fix(labels): show only changed label-set output

roar/application/query/label.py

@@ -2,6 +2,9 @@
 
 from __future__ import annotations
 
+from copy import deepcopy
+from typing import Any
+
 from ...db.context import create_database_context
 from ...integrations.glaas import GlaasClient
 from ..label_rendering import flatten_label_metadata
@@ -33,14 +36,20 @@ def build_set_labels_summary(request: LabelSetRequest) -> LabelCurrentSummary:
         service = LabelService(db_ctx, request.cwd)
         resolved = service.resolve_target(request.entity_type, request.target)
         patch = parse_label_pairs(request.pairs)
+        current_metadata = service.current_metadata(resolved)
         result = service.set_metadata(resolved, patch)
 
     heading = (
         f"Updated labels (version {result.version}):"
         if result.changed
         else f"Labels unchanged (version {result.version}):"
     )
-    return _build_current_summary(result.metadata, heading=heading)
+    changed_metadata = _extract_changed_metadata(current_metadata, result.metadata)
+    return _build_current_summary(
+        changed_metadata,
+        heading=heading,
+        empty_message="No label changes.",
+    )
 
 
 def copy_labels(request: LabelCopyRequest) -> str:
@@ -150,13 +159,44 @@ def build_label_history_summary(request: LabelHistoryRequest) -> LabelHistorySum
     )
 
 
-def _build_current_summary(metadata: dict, *, heading: str | None = None) -> LabelCurrentSummary:
+def _build_current_summary(
+    metadata: dict,
+    *,
+    heading: str | None = None,
+    empty_message: str = "No labels.",
+) -> LabelCurrentSummary:
     return LabelCurrentSummary(
         heading=heading,
         entries=_build_label_entries(metadata),
+        empty_message=empty_message,
     )
 
 
+_UNCHANGED = object()
+
+
+def _extract_changed_metadata(before: dict[str, Any], after: dict[str, Any]) -> dict[str, Any]:
+    changed = _diff_metadata(before, after)
+    return changed if isinstance(changed, dict) else {}
+
+
+def _diff_metadata(before: Any, after: Any) -> Any:
+    if isinstance(before, dict) and isinstance(after, dict):
+        changed: dict[str, Any] = {}
+        for key, after_value in after.items():
+            if key not in before:
+                changed[key] = deepcopy(after_value)
+                continue
+            diff = _diff_metadata(before[key], after_value)
+            if diff is not _UNCHANGED:
+                changed[key] = diff
+        return changed if changed else _UNCHANGED
+
+    if before == after:
+        return _UNCHANGED
+    return deepcopy(after)
+
+
 def _build_label_entries(metadata: dict) -> list[LabelEntrySummary]:
     return [
         LabelEntrySummary(key=key, display_value=value)

roar/application/query/results.py

@@ -89,13 +89,17 @@ def render(self, *, indent: str = "") -> str:
 class LabelCurrentSummary:
     heading: str | None = None
     entries: list[LabelEntrySummary] = field(default_factory=list)
+    empty_message: str = "No labels."
 
     def render(self) -> str:
         lines: list[str] = []
         if self.heading:
             lines.append(self.heading)
         if not self.entries:
-            lines.append("No labels.")
+            message = self.empty_message
+            if self.heading:
+                message = f"  {message}"
+            lines.append(message)
             return "\n".join(lines)
         indent = "  " if self.heading else ""
         lines.extend(entry.render(indent=indent) for entry in self.entries)

tests/application/query/test_label.py

@@ -72,16 +72,26 @@ def _push_request(tmp_path: Path, **overrides) -> LabelPushRequest:
     )
 
