Start with causality inference

BEdit/AGENTS.md

@@ -56,8 +56,9 @@ Keep the root of `src/bedit` minimal. New UI modules should go into the relevant
   anchors may change without changing IDs.
 - Parameters belong to `Component` rather than a particular implementation kind,
   so graph and text components share stable-ID name/type/value records.
-- Port orientation is presented as one unified list in the UI, while the model
+- Components store one ordered `ports` list. Each port's `orientation` field is
-  indexes inputs and outputs separately for connection semantics.
+  authoritative (`input`, `output`, or power-only `indifferent`); connection and
+  presentation code derives any directional groupings when needed.
 - Port types are registered in `core/port_types.py`. Only compatible types may be
   connected. Signal ports connect by type; power ports additionally require the
   same domain. Editable power domains and causalities live in
@@ -72,9 +73,15 @@ Keep the root of `src/bedit` minimal. New UI modules should go into the relevant
 - Port removal or reorientation must be rejected when it would invalidate an
   existing connection.
 - Connections reference port IDs, never port names.
+- Connections store their port type and bond-graph causality explicitly.
+  `core/bond_graph.py` owns causality inference; the simulation service invokes
+  it before Modelica composition. The controller copies inferred values into the
+  live model and refreshes the workspace before compile, export, or run.
+  Causality values are `none`, `source`, `target`, `warn_source`, and `warn_target`.
 - Connection junctions are explicit typed graph objects. Splitting a connection
   creates one incoming and one outgoing segment; the junction can source further
-  branches without overlapping full connection paths.
+  branches without overlapping full connection paths. Power bond connections
+  cannot contain junctions.
 - Graph interaction has separate Pointer and Connect modes. Port hints are only
   visible in Connect mode. Connecting two blocks opens the compatible port-pair
   chooser; explicit port clicks determine its default selection. Connections
@@ -324,6 +331,7 @@ PYTHONPATH=src python3 -m bedit
 ```
 
 The installed GUI entry point is `bedit.gui.app:main`.
+The first non-flag launch argument is opened as the initial document.
 
 ## Completion checklist
 

BEdit/README.md

@@ -159,12 +159,12 @@ Every component owns its ports, declarative icon, properties, and child graph:
     "name": "My Component",
     "position": {"x": 0, "y": 0},
     "interface": {
-      "inputs": [{"id": "in", "name": "Input", "type": "signal", "properties": {
+      "ports": [
-        "iconPosition": {"x": 0, "y": 40}
+        {"id": "in", "name": "Input", "type": "signal", "orientation": "input",
-      }}],
+         "properties": {"iconPosition": {"x": 0, "y": 40}}},
-      "outputs": [{"id": "out", "name": "Output", "type": "signal", "properties": {
+        {"id": "out", "name": "Output", "type": "signal", "orientation": "output",
-        "iconPosition": {"x": 128, "y": 64}
+         "properties": {"iconPosition": {"x": 128, "y": 64}}}
-      }}]
+      ]
     },
     "icon": {
       "size": {"width": 128, "height": 128},

BEdit/src/bedit/core/bond_graph.py

@@ -0,0 +1,134 @@
+"""Bond-graph analysis hooks.
+
+This module intentionally has no GUI or simulation-engine dependencies.  The
+causality inference algorithm can grow here without coupling the document model
+to OpenModelica or Qt.
+"""
+
+from __future__ import annotations
+from typing import Any
+
+from bedit.core.application_log import get_logger
+
+log = get_logger(__name__)
+
+def infer_causality(component: dict[str, Any], toplevel: bool = True) -> dict[str, Any]:
+    """Infer power-connection causality in a serialized component tree.
+
+    This is currently a traversal stub: it ensures every power connection has a
+    causality value, while preserving causality already supplied by callers.
+    Future inference rules should assign ``source``, ``target``,
+    ``warn_source``, or ``warn_target`` here and return the same tree.
+
+    The input is mutated and returned so the composer receives the inferred
+    representation without needing a second document conversion.
+    """
+
+    if toplevel:
+        log.info("Causality inference")
+
+        # Reset causalities
+        reset_causality(component)
+
+    implementation = component.get("implementation", {})
+    graph = implementation.get("graph") if isinstance(implementation, dict) else None
+    if not isinstance(graph, dict):
+        return component
+    
+    id_list = build_id_list(component)
+
+    # Check fixed causality
+    for connection in graph.get("connections", []):
+        if isinstance(connection, dict) and connection.get("type") == "power":
+            source, target = get_ports_from_bond(connection, id_list)
+            log.info(source)
+            log.info(target)
+            if source.get('causality', 'indifferent') == 'fixed effort out':
+                connection['causality'] = 'target'
+            elif source.get('causality', 'indifferent') == 'fixed flow out':
+                connection['causality'] = 'source'
+
+    for block in graph.get("blocks", []):
+        if isinstance(block, dict):
+            infer_causality(block, False)
+
+    return component
+
+def reset_causality(component: dict[str, Any]) -> None:
+    implementation = component.get("implementation", {})
+    graph = implementation.get("graph") if isinstance(implementation, dict) else None
+    if not isinstance(graph, dict):
+        return
+    for connection in graph.get("connections", []):
+        if isinstance(connection, dict) and connection.get("type") == "power":
+            connection["causality"] = "none"
+    for block in graph.get("blocks", []):
+        if isinstance(block, dict):
+            reset_causality(block)
+
+def build_id_list(graph: dict[str, Any]) -> dict[str, Any]:
+    """Index all addressable objects in a component tree by their stable ID."""
+
+    id_list: dict[str, Any] = {}
+    id_kinds: dict[str, str] = {}
+
+    def add(item: dict[str, Any], description: str) -> None:
+        item_id = item.get("id")
+        if not item_id:
+            raise ValueError(f"{description} has no ID")
+        # Port IDs identify a port on a component definition and may therefore
+        # recur in cloned component instances. Component and junction IDs are
+        # document objects and must remain globally unique.
