Remove unused server_timestamp() from IDatabase

backend/app/database/dependencies.py

@@ -40,7 +40,7 @@ async def create_generation_session(
             generation_id = str(uuid.uuid4())
             db.set(COL_GENERATION_SESSIONS, generation_id, {
                 "status": "pending",
-                "created_at": db.server_timestamp(),
+                "created_at": datetime.now(UTC),
                 **data.dict()
             })
             return {"id": generation_id}

backend/app/database/firestore.py

@@ -234,10 +234,6 @@ def list_subcollection(
             out.append(row)
         return out
 
-    def server_timestamp(self) -> Any:
-        """Get server timestamp sentinel."""
-        return firestore.SERVER_TIMESTAMP
-
     def get_api_key_by_uid(self, key_uid: str) -> Optional[Dict[str, Any]]:
         """Return the api_keys document whose key_uid field matches."""
         results = self.query("api_keys", filters=[("key_uid", "==", key_uid)])

backend/app/database/interface.py

@@ -127,7 +127,6 @@ class IDatabase(ABC):
     - CRUD operations (get, set, update, delete)
     - Queries with filters and ordering
     - Atomic transactions
-    - Server timestamps
     - Array operations
     """
 
@@ -162,7 +161,7 @@ def set(self, collection: str, doc_id: str, data: Dict[str, Any]) -> None:
         Example:
             >>> db.set("generation_sessions", "est-123", {
             ...     "status": "pending",
-            ...     "created_at": db.server_timestamp()
+            ...     "created_at": datetime.now(UTC)
             ... })
         """
         pass
@@ -279,7 +278,7 @@ def run_transaction(self, callback: Callable[[ITransactionContext], T]) -> T:
             ...     # 2. Then perform all writes
             ...     tx.update("workspaces", ws_id, {
             ...         "status": "allocated",
-            ...         "locked_at": db.server_timestamp()
+            ...         "locked_at": datetime.now(UTC)
             ...     })
             ...     
             ...     return ws_id
@@ -322,27 +321,6 @@ def list_subcollection(
         Each returned dict includes ``_id`` with the child document id.
         """
 
-    @abstractmethod
-    def server_timestamp(self) -> Any:
-        """
-        Get a server timestamp value for use in set/update operations.
-
-        When this value is written to the database, it will be replaced with
-        the actual server timestamp. This ensures consistent timestamps across
-        all clients regardless of clock skew.
-
-        Returns:
-            A sentinel value representing server timestamp
-
-        Example:
-            >>> db.set("generation_sessions", "est-123", {
-            ...     "created_at": db.server_timestamp(),
-            ...     "status": "pending"
-            ... })
-        """
-        pass
-
-
     @abstractmethod
     def get_api_key_by_uid(self, key_uid: str) -> Optional[Dict[str, Any]]:
         """

backend/app/database/memory.py

@@ -6,7 +6,6 @@
 """
 
 import threading
-from datetime import UTC, datetime
 from typing import Any, Callable, Dict, List, Optional, TypeVar
 
 from app.database.interface import (
@@ -43,12 +42,6 @@ def _apply_dot_notation_update(doc: Dict[str, Any], key: str, value: Any) -> Non
     target[parts[-1]] = value
 
 
-class _ServerTimestamp:
-    """Sentinel class for server timestamps in memory database."""
-
-    pass
-
-
 class InMemoryTransactionContext(ITransactionContext):
     """Transaction context for in-memory database."""
 
@@ -156,12 +149,10 @@ def _apply_writes(self) -> None:
                 self._data[collection].pop(doc_id, None)
 
     def _process_timestamps(self, data: Dict[str, Any]) -> Dict[str, Any]:
-        """Replace server timestamp sentinels with actual timestamps."""
+        """Deep-copy the payload, recursing into nested maps."""
         result = {}
         for key, value in data.items():
-            if isinstance(value, _ServerTimestamp):
-                result[key] = datetime.now(UTC).replace(tzinfo=None)
-            elif isinstance(value, dict):
+            if isinstance(value, dict):
                 result[key] = self._process_timestamps(value)
             else:
                 result[key] = value
@@ -351,10 +342,6 @@ def list_subcollection(
                     out.append(row)
             return out
 
