test(harness): free-text rationale-capture contract (D13, §4.6)

D13 instructs the model to evaluate Altro/Rifiuta/steering free text in context,
act on it, re-ask if ambiguous, and record the user's words in the decision
rationale. The actual interpretation is model behavior enforced by the skill prose
+ gate, validated at L2; this test pins the RECORDING contract the gate relies on:
free text from 'Altro' round-trips into the decision rationale and survives
persistence, never silently discarded.

L1: test_freetext_interpretation (4 tests) -- Altro text preserved, persistence
roundtrip (exact), multiline steering intact, empty rationale allowed.

The skill prose ('Interpretazione del testo libero') ports with the .pi/ skill
in Phase D.

harness/tests/test_freetext_interpretation.py

@@ -0,0 +1,62 @@
+"""L1: free-text interpretation -- rationale capture contract (spec D13, §4.6).
+
+D13 instructs the model to evaluate Altro/Rifiuta/steering free text in context,
+act on it, re-ask if ambiguous (instead of defaulting), and record the user's
+words in the decision rationale. The actual interpretation is model behavior
+enforced by the skill prose + gate, validated at L2; this test pins the RECORDING
+contract the gate relies on: free text from "Altro" must round-trip into the
+decision rationale and survive persistence, never silently discarded.
+"""
+from pathlib import Path
+
+from nsp.decisions import append_decision, list_decisions
+
+
+def test_altro_freetext_recorded_in_rationale(tmp_path):
+    s = tmp_path / "sess"
+    s.mkdir()
+    # The gate, on receiving Altro text, appends a decision whose rationale carries
+    # the user's words verbatim (not discarded, not paraphrased away).
+    append_decision(
+        s,
+        type="table_promoted",
+        subject="phase:4",
+        detail="ablazione",
+        rationale="Utente (Altro): 'ablazione' va cercato anche in patologia, non solo nel flag",
+    )
+    decisions = list_decisions(s)
+    assert len(decisions) == 1
+    assert "patologia" in decisions[0].rationale  # user text preserved
+    assert "Altro" in decisions[0].rationale
+
+
+def test_freetext_survives_persistence_roundtrip(tmp_path):
+    s = tmp_path / "sess"
+    s.mkdir()
+    user_text = "Rifiuto: la join corretta e' su id_episodio, non id_ricovero"
+    append_decision(s, type="join_modified", subject="phase:4",
+                    detail="t1.id_ricovero", rationale=user_text)
+    append_decision(s, type="table_excluded", subject="phase:4",
+                    detail="dimessi", rationale="ok")  # a second, unrelated decision
+    reloaded = list_decisions(s)
+    assert reloaded[0].rationale == user_text  # exact preservation
+    assert reloaded[1].rationale == "ok"
+
+
+def test_multiline_steering_text_preserved(tmp_path):
+    s = tmp_path / "sess"
+    s.mkdir()
+    steering = "Considera solo il 2025.\nEscludi i day-hospital.\nUsa la data di dimissione."
+    append_decision(s, type="concept_clarified", subject="phase:1",
+                    detail="periodo", rationale=steering)
+    assert list_decisions(s)[0].rationale == steering
+    # the multi-line steering is intact, including newlines
+    assert "\n" in list_decisions(s)[0].rationale
+
+
+def test_empty_rationale_is_allowed(tmp_path):
+    # a decision can legitimately have no free text (e.g. a clean promote).
+    s = tmp_path / "sess"
+    s.mkdir()
+    append_decision(s, type="table_promoted", subject="phase:4", detail="pazienti")
+    assert list_decisions(s)[0].rationale == ""