diff --git a/app/main.py b/app/main.py
index c6583f8..33c5e27 100644
--- a/app/main.py
+++ b/app/main.py
@@ -61,6 +61,7 @@ from app.routes import (
     saved_views,
     webhooks,
     backups,
+    owner_transfer,
 )
 
 
@@ -396,6 +397,7 @@ def create_app() -> FastAPI:
     app.include_router(bank_accounts.router)
     app.include_router(audit.router)
     app.include_router(backups.router)
+    app.include_router(owner_transfer.router)
     app.include_router(custom_field_definitions.router)
     app.include_router(custom_fields.router)
     app.include_router(saved_filters.router)
diff --git a/app/models/auth.py b/app/models/auth.py
index 8e34822..39cf3e4 100644
--- a/app/models/auth.py
+++ b/app/models/auth.py
@@ -43,7 +43,7 @@ class ApiToken(Base, TenantMixin):
     )
     token_hash: Mapped[str] = mapped_column(String(255), nullable=False, index=True)
     name: Mapped[str] = mapped_column(String(200), nullable=False)
-    scopes: Mapped[list] = mapped_column(JSONB, nullable=False)
+    scopes: Mapped[list[str]] = mapped_column(JSONB, nullable=False, default=list)
     expires_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
     last_used_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
     created_at: Mapped[datetime] = mapped_column(
diff --git a/app/routes/contacts.py b/app/routes/contacts.py
index 56866fc..3571703 100644
--- a/app/routes/contacts.py
+++ b/app/routes/contacts.py
@@ -23,6 +23,7 @@ from app.commands.contact_commands import (
     MergeContactsCommand,
 )
 from app.core.db import get_db
+from app.core.visibility import check_single_entity_access
 from app.deps import get_current_user, get_redis_dep, require_permission
 from app.schemas.contact import (
     ContactCreate,
@@ -276,6 +277,31 @@ async def merge_duplicate_contacts(
     current_user: dict = Depends(require_permission("contacts:write")),
 ):
     """Merge two contacts (source → target) via MergeContactsCommand."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    is_admin = current_user.get("is_system_admin", False)
+
+    # Check write access on both contacts
+    try:
+        source_uuid = uuid.UUID(body.source_contact_id)
+        target_uuid = uuid.UUID(body.target_contact_id)
+    except (ValueError, TypeError):
+        raise HTTPException(status_code=400, detail="Invalid contact ID")
+
+    source_access = await check_single_entity_access(
+        db, "contact", source_uuid, user_id, tenant_id,
+        required_level="write", is_system_admin=is_admin,
+    )
+    if not source_access:
+        raise HTTPException(status_code=403, detail="No write access to source contact")
+
+    target_access = await check_single_entity_access(
+        db, "contact", target_uuid, user_id, tenant_id,
+        required_level="write", is_system_admin=is_admin,
+    )
+    if not target_access:
+        raise HTTPException(status_code=403, detail="No write access to target contact")
+
     cmd = MergeContactsCommand(
         source_contact_id=body.source_contact_id,
         target_contact_id=body.target_contact_id,
diff --git a/app/routes/owner_transfer.py b/app/routes/owner_transfer.py
new file mode 100644
index 0000000..a227179
--- /dev/null
+++ b/app/routes/owner_transfer.py
@@ -0,0 +1,58 @@
+"""Owner transfer routes — admin-only bulk ownership transfer."""
+
+from __future__ import annotations
+
+import uuid
+from typing import Any
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.deps import require_admin
+from app.services.owner_transfer_service import transfer_ownership
+
+router = APIRouter(prefix="/api/v1/ownership", tags=["ownership"])
+
+
+class TransferRequest(BaseModel):
+    from_user_id: str
+    to_user_id: str
+    entity_types: list[str] | None = None
+
+
+@router.post("/transfer")
+async def transfer_ownership_endpoint(
+    body: TransferRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict[str, Any] = Depends(require_admin),
+):
+    """Bulk-transfer all records from one user to another.
+
+    Admin-only endpoint. If entity_types is None, all known entity types
+    are transferred.
+    """
+    try:
+        from_uid = uuid.UUID(body.from_user_id)
+        to_uid = uuid.UUID(body.to_user_id)
+    except ValueError:
+        raise HTTPException(
+            400,
+            detail={"detail": "Invalid user_id format", "code": "invalid_id"},
+        )
+
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+
+    results = await transfer_ownership(
+        db,
+        tenant_id,
+        from_uid,
+        to_uid,
+        body.entity_types,
+    )
+
+    return {
+        "message": "Ownership transfer completed",
+        "results": results,
+    }
diff --git a/app/routes/users.py b/app/routes/users.py
index 870901e..2e75ee2 100644
--- a/app/routes/users.py
+++ b/app/routes/users.py
@@ -18,6 +18,7 @@ from app.deps import get_current_user, require_permission
 from app.models.user import User, UserTenant
 from app.schemas.user import UserCreate, UserUpdate, UserResponse, PaginatedUsers
 from app.services.user_service import user_service, _UNSET
+from app.services.owner_transfer_service import transfer_ownership
 
