github · marcelsafin · Jul 7, 2026
@@ -51,6 +51,18 @@
 }
 
 
+def yaml_quote(value: str) -> str:
+    """Emit *value* as a double-quoted YAML scalar on a single line.
+
+    A hand-rolled quote cannot carry raw newlines (YAML folds them to
+    spaces) or control characters (the reader rejects them), so let the
+    YAML emitter produce the escapes.
+    """
+    return yaml.safe_dump(
+        str(value), default_style='"', allow_unicode=True, width=sys.maxsize
+    ).strip()
+
+
 # ---------------------------------------------------------------------------
 # IntegrationOption
 # ---------------------------------------------------------------------------
@@ -1475,21 +1487,17 @@ def setup(
             if not description:
                 description = f"Spec Kit: {command_name} workflow"
 
-            # Build SKILL.md with manually formatted frontmatter to match
-            # the release packaging script output exactly (double-quoted
-            # values, no yaml.safe_dump quoting differences).
-            def _quote(v: str) -> str:
-                escaped = v.replace("\\", "\\\\").replace('"', '\\"')
-                return f'"{escaped}"'
-
+            # Build SKILL.md with manually formatted frontmatter (stable
+            # double-quoted values). yaml_quote escapes newlines and control
+            # characters that a plain quoted f-string cannot carry.
             skill_content = (
                 f"---\n"
-                f"name: {_quote(skill_name)}\n"
-                f"description: {_quote(description)}\n"
-                f"compatibility: {_quote('Requires spec-kit project structure with .specify/ directory')}\n"
+                f"name: {yaml_quote(skill_name)}\n"
+                f"description: {yaml_quote(description)}\n"
+                f"compatibility: {yaml_quote('Requires spec-kit project structure with .specify/ directory')}\n"
                 f"metadata:\n"
-                f"  author: {_quote('github-spec-kit')}\n"
-                f"  source: {_quote('templates/commands/' + src_file.name)}\n"
+                f"  author: {yaml_quote('github-spec-kit')}\n"
+                f"  source: {yaml_quote('templates/commands/' + src_file.name)}\n"
                 f"---\n"
                 f"{processed_body}"
             )

@@ -18,7 +18,7 @@
 
 import yaml
 
-from ..base import IntegrationOption, SkillsIntegration
+from ..base import IntegrationOption, SkillsIntegration, yaml_quote
 from ..manifest import IntegrationManifest
 
 
@@ -153,20 +153,18 @@ def setup(
             if not description:
                 description = f"Spec Kit: {command_name} workflow"
 
-            # Build SKILL.md with manually formatted frontmatter
-            def _quote(v: str) -> str:
-                escaped = v.replace("\\", "\\\\").replace('"', '\\"')
-                return f'"{escaped}"'
-
+            # Build SKILL.md with manually formatted frontmatter. yaml_quote
+            # escapes newlines and control characters that a plain quoted
+            # f-string cannot carry.
             skill_content = (
                 f"---\n"
-                f"name: {_quote(skill_name)}\n"
-                f"description: {_quote(description)}\n"
+                f"name: {yaml_quote(skill_name)}\n"
+                f"description: {yaml_quote(description)}\n"
                 f"compatibility: "
-                f"{_quote('Requires spec-kit project structure with .specify/ directory')}\n"
+                f"{yaml_quote('Requires spec-kit project structure with .specify/ directory')}\n"
                 f"metadata:\n"
-                f"  author: {_quote('github-spec-kit')}\n"
-                f"  source: {_quote('templates/commands/' + src_file.name)}\n"
+                f"  author: {yaml_quote('github-spec-kit')}\n"
+                f"  source: {yaml_quote('templates/commands/' + src_file.name)}\n"
                 f"---\n"
                 f"{processed_body}"
             )

