concurrent foreach preparation, types, validation, refactors

src/wf_core/validation/core.py

@@ -75,7 +75,12 @@ def _validate_nodes(
             )
         elif isinstance(node, ForeachNode):
             validate_foreach_node(
-                node, index, report, state_root_fields, input_root_fields
+                node,
+                index,
+                report,
+                state_root_fields,
+                input_root_fields,
+                workflow,
             )
         elif isinstance(node, InterruptNode):
             validate_interrupt_node(

src/wf_core/validation/issues.py

@@ -21,6 +21,7 @@ class ValidationIssueCode(StrEnum):
     EMPTY_CONDITION_ARGS = "empty_condition_args"
     INVALID_CONDITION_PATH = "invalid_condition_path"
     INVALID_FOREACH_SOURCE = "invalid_foreach_source"
+    INVALID_FOREACH_COLLECT_DESTINATION = "invalid_foreach_collect_destination"
     INVALID_INTERRUPT_SOURCE = "invalid_interrupt_source"
     INVALID_INTERRUPT_DESTINATION = "invalid_interrupt_destination"
 

src/wf_core/validation/outcomes.py

@@ -13,7 +13,10 @@ def declared_outcomes_for_step(step: Step, node_defs: dict[str, NodeDef]) -> set
     if step.type == "condition":
         return {"true", "false"}
     if step.type == "foreach":
-        return {"loop", "done"}
+        outcomes = {"loop", "done"}
+        if step.item_error.action in {"skip", "collect"}:
+            outcomes.add("completed_with_errors")
+        return outcomes
     if step.type == "join":
         return {"done"}
     if isinstance(step, InterruptNode):

src/wf_core/validation/steps.py

@@ -149,6 +149,7 @@ def validate_foreach_node(
     report: ValidationReport,
     state_root_fields: set[str],
     input_root_fields: set[str],
+    workflow: Workflow,
 ) -> None:
     if not is_valid_source_path(node.over, state_root_fields, input_root_fields):
         report.add(
@@ -156,6 +157,27 @@ def validate_foreach_node(
             f"nodes[{index}].over",
             "foreach source path must start with input. or state. and reference a declared root field",
         )
+    if node.item_error.action != "collect":
+        return
+    collect_to = node.item_error.collect_to
+    if collect_to is None:
+        return
+    destination_root = _state_destination_root(collect_to)
+    state_fields = workflow.state_schema.field_index()
+    field = state_fields.get(collect_to)
+    if destination_root is None or destination_root not in state_root_fields:
+        report.add(
+            ValidationIssueCode.INVALID_FOREACH_COLLECT_DESTINATION,
+            f"nodes[{index}].item_error.collect_to",
+            "collect_to must start with state. and reference a declared state field",
+        )
+        return
+    if field is None or field.type != "array":
+        report.add(
+            ValidationIssueCode.INVALID_FOREACH_COLLECT_DESTINATION,
+            f"nodes[{index}].item_error.collect_to",
+            "collect_to must reference a declared array state field",
+        )
 
 
 def validate_interrupt_node(