fix: reject missing tool field, escape newlines in quoted strings (conformance)

Author: blackwell-systems

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## v0.1.3 (2026-06-04)
+
+- Docs: update README for PyPI discoverability (gcformat.com, proxy, vs-toon links)
+- Fix: decoder rejects headers missing required `tool` field (conformance)
+- Fix: escape newlines as `\n` in quoted strings in `encode_generic`
+
 ## v0.1.2 (2026-06-04)
 
 - Fix: escape `"` inside quoted strings in `encode_generic`

src/gcf/decode.py

@@ -34,6 +34,9 @@ def decode(input_text: str) -> Payload:
         raise DecodeError(f"invalid header, expected 'GCF ...' got {header!r}")
     _parse_header(header[4:], p)
 
+    if not p.tool:
+        raise DecodeError("header missing required 'tool' field")
+
     # Parse body: symbols and edges.
     symbols: list[Symbol] = []
     sym_by_id: dict[int, Symbol] = {}

src/gcf/generic.py

@@ -142,7 +142,7 @@ def _format_value(value: Any) -> str:
         return str(value)
     s = str(value)
     if "|" in s or "\n" in s or s == "":
-        escaped = s.replace("\\", "\\\\").replace('"', '\\"')
+        escaped = s.replace("\\", "\\\\").replace('"', '\\"').replace("\n", "\\n")
         return f'"{escaped}"'
     return s