project workflow state -> output

src/wf_core/validation/core.py

@@ -20,6 +20,7 @@ from wf_core.validation.steps import (
     validate_interrupt_node,
     validate_node_use,
     validate_subgraph_node,
+    validate_workflow_output_bindings,
 )
 
 
@@ -27,6 +28,7 @@ def validate_workflow(workflow: Workflow) -> ValidationReport:
     report = ValidationReport()
 
     node_defs = _collect_node_defs(workflow, report)
+    validate_workflow_output_bindings(workflow.output, workflow, report)
     nodes_by_id = _validate_nodes(workflow, node_defs, report)
     _validate_start(workflow, nodes_by_id, report)
     outgoing = _validate_edges(workflow, nodes_by_id, node_defs, report)

src/wf_core/validation/issues.py

@@ -18,6 +18,7 @@ class ValidationIssueCode(StrEnum):
     INVALID_NODE_INPUT_FIELD = "invalid_node_input_field"
     INVALID_SOURCE_PATH = "invalid_source_path"
     INVALID_NODE_OUTPUT_FIELD = "invalid_node_output_field"
+    INVALID_WORKFLOW_OUTPUT_FIELD = "invalid_workflow_output_field"
     INVALID_DESTINATION_PATH = "invalid_destination_path"
     EMPTY_CONDITION_ARGS = "empty_condition_args"
     INVALID_CONDITION_PATH = "invalid_condition_path"

src/wf_core/validation/steps.py

@@ -16,6 +16,7 @@ from wf_core.models.steps import (
     ForeachNode,
     InputBinding,
     InputPathBinding,
+    InputValueBinding,
     InterruptNode,
     NodeUse,
     OutputBinding,
@@ -153,6 +154,56 @@ def _validate_boundary_bindings(
         )
 
 
+def validate_workflow_output_bindings(
+    bindings: list[InputBinding],
+    workflow: Workflow,
+    report: ValidationReport,
+) -> None:
+    """Validate final workflow output projection bindings.
+
+    Root output bindings reuse input-binding shape: graph paths flow into a
+    local output payload that is later validated against `output_schema`.
+    """
+    output_fields = set(workflow.output_schema.properties)
+    state_root_fields = workflow.state_schema.root_fields()
+    input_root_fields = set(workflow.input_schema.properties)
+    output_targets = []
+    for output_index, binding in enumerate(bindings):
+        output_targets.append(binding.target)
+        destination_root = _local_root(binding.target)
+        if destination_root is None or (
+            destination_root != "." and destination_root not in output_fields
+        ):
+            report.add(
+                ValidationIssueCode.INVALID_WORKFLOW_OUTPUT_FIELD,
+                f"output[{output_index}].target",
+                "destination field is not declared in workflow output schema",
+            )
+        if isinstance(binding, InputPathBinding) and not is_valid_source_path(
+            binding.path,
+            state_root_fields,
+            input_root_fields,
+            allow_context=True,
+        ):
+            report.add(
+                ValidationIssueCode.INVALID_SOURCE_PATH,
+                f"output[{output_index}].path",
+                "source path must start with input., state., or context. and reference a declared root field when applicable",
+            )
+        elif not isinstance(binding, (InputPathBinding, InputValueBinding)):
+            report.add(
+                ValidationIssueCode.INVALID_WORKFLOW_OUTPUT_FIELD,
+                f"output[{output_index}]",
+                "unsupported workflow output binding",
+            )
+    if has_overlapping_paths(output_targets):
+        report.add(
+            ValidationIssueCode.INVALID_WORKFLOW_OUTPUT_FIELD,
+            "output",
+            "workflow output has overlapping output payload paths",
+        )
+
+
 def _local_root(path: str | LocalPath) -> str | None:
     try:
         parts = split_local_path(path)