+        if item_id in id_list and not (
+            description == "port" and id_kinds[item_id] == "port"
+        ):
+            raise ValueError(f"Duplicate simulation object ID: {item_id}")
+        id_list[item_id] = item
+        id_kinds[item_id] = description
+
+    def visit(component: dict[str, Any]) -> None:
+        add(component, "component")
+        interface = component.get("interface", {})
+        for port in interface.get("ports", []):
+            add(port, "port")
+
+        implementation = component.get("implementation", {})
+        if implementation.get("kind") != "graph":
+            return
+        nested_graph = implementation.get("graph", {})
+        for junction in nested_graph.get("junctions", []):
+            add(junction, "junction")
+        for block in nested_graph.get("blocks", []):
+            visit(block)
+
+    visit(graph)
+    return id_list
+
+def get_ports_from_bond(bond: dict[str, Any], id_list: dict[str, Any]) -> tuple[dict[str,Any], dict[str,Any]]:
+    source = bond.get('source', None)
+    target = bond.get('target', None)
+    if source is None or target is None:
+        raise ValueError("Source and Target of a power bond cannot be None")
+    
+    source_component = id_list.get(source.get('block'), None)
+    target_component = id_list.get(target.get('block'), None)
+    if source_component is None or target_component is None:
+        raise ValueError("Source or Target blocks not found")
+    
+    def _find_port(ports: list[dict[str, Any]], port: str) -> dict[str, Any] | None:
+        for pi in ports:
+            if pi.get('id', '') == port:
+                return pi
+        return None
+
+    source_port = _find_port(source_component.get('interface', {}).get('ports', []), source.get('port'))
+    target_port = _find_port(target_component.get('interface', {}).get('ports', []), target.get('port'))
+    if source_port is None or target_port is None:
+        raise ValueError("Source or Target port not found")
+    
+    if source_port.get('type') != 'power':
+        raise ValueError("Source port is not a power port")
+    if target_port.get('type') != 'power':
+        raise ValueError("Target port is not a power port")
+    
+    return source_port, target_port

BEdit/src/bedit/core/model.py

@@ -180,6 +180,8 @@ class Connection:
     target: Endpoint
     name: str = ""
     properties: dict[str, Any] = field(default_factory=dict)
+    type: str = "signal"
+    causality: str = "none"
 
     def to_dict(self) -> dict[str, Any]:
         return {
@@ -188,6 +190,8 @@ class Connection:
             "target": self.target.to_dict(),
             "name": self.name,
             "properties": self.properties,
+            "type": self.type,
+            "causality": self.causality,
         }
 
     @classmethod
@@ -198,6 +202,8 @@ class Connection:
             target=Endpoint.from_dict(data["target"]),
             name=str(data.get("name", "")),
             properties=dict(data.get("properties", {})),
+            type=str(data.get("type", "signal")),
+            causality=str(data.get("causality", "none")),
         )
 
 
@@ -360,8 +366,7 @@ class Component:
     x: float = 0.0
     y: float = 0.0
     rotation: float = 0.0
-    inputs: list[Port] = field(default_factory=list)
+    ports: list[Port] = field(default_factory=list)
-    outputs: list[Port] = field(default_factory=list)
     parameters: list[Parameter] = field(default_factory=list)
     icon: Icon = field(default_factory=Icon)
     properties: dict[str, Any] = field(default_factory=dict)
@@ -381,10 +386,7 @@ class Component:
             "name": self.name,
             "position": {"x": self.x, "y": self.y},
             "rotation": self.rotation,
-            "interface": {
+            "interface": {"ports": [port.to_dict() for port in self.ports]},
-                "inputs": [port.to_dict() for port in self.inputs],
-                "outputs": [port.to_dict() for port in self.outputs],
-            },
             "parameters": [parameter.to_dict() for parameter in self.parameters],
             "icon": self.icon.to_dict(),
             "properties": self.properties,
@@ -427,8 +429,7 @@ class Component:
             x=float(position.get("x", 0.0)),
             y=float(position.get("y", 0.0)),
             rotation=float(data.get("rotation", 0.0)),
-            inputs=[Port.from_dict(item, "input") for item in interface.get("inputs", [])],
+            ports=[Port.from_dict(item) for item in interface.get("ports", [])],
-            outputs=[Port.from_dict(item, "output") for item in interface.get("outputs", [])],
             parameters=[Parameter.from_dict(item) for item in parameters],
             icon=Icon.from_dict(data.get("icon")),
             properties=dict(data.get("properties", {})),
@@ -532,11 +533,10 @@ class GraphDocument:
             raise ValueError(
                 f"Component names inside {owner.name!r} must be unique"
             )
-        input_ids = {port.id for port in owner.inputs}
+        port_ids = {port.id for port in owner.ports}
-        output_ids = {port.id for port in owner.outputs}
+        if len(port_ids) != len(owner.ports):
-        if len(input_ids) != len(owner.inputs) or len(output_ids) != len(owner.outputs):
             raise ValueError(f"Component {owner.name} contains duplicate port IDs")
-        for port in (*owner.inputs, *owner.outputs):
+        for port in owner.ports:
             PortTypeRegistry.get(port.type)
             if port.orientation not in {"input", "output", "indifferent"}:
                 raise ValueError(f"Port {port.name!r} has an invalid orientation")
@@ -553,8 +553,18 @@ class GraphDocument:
                 raise ValueError(f"Port {port.name!r} has invalid dimensions")
         for junction in owner.graph.junctions.values():
             PortTypeRegistry.get(junction.type)
+            if junction.type == "power":
+                raise ValueError("Power bond connections cannot contain junctions")
         endpoint_counts: dict[tuple[str, str, str], int] = {}
         for connection in owner.graph.connections.values():
+            if connection.causality not in {
+                "none",
+                "source",
+                "target",
+                "warn_source",
+                "warn_target",
+            }:
+                raise ValueError(f"Connection {connection.id} has invalid causality")
             if connection.source.junction is not None:
                 junction = owner.graph.junctions.get(connection.source.junction)
                 if junction is None:
@@ -563,17 +573,25 @@ class GraphDocument:
                     )
                 source_port = Port(junction.id, "Junction", type=junction.type)
             elif connection.source.interface is not None:
-                if connection.source.interface not in input_ids:
+                source_ports = [
+                    port
+                    for port in owner.ports
+                    if port.orientation in {"input", "indifferent"}
+                ]
+                if connection.source.interface not in {port.id for port in source_ports}:
                     raise ValueError(f"Connection {connection.id} uses an unknown interface input")
-                source_port = next(p for p in owner.inputs if p.id == connection.source.interface)
+                source_port = next(
+                    port for port in source_ports if port.id == connection.source.interface
+                )
             else:
                 source = owner.graph.blocks.get(connection.source.block or "")
                 source_ports = (
                     []
                     if source is None
                     else [
-                        *source.outputs,
+                        port
-                        *(p for p in source.inputs if p.orientation == "indifferent"),
+                        for port in source.ports
+                        if port.orientation in {"output", "indifferent"}
                     ]
                 )
                 if source is None or connection.source.port not in {p.id for p in source_ports}:
@@ -592,21 +610,34 @@ class GraphDocument:
                     allows_multiple_connections=False,
                 )
             elif connection.target.interface is not None:
-                indifferent_ids = {
+                target_ports = [
-                    port.id for port in owner.inputs if port.orientation == "indifferent"
+                    port
-                }
+                    for port in owner.ports
-                if connection.target.interface not in output_ids | indifferent_ids:
+                    if port.orientation in {"output", "indifferent"}
+                ]
+                if connection.target.interface not in {port.id for port in target_ports}:
                     raise ValueError(f"Connection {connection.id} uses an unknown interface output")
                 target_port = next(
-                    p
+                    port for port in target_ports if port.id == connection.target.interface
-                    for p in (*owner.outputs, *owner.inputs)
-                    if p.id == connection.target.interface
                 )
             else:
                 target = owner.graph.blocks.get(connection.target.block or "")
-                if target is None or connection.target.port not in {p.id for p in target.inputs}:
+                target_ports = (
+                    []
+                    if target is None
+                    else [
+                        port
+                        for port in target.ports
+                        if port.orientation in {"input", "indifferent"}
+                    ]
+                )
+                if target is None or connection.target.port not in {
+                    port.id for port in target_ports
+                }:
                     raise ValueError(f"Connection {connection.id} uses an unknown block input")
-                target_port = next(p for p in target.inputs if p.id == connection.target.port)
+                target_port = next(
+                    port for port in target_ports if port.id == connection.target.port
+                )
             if not PortTypeRegistry.compatible(
                 source_port.type,
                 target_port.type,
@@ -614,6 +645,9 @@ class GraphDocument:
                 target_port.domain,
             ):
                 raise ValueError(f"Connection {connection.id} joins incompatible port types")
+            # The endpoint ports remain authoritative. This also upgrades older
+            # documents whose connections predate the explicit type field.
