feat(s52): Notifier protocol + console notifier + MAF-free registration

tests/test_notify.py

@@ -0,0 +1,42 @@
+"""S5.2 — Varsling: unit/contract tests for ``notify.py`` (Notifier protocol + notifiers).
+
+Detach-seam (RED-when-detached) twins live in ``tests/test_notify_loadbearing.py``. Tests may
+import MAF-tainted modules freely (``verdicts``) — only ``notify.py`` itself must stay MAF-free.
+"""
+
+from __future__ import annotations
+
+import io
+
+from portfolio_optimiser.notify import ConsoleNotifier, Notifier
+from portfolio_optimiser.verdicts import ProposalFeatures, Verdict, capture_verdict
+
+
+def _verdict() -> Verdict:
+    return capture_verdict(
+        ProposalFeatures(
+            affected_codes=frozenset({"05.2", "03.1"}),
+            measure_type="scope_reduction",
+            claimed_saving_nok=200_000.0,
+            description="LED retrofit",
+        ),
+        "approved",
+        "feasible within range",
+    )
+
+
+def test_plain_callable_satisfies_notifier() -> None:
+    """The seam promise: any plain callable satisfies the runtime-checkable ``Notifier`` protocol,
+    so ``run_project(notify=lambda v: ...)`` stays valid — a structural superset of
+    ``Callable[[Verdict], None]``, not a new ABC (needs ``@runtime_checkable``)."""
+    assert isinstance(lambda v: None, Notifier)
+
+
+def test_console_emits_id_and_decision() -> None:
+    """ConsoleNotifier writes the verdict id + decision to the injected stream (never a URL)."""
+    stream = io.StringIO()
+    verdict = _verdict()
+    ConsoleNotifier(stream=stream)(verdict)
+    out = stream.getvalue()
+    assert verdict.id in out
+    assert verdict.decision in out