-    def server_timestamp(self) -> Any:
-        """Get server timestamp sentinel."""
-        return _ServerTimestamp()
-
     def get_api_key_by_uid(self, key_uid: str) -> Optional[Dict[str, Any]]:
         """Return the api_keys document whose key_uid field matches."""
         with self._lock:
@@ -366,12 +353,10 @@ def get_api_key_by_uid(self, key_uid: str) -> Optional[Dict[str, Any]]:
         return None
 
     def _process_timestamps(self, data: Dict[str, Any]) -> Dict[str, Any]:
-        """Replace server timestamp sentinels with actual timestamps."""
+        """Deep-copy the payload, recursing into nested maps."""
         result = {}
         for key, value in data.items():
-            if isinstance(value, _ServerTimestamp):
-                result[key] = datetime.now(UTC).replace(tzinfo=None)
-            elif isinstance(value, dict):
+            if isinstance(value, dict):
                 result[key] = self._process_timestamps(value)
             else:
                 result[key] = value

backend/test/database/test_firestore_db.py

@@ -15,7 +15,6 @@
 
 import os
 import pytest
-from datetime import datetime
 
 from app.database.emulator import EmulatorDatabase
 from app.database.interface import DocumentNotFoundError
@@ -215,31 +214,6 @@ def test_array_union_no_duplicates(self, db):
         assert "vue" in user["tags"]
 
 
-class TestServerTimestamp:
-    """Test server timestamp functionality against Firestore emulator."""
-
-    def test_server_timestamp_on_set(self, db):
-        """Test server timestamp is replaced with actual time."""
-        db.set("users", "user-1", {
-            "name": "Alice",
-            "created_at": db.server_timestamp()
-        })
-
-        user = db.get("users", "user-1")
-        assert "created_at" in user
-        # Firestore returns datetime objects
-        assert isinstance(user["created_at"], datetime)
-
-    def test_server_timestamp_on_update(self, db):
-        """Test server timestamp in update operation."""
-        db.set("users", "user-1", {"name": "Alice"})
-        db.update("users", "user-1", {"updated_at": db.server_timestamp()})
-
-        user = db.get("users", "user-1")
-        assert "updated_at" in user
-        assert isinstance(user["updated_at"], datetime)
-
-
 class TestEmulatorConnection:
     """Test emulator-specific functionality."""
 

backend/test/database/test_memory_db.py

@@ -5,7 +5,6 @@
 """
 
 import pytest
-from datetime import datetime
 from app.database.memory import InMemoryDatabase
 from app.database.interface import DocumentNotFoundError
 
@@ -345,43 +344,6 @@ def test_array_union_nonexistent_doc(self, db):
             db.array_union("users", "nonexistent", "tags", ["python"])
 
 
-class TestServerTimestamp:
-    """Test server timestamp functionality."""
-
-    def test_server_timestamp_on_set(self, db):
-        """Test server timestamp is replaced with actual time."""
-        db.set("users", "user-1", {
-            "name": "Alice",
-            "created_at": db.server_timestamp()
-        })
-
-        user = db.get("users", "user-1")
-        assert "created_at" in user
-        assert isinstance(user["created_at"], datetime)
-
-    def test_server_timestamp_on_update(self, db):
-        """Test server timestamp in update operation."""
-        db.set("users", "user-1", {"name": "Alice"})
-        db.update("users", "user-1", {"updated_at": db.server_timestamp()})
-
-        user = db.get("users", "user-1")
-        assert "updated_at" in user
-        assert isinstance(user["updated_at"], datetime)
-
-    def test_server_timestamp_in_transaction(self, db):
-        """Test server timestamp in transaction."""
-        def create_with_timestamp(tx):
-            tx.set("users", "user-1", {
-                "name": "Alice",
-                "created_at": db.server_timestamp()
-            })
-
-        db.run_transaction(create_with_timestamp)
-
-        user = db.get("users", "user-1")
-        assert isinstance(user["created_at"], datetime)
-
-
 class TestIsolation:
     """Test data isolation and cleanup."""