feat(memory): filter gate-declined candidates from promotion preview

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

harness/tests/test_memory_promotion.py

@@ -8,7 +8,9 @@ la rende un passo del workflow. Questi test fissano il contratto harness-side:
 """
 from datetime import datetime
 
-from tht.decisions import DecisionRecord
+from tht.decisions import DecisionRecord, append_decision
+from tht.memory import declined_promotion_seqs, reusable_promotions
+from tht.session.models import SessionManifest
 from tht.workflow import load_workflow
 
 
@@ -24,3 +26,39 @@ def test_promotion_decision_types_min_phase_is_f8():
     wf = load_workflow()
     assert wf.decision_min_phase("memory_promoted") == 8
     assert wf.decision_min_phase("memory_promotion_declined") == 8
+
+
+def _manifest() -> SessionManifest:
+    return SessionManifest(
+        id="s1", created_at=datetime(2026, 1, 1), question="domanda originale",
+        database="db", schema="public",
+    )
+
+
+def test_declined_promotion_seqs_parses_seq_detail():
+    d = DecisionRecord(
+        seq=9, ts=datetime(2026, 1, 1), type="memory_promotion_declined",
+        subject="fact_x", detail="seq:5",
+    )
+    assert declined_promotion_seqs([d]) == {5}
+
+
+def test_declined_promotion_seqs_ignores_malformed_and_other_types():
+    ds = [
+        DecisionRecord(seq=1, ts=datetime(2026, 1, 1),
+                       type="memory_promotion_declined", subject="x", detail=""),
+        DecisionRecord(seq=2, ts=datetime(2026, 1, 1),
+                       type="table_promoted", subject="x", detail="seq:3"),
+    ]
+    assert declined_promotion_seqs(ds) == set()
+
+
+def test_reusable_promotions_exclude_declined(tmp_path):
+    append_decision(tmp_path, type="table_promoted", subject="fact_a",
+                    detail="tab principale", rationale="scelta reviewer")     # seq 1
+    append_decision(tmp_path, type="concept_clarified", subject="attivo",
+                    detail="flag_attivo = TRUE")                              # seq 2
+    append_decision(tmp_path, type="memory_promotion_declined",
+                    subject="fact_a", detail="seq:1")                         # seq 3
+    cand = reusable_promotions(tmp_path, _manifest(), tmp_path / "registry.jsonl")
+    assert [c.decision_seq for c in cand] == [2]