diff --git a/zeeguu/core/model/__init__.py b/zeeguu/core/model/__init__.py
index e3868ba8..f23ef697 100644
--- a/zeeguu/core/model/__init__.py
+++ b/zeeguu/core/model/__init__.py
@@ -44,6 +44,7 @@
 from .user_language import UserLanguage
 
 from .user_article import UserArticle
+from .starred_article import StarredArticle
 from .article_difficulty_feedback import ArticleDifficultyFeedback
 
 from .feed import Feed
diff --git a/zeeguu/core/model/context_type.py b/zeeguu/core/model/context_type.py
index 3519fafe..530f6967 100644
--- a/zeeguu/core/model/context_type.py
+++ b/zeeguu/core/model/context_type.py
@@ -37,7 +37,11 @@ class ContextType(db.Model):
         EXAMPLE_SENTENCE,
     ]
 
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # Named for the index production already has, so nobody generates a second one.
+    __table_args__ = (
+        db.UniqueConstraint("type", name="unique_context_type"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = db.Column(db.Integer, primary_key=True)
     type = db.Column(db.String(45))
diff --git a/zeeguu/core/model/level_adapted_article_text.py b/zeeguu/core/model/level_adapted_article_text.py
index 386856a6..fefa4fac 100644
--- a/zeeguu/core/model/level_adapted_article_text.py
+++ b/zeeguu/core/model/level_adapted_article_text.py
@@ -38,7 +38,13 @@ class LevelAdaptedArticleText(db.Model):
     added — renaming it would have churned the two context joins and every FK.)
     """
 
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # Named for the index production already has (added by
+    # tools/migrations/26-08-12--add_article_level_summary.sql), so nobody
+    # generates a second one.
+    __table_args__ = (
+        db.UniqueConstraint("article_id", "cefr_level", name="uq_article_level"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = db.Column(db.Integer, primary_key=True)
 
diff --git a/zeeguu/core/model/new_text.py b/zeeguu/core/model/new_text.py
index 307562f2..9db8c4b5 100644
--- a/zeeguu/core/model/new_text.py
+++ b/zeeguu/core/model/new_text.py
@@ -8,7 +8,12 @@
 
 
 class NewText(db.Model):
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # HASH_INDEX is production's own name for this index; keep it so nobody
+    # generates a second one.
+    __table_args__ = (
+        db.UniqueConstraint("content_hash", name="HASH_INDEX"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = db.Column(db.Integer, primary_key=True)
 
diff --git a/zeeguu/core/model/source_text.py b/zeeguu/core/model/source_text.py
index ab64c8fe..39753ce9 100644
--- a/zeeguu/core/model/source_text.py
+++ b/zeeguu/core/model/source_text.py
@@ -11,7 +11,12 @@
 
 
 class SourceText(db.Model):
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # HASH_INDEX is production's own name for this index; keep it so nobody
+    # generates a second one. It is what find_or_create's hash lookup relies on.
+    __table_args__ = (
+        db.UniqueConstraint("content_hash", name="HASH_INDEX"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = db.Column(db.Integer, primary_key=True)
     # this mapes to TEXT in the mysql which can hold about 15K words
diff --git a/zeeguu/core/model/starred_article.py b/zeeguu/core/model/starred_article.py
index 62706a7e..9ad5c7ad 100644
--- a/zeeguu/core/model/starred_article.py
+++ b/zeeguu/core/model/starred_article.py
@@ -25,7 +25,15 @@ class StarredArticle(db.Model):
 
     """
 
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # url_id is production's own name for this index; keep it so nobody
+    # generates a second one. This was a bare UniqueConstraint further down the
+    # class body -- which does attach to the table -- but the module was missing
+    # from zeeguu.core.model's imports, so the table never reached
+    # db.create_all() and the test database had no starred_article at all.
+    __table_args__ = (
+        UniqueConstraint("url_id", "user_id", name="url_id"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = Column(Integer, primary_key=True)
 
@@ -43,9 +51,6 @@ class StarredArticle(db.Model):
     # Useful for ordering past read articles
     starred_date = Column(DateTime)
 
