fix: persist edge animation mode (None/Snake/Flow) end-to-end

- canvasStore.onConnect: include animated in edge data object (was silently dropped)
- Backend schemas: normalize animated bool/int to string ('none'/'snake'/'flow') via field_validator
- ORM model: change animated column from Boolean to String
- DB migration: convert existing 0/1 boolean rows to 'none'/'snake' strings

backend/app/db/database.py

@@ -2,6 +2,7 @@ from collections.abc import AsyncGenerator
 from contextlib import suppress
 from pathlib import Path
 
+from sqlalchemy.exc import OperationalError
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 from sqlalchemy.orm import DeclarativeBase
 
@@ -26,36 +27,42 @@ async def init_db() -> None:
     async with engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
         # Add columns introduced after initial schema (idempotent)
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN container_mode BOOLEAN NOT NULL DEFAULT 0")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN custom_colors JSON")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN custom_color TEXT")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN path_style TEXT")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN custom_icon TEXT")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN source_handle TEXT")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN target_handle TEXT")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN animated BOOLEAN NOT NULL DEFAULT 0")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN cpu_count INTEGER")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN cpu_model TEXT")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN ram_gb REAL")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN disk_gb REAL")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN show_hardware BOOLEAN NOT NULL DEFAULT 0")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN width REAL")
-        with suppress(Exception):
+        with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN height REAL")
+        # Migrate animated column from boolean (0/1) to string ('none'/'snake')
+        with suppress(OperationalError):
+            await conn.exec_driver_sql("UPDATE edges SET animated = 'snake' WHERE animated = '1' OR animated = 1")
+        with suppress(OperationalError):
+            sql = "UPDATE edges SET animated = 'none' WHERE animated = '0' OR animated = 0 OR animated IS NULL"
+            await conn.exec_driver_sql(sql)
 
 
 async def get_db() -> AsyncGenerator[AsyncSession, None]:

backend/app/db/models.py

@@ -33,7 +33,7 @@ class Node(Base):
     notes: Mapped[str | None] = mapped_column(Text)
     pos_x: Mapped[float] = mapped_column(Float, default=0)
     pos_y: Mapped[float] = mapped_column(Float, default=0)
-    parent_id: Mapped[str | None] = mapped_column(String, ForeignKey("nodes.id"))
+    parent_id: Mapped[str | None] = mapped_column(String, ForeignKey("nodes.id", ondelete="CASCADE"))
     container_mode: Mapped[bool] = mapped_column(Boolean, default=False)
     custom_colors: Mapped[dict[str, Any] | None] = mapped_column(JSON, nullable=True)
     custom_icon: Mapped[str | None] = mapped_column(String, nullable=True)
@@ -65,7 +65,7 @@ class Edge(Base):
     speed: Mapped[str | None] = mapped_column(String)
     custom_color: Mapped[str | None] = mapped_column(String)
     path_style: Mapped[str | None] = mapped_column(String)
-    animated: Mapped[bool] = mapped_column(Boolean, default=False)
+    animated: Mapped[str] = mapped_column(String, nullable=False, default='none')
     source_handle: Mapped[str | None] = mapped_column(String)
     target_handle: Mapped[str | None] = mapped_column(String)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now)

backend/app/schemas/canvas.py

@@ -1,9 +1,10 @@
 from typing import Any
 
-from pydantic import BaseModel
+from pydantic import BaseModel, field_validator
 
 from app.schemas.edges import EdgeResponse
 from app.schemas.nodes import NodeResponse
+from app.schemas.utils import normalize_animated
 
 
 class NodeSave(BaseModel):
@@ -44,10 +45,15 @@ class EdgeSave(BaseModel):
     speed: str | None = None
     custom_color: str | None = None
     path_style: str | None = None
-    animated: bool = False
+    animated: str = 'none'
     source_handle: str | None = None
     target_handle: str | None = None
 
+    @field_validator('animated', mode='before')
+    @classmethod
+    def validate_animated(cls, v: object) -> str:
+        return normalize_animated(v)
+
 
 class CanvasSaveRequest(BaseModel):
     nodes: list[NodeSave] = []

backend/app/schemas/edges.py

@@ -1,6 +1,8 @@
 from datetime import datetime
 
-from pydantic import BaseModel
+from pydantic import BaseModel, field_validator
+
+from app.schemas.utils import normalize_animated
 
 
 class EdgeBase(BaseModel):
@@ -12,10 +14,15 @@ class EdgeBase(BaseModel):
     speed: str | None = None
     custom_color: str | None = None
     path_style: str | None = None
-    animated: bool = False
+    animated: str = 'none'
     source_handle: str | None = None
     target_handle: str | None = None
 
+    @field_validator('animated', mode='before')
+    @classmethod
+    def validate_animated(cls, v: object) -> str:
+        return normalize_animated(v)
+
 
 class EdgeCreate(EdgeBase):
     pass
@@ -28,10 +35,17 @@ class EdgeUpdate(BaseModel):
     speed: str | None = None
     custom_color: str | None = None
     path_style: str | None = None
-    animated: bool | None = None
+    animated: str | None = None
     source_handle: str | None = None
     target_handle: str | None = None
 
+    @field_validator('animated', mode='before')
+    @classmethod
+    def validate_animated(cls, v: object) -> str | None:
+        if v is None:
+            return None
+        return normalize_animated(v)
+
 
 class EdgeResponse(EdgeBase):
     id: str

backend/app/schemas/utils.py

@@ -0,0 +1,9 @@
+def normalize_animated(v: object) -> str:
+    """Normalize legacy bool/int animated values to string mode ('none'/'snake'/'flow')."""
+    if v is True or v == 1 or v == '1':
+        return 'snake'
+    if v is False or v == 0 or v == '0' or v is None or v == 'none':
+        return 'none'
+    if v in ('snake', 'flow'):
+        return str(v)
+    return 'none'