = (
         # Index for finding active and verified domains
         Index("ix_domains_active_verified", "active", "verified"),
+        # Workspace-scoped domain lookups for MSP mode.
+        Index("ix_domains_workspace_name", "workspace_id", "name"),
         # Index for finding domains by policy
         Index("ix_domains_policy", "dmarc_policy"),
         # Index for finding recently updated domains

backend/app/models/mail_source.py

@@ -1,6 +1,6 @@
 from datetime import datetime
 
-from sqlalchemy import Boolean, Column, DateTime, Integer, String, Text
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Index, Integer, String, Text
 from sqlalchemy.orm import relationship
 
 from app.core.credential_encryption import decrypt_secret, encrypt_secret, is_encrypted_secret
@@ -24,6 +24,7 @@ class MailSource(Base):
     __tablename__ = "mail_sources"
 
     id = Column(Integer, primary_key=True, index=True)
+    workspace_id = Column(Integer, ForeignKey("workspaces.id"), nullable=True, index=True)
 
     # Human-readable label for the source
     name = Column(String, nullable=False)
@@ -80,6 +81,9 @@ class MailSource(Base):
         back_populates="mail_source",
         cascade="all, delete-orphan",
     )
+    workspace = relationship("Workspace", back_populates="mail_sources")
+
+    __table_args__ = (Index("ix_mail_sources_workspace_enabled", "workspace_id", "enabled"),)
 
     def __repr__(self):
         return f"<MailSource id={self.id} name={self.name!r} method={self.method!r}>"

backend/app/models/user.py

@@ -1,6 +1,6 @@
 from datetime import datetime
 
-from sqlalchemy import Boolean, Column, DateTime, Integer, String
+from sqlalchemy import Boolean, Column, DateTime, ForeignKey, Integer, String
 from sqlalchemy.orm import relationship
 
 from app.core.database import Base
@@ -12,6 +12,7 @@ class User(Base):
     __tablename__ = "users"
 
     id = Column(Integer, primary_key=True, index=True)
+    workspace_id = Column(Integer, ForeignKey("workspaces.id"), nullable=True, index=True)
     email = Column(String, unique=True, index=True, nullable=False)
     # Logto subject claim (the user's stable ID inside Logto).
     # Null for users that pre-date Logto integration or for
@@ -41,4 +42,5 @@ class User(Base):
     )
 
     # Relationships
+    workspace = relationship("Workspace", back_populates="users")
     user_domains = relationship("UserDomain", back_populates="user", cascade="all, delete-orphan")

backend/app/models/workspace.py

@@ -0,0 +1,29 @@
+from datetime import datetime
+
+from sqlalchemy import Boolean, Column, DateTime, Index, Integer, String, Text
+from sqlalchemy.orm import relationship
+
+from app.core.database import Base
+
+
+class Workspace(Base):
+    """Tenant/workspace boundary for monitored DMARC assets."""
+
+    __tablename__ = "workspaces"
+
+    id = Column(Integer, primary_key=True, index=True)
+    slug = Column(String, unique=True, nullable=False, index=True)
+    name = Column(String, nullable=False)
+    description = Column(Text, nullable=True)
+    active = Column(Boolean, default=True, nullable=False, index=True)
+    created_at = Column(DateTime, default=datetime.utcnow, index=True)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    domains = relationship("Domain", back_populates="workspace")
+    mail_sources = relationship("MailSource", back_populates="workspace")
+    users = relationship("User", back_populates="workspace")
+
+    __table_args__ = (Index("ix_workspaces_active_slug", "active", "slug"),)
+
+    def __repr__(self):
+        return f"<Workspace {self.slug}>"

backend/app/services/cloudflare_dns.py

@@ -16,6 +16,7 @@ from app.models.dns_cache import DNSRecordChange, DNSRecordSnapshot
 from app.models.domain import Domain
 from app.models.setting import Setting
 from app.services.dns_resolver import CloudflareDNSProvider, extract_dmarc_policy
+from app.services.workspaces import assign_default_workspace_to_unscoped_rows
 
 PROVIDER_NAME = "cloudflare"
 