-    # Together an url_id and user_id identify an article
-    UniqueConstraint(url_id, user_id)
-
     def __init__(self, user, url, _title: str, language):
         self.user = user
         self.url = url
diff --git a/zeeguu/core/model/teacher_cohort_map.py b/zeeguu/core/model/teacher_cohort_map.py
index b0b5fa59..22d6c5b4 100644
--- a/zeeguu/core/model/teacher_cohort_map.py
+++ b/zeeguu/core/model/teacher_cohort_map.py
@@ -7,7 +7,12 @@
 
 
 class TeacherCohortMap(db.Model):
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # user_id_2 is production's own (auto-generated) name for this index; keep it
+    # so nobody generates a second one under a tidier name.
+    __table_args__ = (
+        db.UniqueConstraint("user_id", "cohort_id", name="user_id_2"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = Column(Integer, primary_key=True)
 
diff --git a/zeeguu/core/model/text.py b/zeeguu/core/model/text.py
index bb41e5df..6bafc0b6 100644
--- a/zeeguu/core/model/text.py
+++ b/zeeguu/core/model/text.py
@@ -13,7 +13,11 @@
 
 
 class Text(db.Model):
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # Named for the index production already has, so nobody generates a second one.
+    __table_args__ = (
+        db.UniqueConstraint("content_hash", name="content_hash"),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = db.Column(db.Integer, primary_key=True)
 
diff --git a/zeeguu/core/model/user_avatar.py b/zeeguu/core/model/user_avatar.py
index 7b741415..357c31c7 100644
--- a/zeeguu/core/model/user_avatar.py
+++ b/zeeguu/core/model/user_avatar.py
@@ -7,6 +7,11 @@
 
 class UserAvatar(db.Model):
     __tablename__ = "user_avatar"
+    # One avatar per user. Named for the index production already has
+    # (tools/migrations/26-03-13--add_user_avatar.sql), so nobody generates a
+    # second one -- and so update_or_create's find-then-insert cannot quietly
+    # produce two avatars for a user in the test database.
+    __table_args__ = (db.UniqueConstraint("user_id", name="user_id"),)
 
     id = db.Column(db.Integer, primary_key=True)
     user_id = db.Column(db.Integer, db.ForeignKey("user.id"), nullable=False)
diff --git a/zeeguu/core/model/user_onboarding_message.py b/zeeguu/core/model/user_onboarding_message.py
index 4e0b6f37..0734696e 100644
--- a/zeeguu/core/model/user_onboarding_message.py
+++ b/zeeguu/core/model/user_onboarding_message.py
@@ -13,7 +13,15 @@ class UserOnboardingMessage(db.Model):
     when that dismissal was performed. If not, this field will be null
 
     """
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # Named for the index production already has, so nobody generates a second one.
+    __table_args__ = (
+        db.UniqueConstraint(
+            "user_id",
+            "onboarding_message_id",
+            name="ux_user_onboarding_message_user_message",
+        ),
+        {"mysql_collate": "utf8_bin"},
+    )
 
     id = db.Column(db.Integer, primary_key=True)
 
diff --git a/zeeguu/core/model/user_word.py b/zeeguu/core/model/user_word.py
index 62298803..63636669 100644
--- a/zeeguu/core/model/user_word.py
+++ b/zeeguu/core/model/user_word.py
@@ -14,7 +14,15 @@
 
 
 class UserWord(db.Model):
-    __table_args__ = {"mysql_collate": "utf8_bin"}
+    # Named for the index production already has (added by
+    # tools/migrations/25-05-24--adding_the_user_word_table.sql), so nobody
+    # generates a second one under a different name. Declared here so the
+    # SQLite test database refuses the duplicate pairs MySQL refuses -- without
+    # it, a test exercising the find_or_create race passes against unfixed code.
+    __table_args__ = (
+        db.UniqueConstraint("user_id", "meaning_id", name="unique_user_word"),
+        {"mysql_collate": "utf8_bin"},
+    )
     __tablename__ = "user_word"  # Explicitly set table name for migration
 
     id = db.Column(db.Integer, primary_key=True)