feat: audit ai config changes

apps/ai/models.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.db import models
 
@@ -133,3 +134,41 @@ class ModelAlias(models.Model):
     def save(self, *args, **kwargs) -> None:
         self.full_clean()
         super().save(*args, **kwargs)
+
+
+class AiConfigAuditLog(models.Model):
+    class TargetType(models.TextChoices):
+        AI_MODEL = "ai_model", "AI model"
+        MODEL_ALIAS = "model_alias", "Model alias"
+
+    class Action(models.TextChoices):
+        CREATE = "create", "Create"
+        UPDATE = "update", "Update"
+        DELETE = "delete", "Delete"
+
+    actor = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        null=True,
+        blank=True,
+        on_delete=models.SET_NULL,
+        related_name="+",
+    )
+    action = models.CharField(max_length=16, choices=Action.choices)
+    target_type = models.CharField(max_length=32, choices=TargetType.choices)
+    target_id = models.PositiveBigIntegerField(null=True, blank=True)
+    target_repr = models.CharField(max_length=255)
+    changed_fields = models.JSONField(default=list, blank=True)
+    changes = models.JSONField(default=dict, blank=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        db_table = "ai_config_audit_log"
+        ordering = ("-created_at", "-id")
+        indexes = [
+            models.Index(fields=("target_type", "target_id")),
+            models.Index(fields=("action", "created_at")),
+            models.Index(fields=("actor", "created_at")),
+        ]
+
+    def __str__(self) -> str:
+        return f"{self.created_at:%Y-%m-%d %H:%M:%S} {self.action} {self.target_repr}"