@@ -90,6 +91,7 @@ async def import_cloudflare_domains(
 ) -> Dict[str, Any]:
     """Create Domain rows for Cloudflare zones, returning imported and existing names."""
     zones = await discover_cloudflare_zones(db)
+    workspace = assign_default_workspace_to_unscoped_rows(db)
     requested = {domain.strip().lower() for domain in requested_domains or [] if domain.strip()}
     imported: List[str] = []
     existing: List[str] = []
@@ -100,9 +102,13 @@ async def import_cloudflare_domains(
         if requested and name not in requested:
             skipped.append(name)
             continue
-        domain = db.query(Domain).filter(Domain.name == name).first()
+        domain = (
+            db.query(Domain)
+            .filter(Domain.name == name, Domain.workspace_id == workspace.id)
+            .first()
+        )
         if domain is None:
-            db.add(Domain(name=name, active=True, verified=True))
+            db.add(Domain(name=name, active=True, verified=True, workspace_id=workspace.id))
             imported.append(name)
         else:
             existing.append(name)

backend/app/services/forensic_persistence.py

@@ -7,6 +7,7 @@ from sqlalchemy.orm import Session
 from app.models.domain import Domain
 from app.models.report import ForensicReport
 from app.services.forensic_redaction import ForensicRedactionPolicy, redact_forensic_value
+from app.services.workspaces import assign_default_workspace_to_unscoped_rows
 from app.utils.domain_validator import DomainValidationError, validate_domain
 
 
@@ -28,9 +29,14 @@ def _domain_for_report(db: Session, domain_name: Optional[str]) -> Optional[Doma
     if not is_valid and error_code != DomainValidationError.DNS_RESOLUTION_FAILED:
         return None
 
-    domain = db.query(Domain).filter(Domain.name == normalized).first()
+    workspace = assign_default_workspace_to_unscoped_rows(db, commit=False)
+    domain = (
+        db.query(Domain)
+        .filter(Domain.name == normalized, Domain.workspace_id == workspace.id)
+        .first()
+    )
     if domain is None:
-        domain = Domain(name=normalized)
+        domain = Domain(name=normalized, workspace_id=workspace.id)
         db.add(domain)
         db.flush()
     return domain

backend/app/services/report_persistence.py

@@ -7,6 +7,7 @@ from sqlalchemy.orm import Session, selectinload
 from app.models.domain import Domain
 from app.models.report import DMARCReport, ReportRecord
 from app.services.report_store import ReportStore
+from app.services.workspaces import assign_default_workspace_to_unscoped_rows
 
 
 def _parse_timestamp(value: Any) -> int:
@@ -98,10 +99,15 @@ def save_parsed_report(db: Session, report: Dict[str, Any]) -> tuple[DMARCReport
     domain_name = report.get("domain") or "unknown"
     report_id = report.get("report_id") or ""
     policy = _policy_parts(report)
+    workspace = assign_default_workspace_to_unscoped_rows(db, commit=False)
 
-    domain = db.query(Domain).filter(Domain.name == domain_name).first()
+    domain = (
+        db.query(Domain)
+        .filter(Domain.name == domain_name, Domain.workspace_id == workspace.id)
+        .first()
+    )
     if domain is None:
-        domain = Domain(name=domain_name, dmarc_policy=policy["p"])
+        domain = Domain(name=domain_name, dmarc_policy=policy["p"], workspace_id=workspace.id)
         db.add(domain)
         db.flush()
     elif policy.get("p"):

backend/app/services/tls_report_persistence.py

@@ -12,9 +12,9 @@ from sqlalchemy.orm import Session, selectinload
 
 from app.models.domain import Domain
 from app.models.report import TLSReport, TLSReportFailure
+from app.services.workspaces import assign_default_workspace_to_unscoped_rows
 from app.utils.domain_validator import DomainValidationError, validate_domain
 
-
 TLS_REPORT_PRIVACY_CONTROLS = {
     "retention": (
         "TLS reports store aggregate session counts, reporting organization metadata, "
@@ -69,9 +69,14 @@ def _domain_for_report(db: Session, domain_name: Optional[str]) -> Optional[Doma
     if not is_valid and error_code != DomainValidationError.DNS_RESOLUTION_FAILED:
         return None
 
-    domain = db.query(Domain).filter(Domain.name == normalized).first()
+    workspace = assign_default_workspace_to_unscoped_rows(db, commit=False)
+    domain = (
+        db.query(Domain)
+        .filter(Domain.name == normalized, Domain.workspace_id == workspace.id)
+        .first()
+    )
     if domain is None:
-        domain = Domain(name=normalized)
+        domain = Domain(name=normalized, workspace_id=workspace.id)
         db.add(domain)
         db.flush()
     return domain