+            connection.type = source_port.type
             source_key = (
                 "source-junction"
                 if connection.source.junction is not None
@@ -676,6 +710,8 @@ def clone_component(source: Component) -> Component:
                     remap(connection.target),
                     connection.name,
                     deepcopy(connection.properties),
+                    connection.type,
+                    connection.causality,
                 )
                 for connection in current.graph.connections.values()
                 for new_id in [str(uuid4())]
@@ -708,14 +744,7 @@ def clone_component(source: Component) -> Component:
             name=current.name,
             x=current.x,
             y=current.y,
-            inputs=[
+            ports=[Port.from_dict(port.to_dict()) for port in current.ports],
-                Port.from_dict(port.to_dict(), "input")
-                for port in current.inputs
-            ],
-            outputs=[
-                Port.from_dict(port.to_dict(), "output")
-                for port in current.outputs
-            ],
             parameters=deepcopy(current.parameters),
             icon=Icon.from_dict(current.icon.to_dict()),
             properties=deepcopy(current.properties),

BEdit/src/bedit/core/simulation/composer.py

@@ -59,9 +59,7 @@ def build_id_list(graph: dict[str, Any]) -> dict[str, Any]:
     def visit(component: dict[str, Any]) -> None:
         add(component, "component")
         interface = component.get("interface", {})
-        for port in interface.get("inputs", []):
+        for port in interface.get("ports", []):
-            add(port, "port")
-        for port in interface.get("outputs", []):
             add(port, "port")
 
         implementation = component.get("implementation", {})
@@ -110,10 +108,9 @@ def emit_model(
             )
 
     interface = graph.get("interface", {})
-    for port in interface.get("inputs", []):
+    for port in interface.get("ports", []):
-        lines.append(_port_declaration(port, "input", indent + 1, macros))
+        direction = "output" if port.get("orientation") == "output" else "input"
-    for port in interface.get("outputs", []):
+        lines.append(_port_declaration(port, direction, indent + 1, macros))
-        lines.append(_port_declaration(port, "output", indent + 1, macros))
 
     for parameter in graph.get("parameters", []):
         parameter_type = modelica_type(parameter.get("type", "real"))
@@ -332,7 +329,7 @@ def _port_count_macros(
 ) -> dict[str, str]:
     macros: dict[str, str] = {}
     interface = component.get("interface", {})
-    for port in (*interface.get("inputs", []), *interface.get("outputs", [])):
+    for port in interface.get("ports", []):
         if port.get("multipleConnections", False):
             macros[f"{identifier(port['name'])}_N"] = str(
                 connection_counts.get(port["id"], 0)
@@ -354,8 +351,7 @@ def expand_bevalues(text: str, values: dict[str, str]) -> str:
 
 def _find_port(component: dict[str, Any], port_id: str) -> dict[str, Any]:
     interface = component.get("interface", {})
-    ports = [*interface.get("inputs", []), *interface.get("outputs", [])]
+    for port in interface.get("ports", []):
-    for port in ports:
         if port.get("id") == port_id:
             return port
     raise ValueError(

BEdit/src/bedit/core/simulation/service.py

@@ -2,6 +2,7 @@ from collections.abc import Callable
 from typing import Any
 
 from bedit.core.application_log import get_logger
+from bedit.core.bond_graph import infer_causality
 from bedit.core.simulation.composer import compose_graph
 from bedit.core.simulation.openmodelica import (
     ErrorCallback,
@@ -87,6 +88,7 @@ class Simulation:
     def compose_source(self, graph: dict[str, Any]) -> tuple[str, str]:
         """Compose Modelica source without asking OpenModelica to build it."""
 
+        infer_causality(graph)
         result = compose_graph(graph)
         self.last_composition_input = result.graph
         self.id_list = result.objects_by_id

BEdit/src/bedit/gui/app.py

@@ -1,4 +1,6 @@
 import sys
+from collections.abc import Sequence
+from pathlib import Path
 
 from PySide6.QtCore import QCoreApplication, Qt
 from PySide6.QtGui import QColor, QPalette
@@ -38,14 +40,26 @@ def apply_light_theme(app: QApplication) -> None:
     app.setPalette(palette)
 
 
-def main() -> int:
+def _document_argument(arguments: Sequence[str]) -> Path | None:
+    """Return the first positional application argument, if present."""
+
+    return next(
+        (Path(argument) for argument in arguments[1:] if not argument.startswith("-")),
+        None,
+    )
+
+
+def main(argv: Sequence[str] | None = None) -> int:
     QCoreApplication.setApplicationName("BEdit")
     QCoreApplication.setOrganizationName("BEdit")
     QCoreApplication.setApplicationVersion("0.1.0")
-    app = QApplication(sys.argv)
+    app = QApplication(list(sys.argv if argv is None else argv))
     app.setApplicationDisplayName("BEdit")
 
     apply_light_theme(app)
     window = MainWindow()
+    document_path = _document_argument(app.arguments())
+    if document_path is not None:
+        window.open_document_path(document_path, check_unsaved=False)
     window.show()
     return app.exec()

BEdit/src/bedit/gui/controllers/commands.py

@@ -311,24 +311,21 @@ class DeleteSelectionCommand(QUndoCommand):
         owner_id: str | None,
         blocks: dict[str, Component],
         connections: dict[str, Connection],
-        inputs: list[Port],
+        ports: list[Port],
-        outputs: list[Port],
     ) -> None:
         super().__init__("Delete selection")
         self.controller = controller
         self.owner_id = owner_id
         self.blocks = blocks
         self.connections = connections
-        self.inputs = inputs
+        self.ports = ports
-        self.outputs = outputs
 
     def redo(self) -> None:
         self.controller._delete_items(
             self.owner_id,
             set(self.blocks),
             set(self.connections),
-            {port.id for port in self.inputs},
+            {port.id for port in self.ports},
-            {port.id for port in self.outputs},
         )
 
     def undo(self) -> None:
@@ -336,8 +333,7 @@ class DeleteSelectionCommand(QUndoCommand):
             self.owner_id,
             self.blocks,
             self.connections,
-            self.inputs,
+            self.ports,
-            self.outputs,
         )
 
 
@@ -361,7 +357,6 @@ class PasteSelectionCommand(QUndoCommand):
             self.blocks,
             self.connections,
             [],
-            [],
         )
 
     def undo(self) -> None:
@@ -370,7 +365,6 @@ class PasteSelectionCommand(QUndoCommand):
             set(self.blocks),
             set(self.connections),
             set(),
-            set(),
         )
 
 

BEdit/src/bedit/gui/controllers/document.py

@@ -40,6 +40,7 @@ from bedit.core.model import (
     Port,
     clone_component,
 )
+from bedit.core.bond_graph import infer_causality
 from bedit.core.simulation import Simulation
 from bedit.core.port_types import PortTypeRegistry
 from bedit.core.serializer import DocumentSerializer
@@ -307,6 +308,7 @@ class DocumentController(QObject):
             properties={
                 "waypoints": [{"x": point.x(), "y": point.y()} for point in (waypoints or [])],
             },
+            type=source_port.type,
         )
         self.undo_stack.push(AddConnectionCommand(self, self.active_component_id, connection))
         return connection.id
@@ -324,6 +326,8 @@ class DocumentController(QObject):
         if original is None:
             raise ValueError("The connection no longer exists")
         port_type = self.connection_port_type(original)
+        if port_type == "power":
+            raise ValueError("Power bond connections cannot contain junctions")
         junction = Junction(str(uuid4()), position.x(), position.y(), port_type)
         first_properties = deepcopy(original.properties)
         first_properties["waypoints"] = [
@@ -338,6 +342,8 @@ class DocumentController(QObject):
             Endpoint(junction=junction.id),
             original.name,
             first_properties,
+            original.type,
+            original.causality,
         )
         second = Connection(
             str(uuid4()),
@@ -345,6 +351,8 @@ class DocumentController(QObject):
             original.target,
             "",
             second_properties,
+            original.type,
+            original.causality,
         )
         self.undo_stack.push(
             SplitConnectionCommand(
@@ -442,12 +450,14 @@ class DocumentController(QObject):
         component = self.active_component
         if component is None or component.implementation_kind != "graph":
             raise ValueError("Open a graph component before composing")
+        self._infer_active_graph_causality(component)
         self.simulation.compose(component.to_dict())
 
     def compose_active_graph_source(self) -> tuple[str, str]:
         component = self.active_component
         if component is None or component.implementation_kind != "graph":
             raise ValueError("Open a graph component before exporting a model")
+        self._infer_active_graph_causality(component)
         return self.simulation.compose_source(component.to_dict())
 
     def run_simulation(
@@ -460,6 +470,7 @@ class DocumentController(QObject):
         component = self.active_component
         if component is None or component.implementation_kind != "graph":
             raise ValueError("Open a graph component before running a simulation")
+        self._infer_active_graph_causality(component)
         self.simulation.run_simulation(
             component.to_dict(),
             progress_callback,
@@ -468,6 +479,34 @@ class DocumentController(QObject):
             error_callback,
         )
 
+    def _infer_active_graph_causality(self, component: Component) -> None:
+        """Infer causality and copy the derived values into the live model."""
