feat: implement t-604 keyword prompt moderation

apps/moderation/models.py

@@ -0,0 +1,51 @@
+from __future__ import annotations
+
+from django.core.exceptions import ValidationError
+from django.db import models
+
+from .normalization import normalize_text
+
+
+class SensitiveWord(models.Model):
+    class Action(models.TextChoices):
+        BLOCK = "block", "拦截"
+
+    word = models.CharField("敏感词", max_length=255)
+    normalized_word = models.CharField("归一化敏感词", max_length=255, editable=False)
+    category = models.CharField("分类", max_length=64, default="custom", blank=True)
+    action = models.CharField("动作", max_length=16, choices=Action.choices, default=Action.BLOCK)
+    is_active = models.BooleanField("启用", default=True)
+    created_at = models.DateTimeField("创建时间", auto_now_add=True)
+    updated_at = models.DateTimeField("更新时间", auto_now=True)
+
+    class Meta:
+        db_table = "sensitive_word"
+        verbose_name = "敏感词"
+        verbose_name_plural = "敏感词"
+        ordering = ("category", "word")
+        constraints = [
+            models.UniqueConstraint(
+                fields=("category", "normalized_word"),
+                name="unique_sensitive_word_per_category",
+            ),
+        ]
+        indexes = [
+            models.Index(fields=("is_active", "category"), name="sw_active_category_idx"),
+            models.Index(fields=("normalized_word",), name="sw_normalized_word_idx"),
+        ]
+
+    def __str__(self) -> str:
+        return self.word
+
+    def clean(self) -> None:
+        self.word = (self.word or "").strip()
+        self.category = (self.category or "custom").strip() or "custom"
+        self.normalized_word = normalize_text(self.word)
+        if not self.normalized_word:
+            raise ValidationError({"word": "敏感词归一化后不能为空"})
+        if self.action != self.Action.BLOCK:
+            raise ValidationError({"action": "MVP 只支持 block 动作"})
+
+    def save(self, *args, **kwargs) -> None:
+        self.full_clean()
+        super().save(*args, **kwargs)