backend/local_events_util.py

@@ -36,7 +36,7 @@ def resolve_creator(ev: models.LocalEvent, *, name_cache: Optional[dict] = None)
         if name_cache is not None:
             display = name_cache.get(ev.creator_id)
         if display is None and ev.creator is not None:
-            display = ev.creator.username
+            display = ev.creator.display_name or ev.creator.username
         if display is not None:
             return {"id": ev.creator_id, "display_name": display}
     if ev.creator_name_external:

backend/main.py

@@ -163,6 +163,18 @@ def _migrate():
             logging.info("Migration: added group_visible_calendar_id to user_settings")
         except Exception:
             pass
+        try:
+            conn.execute(text("ALTER TABLE users ADD COLUMN display_name VARCHAR(100)"))
+            conn.commit()
+            logging.info("Migration: added display_name to users")
+        except Exception:
+            pass
+        # Backfill display_name from username for existing rows (only where empty).
+        try:
+            conn.execute(text("UPDATE users SET display_name = username WHERE display_name IS NULL OR display_name = ''"))
+            conn.commit()
+        except Exception:
+            pass
 
 _migrate()
 

backend/models.py

@@ -7,7 +7,10 @@ class User(Base):
     __tablename__ = "users"
 
     id = Column(Integer, primary_key=True, index=True)
+    # Login name: always lowercase, unique, used for authentication.
     username = Column(String(50), unique=True, nullable=False)
+    # Human-facing name with original casing; editable. Falls back to username.
+    display_name = Column(String(100), nullable=True)
     email = Column(String(100), unique=True, nullable=True)
     password_hash = Column(String(255), nullable=False)
     is_admin = Column(Boolean, default=False)
@@ -35,9 +38,9 @@ class User(Base):
     )
 
     @property
-    def display_name(self) -> str:
+    def display(self) -> str:
-        """No dedicated display-name column exists — fall back to the username."""
+        """The name to show users: display_name if set, else the login name."""
-        return self.username
+        return self.display_name or self.username
 
 
 class CalDAVAccount(Base):

backend/routers/auth_router.py

@@ -32,7 +32,12 @@ class LoginRequest(BaseModel):
 
 
 def _user_dict(user: models.User) -> dict:
-    return {"id": user.id, "username": user.username, "is_admin": user.is_admin}
+    return {
+        "id": user.id,
+        "username": user.username,
+        "display_name": user.display_name or user.username,
+        "is_admin": user.is_admin,
+    }
 
 
 @router.get("/setup-required")
@@ -46,6 +51,7 @@ def setup(req: SetupRequest, db: Session = Depends(get_db)):
         raise HTTPException(400, "Setup already completed")
     user = models.User(
         username=req.username.lower(),
+        display_name=req.username.strip(),  # keep the original casing for display
         email=req.email,
         password_hash=get_password_hash(req.password),
         is_admin=True,
@@ -113,6 +119,7 @@ def me(current_user: models.User = Depends(get_current_user)):
     return {
         "id": current_user.id,
         "username": current_user.username,
+        "display_name": current_user.display_name or current_user.username,
         "email": current_user.email,
         "is_admin": current_user.is_admin,
         "has_avatar": current_user.avatar_filename is not None,

backend/routers/caldav_router.py

@@ -334,7 +334,7 @@ def get_events(
         )
         .all()
     ) if readable_ids else []
-    name_cache = {u.id: u.username for u in db.query(models.User).all()}
+    name_cache = {u.id: (u.display_name or u.username) for u in db.query(models.User).all()}
     for local_cal in local_calendars:
         local_events = (
             db.query(models.LocalEvent)

backend/routers/groups_router.py

@@ -149,7 +149,7 @@ def _group_detail(db: Session, group: models.Group, current_user: models.User) -
         u = db.query(models.User).filter(models.User.id == m.user_id).first()
         member_dicts.append({
             "id": m.user_id,
-            "display_name": u.username if u else None,
+            "display_name": (u.display_name or u.username) if u else None,
             "role": m.role,
         })
     return {
@@ -264,7 +264,7 @@ def combined_events(
         end_dt = end_dt.replace(tzinfo=timezone.utc)
 
     members = db.query(models.GroupMember).filter(models.GroupMember.group_id == group_id).all()
-    name_cache = {u.id: u.username for u in db.query(models.User).all()}
+    name_cache = {u.id: (u.display_name or u.username) for u in db.query(models.User).all()}
     visibility_cache: dict[int, str] = {}
 
     def visibility_for(user_id: int) -> str:

backend/routers/local_router.py

@@ -134,7 +134,7 @@ def list_calendars(
         owner = db.query(models.User).filter(models.User.id == cal.user_id).first()
         d = _cal_dict(
             cal, owned=False,
-            shared_by=owner.username if owner else None,
+            shared_by=(owner.display_name or owner.username) if owner else None,
             permission=share.permission,
         )
         if cal.id in group_cal_map:
@@ -330,7 +330,7 @@ def list_shares(
         u = db.query(models.User).filter(models.User.id == s.user_id).first()
         out.append({
             "user_id": s.user_id,
-            "display_name": u.username if u else None,
+            "display_name": (u.display_name or u.username) if u else None,
             "permission": s.permission,
             "created_at": s.created_at,
         })
@@ -501,7 +501,7 @@ def export_calendar(
         .all()
     )
     # Resolve creator display names for ORGANIZER.
-    name_cache = {u.id: u.username for u in db.query(models.User).all()}
+    name_cache = {u.id: (u.display_name or u.username) for u in db.query(models.User).all()}
     ics = ical_io.build_ics(cal, events, name_cache=name_cache)
     safe_name = "".join(c for c in cal.name if c.isalnum() or c in (" ", "-", "_")).strip() or "calendar"
     return Response(

backend/routers/profile_router.py

@@ -11,8 +11,10 @@ from PIL import Image
 from pydantic import BaseModel
 from sqlalchemy.orm import Session
 