+
+        inferred = infer_causality(component.to_dict())
+        causalities: dict[str, str] = {}
+
+        def collect(serialized_component: dict) -> None:
+            graph = serialized_component.get("implementation", {}).get("graph", {})
+            for connection in graph.get("connections", []):
+                causalities[str(connection["id"])] = str(
+                    connection.get("causality", "none")
+                )
+            for block in graph.get("blocks", []):
+                collect(block)
+
+        collect(inferred)
+        changed = False
+        for nested_component in self._component_subtree(component):
+            for connection in nested_component.graph.connections.values():
+                causality = causalities.get(connection.id, "none")
+                if connection.causality != causality:
+                    connection.causality = causality
+                    changed = True
+        if changed:
+            if self.document is not None:
+                self.document.validate()
+            self.documentReset.emit()
+
     def set_route_waypoints(self, item_kind: str, item_id: str, waypoints: list[QPointF]) -> None:
         item = (
             self.active_graph.connections
@@ -577,24 +616,25 @@ class DocumentController(QObject):
                 allows_multiple_connections=role == "source",
             )
         if endpoint.interface is not None:
-            ports = owner.inputs if role == "source" else owner.outputs
+            orientations = (
+                {"input", "indifferent"}
+                if role == "source"
+                else {"output", "indifferent"}
+            )
             ports = [
-                *ports,
+                port for port in owner.ports if port.orientation in orientations
-                *(
-                    port
-                    for port in owner.inputs
-                    if port.orientation == "indifferent" and port not in ports
-                ),
             ]
         else:
             component = owner.graph.blocks.get(endpoint.block or "")
             if component is None:
                 return None
-            ports = component.outputs if role == "source" else component.inputs
+            orientations = (
-            if role == "source":
+                {"output", "indifferent"}
+                if role == "source"
+                else {"input", "indifferent"}
+            )
             ports = [
-                    *ports,
+                port for port in component.ports if port.orientation in orientations
-                    *(port for port in component.inputs if port.orientation == "indifferent"),
             ]
         return next(
             (port for port in ports if port.id == (endpoint.interface or endpoint.port)), None
@@ -619,12 +659,13 @@ class DocumentController(QObject):
         component = self.active_component
         if component is None or component.implementation_kind != "graph":
             raise ValueError("Open a graph component before adding an interface")
-        ports = component.inputs if direction == "input" else component.outputs
+        ports = [port for port in component.ports if port.orientation == direction]
         port = Port(
             id=f"{direction}-{uuid4().hex[:8]}",
             name=f"{direction.title()} {len(ports) + 1}",
             x=position.x(),
             y=position.y(),
+            orientation=direction,
         )
         self.undo_stack.push(AddInterfacePortCommand(self, component.id, direction, port))
         return port.id
@@ -639,7 +680,7 @@ class DocumentController(QObject):
         owner = self.active_component
         if owner is None:
             return
-        port = next((p for p in (*owner.inputs, *owner.outputs) if p.id == port_id), None)
+        port = next((port for port in owner.ports if port.id == port_id), None)
         if port is not None and port.name != name:
             self.undo_stack.push(
                 RenameInterfacePortCommand(self, owner.id, port_id, port.name, name)
@@ -670,8 +711,7 @@ class DocumentController(QObject):
 
     def replace_active_text_definition(
         self,
-        inputs: list[Port],
+        ports: list[Port],
-        outputs: list[Port],
         declarations: str,
         initial_equations: str,
         equations: str,
@@ -680,14 +720,17 @@ class DocumentController(QObject):
         component = self.active_component
         if component is None or component.implementation_kind != "text":
             raise ValueError("Only text-defined components can be edited here")
-        input_ids = [port.id for port in inputs]
+        port_ids = [port.id for port in ports]
-        output_ids = [port.id for port in outputs]
+        input_ids = {
-        source_ids = output_ids + [
+            port.id for port in ports if port.orientation in {"input", "indifferent"}
-            port.id for port in inputs if port.orientation == "indifferent"
+        }
-        ]
+        output_ids = {
-        if len(set(input_ids)) != len(input_ids) or len(set(output_ids)) != len(output_ids):
+            port.id for port in ports if port.orientation in {"output", "indifferent"}
-            raise ValueError("Input and output IDs must be unique")
+        }
-        if any(not port.name.strip() for port in (*inputs, *outputs)):
+        source_ids = output_ids
+        if len(set(port_ids)) != len(port_ids):
+            raise ValueError("Port IDs must be unique")
+        if any(not port.name.strip() for port in ports):
             raise ValueError("Every port must have a name")
         parameter_ids = [parameter.id for parameter in parameters]
         if len(set(parameter_ids)) != len(parameter_ids):
@@ -713,14 +756,12 @@ class DocumentController(QObject):
                             f"Output {connection.source.port!r} is still connected in the containing graph"
                         )
         old = {
-            "inputs": [port.to_dict() for port in component.inputs],
+            "ports": [port.to_dict() for port in component.ports],
-            "outputs": [port.to_dict() for port in component.outputs],
             "source": deepcopy(component.source),
             "parameters": [parameter.to_dict() for parameter in component.parameters],
         }
         new = {
-            "inputs": [port.to_dict() for port in inputs],
+            "ports": [port.to_dict() for port in ports],
-            "outputs": [port.to_dict() for port in outputs],
             "source": {
                 "equations": equations,
                 "declarations": declarations,
@@ -731,8 +772,7 @@ class DocumentController(QObject):
         if old != new:
             candidate = deepcopy(self.document)
             candidate_component = candidate.find_component(component.id)
-            candidate_component.inputs = deepcopy(inputs)
+            candidate_component.ports = deepcopy(ports)
-            candidate_component.outputs = deepcopy(outputs)
             candidate_component.source = deepcopy(new["source"])
             candidate_component.parameters = deepcopy(parameters)
             candidate.validate()
@@ -743,8 +783,7 @@ class DocumentController(QObject):
         component_id: str,
         name: str,
         icon: Icon,
-        inputs: list[Port],
+        ports: list[Port],
-        outputs: list[Port],
         show_subtree: bool,
         show_name: bool,
     ) -> None:
@@ -759,8 +798,7 @@ class DocumentController(QObject):
         old = {
             "name": component.name,
             "icon": component.icon.to_dict(),
-            "inputs": [port.to_dict() for port in component.inputs],
+            "ports": [port.to_dict() for port in component.ports],
-            "outputs": [port.to_dict() for port in component.outputs],
             "show_subtree": component.show_subtree_in_library,
             "properties": deepcopy(component.properties),
         }
@@ -772,8 +810,7 @@ class DocumentController(QObject):
         new = {
             "name": name,
             "icon": icon.to_dict(),
-            "inputs": [port.to_dict() for port in inputs],
+            "ports": [port.to_dict() for port in ports],
-            "outputs": [port.to_dict() for port in outputs],
             "show_subtree": show_subtree,
             "properties": properties,
         }
@@ -782,8 +819,7 @@ class DocumentController(QObject):
             candidate_component = candidate.find_component(component_id)
             candidate_component.name = name
             candidate_component.icon = Icon.from_dict(icon.to_dict())
-            candidate_component.inputs = deepcopy(inputs)
+            candidate_component.ports = deepcopy(ports)
-            candidate_component.outputs = deepcopy(outputs)
             candidate_component.properties = deepcopy(properties)
             candidate.validate()
             self.undo_stack.push(EditComponentAppearanceCommand(self, component_id, old, new))
@@ -853,19 +889,19 @@ class DocumentController(QObject):
                 )
             )
 
-    def edit_component_ports(
+    def edit_component_ports(self, component_id: str, ports: list[Port]) -> None:
-        self, component_id: str, inputs: list[Port], outputs: list[Port]
-    ) -> None:
         if self.document is None:
             return
         component = self.document.find_component(component_id)
         if component is None:
             return
-        input_ids = {port.id for port in inputs}
+        input_ids = {
-        output_ids = {port.id for port in outputs}
+            port.id for port in ports if port.orientation in {"input", "indifferent"}
-        source_ids = output_ids | {
-            port.id for port in inputs if port.orientation == "indifferent"
         }
+        output_ids = {
+            port.id for port in ports if port.orientation in {"output", "indifferent"}
+        }
+        source_ids = output_ids
         parent = self.document.find_parent(component_id)
         if parent is not None:
             for connection in parent.graph.connections.values():
@@ -886,21 +922,18 @@ class DocumentController(QObject):
                 raise ValueError("An interface output cannot be removed while connected")
         candidate = deepcopy(self.document)
