feat(api): add optimistic locking to LLM model config updates

- Include `version` field in all LLM model config response schemas
- Add `expected_version` parameter to update endpoints for optimistic locking
- Handle concurrent modification errors with HTTP 409 Conflict status
- Update both user and group config endpoints consistently

gns3server/db/models/llm_model_configs.py

@@ -15,7 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-from sqlalchemy import Column, Boolean, ForeignKey, CheckConstraint, UniqueConstraint, Index
+from sqlalchemy import Column, Boolean, ForeignKey, CheckConstraint, UniqueConstraint, Index, Integer
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import relationship
 
@@ -39,6 +39,7 @@ class LLMModelConfig(BaseTable):
     user_id = Column(GUID, ForeignKey("users.user_id", ondelete="CASCADE"), nullable=True)
     group_id = Column(GUID, ForeignKey("user_groups.user_group_id", ondelete="CASCADE"), nullable=True)
     is_default = Column(Boolean, default=False, nullable=False)
+    version = Column(Integer, default=0, nullable=False)  # Optimistic locking version
 
     # Relationships
     user = relationship("User", backref="llm_model_configs")
@@ -69,4 +70,4 @@ class LLMModelConfig(BaseTable):
     def __repr__(self):
         config_name = self.config.get("name", "unnamed") if self.config else "unnamed"
         owner = f"user_{self.user_id}" if self.user_id else f"group_{self.group_id}"
-        return f"<LLMModelConfig {config_name} for {owner} (default={self.is_default})>"
+        return f"<LLMModelConfig {config_name} for {owner} (default={self.is_default}, version={self.version})>"

gns3server/db/repositories/llm_model_configs.py

@@ -96,9 +96,19 @@ class LLMModelConfigsRepository(BaseRepository):
         self,
         config_id: UUID,
         user_id: UUID,
-        updates: Dict[str, Any]
+        updates: Dict[str, Any],
+        expected_version: Optional[int] = None
     ) -> Optional[models.LLMModelConfig]:
-        """Update a user's LLM model configuration."""
+        """
+        Update a user's LLM model configuration.
+        Uses optimistic locking to prevent concurrent modifications.
+
+        :param config_id: Configuration ID
+        :param user_id: User ID
+        :param updates: Dictionary of fields to update
+        :param expected_version: Expected version for optimistic locking (raises error if mismatch)
+        :raises ValueError: If version mismatch (concurrent modification)
+        """
         query = select(models.LLMModelConfig).where(
             and_(
                 models.LLMModelConfig.config_id == config_id,
@@ -111,6 +121,13 @@ class LLMModelConfigsRepository(BaseRepository):
         if not db_config:
             return None
 
+        # Check optimistic lock if expected_version is provided
+        if expected_version is not None and db_config.version != expected_version:
+            raise ValueError(
+                f"Concurrent modification detected. Expected version {expected_version}, "
+                f"but current version is {db_config.version}. Please retry."
+            )
+
         # Encrypt API key if present in updates
         from gns3server.utils.encryption import encrypt
         updates_copy = updates.copy()
@@ -130,6 +147,8 @@ class LLMModelConfigsRepository(BaseRepository):
                 current_config[key] = value
 
         db_config.config = current_config
+        # Increment version for optimistic locking
+        db_config.version = db_config.version + 1
         await self._db_session.commit()
         await self._db_session.refresh(db_config)
         return db_config
@@ -234,9 +253,19 @@ class LLMModelConfigsRepository(BaseRepository):
         self,
         config_id: UUID,
         group_id: UUID,
-        updates: Dict[str, Any]
+        updates: Dict[str, Any],
+        expected_version: Optional[int] = None
     ) -> Optional[models.LLMModelConfig]:
-        """Update a group's LLM model configuration."""
+        """
+        Update a group's LLM model configuration.
+        Uses optimistic locking to prevent concurrent modifications.
+
+        :param config_id: Configuration ID
+        :param group_id: Group ID
+        :param updates: Dictionary of fields to update
+        :param expected_version: Expected version for optimistic locking (raises error if mismatch)
+        :raises ValueError: If version mismatch (concurrent modification)
+        """
         query = select(models.LLMModelConfig).where(
             and_(
                 models.LLMModelConfig.config_id == config_id,
@@ -249,6 +278,13 @@ class LLMModelConfigsRepository(BaseRepository):
         if not db_config:
             return None
 
+        # Check optimistic lock if expected_version is provided
+        if expected_version is not None and db_config.version != expected_version:
+            raise ValueError(
+                f"Concurrent modification detected. Expected version {expected_version}, "
+                f"but current version is {db_config.version}. Please retry."
+            )
+
         # Encrypt API key if present in updates
         from gns3server.utils.encryption import encrypt
         updates_copy = updates.copy()
@@ -268,6 +304,8 @@ class LLMModelConfigsRepository(BaseRepository):
                 current_config[key] = value
 
         db_config.config = current_config
+        # Increment version for optimistic locking
+        db_config.version = db_config.version + 1
         await self._db_session.commit()
         await self._db_session.refresh(db_config)
         return db_config