 router = APIRouter(prefix="/api/v1/users", tags=["users"])
 
@@ -235,6 +236,16 @@ async def update_user(
         raise HTTPException(404, detail={"detail": "User not found", "code": "not_found"})
 
     user, user_tenant = result
+
+    # Auto-transfer ownership when user is deactivated
+    if body.is_active is False:
+        await transfer_ownership(
+            db,
+            tenant_id,
+            from_user_id=uid,
+            to_user_id=acting_user_id,
+        )
+
     await log_audit(db, tenant_id, acting_user_id, "update", "user", uid, changes=changes)
 
     # Invalidate permission cache for the updated user
diff --git a/app/services/ai_copilot_service.py b/app/services/ai_copilot_service.py
index 1caffef..9932998 100644
--- a/app/services/ai_copilot_service.py
+++ b/app/services/ai_copilot_service.py
@@ -12,6 +12,8 @@ from sqlalchemy.ext.asyncio import AsyncSession
 from app.ai.llm_client import get_llm_client
 from app.core.audit import log_audit
 from app.core.auth import check_permission
+from app.core.visibility import apply_visibility_filter
+from app.core.visibility import check_single_entity_access
 from app.models.ai_conversation import AIConversation, AIMessage
 from app.models.contact import Contact
 from app.models.contact import Contact
@@ -64,6 +66,7 @@ async def process_query(
     query: str,
     conversation_id: str | None = None,
     context: dict[str, Any] | None = None,
+    is_system_admin: bool = False,
 ) -> dict[str, Any]:
     """Process a natural language query and return proposed actions.
 
@@ -159,6 +162,7 @@ async def execute_action(
     role: str,
     conversation_id: str,
     action: dict[str, Any],
+    is_system_admin: bool = False,
 ) -> dict[str, Any]:
     """Execute a proposed action with RBAC enforcement.
 
@@ -195,9 +199,31 @@ async def execute_action(
             "success": False,
         }
 
+    # Check single entity access for write operations
+    if method in ("POST", "PATCH", "DELETE"):
+        parts = path.replace("/api/v1/", "").strip("/").split("/")
+        entity_type = parts[0] if parts else ""
+        entity_id = parts[1] if len(parts) > 1 else None
+        if entity_id:
+            try:
+                entity_uuid = uuid.UUID(entity_id)
+            except (ValueError, TypeError):
+                entity_uuid = None
+            if entity_uuid:
+                has_access = await check_single_entity_access(
+                    db, entity_type, entity_uuid, user_id, tenant_id,
+                    required_level="write", is_system_admin=is_system_admin,
+                )
+                if not has_access:
+                    return {
+                        "error": "Insufficient access to this entity",
+                        "status_code": 403,
+                        "success": False,
+                    }
+
     # Execute the action
     try:
-        exec_result = await _execute_api_action(db, tenant_id, user_id, method, path, body)
+        exec_result = await _execute_api_action(db, tenant_id, user_id, method, path, body, is_system_admin=is_system_admin)
     except Exception as exc:
         exec_result = {"error": str(exc), "status_code": 500}
 
@@ -303,6 +329,7 @@ async def _execute_api_action(
     method: str,
     path: str,
     body: dict[str, Any],
+    is_system_admin: bool = False,
 ) -> dict[str, Any]:
     """Execute an API action directly against the database.
 