         candidate_component = candidate.find_component(component_id)
-        candidate_component.inputs = deepcopy(inputs)
+        candidate_component.ports = deepcopy(ports)
-        candidate_component.outputs = deepcopy(outputs)
         candidate.validate()
         old = {
             "name": component.name,
             "icon": component.icon.to_dict(),
-            "inputs": [port.to_dict() for port in component.inputs],
+            "ports": [port.to_dict() for port in component.ports],
-            "outputs": [port.to_dict() for port in component.outputs],
             "show_subtree": component.show_subtree_in_library,
             "properties": deepcopy(component.properties),
         }
         new = {
             **old,
-            "inputs": [port.to_dict() for port in inputs],
+            "ports": [port.to_dict() for port in ports],
-            "outputs": [port.to_dict() for port in outputs],
         }
         if old != new:
             self.undo_stack.push(EditComponentAppearanceCommand(self, component_id, old, new))
@@ -930,8 +963,7 @@ class DocumentController(QObject):
         self,
         block_ids: set[str],
         connection_ids: set[str],
-        input_ids: set[str],
+        port_ids: set[str],
-        output_ids: set[str],
     ) -> None:
         component = self.active_component
         if component is None or component.implementation_kind != "graph":
@@ -942,8 +974,8 @@ class DocumentController(QObject):
             if (
                 connection.source.block in block_ids
                 or connection.target.block in block_ids
-                or connection.source.interface in input_ids
+                or connection.source.interface in port_ids
-                or connection.target.interface in output_ids
+                or connection.target.interface in port_ids
             ):
                 all_connection_ids.add(connection.id)
         blocks = {
@@ -954,9 +986,8 @@ class DocumentController(QObject):
             for connection_id in all_connection_ids
             if connection_id in graph.connections
         }
-        inputs = [port for port in component.inputs if port.id in input_ids]
+        ports = [port for port in component.ports if port.id in port_ids]
-        outputs = [port for port in component.outputs if port.id in output_ids]
+        if not (blocks or connections or ports):
-        if not (blocks or connections or inputs or outputs):
             return
         self.undo_stack.push(
             DeleteSelectionCommand(
@@ -964,8 +995,7 @@ class DocumentController(QObject):
                 component.id,
                 blocks,
                 connections,
-                inputs,
+                ports,
-                outputs,
             )
         )
 
@@ -1003,6 +1033,8 @@ class DocumentController(QObject):
                 target=Endpoint(block=id_map[source.target.block], port=source.target.port),
                 name=source.name,
                 properties=properties,
+                type=source.type,
+                causality=source.causality,
             )
             connections[connection.id] = connection
         if blocks:
@@ -1063,6 +1095,8 @@ class DocumentController(QObject):
                     ),
                     name=source.name,
                     properties=properties,
+                    type=source.type,
+                    causality=source.causality,
                 )
                 connections[connection.id] = connection
 
@@ -1278,9 +1312,9 @@ class DocumentController(QObject):
         owner = self.document.find_component(owner_id)
         if owner is None:
             return
-        ports = owner.inputs if direction == "input" else owner.outputs
+        port.orientation = direction
-        if all(existing.id != port.id for existing in ports):
+        if all(existing.id != port.id for existing in owner.ports):
-            ports.append(port)
+            owner.ports.append(port)
         self.interfaceChanged.emit()
         self.documentReset.emit()
 
@@ -1290,8 +1324,7 @@ class DocumentController(QObject):
         owner = self.document.find_component(owner_id)
         if owner is None:
             return
-        ports = owner.inputs if direction == "input" else owner.outputs
+        owner.ports[:] = [port for port in owner.ports if port.id != port_id]
-        ports[:] = [port for port in ports if port.id != port_id]
         self.interfaceChanged.emit()
         self.documentReset.emit()
 
@@ -1301,7 +1334,7 @@ class DocumentController(QObject):
         owner = self.document.find_component(owner_id)
         if owner is None:
             return
-        port = next((p for p in (*owner.inputs, *owner.outputs) if p.id == port_id), None)
+        port = next((port for port in owner.ports if port.id == port_id), None)
         if port is not None:
             port.x, port.y = position.x(), position.y()
         self.interfaceChanged.emit()
@@ -1311,7 +1344,7 @@ class DocumentController(QObject):
         owner = self.document.find_component(owner_id) if self.document else None
         if owner is None:
             return
-        port = next((p for p in (*owner.inputs, *owner.outputs) if p.id == port_id), None)
+        port = next((port for port in owner.ports if port.id == port_id), None)
         if port is not None:
             port.name = name
             self.interfaceChanged.emit()
@@ -1342,8 +1375,7 @@ class DocumentController(QObject):
             return
         component.name = values["name"]
         component.icon = Icon.from_dict(values["icon"])
-        component.inputs = [Port.from_dict(port) for port in values["inputs"]]
+        component.ports = [Port.from_dict(port) for port in values["ports"]]
-        component.outputs = [Port.from_dict(port) for port in values["outputs"]]
         component.show_subtree_in_library = values["show_subtree"]
         component.properties = deepcopy(values["properties"])
         self.documentReset.emit()
@@ -1374,8 +1406,7 @@ class DocumentController(QObject):
         owner_id: str | None,
         block_ids: set[str],
         connection_ids: set[str],
-        input_ids: set[str],
+        port_ids: set[str],
-        output_ids: set[str],
     ) -> None:
         if self.document is None:
             return
@@ -1398,8 +1429,7 @@ class DocumentController(QObject):
                 owner.graph.blocks.pop(block_id, None)
             for connection_id in connection_ids:
                 owner.graph.connections.pop(connection_id, None)
-            owner.inputs[:] = [port for port in owner.inputs if port.id not in input_ids]
+            owner.ports[:] = [port for port in owner.ports if port.id not in port_ids]
-            owner.outputs[:] = [port for port in owner.outputs if port.id not in output_ids]
         if active_was_deleted:
             self.active_component_id = owner_id or next(iter(self.document.roots), None)
             self.activeGraphChanged.emit()
@@ -1410,8 +1440,7 @@ class DocumentController(QObject):
         owner_id: str | None,
         blocks: dict[str, Component],
         connections: dict[str, Connection],
-        inputs: list[Port],
+        ports: list[Port],
-        outputs: list[Port],
     ) -> None:
         if self.document is None:
             return
@@ -1423,10 +1452,8 @@ class DocumentController(QObject):
                 return
             owner.graph.blocks.update(blocks)
             owner.graph.connections.update(connections)
-            existing_inputs = {port.id for port in owner.inputs}
+            existing_ports = {port.id for port in owner.ports}
-            existing_outputs = {port.id for port in owner.outputs}
+            owner.ports.extend(port for port in ports if port.id not in existing_ports)
-            owner.inputs.extend(port for port in inputs if port.id not in existing_inputs)
-            owner.outputs.extend(port for port in outputs if port.id not in existing_outputs)
         self.documentReset.emit()
 
     @staticmethod
@@ -1441,8 +1468,7 @@ class DocumentController(QObject):
         component = self.document.find_component(component_id)
         if component is None:
             return
-        component.inputs = [Port.from_dict(item) for item in values["inputs"]]
+        component.ports = [Port.from_dict(item) for item in values["ports"]]
-        component.outputs = [Port.from_dict(item) for item in values["outputs"]]
         component.source = deepcopy(values["source"])
         component.parameters = [
             Parameter.from_dict(item) for item in values.get("parameters", [])

BEdit/src/bedit/gui/dialogs/component_options.py

@@ -12,8 +12,7 @@ class ComponentOptionsDialog(QDialog):
         self.ui.setupUi(self)
         self.component = component
         self.edited_icon = component.icon
-        self.edited_inputs = component.inputs
+        self.edited_ports = component.ports
-        self.edited_outputs = component.outputs
         self.ui.nameEdit.setText(component.name)
         self.ui.editIconButton.clicked.connect(self.edit_icon)
         self.ui.showSubtreeCheckBox.setChecked(component.show_subtree_in_library)
@@ -22,13 +21,11 @@ class ComponentOptionsDialog(QDialog):
     def edit_icon(self) -> None:
         working = Component.from_dict(self.component.to_dict())
         working.icon = self.edited_icon
-        working.inputs = self.edited_inputs
+        working.ports = self.edited_ports
-        working.outputs = self.edited_outputs
         dialog = IconEditorDialog(working, self)
         if dialog.exec() == dialog.DialogCode.Accepted:
             self.edited_icon = dialog.icon
-            self.edited_inputs = dialog.inputs
+            self.edited_ports = dialog.ports
-            self.edited_outputs = dialog.outputs
 
     def accept(self) -> None:
         if not self.ui.nameEdit.text().strip():

BEdit/src/bedit/gui/dialogs/port_options.py

@@ -14,13 +14,6 @@ from bedit.gui.generated.ui_port_options_dialog import Ui_PortOptionsDialog
 PORT_ROLE = Qt.ItemDataRole.UserRole
 
 
-def _oriented_copy(port: Port, fallback: str) -> Port:
-    copied = deepcopy(port)
-    if copied.orientation != "indifferent":
-        copied.orientation = fallback
-    return copied
-
-
 class PortOptionsDialog(QDialog):
     """Unified editor for a component's typed, oriented ports."""
