diff --git a/src/wf_client/authoring.py b/src/wf_client/authoring.py
index 1d7726c9..4c33f232 100644
--- a/src/wf_client/authoring.py
+++ b/src/wf_client/authoring.py
@@ -221,11 +221,32 @@ def _seed_remote_node_defs(
     for requirement in artifact.required_capabilities:
         if requirement.kind != "node_spec":
             continue
-        input_schema = requirement.input_schema_snapshot
-        output_schema = requirement.output_schema_snapshot
-        if not isinstance(input_schema, dict) or not isinstance(output_schema, dict):
-            continue
         name = str(requirement.capability_ref())
+        node_uses = [
+            node
+            for node in artifact.workflow.nodes
+            if isinstance(node, NodeUse) and node.node == name
+        ]
+        input_fields = {
+            field
+            for node in node_uses
+            for binding in node.input
+            if (field := _binding_root_field(binding.target)) is not None
+        }
+        output_fields = {
+            field
+            for node in node_uses
+            for binding in node.output
+            if (field := _binding_root_field(binding.source)) is not None
+        }
+        input_schema = _snapshot_or_permissive_schema(
+            requirement.input_schema_snapshot,
+            input_fields,
+        )
+        output_schema = _snapshot_or_permissive_schema(
+            requirement.output_schema_snapshot,
+            output_fields,
+        )
         builder.seeded_node_defs.setdefault(
             name,
             NodeDef(
@@ -235,3 +256,29 @@ def _seed_remote_node_defs(
                 outcomes=outcomes_by_node.get(name, ["ok"]),
             ),
         )
+
+
+def _binding_root_field(path: object) -> str | None:
+    """Return a local binding's first field, excluding whole-payload ``.``."""
+    parts = getattr(path, "parts", ())
+    if not parts:
+        return None
+    return parts[0]
+
+
+def _snapshot_or_permissive_schema(
+    snapshot: object,
+    fields: set[str],
+) -> dict[str, Any]:
+    """Use a saved snapshot or an unconstrained schema for its used fields.
+
+    A missing server snapshot carries no type information. Declaring only the
+    fields already referenced by graph bindings lets local structural checks
+    proceed without inventing validation constraints for remote data.
+    """
+    if isinstance(snapshot, dict):
+        return snapshot
+    return {
+        "type": "object",
+        "properties": {field: {} for field in sorted(fields)},
+    }
diff --git a/tests/wf_client/test_authoring.py b/tests/wf_client/test_authoring.py
index 9e63ec47..ce1750ca 100644
--- a/tests/wf_client/test_authoring.py
+++ b/tests/wf_client/test_authoring.py
@@ -61,6 +61,37 @@ def valid_plan(version: int = 1) -> dict[str, Any]:
     }
 
 
+def remote_plan_without_schema_snapshots(version: int = 1) -> dict[str, Any]:
+    payload = valid_plan(version)
+    payload["plan"]["nodes"] = [
+        {
+            "id": "remote",
+            "type": "node",
+            "node": "app.default.remote",
+            "input": [],
+            "output": [],
+        },
+        {"id": "done", "type": "end", "outcome": "ok"},
+    ]
+    payload["plan"]["start"] = "remote"
+    payload["plan"]["edges"] = [
+        {"from": "remote", "outcome": "ok", "to": "done"}
+    ]
+    payload["required_capabilities"] = [
+        {
+            "ref": {"source": "app.default", "capability_key": "remote"},
+            "kind": "node_spec",
+            "input_schema_hash": None,
+            "input_schema_snapshot": None,
+            "output_schema_hash": None,
+            "output_schema_snapshot": None,
+            "observed_concrete_source": None,
+            "observed_at_epoch_ms": None,
+        }
+    ]
+    return payload
+
+
 @pytest.mark.asyncio
 async def test_validate_stops_before_remote_call_when_local_graph_is_invalid() -> None:
     port = FakePort()
@@ -118,3 +149,19 @@ async def test_edit_and_save_inspects_exact_saved_version() -> None:
     assert inspect == {"artifact_id": "report", "version": 2}
     assert saved.ref == ArtifactRef("report", 2)
     assert str(saved.workflow.output[0].target) == "value"
+
+
+@pytest.mark.asyncio
+async def test_editable_artifact_without_schema_snapshots_remains_saveable() -> None:
+    port = FakePort()
+    port.inspect_artifact_result = remote_plan_without_schema_snapshots(version=1)
+    graph = await App._from_port(cast(WorkflowClientPort, port)).edit_workflow(
+        "report", version=1
+    )
+
+    result = graph.validate_local()
+
+    assert result.ok is True
+    port.inspect_artifact_result = remote_plan_without_schema_snapshots(version=2)
+    saved = await graph.save(version=2)
+    assert saved.ref == ArtifactRef("report", 2)