feat(skill-learning): merge plugin skill updates

app-instance/backend/tests/unit/test_skill_learning_preservation.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from beaver.skills.learning.preservation import check_preservation
+from beaver.skills.learning.preservation import check_plugin_merge_preservation, check_preservation
 
 
 def test_preservation_passes_when_base_sections_remain() -> None:
@@ -25,3 +25,29 @@ def test_preservation_flags_dropped_section() -> None:
     assert report["passed"] is False
     assert report["risk_level"] == "high"
     assert "Safety" in report["dropped_sections"]
+
+
+def test_plugin_merge_preservation_checks_local_and_upstream_and_conflicts() -> None:
+    report = check_plugin_merge_preservation(
+        local_content="# Local\n\n## Review\n\nKeep review.\n",
+        upstream_content="# Upstream\n\n## Safety\n\nDo not leak secrets.\n",
+        draft_content="# Draft\n\n## Review\n\nKeep review.\n\n## Safety\n\nDo not leak secrets.\n",
+        merge_decisions={"resolved_conflicts": ["ordering"], "unresolved_conflicts": []},
+    )
+
+    assert report["mode"] == "plugin_three_way"
+    assert report["passed"] is True
+    assert report["local"]["passed"] is True
+    assert report["upstream"]["passed"] is True
+
+
+def test_plugin_merge_preservation_fails_unresolved_conflicts() -> None:
+    report = check_plugin_merge_preservation(
+        local_content="# Local\n\n## Review\n\nKeep review.\n",
+        upstream_content="# Upstream\n\n## Safety\n\nDo not leak secrets.\n",
+        draft_content="# Draft\n\n## Review\n\nKeep review.\n",
+        merge_decisions={"unresolved_conflicts": ["Safety conflict"]},
+    )
+
+    assert report["passed"] is False
+    assert report["unresolved_conflicts"] == ["Safety conflict"]