backend/app/services/workspaces.py

@@ -0,0 +1,116 @@
+"""Workspace/tenant helpers for MSP mode foundations."""
+
+from __future__ import annotations
+
+from typing import Optional
+
+from sqlalchemy.orm import Query, Session
+
+from app.models.domain import Domain
+from app.models.mail_source import MailSource
+from app.models.user import User
+from app.models.workspace import Workspace
+
+DEFAULT_WORKSPACE_SLUG = "default"
+DEFAULT_WORKSPACE_NAME = "Default Workspace"
+
+
+def normalize_workspace_slug(value: str) -> str:
+    """Normalize a workspace slug for stable lookups."""
+    slug = (value or "").strip().lower()
+    cleaned = []
+    previous_dash = False
+    for char in slug:
+        if char.isalnum():
+            cleaned.append(char)
+            previous_dash = False
+        elif not previous_dash:
+            cleaned.append("-")
+            previous_dash = True
+    return "".join(cleaned).strip("-")
+
+
+def get_or_create_default_workspace(db: Session, *, commit: bool = True) -> Workspace:
+    """Return the single-tenant default workspace, creating it when needed."""
+    workspace = db.query(Workspace).filter(Workspace.slug == DEFAULT_WORKSPACE_SLUG).first()
+    if workspace:
+        return workspace
+
+    workspace = Workspace(
+        slug=DEFAULT_WORKSPACE_SLUG,
+        name=DEFAULT_WORKSPACE_NAME,
+        description="Automatically created for existing single-tenant installs.",
+        active=True,
+    )
+    db.add(workspace)
+    if commit:
+        db.commit()
+        db.refresh(workspace)
+    else:
+        db.flush()
+    return workspace
+
+
+def assign_default_workspace_to_unscoped_rows(
+    db: Session,
+    *,
+    commit: bool = True,
+) -> Workspace:
+    """Attach legacy unscoped rows to the default workspace."""
+    workspace = get_or_create_default_workspace(db, commit=commit)
+    for model in (Domain, MailSource, User):
+        db.query(model).filter(model.workspace_id.is_(None)).update(
+            {model.workspace_id: workspace.id},
+            synchronize_session=False,
+        )
+    if commit:
+        db.commit()
+    else:
+        db.flush()
+    return workspace
+
+
+def resolve_workspace(
+    db: Session,
+    *,
+    workspace_id: Optional[int] = None,
+    slug: Optional[str] = None,
+) -> Workspace:
+    """Resolve a workspace, defaulting to the single-tenant workspace."""
+    if workspace_id is not None:
+        workspace = (
+            db.query(Workspace)
+            .filter(Workspace.id == workspace_id, Workspace.active.is_(True))
+            .first()
+        )
+        if workspace:
+            return workspace
+        raise ValueError("Workspace not found")
+
+    if slug:
+        normalized = normalize_workspace_slug(slug)
+        workspace = (
+            db.query(Workspace)
+            .filter(Workspace.slug == normalized, Workspace.active.is_(True))
+            .first()
+        )
+        if workspace:
+            return workspace
+        raise ValueError("Workspace not found")
+
+    return assign_default_workspace_to_unscoped_rows(db)
+
+
+def workspace_domain_query(db: Session, workspace: Workspace) -> Query:
+    """Return the default scoped domain query for a workspace."""
+    return db.query(Domain).filter(Domain.workspace_id == workspace.id)
+
+
+def workspace_mail_source_query(db: Session, workspace: Workspace) -> Query:
+    """Return the default scoped mail-source query for a workspace."""
+    return db.query(MailSource).filter(MailSource.workspace_id == workspace.id)
+
+
+def workspace_user_query(db: Session, workspace: Workspace) -> Query:
+    """Return the default scoped user query for a workspace."""
+    return db.query(User).filter(User.workspace_id == workspace.id)

backend/app/tests/conftest.py

@@ -16,6 +16,7 @@ import app.models.report  # noqa: F401  # pylint: disable=unused-import
 import app.models.setting  # noqa: F401  # pylint: disable=unused-import
 import app.models.user  # noqa: F401  # pylint: disable=unused-import
 import app.models.webhook  # noqa: F401  # pylint: disable=unused-import
+import app.models.workspace  # noqa: F401  # pylint: disable=unused-import
 from app.core.database import Base, get_db
 from app.core.security import require_admin_auth
 from app.main import create_app