 
@@ -32,10 +25,7 @@ class PortOptionsDialog(QDialog):
         self.ui.setupUi(self)
         self.setWindowTitle(f"Port Options — {component.name}")
         self.read_only = read_only
-        self.ports: list[tuple[Port, str]] = [
+        self.ports = deepcopy(component.ports)
-            *((_oriented_copy(port, "input"), port.orientation or "input") for port in component.inputs),
-            *((_oriented_copy(port, "output"), "output") for port in component.outputs),
-        ]
         self._loading = False
         self.ui.typeCombo.clear()
         for port_type in PortTypeRegistry.all():
@@ -77,22 +67,10 @@ class PortOptionsDialog(QDialog):
             self.ui.buttonBox.button(QDialogButtonBox.StandardButton.Cancel).hide()
         self._rebuild_list(0 if self.ports else -1)
 
-    @property
-    def inputs(self) -> list[Port]:
-        return [
-            port
-            for port, orientation in self.ports
-            if orientation in {"input", "indifferent"}
-        ]
-
-    @property
-    def outputs(self) -> list[Port]:
-        return [port for port, orientation in self.ports if orientation == "output"]
-
     def _rebuild_list(self, row: int = -1) -> None:
         self.ui.portList.clear()
-        for port, orientation in self.ports:
+        for port in self.ports:
-            item = QListWidgetItem(f"{port.name}   [{orientation}, {port.type}]")
+            item = QListWidgetItem(f"{port.name}   [{port.orientation}, {port.type}]")
             item.setData(PORT_ROLE, port.id)
             self.ui.portList.addItem(item)
         self.ui.portList.setCurrentRow(min(row, len(self.ports) - 1))
@@ -102,10 +80,12 @@ class PortOptionsDialog(QDialog):
         self._loading = True
         enabled = 0 <= row < len(self.ports)
         if enabled:
-            port, orientation = self.ports[row]
+            port = self.ports[row]
             self.ui.nameEdit.setText(port.name)
             self.ui.typeCombo.setCurrentIndex(self.ui.typeCombo.findData(port.type))
-            self.ui.orientationCombo.setCurrentIndex(self.ui.orientationCombo.findData(orientation))
+            self.ui.orientationCombo.setCurrentIndex(
+                self.ui.orientationCombo.findData(port.orientation)
+            )
             self.ui.multipleConnectionsCheckBox.setChecked(
                 port.allows_multiple_connections
             )
@@ -161,7 +141,7 @@ class PortOptionsDialog(QDialog):
         row = self.ui.portList.currentRow()
         if self._loading or not (0 <= row < len(self.ports)):
             return
-        port, _orientation = self.ports[row]
+        port = self.ports[row]
         port.name = self.ui.nameEdit.text()
         port.type = self.ui.typeCombo.currentData()
         port.allows_multiple_connections = self.ui.multipleConnectionsCheckBox.isChecked()
@@ -179,18 +159,12 @@ class PortOptionsDialog(QDialog):
         )
         orientation = self.ui.orientationCombo.currentData()
         port.orientation = orientation
-        self.ports[row] = (port, orientation)
+        self.ui.portList.item(row).setText(f"{port.name}   [{port.orientation}, {port.type}]")
-        self.ui.portList.item(row).setText(
-            f"{port.name}   [{self.ports[row][1]}, {port.type}]"
-        )
         self.edited.emit()
 
-    def set_ports(self, inputs: list[Port], outputs: list[Port]) -> None:
+    def set_ports(self, ports: list[Port]) -> None:
         self._loading = True
-        self.ports = [
+        self.ports = deepcopy(ports)
-            *((_oriented_copy(port, "input"), port.orientation or "input") for port in inputs),
-            *((_oriented_copy(port, "output"), "output") for port in outputs),
-        ]
         self._loading = False
         self._rebuild_list(0 if self.ports else -1)
 
@@ -201,7 +175,7 @@ class PortOptionsDialog(QDialog):
             properties={"iconPosition": {"x": 0.0, "y": 0.0}},
             type="signal",
         )
-        self.ports.append((port, "input"))
+        self.ports.append(port)
         self._rebuild_list(len(self.ports) - 1)
         self.ui.nameEdit.selectAll()
         self.ui.nameEdit.setFocus()
@@ -216,7 +190,7 @@ class PortOptionsDialog(QDialog):
 
     def accept(self) -> None:
         self._store_current()
-        if any(not port.name.strip() for port, _orientation in self.ports):
+        if any(not port.name.strip() for port in self.ports):
             QMessageBox.warning(self, "Invalid port", "Every port must have a name.")
