feat(s52): MAF-free nested payload builder (verdict_to_dict oracle) + file notifier

tests/test_notify.py

@@ -7,9 +7,10 @@ import MAF-tainted modules freely (``verdicts``) — only ``notify.py`` itself m
 from __future__ import annotations
 
 import io
+import json
 
-from portfolio_optimiser.notify import ConsoleNotifier, Notifier
-from portfolio_optimiser.verdicts import ProposalFeatures, Verdict, capture_verdict
+from portfolio_optimiser.notify import ConsoleNotifier, FileNotifier, Notifier, _verdict_payload
+from portfolio_optimiser.verdicts import ProposalFeatures, Verdict, capture_verdict, verdict_to_dict
 
 
 def _verdict() -> Verdict:
@@ -40,3 +41,31 @@ def test_console_emits_id_and_decision() -> None:
     out = stream.getvalue()
     assert verdict.id in out
     assert verdict.decision in out
+
+
+def test_payload_matches_verdict_to_dict_oracle() -> None:
+    """DRIFT-ORACLE: the duck-typed ``_verdict_payload`` reproduces ``verdict_to_dict``'s exact
+    NESTED shape (verdicts.py:124-139) without importing it at runtime — the test imports both
+    (tests may pull MAF freely) and pins them equal, so a ``Verdict`` shape change goes RED here
+    instead of silently diverging the notified payload."""
+    verdict = _verdict()
+    assert _verdict_payload(verdict) == verdict_to_dict(verdict)
+
+
+def test_file_notifier_byte_deterministic(tmp_path) -> None:
+    """FileNotifier appends one JSONL line per verdict — two writes of the same verdict are
+    byte-identical, LF-terminated, nested per the oracle shape, and carry no wall-clock key."""
+    path = tmp_path / "sub" / "notify.jsonl"
+    verdict = _verdict()
+    notifier = FileNotifier(str(path))
+    notifier(verdict)
+    first = path.read_bytes()
+    notifier(verdict)
+    second = path.read_bytes()
+    assert second == first * 2  # identical appended line bytes
+    line = first.decode("utf-8")
+    assert line.endswith("\n")
+    payload = json.loads(line)
+    assert payload["id"] == verdict.id
+    assert payload["proposal_features"]["affected_codes"] == ["03.1", "05.2"]
+    assert not any(k in payload for k in ("date", "timestamp", "created", "ts"))