backend/app/tests/test_workspaces.py

@@ -0,0 +1,107 @@
+from fastapi.testclient import TestClient
+from sqlalchemy.orm import Session
+
+from app.models.domain import Domain
+from app.models.mail_source import MailSource
+from app.models.user import User
+from app.models.workspace import Workspace
+from app.services.workspaces import (
+    DEFAULT_WORKSPACE_SLUG,
+    assign_default_workspace_to_unscoped_rows,
+    get_or_create_default_workspace,
+    normalize_workspace_slug,
+    resolve_workspace,
+    workspace_domain_query,
+    workspace_mail_source_query,
+    workspace_user_query,
+)
+
+
+def test_default_workspace_claims_legacy_rows(db_session: Session):
+    """Existing single-tenant rows are attached to the default workspace."""
+    domain = Domain(name="legacy.example", active=True)
+    source = MailSource(name="Legacy inbox", method="IMAP", enabled=True)
+    user = User(email="operator@example.com")
+    db_session.add_all([domain, source, user])
+    db_session.commit()
+
+    workspace = assign_default_workspace_to_unscoped_rows(db_session)
+
+    db_session.refresh(domain)
+    db_session.refresh(source)
+    db_session.refresh(user)
+    assert workspace.slug == DEFAULT_WORKSPACE_SLUG
+    assert domain.workspace_id == workspace.id
+    assert source.workspace_id == workspace.id
+    assert user.workspace_id == workspace.id
+
+
+def test_workspace_scoped_queries_exclude_other_tenants(db_session: Session):
+    """Default scoped queries only return rows owned by that workspace."""
+    default = get_or_create_default_workspace(db_session)
+    other = Workspace(slug="client-two", name="Client Two", active=True)
+    db_session.add(other)
+    db_session.flush()
+    db_session.add_all(
+        [
+            Domain(name="default.example", workspace_id=default.id, active=True),
+            Domain(name="client-two.example", workspace_id=other.id, active=True),
+            MailSource(name="default inbox", method="IMAP", workspace_id=default.id),
+            MailSource(name="client two inbox", method="IMAP", workspace_id=other.id),
+            User(email="default@example.com", workspace_id=default.id),
+            User(email="client-two@example.com", workspace_id=other.id),
+        ]
+    )
+    db_session.commit()
+
+    assert [row.name for row in workspace_domain_query(db_session, default).all()] == [
+        "default.example"
+    ]
+    assert [row.name for row in workspace_mail_source_query(db_session, default).all()] == [
+        "default inbox"
+    ]
+    assert [row.email for row in workspace_user_query(db_session, default).all()] == [
+        "default@example.com"
+    ]
+
+
+def test_workspace_resolution_and_slug_validation(db_session: Session):
+    """Workspace lookup supports default, id, and normalized slug paths."""
+    default = resolve_workspace(db_session)
+    other = Workspace(slug="client-two", name="Client Two", active=True)
+    db_session.add(other)
+    db_session.commit()
+    db_session.refresh(other)
+
+    assert normalize_workspace_slug(" Client Two!! ") == "client-two"
+    assert resolve_workspace(db_session).id == default.id
+    assert resolve_workspace(db_session, workspace_id=other.id).id == other.id
+    assert resolve_workspace(db_session, slug="Client Two").id == other.id
+
+
+def test_domain_api_defaults_to_default_workspace(
+    authed_client: TestClient,
+    db_session: Session,
+):
+    """Domain API creates and lists rows inside the default workspace boundary."""
+    other = Workspace(slug="client-two", name="Client Two", active=True)
+    db_session.add(other)
+    db_session.flush()
+    db_session.add(Domain(name="other.example", workspace_id=other.id, active=True))
+    db_session.commit()
+
+    created = authed_client.post(
+        "/api/v1/domains/domains",
+        json={"name": "Default.Example", "description": "Default tenant"},
+    )
+    assert created.status_code == 201
+
+    workspace = get_or_create_default_workspace(db_session)
+    domain = db_session.query(Domain).filter(Domain.name == "default.example").first()
+    assert domain.workspace_id == workspace.id
+
+    listed = authed_client.get("/api/v1/domains/domains")
+    assert listed.status_code == 200
+    names = {item["name"] for item in listed.json()}
+    assert "default.example" in names
+    assert "other.example" not in names

docs/milestones.md

@@ -246,12 +246,14 @@ Exit criteria:
 
 ## Milestone 15: Workspaces / MSP Mode (Multi-Org Governance)
 
-Status: Backlog
+Status: In progress
 
 Goal: support multi-org deployments (e.g., MSPs) with strong isolation, ownership, and operator ergonomics.
 
