fix(skill_engine): unescape multiline scalars without PyYAML

openspace/skill_engine/skill_utils.py

@@ -77,7 +77,12 @@ def _yaml_unquote(value: str) -> str:
            (value[0] == "'" and value[-1] == "'"):
             inner = value[1:-1]
             if value[0] == '"':
-                inner = inner.replace('\\"', '"').replace("\\\\", "\\")
+                inner = (
+                    inner.replace("\\\\", "\0")
+                    .replace('\\"', '"')
+                    .replace("\\n", "\n")
+                    .replace("\0", "\\")
+                )
             return inner
     return value
 

tests/skill_engine/test_set_frontmatter_multiline.py

@@ -2,7 +2,13 @@
 
 from __future__ import annotations
 
-from openspace.skill_engine.skill_utils import parse_frontmatter, set_frontmatter_field
+import builtins
+
+from openspace.skill_engine.skill_utils import (
+    get_frontmatter_field,
+    parse_frontmatter,
+    set_frontmatter_field,
+)
 
 
 def test_set_frontmatter_field_preserves_multiline_description():
@@ -16,3 +22,17 @@ def test_set_frontmatter_field_replaces_block_scalar_without_orphan_lines():
     assert parse_frontmatter(out)["description"] == "new1\nnew2"
     assert "old1" not in out
     assert "old2" not in out
+
+
+def test_multiline_round_trip_without_pyyaml(monkeypatch):
+    real_import = builtins.__import__
+
+    def no_yaml(name, *args, **kwargs):
+        if name == "yaml" or name.startswith("yaml."):
+            raise ImportError("forced missing yaml")
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", no_yaml)
+    out = set_frontmatter_field("---\nname: x\n---\n", "description", "line1\nline2")
+    assert get_frontmatter_field(out, "description") == "line1\nline2"
+    assert parse_frontmatter(out)["description"] == "line1\nline2"