@@ -0,0 +1,111 @@
+"""Regression tests for SKILL.md frontmatter quoting (#3391).
+
+The skills setup path builds SKILL.md frontmatter by hand with
+double-quoted values. A double-quoted YAML scalar cannot carry a raw
+newline (the parser folds it to a space) or a control character (the
+reader rejects the document), so descriptions taken from template
+frontmatter must be escaped by the YAML emitter.
+"""
+
+from pathlib import Path
+
+import yaml
+
+from specify_cli.integrations import get_integration
+from specify_cli.integrations.base import yaml_quote
+from specify_cli.integrations.manifest import IntegrationManifest
+
+MULTILINE = "first line\nsecond line\n"
+CONTROL = "ding\aling"
+
+HOSTILE_TEMPLATE = """---
+description: |
+  first line
+  second line
+---
+
+Body of the command.
+"""
+
+CONTROL_TEMPLATE = """---
+description: "ding\\aling"
+---
+
+Body of the command.
+"""
+
+
+def _parse_frontmatter(skill_file: Path) -> dict:
+    content = skill_file.read_text(encoding="utf-8")
+    assert content.startswith("---\n")
+    return yaml.safe_load(content.split("---", 2)[1])
+
+
+def _fake_templates(tmp_path: Path, body: str) -> Path:
+    templates = tmp_path / "templates"
+    templates.mkdir(exist_ok=True)
+    (templates / "plan.md").write_text(body, encoding="utf-8")
+    return templates
+
+
+class TestYamlQuote:
+    def test_simple_value_keeps_plain_double_quoted_form(self):
+        assert yaml_quote("speckit-plan") == '"speckit-plan"'
+        assert yaml_quote('say "hi"') == '"say \\"hi\\""'
+        assert yaml_quote("back\\slash") == '"back\\\\slash"'
+
+    def test_multiline_value_round_trips(self):
+        quoted = yaml_quote(MULTILINE)
+        assert "\n" not in quoted
+        assert yaml.safe_load(quoted) == MULTILINE
+
+    def test_control_character_round_trips(self):
+        quoted = yaml_quote(CONTROL)
+        assert "\a" not in quoted
+        assert yaml.safe_load(quoted) == CONTROL
+
+
+class TestSkillFrontmatterQuoting:
+    def _generate(self, tmp_path, monkeypatch, template: str) -> Path:
+        integration = get_integration("agy")
+        monkeypatch.setattr(
+            integration,
+            "shared_commands_dir",
+            lambda: _fake_templates(tmp_path, template),
+        )
+        manifest = IntegrationManifest("agy", tmp_path)
+        created = integration.setup(tmp_path, manifest)
+        skill_files = [f for f in created if f.name == "SKILL.md"]
+        assert len(skill_files) == 1
+        return skill_files[0]
+
+    def test_multiline_description_survives(self, tmp_path, monkeypatch):
+        skill_file = self._generate(tmp_path, monkeypatch, HOSTILE_TEMPLATE)
+        fm = _parse_frontmatter(skill_file)
+        assert fm["description"] == MULTILINE
+
+    def test_control_character_description_parses(self, tmp_path, monkeypatch):
+        skill_file = self._generate(tmp_path, monkeypatch, CONTROL_TEMPLATE)
+        fm = _parse_frontmatter(skill_file)
+        assert fm["description"] == CONTROL
+
+
+class TestHermesSkillFrontmatterQuoting:
+    def test_multiline_description_survives(self, tmp_path, monkeypatch):
+        home = tmp_path / "home"
+        home.mkdir(exist_ok=True)
+        monkeypatch.setattr(Path, "home", lambda: home)
+
+        integration = get_integration("hermes")
+        monkeypatch.setattr(
+            integration,
+            "shared_commands_dir",
+            lambda: _fake_templates(tmp_path, HOSTILE_TEMPLATE),
+        )
+        manifest = IntegrationManifest("hermes", tmp_path)
+        created = integration.setup(tmp_path, manifest)
+        skill_files = [f for f in created if f.name == "SKILL.md"]
+        assert len(skill_files) == 1
+
+        fm = _parse_frontmatter(skill_files[0])
+        assert fm["description"] == MULTILINE