declarative Markdown workflow layer

src/markitect_tool/extension/builtins.py

@@ -11,7 +11,10 @@ def builtin_extension_registry() -> ExtensionRegistry:
     """Return descriptors for built-in Markitect extensions."""
 
     registry = default_query_engine_registry().extension_registry()
-    for descriptor in _processor_descriptors() + [_local_sqlite_backend_descriptor()]:
+    for descriptor in _processor_descriptors() + [
+        _local_sqlite_backend_descriptor(),
+        _workflow_engine_descriptor(),
+    ]:
         registry.register(descriptor)
     return registry
 
@@ -90,3 +93,30 @@ def _local_sqlite_backend_descriptor() -> ExtensionDescriptor:
         docs=["docs/local-index-backend.md", "docs/backend-fabric.md"],
         examples=["examples/backends/local-sqlite-backend.md"],
     )
+
+
+def _workflow_engine_descriptor() -> ExtensionDescriptor:
+    return ExtensionDescriptor(
+        id="workflow.markdown-dataflow",
+        kind="workflow-engine",
+        summary="Declarative Markdown dataflow workflow engine.",
+        capabilities=[
+            ProcessingCapability(id="workflow", kind="execute"),
+            ProcessingCapability(id="markdown", kind="read"),
+            ProcessingCapability(id="templates", kind="execute"),
+            ProcessingCapability(id="provenance", kind="emit"),
+        ],
+        safety={
+            "reads_files": True,
+            "writes_output_files": True,
+            "network": False,
+            "assisted_generation": "adapter-only",
+        },
+        input_contract="Markdown/YAML workflow definition",
+        output_contract="WorkflowRunResult",
+        diagnostics_namespace="workflow",
+        provenance_prefix="workflow",
+        cli={"commands": ["mkt workflow inspect", "mkt workflow plan", "mkt workflow run"]},
+        docs=["docs/workflow-definition-standard.md"],
+        examples=["examples/workflows/adr-release-notes.workflow.md"],
+    )