 Planned:
-- Workspace/tenant concept with clear domain ownership.
+- Workspace/tenant concept with clear domain ownership. Delivered in M15.1:
+  default workspace migration, ownership columns for domains/users/mail sources,
+  and scoped query helpers.
 - Workspace-scoped RBAC and audit logs.
 - Templates for onboarding new workspaces (domains + mail sources + notifications).
 - Cross-workspace operator views for MSP admins, without weakening tenant isolation.

docs/reference/database.md

@@ -12,6 +12,22 @@ DMARQ uses a relational database to store all its data. The schema is designed t
 
 ## Core Tables
 
+### Workspaces
+
+The `workspaces` table stores tenant boundaries for multi-organization and MSP
+deployments. Existing single-tenant installs are attached to the default
+workspace during migration.
+
+| Column | Type | Description |
+|--------|------|-------------|
+| id | INTEGER | Primary key |
+| slug | VARCHAR | Unique stable workspace slug |
+| name | VARCHAR | Display name |
+| description | TEXT | Optional operator-facing description |
+| active | BOOLEAN | Whether the workspace can be used |
+| created_at | TIMESTAMP | When the workspace was created |
+| updated_at | TIMESTAMP | When the workspace was last updated |
+
 ### Domains
 
 The `domains` table stores information about the domains being monitored.
@@ -19,6 +35,7 @@ The `domains` table stores information about the domains being monitored.
 | Column | Type | Description |
 |--------|------|-------------|
 | id | INTEGER | Primary key |
+| workspace_id | INTEGER | Foreign key to workspaces.id |
 | name | VARCHAR(255) | Domain name (e.g., example.com) |
 | created_at | TIMESTAMP | When the domain was added |
 | active | BOOLEAN | Whether the domain is actively monitored |
@@ -105,6 +122,7 @@ The `users` table stores user account information.
 | Column | Type | Description |
 |--------|------|-------------|
 | id | INTEGER | Primary key |
+| workspace_id | INTEGER | Foreign key to workspaces.id |
 | username | VARCHAR(50) | Username |
 | email | VARCHAR(255) | Email address |
 | password_hash | VARCHAR(255) | Hashed password |
@@ -177,6 +195,26 @@ The `webhook_deliveries` table records delivery attempts and retry state.
 
 ## DNS and Configuration Tables
 
+### Mail_Sources
+
+The `mail_sources` table stores configured inboxes used to retrieve DMARC,
+forensic, and SMTP TLS reports.
+
+| Column | Type | Description |
+|--------|------|-------------|
+| id | INTEGER | Primary key |
+| workspace_id | INTEGER | Foreign key to workspaces.id |
+| name | VARCHAR | Human-readable source name |
+| method | VARCHAR | Source type such as IMAP, Gmail API, or Microsoft Graph |
+| server | VARCHAR | IMAP/POP server hostname |
+| port | INTEGER | IMAP/POP server port |
+| username | VARCHAR | Mailbox username |
+| password | TEXT | Encrypted mailbox password |
+| enabled | BOOLEAN | Whether scheduled imports should poll this source |
+| last_checked | TIMESTAMP | Last polling attempt time |
+| created_at | TIMESTAMP | When the source was created |
+| updated_at | TIMESTAMP | When the source was last updated |
+
 ### DNS_Records
 
 The `dns_records` table stores DNS record information for domains.

docs/reference/workspaces.md

@@ -0,0 +1,42 @@
+# Workspace Foundations
+
+DMARQ uses a workspace as the tenant boundary for multi-organization and MSP
+deployments. Milestone 15 starts with a default single-tenant workspace so
+existing deployments have a clear migration path before workspace RBAC and MSP
+views are added.
+
+## Default Workspace
+
+Existing installs are migrated into:
+
+```text
+slug: default
+name: Default Workspace
+```
+
+The migration attaches legacy domains, users, and mail sources to this default
+workspace. New domain rows created by the API also default to this workspace.
+
+## Ownership Boundaries
+
+The initial workspace model relates these core records to a workspace:
+
+- monitored domains
+- mail sources
+- users
+
+Domain, mail-source, and user query helpers scope reads to a workspace by
+default. This prevents cross-tenant reads in new M15 surfaces and gives later
+RBAC work a single ownership field to enforce.
+
+## Migration Story
+
+The migration creates the `workspaces` table, inserts the default workspace, and
+adds nullable `workspace_id` ownership columns to existing domain, user, and
+mail-source tables. Nullable columns keep upgrades safe for older databases and
+for import paths that may be backfilled in stages; runtime helpers attach
+legacy rows to the default workspace when needed.
+
+The current implementation keeps domain names globally unique. That matches the
+existing single-domain ownership model and avoids ambiguous ownership while MSP
+RBAC and onboarding controls are built out.

mkdocs.yml

@@ -42,6 +42,7 @@ nav:
     - API Reference: reference/api.md
     - SIEM Integrations: reference/siem-integrations.md
     - Ticketing and Chatops: reference/ticketing-chatops-integrations.md
+    - Workspaces: reference/workspaces.md
     - Architecture: reference/architecture.md
     - Database Schema: reference/database.md
   - Development: