fix: enforce run ownership on all mutation endpoints

Add require_run_owner helper in auth.py that enforces ownership on
mutation endpoints. Unowned (legacy) runs are now read-only.

Applied ownership checks to:
- All 4 encounter mutation endpoints
- Both boss result mutation endpoints
- Run update/delete endpoints
- All 5 genlocke mutation endpoints (via first leg's run owner)

Also sets owner_id on run creation in genlockes.py (create_genlocke,
advance_leg) and adds 22 comprehensive ownership enforcement tests.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/src/app/api/genlockes.py

@@ -1,3 +1,5 @@
+from uuid import UUID
+
 from fastapi import APIRouter, Depends, HTTPException
 from pydantic import BaseModel
 from sqlalchemy import delete as sa_delete
@@ -6,7 +8,7 @@ from sqlalchemy import update as sa_update
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import selectinload
 
-from app.core.auth import AuthUser, require_auth
+from app.core.auth import AuthUser, require_auth, require_run_owner
 from app.core.database import get_session
 from app.models.encounter import Encounter
 from app.models.evolution import Evolution
@@ -16,6 +18,7 @@ from app.models.genlocke_transfer import GenlockeTransfer
 from app.models.nuzlocke_run import NuzlockeRun
 from app.models.pokemon import Pokemon
 from app.models.route import Route
+from app.models.user import User
 from app.schemas.genlocke import (
     AddLegRequest,
     AdvanceLegRequest,
@@ -41,6 +44,38 @@ from app.services.families import build_families, resolve_base_form
 router = APIRouter()
 
 
+async def _check_genlocke_owner(
+    genlocke_id: int,
+    user: AuthUser,
+    session: AsyncSession,
+) -> None:
+    """
+    Verify user owns the genlocke via the first leg's run.
+    Raises 404 if the genlocke doesn't exist.
+    Raises 403 if the first leg has a run with a different owner.
+    Raises 403 if the first leg has an unowned run (read-only legacy data).
+    """
+    # First check if genlocke exists
+    genlocke = await session.get(Genlocke, genlocke_id)
+    if genlocke is None:
+        raise HTTPException(status_code=404, detail="Genlocke not found")
+
+    leg_result = await session.execute(
+        select(GenlockeLeg)
+        .where(GenlockeLeg.genlocke_id == genlocke_id, GenlockeLeg.leg_order == 1)
+        .options(selectinload(GenlockeLeg.run))
+    )
+    first_leg = leg_result.scalar_one_or_none()
+
+    if first_leg is None or first_leg.run is None:
+        raise HTTPException(
+            status_code=403,
+            detail="Cannot modify genlocke: no run found for first leg",
+        )
+
+    require_run_owner(first_leg.run, user)
+
+
 @router.get("", response_model=list[GenlockeListItem])
 async def list_genlockes(session: AsyncSession = Depends(get_session)):
     result = await session.execute(
@@ -440,7 +475,7 @@ async def get_genlocke_lineages(
 async def create_genlocke(
     data: GenlockeCreate,
     session: AsyncSession = Depends(get_session),
-    _user: AuthUser = Depends(require_auth),
+    user: AuthUser = Depends(require_auth),
 ):
     if not data.game_ids:
         raise HTTPException(status_code=400, detail="At least one game is required")
@@ -455,6 +490,13 @@ async def create_genlocke(
     if missing:
         raise HTTPException(status_code=404, detail=f"Games not found: {missing}")
 
+    # Ensure user exists in local DB
+    user_id = UUID(user.id)
+    db_user = await session.get(User, user_id)
+    if db_user is None:
+        db_user = User(id=user_id, email=user.email or "")
+        session.add(db_user)
+
     # Create genlocke
     genlocke = Genlocke(
         name=data.name.strip(),
@@ -481,6 +523,7 @@ async def create_genlocke(
     first_game = found_games[data.game_ids[0]]
     first_run = NuzlockeRun(
         game_id=first_game.id,
+        owner_id=user_id,
         name=f"{data.name.strip()} \u2014 Leg 1",
         status="active",
         rules=data.nuzlocke_rules,
@@ -571,8 +614,10 @@ async def advance_leg(
     leg_order: int,
     data: AdvanceLegRequest | None = None,
     session: AsyncSession = Depends(get_session),
-    _user: AuthUser = Depends(require_auth),
+    user: AuthUser = Depends(require_auth),
 ):
+    await _check_genlocke_owner(genlocke_id, user, session)
+
     # Load genlocke with legs
     result = await session.execute(
         select(Genlocke)
@@ -653,9 +698,10 @@ async def advance_leg(
         else:
             current_leg.retired_pokemon_ids = []
 
-    # Create a new run for the next leg
+    # Create a new run for the next leg, preserving owner from current run
     new_run = NuzlockeRun(
         game_id=next_leg.game_id,
+        owner_id=current_run.owner_id,
         name=f"{genlocke.name} \u2014 Leg {next_leg.leg_order}",
         status="active",
         rules=genlocke.nuzlocke_rules,
@@ -826,8 +872,10 @@ async def update_genlocke(
     genlocke_id: int,
     data: GenlockeUpdate,
     session: AsyncSession = Depends(get_session),
-    _user: AuthUser = Depends(require_auth),
+    user: AuthUser = Depends(require_auth),
 ):
+    await _check_genlocke_owner(genlocke_id, user, session)
+
     result = await session.execute(
         select(Genlocke)
         .where(Genlocke.id == genlocke_id)
@@ -863,8 +911,10 @@ async def update_genlocke(
 async def delete_genlocke(
     genlocke_id: int,
     session: AsyncSession = Depends(get_session),
-    _user: AuthUser = Depends(require_auth),
+    user: AuthUser = Depends(require_auth),
 ):
+    await _check_genlocke_owner(genlocke_id, user, session)
+
     genlocke = await session.get(Genlocke, genlocke_id)
     if genlocke is None:
         raise HTTPException(status_code=404, detail="Genlocke not found")
@@ -895,8 +945,10 @@ async def add_leg(
     genlocke_id: int,
     data: AddLegRequest,
     session: AsyncSession = Depends(get_session),
-    _user: AuthUser = Depends(require_auth),
+    user: AuthUser = Depends(require_auth),
 ):
+    await _check_genlocke_owner(genlocke_id, user, session)
+
     genlocke = await session.get(Genlocke, genlocke_id)
     if genlocke is None:
         raise HTTPException(status_code=404, detail="Genlocke not found")
@@ -938,8 +990,10 @@ async def remove_leg(
     genlocke_id: int,
     leg_id: int,
     session: AsyncSession = Depends(get_session),
-    _user: AuthUser = Depends(require_auth),
+    user: AuthUser = Depends(require_auth),
 ):
+    await _check_genlocke_owner(genlocke_id, user, session)
+
     result = await session.execute(
         select(GenlockeLeg).where(
             GenlockeLeg.id == leg_id,