             return
         super().accept()

BEdit/src/bedit/gui/editors/text_definition.py

@@ -43,8 +43,8 @@ class TextDefinitionEditor(QWidget):
         return self.ui.initialEquationsEdit.toPlainText()
 
     @property
-    def ports(self) -> tuple[list[Port], list[Port]]:
+    def ports(self) -> list[Port]:
-        return self.ui.portEditor.inputs, self.ui.portEditor.outputs
+        return self.ui.portEditor.ports
 
     @property
     def parameters(self) -> list[Parameter]:
@@ -55,17 +55,16 @@ class TextDefinitionEditor(QWidget):
         declarations: str,
         initial_equations: str,
         equations: str,
-        inputs: list[Port],
+        ports: list[Port],
-        outputs: list[Port],
         parameters: list[Parameter],
     ) -> None:
         self._loading = True
         self.ui.declarationsEdit.setPlainText(declarations)
         self.ui.initialEquationsEdit.setPlainText(initial_equations)
         self.ui.equationsEdit.setPlainText(equations)
-        self.ui.portEditor.set_ports(inputs, outputs)
+        self.ui.portEditor.set_ports(ports)
         self.ui.parameterEditor.set_parameters(parameters)
-        self._set_editor_symbols(inputs, outputs, parameters)
+        self._set_editor_symbols(ports, parameters)
         self._loading = False
         self.set_modified(False)
 
@@ -85,18 +84,20 @@ class TextDefinitionEditor(QWidget):
             self._mark_modified()
 
     def _refresh_editor_symbols(self) -> None:
-        inputs, outputs = self.ports
+        self._set_editor_symbols(self.ports, self.parameters)
-        self._set_editor_symbols(inputs, outputs, self.parameters)
 
     def _set_editor_symbols(
         self,
-        inputs: list[Port],
+        ports: list[Port],
-        outputs: list[Port],
         parameters: list[Parameter],
     ) -> None:
         self._apply_editor_symbols(
-            [port.name for port in inputs],
+            [
-            [port.name for port in outputs],
+                port.name
+                for port in ports
+                if port.orientation in {"input", "indifferent"}
+            ],
+            [port.name for port in ports if port.orientation == "output"],
             [parameter.name for parameter in parameters],
         )
 

BEdit/src/bedit/gui/graphics/icon_editor.py

@@ -458,8 +458,7 @@ class IconEditorDialog(QDialog):
         self.ui.setupUi(self)
         self.setWindowTitle(f"Icon Editor — {component.name}")
         self.icon = Icon.from_dict(component.icon.to_dict())
-        self.inputs = deepcopy(component.inputs)
+        self.ports = deepcopy(component.ports)
-        self.outputs = deepcopy(component.outputs)
         self.tool_group = QButtonGroup(self)
         self.tool_group.setExclusive(True)
         self.tool_group.addButton(self.ui.pointerButton)
@@ -485,8 +484,10 @@ class IconEditorDialog(QDialog):
         self.scene.addRect(self.scene.sceneRect(), QPen(QColor("#64748b"), 0)).setZValue(-100)
         for element in self.icon.elements:
             self.scene.addItem(ShapeItem(element))
-        self._add_ports(self.inputs, "input", 0.0)
+        input_side = [port for port in self.ports if port.orientation != "output"]
-        self._add_ports(self.outputs, "output", self.icon.width)
+        output_side = [port for port in self.ports if port.orientation == "output"]
+        self._add_ports(input_side, "input", 0.0)
+        self._add_ports(output_side, "output", self.icon.width)
         self._initial_fit_pending = True
 
     def showEvent(self, event) -> None:  # noqa: N802 (Qt API name)

BEdit/src/bedit/gui/graphics/workspace.py

@@ -173,8 +173,16 @@ class ComponentGraphicsItem(QGraphicsObject):
             | QGraphicsItem.GraphicsItemFlag.ItemIsSelectable
             | QGraphicsItem.GraphicsItemFlag.ItemSendsGeometryChanges
         )
-        self.input_ports = self._create_ports(component.inputs, "target", 0.0)
+        self.input_ports = self._create_ports(
-        self.output_ports = self._create_ports(component.outputs, "source", self.WIDTH)
+            [port for port in component.ports if port.orientation != "output"],
+            "target",
+            0.0,
+        )
+        self.output_ports = self._create_ports(
+            [port for port in component.ports if port.orientation == "output"],
+            "source",
+            self.WIDTH,
+        )
         self.setTransformOriginPoint(self.hitbox.center())
         self.setRotation(component.rotation)
         self.name_label: NameLabelItem | None = None
@@ -371,8 +379,10 @@ class ConnectionGraphicsItem(QGraphicsPathItem):
         super().__init__()
         self.connection_id = connection.id
         self.name = connection.name
+        self.connection_type = connection.type
         self.source_is_junction = connection.source.junction is not None
         self.target_is_junction = connection.target.junction is not None
+        self.causality = connection.causality
         self.controller = controller
         self.style = style or ConnectionStyle()
         self.start = QPointF()
@@ -417,7 +427,11 @@ class ConnectionGraphicsItem(QGraphicsPathItem):
             self.setSelected(True)
         menu = QMenu()
         add_node_action = menu.addAction("Add Node")
-        add_junction_action = menu.addAction("Add Junction")
+        add_junction_action = (
+            menu.addAction("Add Junction")
+            if self.connection_type != "power"
+            else None
+        )
         menu.addSeparator()
         options_action = menu.addAction("Connection Options…")
         selected = menu.exec(event.screenPos())
@@ -425,7 +439,7 @@ class ConnectionGraphicsItem(QGraphicsPathItem):
             scene = self.scene()
             if isinstance(scene, GraphScene):
                 scene.add_route_node("connection", self.connection_id, event.scenePos())
-        elif selected is add_junction_action:
+        elif add_junction_action is not None and selected is add_junction_action:
             scene = self.scene()
             if isinstance(scene, GraphScene):
                 scene.add_connection_junction(self.connection_id, event.scenePos())
@@ -512,12 +526,36 @@ class ConnectionGraphicsItem(QGraphicsPathItem):
         if self.style.arrow_style == "open":
             painter.drawLine(tip, right)
 
+    def _draw_causality_mark(
+        self, painter: QPainter, point: QPointF, direction: QPointF, *, warning: bool
+    ) -> None:
+        length = max(0.001, (direction.x() ** 2 + direction.y() ** 2) ** 0.5)
+        normal = QPointF(-direction.y() / length, direction.x() / length)
+        half_length = 6.0
+        color = QColor("#c25a00") if warning else self.pen().color()
+        painter.setPen(QPen(color, max(2.0, self.pen().widthF()), Qt.PenStyle.SolidLine))
+        painter.drawLine(point - normal * half_length, point + normal * half_length)
+
     def paint(self, painter: QPainter, option, widget=None) -> None:
         super().paint(painter, option, widget)
         if self.style.arrow_at_target and not self.target_is_junction:
             self._draw_arrow(painter, self.end, self.end_direction)
         if self.style.arrow_at_source and not self.source_is_junction:
             self._draw_arrow(painter, self.start, -self.start_direction)
+        if self.causality in {"source", "warn_source"}:
+            self._draw_causality_mark(
+                painter,
+                self.start,
+                self.start_direction,
+                warning=self.causality == "warn_source",
+            )
+        elif self.causality in {"target", "warn_target"}:
+            self._draw_causality_mark(
+                painter,
+                self.end,
+                self.end_direction,
+                warning=self.causality == "warn_target",
+            )
 
 
 class WaypointHandle(QGraphicsEllipseItem):
@@ -898,12 +936,12 @@ class GraphScene(QGraphicsScene):
         owner = self.controller.active_component
         if owner is None or owner.implementation_kind != "graph":
             return
-        for port in owner.inputs:
+        for port in (port for port in owner.ports if port.orientation != "output"):
             item = InterfaceTerminalItem(port, "input", self.controller)
             self.addItem(item)
             item.setPos(port.x, port.y)
             self.input_items[port.id] = item
-        for port in owner.outputs:
+        for port in (port for port in owner.ports if port.orientation == "output"):
             item = InterfaceTerminalItem(port, "output", self.controller)
             self.addItem(item)
             item.setPos(port.x, port.y)
@@ -1224,15 +1262,16 @@ class GraphScene(QGraphicsScene):
             source_item: ComponentGraphicsItem, target_item: ComponentGraphicsItem
         ) -> None:
             source_ports = [
-                *source_item.component.outputs,
-                *(
                 port
-                    for port in source_item.component.inputs
+                for port in source_item.component.ports
-                    if port.orientation == "indifferent"
+                if port.orientation in {"output", "indifferent"}
-                ),
             ]
             for output in source_ports:
-                for input_port in target_item.component.inputs:
+                for input_port in (
+                    port
+                    for port in target_item.component.ports
+                    if port.orientation in {"input", "indifferent"}
+                ):
                     if not PortTypeRegistry.compatible(
                         output.type,
                         input_port.type,
@@ -1267,7 +1306,11 @@ class GraphScene(QGraphicsScene):
         choices: list[ConnectionChoice] = []
         interface = Endpoint(interface=terminal.port.id)
         if terminal.direction == "input":
-            for port in component.component.inputs:
+            for port in (
+                port
+                for port in component.component.ports
+                if port.orientation in {"input", "indifferent"}
+            ):
                 target = Endpoint(block=component.component_id, port=port.id)
                 if not PortTypeRegistry.compatible(
                     terminal.port.type, port.type, terminal.port.domain, port.domain
@@ -1286,12 +1329,9 @@ class GraphScene(QGraphicsScene):
                 )
