feat: selectable marker shapes per edge endpoint

Replace the on/off arrowhead toggle with a per-end shape picker. Each end
(start/end) independently selects: none, arrow, arrow-open, circle, diamond,
or square. Markers still recolor live from the resolved stroke color.

Frontend:
- MarkerShape type + edgeMarkers util (normalizeMarker, MARKER_GEOMETRY);
  legacy boolean coerces to 'arrow' on read.
- Per-shape <marker> inner geometry; symmetric shapes use fixed orient.
- MarkerShapePicker reused in EdgeModal and CustomStyleModal.
- Serializer normalizes to shape strings.

Backend:
- Edge marker columns Boolean -> String (default 'none'); TEXT migration.
- normalize_marker() + validators coerce legacy bool / unknown values.

ha-relevant: yes

backend/app/db/database.py

@@ -82,9 +82,9 @@ async def init_db() -> None:
         with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN animated BOOLEAN NOT NULL DEFAULT 0")
         with suppress(OperationalError):
-            await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN marker_start BOOLEAN NOT NULL DEFAULT 0")
+            await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN marker_start TEXT NOT NULL DEFAULT 'none'")
         with suppress(OperationalError):
-            await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN marker_end BOOLEAN NOT NULL DEFAULT 0")
+            await conn.exec_driver_sql("ALTER TABLE edges ADD COLUMN marker_end TEXT NOT NULL DEFAULT 'none'")
         with suppress(OperationalError):
             await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN cpu_count INTEGER")
         with suppress(OperationalError):

backend/app/db/models.py

@@ -86,8 +86,8 @@ class Edge(Base):
     custom_color: Mapped[str | None] = mapped_column(String)
     path_style: Mapped[str | None] = mapped_column(String)
     animated: Mapped[str] = mapped_column(String, nullable=False, default='none')
-    marker_start: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
-    marker_end: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    marker_start: Mapped[str] = mapped_column(String, nullable=False, default='none')
+    marker_end: 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)
     waypoints: Mapped[list[dict[str, float]] | None] = mapped_column(JSON, nullable=True)

backend/app/schemas/canvas.py

@@ -4,7 +4,7 @@ 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
+from app.schemas.utils import normalize_animated, normalize_marker
 
 
 class NodeSave(BaseModel):
@@ -52,8 +52,8 @@ class EdgeSave(BaseModel):
     custom_color: str | None = None
     path_style: str | None = None
     animated: str = 'none'
-    marker_start: bool = False
-    marker_end: bool = False
+    marker_start: str = 'none'
+    marker_end: str = 'none'
     source_handle: str | None = None
     target_handle: str | None = None
     waypoints: list[dict[str, float]] | None = None
@@ -63,6 +63,11 @@ class EdgeSave(BaseModel):
     def validate_animated(cls, v: object) -> str:
         return normalize_animated(v)
 
+    @field_validator('marker_start', 'marker_end', mode='before')
+    @classmethod
+    def validate_marker(cls, v: object) -> str:
+        return normalize_marker(v)
+
 
 class CanvasSaveRequest(BaseModel):
     nodes: list[NodeSave] = []

backend/app/schemas/edges.py

@@ -2,7 +2,7 @@ from datetime import datetime
 
 from pydantic import BaseModel, field_validator
 
-from app.schemas.utils import normalize_animated
+from app.schemas.utils import normalize_animated, normalize_marker
 
 
 class EdgeBase(BaseModel):
@@ -15,8 +15,8 @@ class EdgeBase(BaseModel):
     custom_color: str | None = None
     path_style: str | None = None
     animated: str = 'none'
-    marker_start: bool = False
-    marker_end: bool = False
+    marker_start: str = 'none'
+    marker_end: str = 'none'
     source_handle: str | None = None
     target_handle: str | None = None
     waypoints: list[dict[str, float]] | None = None
@@ -26,6 +26,11 @@ class EdgeBase(BaseModel):
     def validate_animated(cls, v: object) -> str:
         return normalize_animated(v)
 
+    @field_validator('marker_start', 'marker_end', mode='before')
+    @classmethod
+    def validate_marker(cls, v: object) -> str:
+        return normalize_marker(v)
+
 
 class EdgeCreate(EdgeBase):
     design_id: str | None = None
@@ -39,8 +44,8 @@ class EdgeUpdate(BaseModel):
     custom_color: str | None = None
     path_style: str | None = None
     animated: str | None = None
-    marker_start: bool | None = None
-    marker_end: bool | None = None
+    marker_start: str | None = None
+    marker_end: str | None = None
     source_handle: str | None = None
     target_handle: str | None = None
     waypoints: list[dict[str, float]] | None = None
@@ -52,6 +57,13 @@ class EdgeUpdate(BaseModel):
             return None
         return normalize_animated(v)
 
+    @field_validator('marker_start', 'marker_end', mode='before')
+    @classmethod
+    def validate_marker(cls, v: object) -> str | None:
+        if v is None:
+            return None
+        return normalize_marker(v)
+
 
 class EdgeResponse(EdgeBase):
     id: str

backend/app/schemas/utils.py

@@ -7,3 +7,21 @@ def normalize_animated(v: object) -> str:
     if v in ('snake', 'flow', 'basic'):
         return str(v)
     return 'none'
+
+
+MARKER_SHAPES = {'none', 'arrow', 'arrow-open', 'circle', 'diamond', 'square'}
+
+
+def normalize_marker(v: object) -> str:
+    """Normalize an edge endpoint marker to a shape string.
+
+    Legacy saves stored a boolean (True = filled arrow); coerce those and any
+    unknown value to a valid MarkerShape ('none' when off/unknown).
+    """
+    if v is True or v == 1 or v == '1':
+        return 'arrow'
+    if v is False or v == 0 or v == '0' or v is None:
+        return 'none'
+    if isinstance(v, str) and v in MARKER_SHAPES:
+        return v
+    return 'none'