feat: expose draft document replacement over rpc

tests/wf_transport_rpc_http/test_app.py

@@ -413,6 +413,60 @@ async def test_rpc_draft_workspace_methods(tmp_path) -> None:
     assert artifact["result"]["artifact_id"] == "remote_artifact"
 
 
+async def test_rpc_replace_document_replaces_complete_draft_workspace(
+    tmp_path,
+) -> None:
+    server = build_local_static_workflow_server(tmp_path / "store")
+    app = create_rpc_app(server)
+    transport = httpx.ASGITransport(app=app)
+    async with httpx.AsyncClient(transport=transport, base_url="http://test") as client:
+        await _rpc(
+            client,
+            "workflow.draft_workspaces.create_empty",
+            {"workspace_id": "report", "name": "initial"},
+        )
+        initial = await _rpc(
+            client,
+            "workflow.draft_workspaces.get",
+            {"workspace_id": "report", "include_draft": True},
+        )
+        replacement = {**initial["result"]["draft"], "name": "replacement"}
+
+        replaced = await _rpc(
+            client,
+            "workflow.draft_workspaces.replace_document",
+            {
+                "workspace_id": "report",
+                "revision": 1,
+                "draft": replacement,
+            },
+        )
+        inspected = await _rpc(
+            client,
+            "workflow.draft_workspaces.get",
+            {"workspace_id": "report", "include_draft": True},
+        )
+        malformed = await _rpc(
+            client,
+            "workflow.draft_workspaces.replace_document",
+            {
+                "workspace_id": "report",
+                "revision": 2,
+                "draft": [],
+            },
+        )
+        after_malformed = await _rpc(
+            client,
+            "workflow.draft_workspaces.get",
+            {"workspace_id": "report", "include_draft": True},
+        )
+
+    assert replaced["result"]["revision"] == 2
+    assert inspected["result"]["draft"] == replacement
+    assert malformed["error"]["code"] == -32602
+    assert after_malformed["result"] == inspected["result"]
+
+
 async def test_rpc_draft_workspace_lifecycle_methods(tmp_path) -> None:
     server = build_local_static_workflow_server(tmp_path / "store")
     app = create_rpc_app(server)

tests/wf_transport_rpc_http/test_client.py

@@ -399,6 +399,44 @@ async def test_rpc_client_sends_exact_draft_lifecycle_payloads() -> None:
     ]
 
 
+async def test_rpc_client_sends_exact_replace_document_payload() -> None:
+    calls: list[dict[str, Any]] = []
+
+    class Client(RpcDraftClientMixin):
+        async def _call(self, method: str, params: dict[str, object]):
+            calls.append({"method": method, "params": params})
+            return {"revision": 5}
+
+    client = Client()
+    draft = {
+        "name": "report",
+        "input_schema": {"type": "object", "properties": {}},
+        "state_schema": {"type": "object", "properties": {}},
+        "output_schema": {"type": "object", "properties": {}},
+        "start": "finish",
+        "steps": {"finish": {"end": {}}},
+        "routes": {},
+    }
+
+    result = await client.replace_draft_workspace_document(
+        workspace_id="report",
+        revision=4,
+        draft=draft,
+    )
+
+    assert result["revision"] == 5
+    assert calls == [
+        {
+            "method": "workflow.draft_workspaces.replace_document",
+            "params": {
+                "workspace_id": "report",
+                "revision": 4,
+                "draft": draft,
+            },
+        }
+    ]
+
+
 async def test_rpc_client_builds_capability_free_draft_lifecycle(tmp_path) -> None:
     server = build_local_static_workflow_server(tmp_path / "store")
     app = create_rpc_app(server)