         else:
             ports = [
-                *component.component.outputs,
-                *(
                 port
-                    for port in component.component.inputs
+                for port in component.component.ports
-                    if port.orientation == "indifferent"
+                if port.orientation in {"output", "indifferent"}
-                ),
             ]
             for port in ports:
                 source = Endpoint(block=component.component_id, port=port.id)
@@ -1319,7 +1359,11 @@ class GraphScene(QGraphicsScene):
     ) -> list[ConnectionChoice]:
         choices: list[ConnectionChoice] = []
         source = junction.endpoint
-        for port in component.component.inputs:
+        for port in (
+            port
+            for port in component.component.ports
+            if port.orientation in {"input", "indifferent"}
+        ):
             target = Endpoint(block=component.component_id, port=port.id)
             if not PortTypeRegistry.compatible(junction.junction.type, port.type):
                 continue
@@ -1600,6 +1644,8 @@ class GraphScene(QGraphicsScene):
         graphics = self.connection_items.get(connection_id)
         if connection is None or graphics is None:
             return
+        if connection.type == "power":
+            return
         snapped = _snapped(position)
         anchors = [graphics.start, *points, graphics.end]
 
@@ -1850,8 +1896,7 @@ class GraphWorkspaceView(QGraphicsView):
             return
         blocks: set[str] = set()
         connections: set[str] = set()
-        inputs: set[str] = set()
+        ports: set[str] = set()
-        outputs: set[str] = set()
         annotations: set[str] = set()
         for item in self.scene().selectedItems():
             if isinstance(item, ComponentGraphicsItem):
@@ -1859,10 +1904,10 @@ class GraphWorkspaceView(QGraphicsView):
             elif isinstance(item, ConnectionGraphicsItem):
                 connections.add(item.connection_id)
             elif isinstance(item, InterfaceTerminalItem):
-                (inputs if item.direction == "input" else outputs).add(item.port.id)
+                ports.add(item.port.id)
             elif isinstance(item, (AnnotationGraphicsItem, LineAnnotationGraphicsItem)):
                 annotations.add(item.annotation_id)
-        self.controller.delete_selection(blocks, connections, inputs, outputs)
+        self.controller.delete_selection(blocks, connections, ports)
         self.controller.delete_annotations(annotations)
 
     def has_selected_components(self) -> bool:

BEdit/src/bedit/gui/main_window.py

@@ -540,8 +540,7 @@ class MainWindow(QMainWindow):
             component.source.get("declarations", ""),
             component.source.get("initialEquations", ""),
             component.source.get("equations", ""),
-            component.inputs,
+            component.ports,
-            component.outputs,
             component.parameters,
         )
 
@@ -569,12 +568,11 @@ class MainWindow(QMainWindow):
     @Slot()
     def apply_text_definition(self) -> bool:
         try:
-            inputs, outputs = self.ui.textDefinitionEditor.ports
+            ports = self.ui.textDefinitionEditor.ports
             self._applying_text_definition = True
             try:
                 self.document_controller.replace_active_text_definition(
-                    inputs,
+                    ports,
-                    outputs,
                     self.ui.textDefinitionEditor.declarations,
                     self.ui.textDefinitionEditor.initial_equations,
                     self.ui.textDefinitionEditor.equations,
@@ -643,12 +641,23 @@ class MainWindow(QMainWindow):
         )
         if not filename:
             return
+        self.open_document_path(Path(filename), check_unsaved=False)
+
+    def open_document_path(self, path: Path, *, check_unsaved: bool = True) -> bool:
+        """Open a document path selected by the UI or supplied at startup."""
+
+        if check_unsaved and (
+            not self._resolve_source_edits() or not self._maybe_save()
+        ):
+            return False
         try:
-            self.document_controller.load(Path(filename))
+            self.document_controller.load(path)
-            self.log.info("Opened document %s", filename)
+            self.log.info("Opened document %s", path)
         except (OSError, ValueError) as error:
-            self.log.error("Could not open document %s: %s", filename, error)
+            self.log.error("Could not open document %s: %s", path, error)
             QMessageBox.critical(self, "Could not open graph", str(error))
+            return False
+        return True
 
     @Slot()
     def save_document(self) -> bool:
@@ -818,9 +827,8 @@ class MainWindow(QMainWindow):
         elif selected is ports_action:
             dialog = PortOptionsDialog(component, self)
             if dialog.exec() == dialog.DialogCode.Accepted:
-                old_inputs, old_outputs = deepcopy(component.inputs), deepcopy(component.outputs)
+                old_ports = deepcopy(component.ports)
-                component.inputs = dialog.inputs
+                component.ports = dialog.ports
-                component.outputs = dialog.outputs
                 library = next(
                     (
                         library
@@ -834,7 +842,7 @@ class MainWindow(QMainWindow):
                         library.document.validate()
                         DocumentSerializer.save(library.document, Path(library.source_path))
                 except (OSError, ValueError) as error:
-                    component.inputs, component.outputs = old_inputs, old_outputs
+                    component.ports = old_ports
                     self.log.error("Could not change library ports: %s", error)
                     QMessageBox.warning(self, "Cannot change library ports", str(error))
                 self.library_tree_model.rebuild()
@@ -876,7 +884,7 @@ class MainWindow(QMainWindow):
             return
         try:
             self.document_controller.edit_component_ports(
-                component_id, dialog.inputs, dialog.outputs
+                component_id, dialog.ports
             )
         except ValueError as error:
             self.log.error("Could not change component ports: %s", error)
@@ -912,8 +920,7 @@ class MainWindow(QMainWindow):
                     component_id,
                     dialog.ui.nameEdit.text().strip(),
                     dialog.edited_icon,
-                    dialog.edited_inputs,
+                    dialog.edited_ports,
-                    dialog.edited_outputs,
                     dialog.ui.showSubtreeCheckBox.isChecked(),
                     dialog.ui.showNameCheckBox.isChecked(),
                 )
@@ -926,8 +933,7 @@ class MainWindow(QMainWindow):
         owner = self.document_controller.active_component
         if owner is None:
             return
-        ports = owner.inputs if direction == "input" else owner.outputs
+        port = next((item for item in owner.ports if item.id == port_id), None)
-        port = next((item for item in ports if item.id == port_id), None)
         if port is None:
             return
         dialog = ItemOptionsDialog(f"{direction.title()} Options", port.name, self)

BEdit/untitled.bedit.json

@@ -14,8 +14,7 @@
       },
       "rotation": 0.0,
       "interface": {
-        "inputs": [],
+        "ports": []
-        "outputs": []
       },
       "parameters": [],
       "icon": {
@@ -69,7 +68,7 @@
               },
               "rotation": 0.0,
               "interface": {
-                "inputs": [
+                "ports": [
                   {
                     "id": "port-2e1d884f",
                     "name": "p",
@@ -96,9 +95,7 @@
                     "orientation": "input",
                     "domain": "power",
                     "causality": "preferred effort out"
-                  }
+                  },
-                ],
-                "outputs": [
                   {
                     "id": "port-ca7716d5",
                     "name": "state",
@@ -193,7 +190,7 @@
               },
               "rotation": 0.0,
               "interface": {
-                "inputs": [
+                "ports": [
                   {
                     "id": "port-3e53bf80",
                     "name": "p",
@@ -221,8 +218,7 @@
                     "domain": "power",
                     "causality": "indifferent"
                   }
-                ],
+                ]
-                "outputs": []
               },
               "parameters": [],
               "icon": {
@@ -275,7 +271,7 @@
               },
               "rotation": 0.0,
               "interface": {
-                "inputs": [
+                "ports": [
                   {
                     "id": "port-2e1d884f",
                     "name": "p",
@@ -303,8 +299,7 @@
                     "domain": "power",
                     "causality": "indifferent"
                   }
-                ],
+                ]
-                "outputs": []
               },
               "parameters": [
                 {
@@ -371,8 +366,7 @@
               },
               "rotation": 0.0,
               "interface": {
-                "inputs": [],
+                "ports": [
-                "outputs": [
                   {
                     "id": "port-2e1d884f",
                     "name": "p",
@@ -473,7 +467,9 @@
               "name": "",
               "properties": {
                 "waypoints": []
-              }
+              },
+              "type": "power",
+              "causality": "none"
             },
             {
               "id": "a73a99a1-54e2-461d-a9a7-2d6d11d500f4",
@@ -488,7 +484,9 @@
               "name": "",
               "properties": {
                 "waypoints": []
-              }
+              },
+              "type": "power",
+              "causality": "none"
             },
             {
               "id": "dd5fb1e2-b125-4b5f-a792-dac89dd89ad3",
@@ -503,7 +501,9 @@
               "name": "",
               "properties": {
                 "waypoints": []
-              }
+              },
+              "type": "power",
+              "causality": "none"
             }
           ],
           "annotations": [],