@@ -314,9 +341,9 @@ async def _execute_api_action(
     entity_id = parts[1] if len(parts) > 1 else None
 
     if entity in ("companies", "contacts"):
-        return await _exec_contacts(db, tenant_id, user_id, method, entity_id, body)
+        return await _exec_contacts(db, tenant_id, user_id, method, entity_id, body, is_system_admin=is_system_admin)
     elif entity == "workflows":
-        return await _exec_workflows(db, tenant_id, user_id, method, entity_id, body)
+        return await _exec_workflows(db, tenant_id, user_id, method, entity_id, body, is_system_admin=is_system_admin)
     else:
         return {"error": f"Unsupported entity: {entity}", "status_code": 400, "success": False}
 
@@ -328,15 +355,18 @@ async def _exec_contacts(
     method: str,
     entity_id: str | None,
     body: dict[str, Any],
+    is_system_admin: bool = False,
 ) -> dict[str, Any]:
     """Execute contact operations (unified: company + person)."""
     if method == "GET":
-        result = await db.execute(
-            select(Contact).where(
-                Contact.tenant_id == tenant_id,
-                Contact.deleted_at.is_(None),
-            )
+        query = select(Contact).where(
+            Contact.tenant_id == tenant_id,
+            Contact.deleted_at.is_(None),
         )
+        query = await apply_visibility_filter(
+            db, query, "contact", Contact, user_id, tenant_id, is_system_admin=is_system_admin
+        )
+        result = await db.execute(query)
         contacts = result.scalars().all()
         return {
             "success": True,
@@ -372,6 +402,7 @@ async def _exec_workflows(
     method: str,
     entity_id: str | None,
     body: dict[str, Any],
+    is_system_admin: bool = False,
 ) -> dict[str, Any]:
     """Execute workflow operations."""
     if method == "GET":
diff --git a/app/services/owner_transfer_service.py b/app/services/owner_transfer_service.py
new file mode 100644
index 0000000..57b554a
--- /dev/null
+++ b/app/services/owner_transfer_service.py
@@ -0,0 +1,97 @@
+"""Service for bulk-transferring ownership of records between users."""
+
+from __future__ import annotations
+
+import logging
+import uuid
+from typing import Any
+
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.audit import log_audit
+
+logger = logging.getLogger(__name__)
+
+# Mapping of entity_type -> database table name
+ENTITY_TABLES: dict[str, str] = {
+    "contacts": "contacts",
+    "addresses": "addresses",
+    "attachments": "attachments",
+    "bank_accounts": "bank_accounts",
+    "workflows": "workflows",
+    "sequences": "sequences",
+    "saved_filters": "saved_filters",
+    "saved_views": "saved_views",
+    "webhooks": "webhooks",
+    "notifications": "notifications",
+    "ai_conversations": "ai_conversations",
+}
+
+
+async def transfer_ownership(
+    db: AsyncSession,
+    tenant_id: uuid.UUID,
+    from_user_id: uuid.UUID,
+    to_user_id: uuid.UUID,
+    entity_types: list[str] | None = None,
+) -> dict[str, int]:
+    """Bulk-transfer all records from one user to another for the given entity types.
+
+    Args:
+        db: Database session.
+        tenant_id: Tenant scope.
+        from_user_id: Current owner whose records will be transferred.
+        to_user_id: New owner for the records.
+        entity_types: List of entity types to transfer. If None, all known types.
+
+    Returns:
+        Dict mapping entity_type -> number of records transferred.
+    """
+    if entity_types is None:
+        entity_types = list(ENTITY_TABLES.keys())
+
+    results: dict[str, int] = {}
+
+    for entity_type in entity_types:
+        table = ENTITY_TABLES.get(entity_type)
+        if table is None:
+            logger.warning("Unknown entity_type=%s, skipping", entity_type)
+            continue
+
+        # Build and execute the UPDATE
+        stmt = text(
+            f"UPDATE {table} SET owner_id = :to_user_id "
+            f"WHERE owner_id = :from_user_id AND tenant_id = :tenant_id"
+        )
+        stmt = stmt.bindparams(
+            to_user_id=str(to_user_id),
+            from_user_id=str(from_user_id),
+            tenant_id=str(tenant_id),
+        )
+        result = await db.execute(stmt)
+        count = result.rowcount
+        results[entity_type] = count if count is not None else 0
+
+        if count and count > 0:
+            logger.info(
+                "Transferred %d %s from user %s to user %s (tenant %s)",
+                count, entity_type, from_user_id, to_user_id, tenant_id,
+            )
+
+    # Log the transfer in audit log
+    await log_audit(
+        db,
+        tenant_id,
+        to_user_id,
+        "transfer_ownership",
+        "ownership",
+        changes={
+            "from_user_id": str(from_user_id),
+            "to_user_id": str(to_user_id),
+            "entity_types": entity_types,
+            "results": results,
+        },
+    )
+
+    return results