fix: persist top/left/right connection-point counts (issue #243)

The backend only stored bottom_handles, so top/left/right_handles were dropped
on canvas save and reset to defaults on reload — a left/right snappoint would
vanish after reload.

- models.py: add top_handles (default 1), left_handles (0), right_handles (0)
- database.py: ALTER TABLE migrations for the three columns
- schemas: add fields to NodeBase, NodeUpdate, and the canvas-save node schema
- tests: save+reload round-trip and default-fallback coverage

ha-relevant: no

backend/app/db/database.py

@@ -99,6 +99,12 @@ async def init_db() -> None:
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN height REAL")
         with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN bottom_handles INTEGER NOT NULL DEFAULT 1")
+        with suppress(OperationalError):
+            await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN top_handles INTEGER NOT NULL DEFAULT 1")
+        with suppress(OperationalError):
+            await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN left_handles INTEGER NOT NULL DEFAULT 0")
+        with suppress(OperationalError):
+            await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN right_handles INTEGER NOT NULL DEFAULT 0")
         with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE pending_devices ADD COLUMN discovery_source TEXT")
         with suppress(OperationalError):

backend/app/db/models.py

@@ -59,6 +59,9 @@ class Node(Base):
     width: Mapped[float | None] = mapped_column(Float, nullable=True)
     height: Mapped[float | None] = mapped_column(Float, nullable=True)
     bottom_handles: Mapped[int] = mapped_column(Integer, default=1)
+    top_handles: Mapped[int] = mapped_column(Integer, default=1)
+    left_handles: Mapped[int] = mapped_column(Integer, default=0)
+    right_handles: Mapped[int] = mapped_column(Integer, default=0)
     ieee_address: Mapped[str | None] = mapped_column(String, index=True, nullable=True)
     last_seen: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
     last_scan: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))

backend/app/schemas/canvas.py

@@ -34,6 +34,9 @@ class NodeSave(BaseModel):
     width: float | None = None
     height: float | None = None
     bottom_handles: int = 1
+    top_handles: int = 1
+    left_handles: int = 0
+    right_handles: int = 0
     pos_x: float = 0
     pos_y: float = 0
 

backend/app/schemas/nodes.py

@@ -32,6 +32,9 @@ class NodeBase(BaseModel):
     width: float | None = None
     height: float | None = None
     bottom_handles: int = 1
+    top_handles: int = 1
+    left_handles: int = 0
+    right_handles: int = 0
 
 
 class NodeCreate(NodeBase):
@@ -66,6 +69,9 @@ class NodeUpdate(BaseModel):
     width: float | None = None
     height: float | None = None
     bottom_handles: int | None = None
+    top_handles: int | None = None
+    left_handles: int | None = None
+    right_handles: int | None = None
 
 
 class NodeResponse(NodeBase):