session-memory Phase 2: evidence-bar + bloat guard (T04)

gating.py: two-tier evidence bar (OQ5) — promote floor (frequency/sessions/
cost_impact) plus a stricter distribution-eligibility floor that sets a
promoted pattern to approved+distribution_ready vs provisional. Wired into
review() so thin approvals land provisional. bloat_warnings flags duplicate
and near-duplicate (same signal-type+locus) candidates (OQ6). [curate]/
[curate.gate] knobs in config.toml. 6 new tests; suite 64/64 green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_curate_gating.py

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+"""Evidence-bar + bloat-guard tests (T04)."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from session_memory.curate.catalog import Catalog  # noqa: E402
+from session_memory.curate.gating import (  # noqa: E402
+    GateConfig,
+    bloat_warnings,
+    evaluate,
+    gate_config,
+)
+from session_memory.curate.review import candidate_to_pattern  # noqa: E402
+
+
+def _candidate(key="success:clean_pass:outcome", freq=5, sessions=5, impact=10.0,
+               cross=True, flavors=("claude", "grok")):
+    return {
+        "key": key,
+        "frequency": freq,
+        "sessions": [f"s{i}" for i in range(sessions)],
+        "cost_impact": impact,
+        "cross_flavor": cross,
+        "flavors": list(flavors),
+    }
+
+
+def test_clears_bar_and_distribution_ready():
+    r = evaluate(_candidate(), GateConfig(dist_min_frequency=3))
+    assert r.promotable and r.distribution_ready
+    assert r.status == "approved"
+
+
+def test_thin_candidate_promotable_but_provisional():
+    # meets promote floor (freq>=2) but below distribution floor (freq<3)
+    r = evaluate(_candidate(freq=2, sessions=2), GateConfig(dist_min_frequency=3))
+    assert r.promotable
+    assert not r.distribution_ready
+    assert r.status == "provisional"
+
+
+def test_below_promote_floor_not_promotable():
+    r = evaluate(_candidate(freq=1, sessions=1))
+    assert not r.promotable
+    assert any("frequency" in reason for reason in r.reasons)
+
+
+def test_cross_flavor_required_for_distribution():
+    r = evaluate(_candidate(cross=False), GateConfig(dist_require_cross_flavor=True))
+    assert r.promotable
+    assert not r.distribution_ready
+    assert any("cross-flavor" in reason for reason in r.reasons)
+
+
+def test_gate_config_reads_toml_dict():
+    cfg = gate_config({"curate": {"gate": {"min_frequency": 9, "dist_require_cross_flavor": True}}})
+    assert cfg.min_frequency == 9
+    assert cfg.dist_require_cross_flavor is True
+    # defaults preserved for unspecified keys
+    assert cfg.dist_min_frequency == 3
+
+
+def test_bloat_flags_duplicate_and_near_duplicate(tmp_path):
+    cat = Catalog(str(tmp_path))
+    cat.upsert(candidate_to_pattern(_candidate(key="success:clean_pass:outcome")))
+    existing = cat.list()
+    # exact same key -> duplicate
+    dup = bloat_warnings(_candidate(key="success:clean_pass:outcome"), existing)
+    assert any("duplicate" in w for w in dup)
+    # different polarity, same signal_type+locus -> near-duplicate
+    near = bloat_warnings(_candidate(key="problem:clean_pass:outcome"), existing)
+    assert any("near-duplicate" in w for w in near)
+    # unrelated -> no warnings
+    assert bloat_warnings(_candidate(key="problem:retry_storm:retries"), existing) == []