+from sqlalchemy import func
+
 import models
-from auth import get_current_user, get_password_hash, verify_password
+from auth import create_access_token, get_current_user, get_password_hash, verify_password
 from database import DATA_DIR, get_db
 
 router = APIRouter()
@@ -26,6 +28,8 @@ ALLOWED_TYPES = {"image/jpeg", "image/png", "image/webp"}
 # ── Schemas ───────────────────────────────────────────────
 class ProfileUpdate(BaseModel):
     email: Optional[str] = None
+    display_name: Optional[str] = None
+    username: Optional[str] = None  # login name (stored lowercase)
 
 
 class PasswordChange(BaseModel):
@@ -47,6 +51,7 @@ def get_profile(current_user: models.User = Depends(get_current_user)):
     return {
         "id": current_user.id,
         "username": current_user.username,
+        "display_name": current_user.display_name or current_user.username,
         "email": current_user.email,
         "is_admin": current_user.is_admin,
         "has_avatar": current_user.avatar_filename is not None,
@@ -60,10 +65,33 @@ def update_profile(
     db: Session = Depends(get_db),
     current_user: models.User = Depends(get_current_user),
 ):
+    result = {"ok": True}
     if data.email is not None:
         current_user.email = data.email or None
+    if data.display_name is not None:
+        dn = data.display_name.strip()
+        current_user.display_name = dn or current_user.username
+    if data.username is not None:
+        new_login = data.username.strip().lower()
+        if not new_login:
+            raise HTTPException(422, "Login name cannot be empty")
+        if new_login != current_user.username:
+            taken = (
+                db.query(models.User)
+                .filter(func.lower(models.User.username) == new_login,
+                        models.User.id != current_user.id)
+                .first()
+            )
+            if taken:
+                raise HTTPException(400, "Username already taken")
+            current_user.username = new_login
             db.commit()
-    return {"ok": True}
+            # The JWT 'sub' is the login name — renaming it invalidates the old
+            # token, so hand back a fresh one for the client to store.
+            result["access_token"] = create_access_token({"sub": new_login})
+            return result
+    db.commit()
+    return result
 
 
 # ── Avatar ────────────────────────────────────────────────

backend/routers/users_router.py

@@ -24,7 +24,13 @@ class ChangePasswordRequest(BaseModel):
 
 
 def _user_dict(u: models.User) -> dict:
-    return {"id": u.id, "username": u.username, "email": u.email, "is_admin": u.is_admin}
+    return {
+        "id": u.id,
+        "username": u.username,
+        "display_name": u.display_name or u.username,
+        "email": u.email,
+        "is_admin": u.is_admin,
+    }
 
 
 @router.get("/")
@@ -51,7 +57,7 @@ def user_directory(
         .order_by(models.User.username)
         .all()
     )
-    return [{"id": u.id, "display_name": u.username} for u in users]
+    return [{"id": u.id, "display_name": u.display_name or u.username} for u in users]
 
 
 @router.post("/")
@@ -64,6 +70,7 @@ def create_user(
         raise HTTPException(400, "Username already taken")
     user = models.User(
         username=req.username.lower(),
+        display_name=req.username.strip(),  # keep the original casing for display
         email=req.email,
         password_hash=get_password_hash(req.password),
         is_admin=req.is_admin,

backend/tests/test_collaboration.py

@@ -225,6 +225,37 @@ def test_member_calendar_hidden_until_designated(client):
     assert any(e["title"] == "Bobs Termin" for e in seen2)
 
 
+def test_display_name_case_preserved_and_login_case_insensitive(client):
+    # Setup with mixed-case name: login name lowercased, display name kept.
+    r = client.post("/api/auth/setup", json={"username": "Guido", "password": "pw"})
+    assert r.status_code == 200, r.text
+    user = r.json()["user"]
+    assert user["username"] == "guido"
+    assert user["display_name"] == "Guido"
+
+    # Login is case-insensitive (typing the display name "GUIDO" works).
+    r2 = client.post("/api/auth/login", json={"username": "GUIDO", "password": "pw"})
+    assert r2.status_code == 200, r2.text
+    tok = r2.json()["access_token"]
+
+    # /me reflects the cased display name.
+    me = client.get("/api/auth/me", headers=auth(tok)).json()
+    assert me["display_name"] == "Guido" and me["username"] == "guido"
+
+
+def test_rename_login_name_returns_new_token(client):
+    admin = register_admin(client, "alice")
+    # Change display name (no token change).
+    r = client.put("/api/profile/", headers=auth(admin), json={"display_name": "Alice W."})
+    assert r.status_code == 200 and "access_token" not in r.json()
+    # Change login name -> fresh token, references survive (id is stable).
+    r2 = client.put("/api/profile/", headers=auth(admin), json={"username": "alice2"})
+    assert r2.status_code == 200 and r2.json().get("access_token")
+    new_tok = r2.json()["access_token"]
+    me = client.get("/api/auth/me", headers=auth(new_tok)).json()
+    assert me["username"] == "alice2" and me["display_name"] == "Alice W."
+
+
 def test_private_visibility_validation(client):
     admin = register_admin(client)
     r = client.put("/api/settings/", headers=auth(admin), json={"private_event_visibility": "bogus"})