fix: preserve escaped instinct strings through serialization

RED: multiline/control serialization and newline decoding failed; C1/NEL cases exposed malformed or folded YAML. GREEN: 40 targeted tests and 126 complete Linux tests pass; quote/parser coverage 100%/97.4%. Unicode, Windows paths and legacy escapes survive round trips; Pi/catalog checks pass.
(cherry picked from commit 1b1119f409)

skills/continuous-learning-v2/scripts/instinct-cli.py

@@ -238,11 +238,10 @@ def _fetch_import_url(source: str, *, max_bytes: int = 2 * 1024 * 1024) -> str:
 def _yaml_quote(value: str) -> str:
     """Quote a string for safe YAML frontmatter serialization.
 
-    Uses double quotes and escapes embedded double-quote characters to
-    prevent malformed YAML when the value contains quotes.
+    JSON double-quoted strings are valid YAML and keep control characters
+    escaped on one line, preserving instinct frontmatter boundaries.
     """
-    escaped = value.replace('\\', '\\\\').replace('"', '\\"')
-    return f'"{escaped}"'
+    return json.dumps(value)
 
 
 # ─────────────────────────────────────────────
@@ -546,7 +545,10 @@ def parse_instinct_file(content: str) -> list[dict]:
                 value = value.strip()
                 # Unescape quoted YAML strings
                 if value.startswith('"') and value.endswith('"'):
-                    value = value[1:-1].replace('\\"', '"').replace('\\\\', '\\')
+                    try:
+                        value = json.loads(value)
+                    except json.JSONDecodeError:
+                        value = value[1:-1].replace('\\"', '"').replace('\\\\', '\\')
                 elif value.startswith("'") and value.endswith("'"):
                     value = value[1:-1].replace("''", "'")
                 if key == 'confidence':

skills/continuous-learning-v2/scripts/test_parse_instinct.py

@@ -281,6 +281,36 @@ def test_parse_confidence_preserves_valid_range(confidence):
     assert parse_instinct_file(content)[0]["confidence"] == confidence
 
 
+@pytest.mark.parametrize("value", [
+    "line one\nline two", "tab\tvalue", "carriage\rreturn",
+    'when writing "quoted" text', r"C:\Users\name", "caf\u00e9",
+    r"literal\ntext", "line\n---\nid: other\n---", "control\x01value",
+])
+def test_quoted_instinct_strings_roundtrip(value: str) -> None:
+    quoted = _mod._yaml_quote(value)
+    assert json.loads(quoted) == value
+    instincts = parse_instinct_file(f"---\nid: roundtrip\ntrigger: {quoted}\n---\nBody")
+    assert len(instincts) == 1
+    assert instincts[0]["trigger"] == value
+
+
+def test_parse_quoted_instinct_decodes_newline_escape() -> None:
+    content = '---\nid: newline\ntrigger: "line one\\nline two"\n---\nBody'
+    assert parse_instinct_file(content)[0]["trigger"] == "line one\nline two"
+
+
+@pytest.mark.parametrize("value", ["line\u0085value", "line\u0090value"])
+def test_unicode_controls_are_escaped_for_yaml(value: str) -> None:
+    quoted = _mod._yaml_quote(value)
+    assert quoted.isascii()
+    assert json.loads(quoted) == value
+
+
+def test_parse_quoted_instinct_preserves_legacy_escape() -> None:
+    content = '---\nid: legacy\ntrigger: "C:\\projects"\n---\nBody'
+    assert parse_instinct_file(content)[0]["trigger"] == r"C:\projects"
+
+
 def test_parse_trigger_strips_quotes():
     content = """\
 ---