 
-def test_build_set_labels_summary_returns_typed_summary(tmp_path: Path) -> None:
+def test_build_set_labels_summary_returns_only_labels_changed_by_the_patch(
+    tmp_path: Path,
+) -> None:
     db_ctx = MagicMock()
     db_ctx.__enter__.return_value = db_ctx
     db_ctx.__exit__.return_value = None
     service = MagicMock()
     service.resolve_target.return_value = object()
+    service.current_metadata.return_value = {
+        "owner": "ml",
+        "roar": {"operation": {"kind": "run"}},
+    }
     service.set_metadata.return_value = MagicMock(
         changed=True,
         version=2,
-        metadata={"owner": "ml", "stage": "gold"},
+        metadata={
+            "owner": "ml",
+            "stage": "gold",
+            "roar": {"operation": {"kind": "run"}},
+        },
     )
 
     with (
@@ -92,10 +102,35 @@ def test_build_set_labels_summary_returns_typed_summary(tmp_path: Path) -> None:
 
     assert summary.heading == "Updated labels (version 2):"
     assert [(entry.key, entry.display_value) for entry in summary.entries] == [
-        ("owner", "ml"),
         ("stage", "gold"),
     ]
-    assert summary.render() == "Updated labels (version 2):\n  owner=ml\n  stage=gold"
+    assert summary.render() == "Updated labels (version 2):\n  stage=gold"
+
+
+def test_build_set_labels_summary_reports_no_label_changes_for_noop_updates(
+    tmp_path: Path,
+) -> None:
+    db_ctx = MagicMock()
+    db_ctx.__enter__.return_value = db_ctx
+    db_ctx.__exit__.return_value = None
+    service = MagicMock()
+    service.resolve_target.return_value = object()
+    service.current_metadata.return_value = {"owner": "ml", "stage": "gold"}
+    service.set_metadata.return_value = MagicMock(
+        changed=False,
+        version=2,
+        metadata={"owner": "ml", "stage": "gold"},
+    )
+
+    with (
+        patch("roar.application.query.label.create_database_context", return_value=db_ctx),
+        patch("roar.application.query.label.LabelService", return_value=service),
+    ):
+        summary = build_set_labels_summary(_set_request(tmp_path))
+
+    assert summary.heading == "Labels unchanged (version 2):"
+    assert summary.entries == []
+    assert summary.render() == "Labels unchanged (version 2):\n  No label changes."
 
 
 def test_build_copy_labels_summary_preserves_no_change_heading(tmp_path: Path) -> None:

tests/happy_path/test_label_command.py

@@ -259,6 +259,52 @@ def test_artifact_label_set_noop_does_not_create_new_version(
         rows = _artifact_label_rows(temp_git_repo, temp_git_repo / "processed.csv")
         assert rows == [(1, {"owner": "ml", "stage": "raw"})]
 
+    def test_job_label_set_output_shows_only_changed_labels_not_system_labels(
+        self,
+        temp_git_repo,
+        roar_cli,
+        git_commit,
+        sample_scripts,
+        sample_data,
+        python_exe,
+    ):
+        result = roar_cli("run", python_exe, "preprocess.py", "input.csv", "processed.csv")
+        assert result.returncode == 0
+        git_commit("After preprocess")
+
+        set_output = _assert_ok(
+            roar_cli(
+                "label",
+                "set",
+                "job",
+                "@1",
+                "phase=preprocess",
+                check=False,
+            )
+        )
+        assert "Updated labels (version 2):" in set_output
+        assert "phase=preprocess" in set_output
+        assert "roar.operation.kind=run" not in set_output
+        assert "roar.git.commit=" not in set_output
+
+        noop_output = _assert_ok(
+            roar_cli(
+                "label",
+                "set",
+                "job",
+                "@1",
+                "phase=preprocess",
+                check=False,
+            )
+        )
+        assert "Labels unchanged (version 2):" in noop_output
+        assert "No label changes." in noop_output
+        assert "phase=preprocess" not in noop_output
+
+        label_show = _assert_ok(roar_cli("label", "show", "job", "@1", check=False))
+        assert "phase=preprocess" in label_show
+        assert "roar.operation.kind=run" in label_show
+
     def test_dag_job_and_artifact_labels_are_visible_in_show_and_dag_json(
         self,
         temp_git_repo,