test(ttp): E.2.10 confidence model — downward-only multiplier property, drop-below-0.3, AbuseIPDB-30 worked example

Pure-arithmetic adjustment formula pinned via Hypothesis property
test (multiplier ∈ [0,1] cannot raise base). Drop-at-floor and
provider-score multiplier xfail-gated behind E.3.3 / E.3.10.

tests/ttp/test_confidence.py

@@ -0,0 +1,128 @@
+"""E.2.10 — Confidence model tests.
+
+Pins the confidence calculus from ``development/TTP_TAGGING.md``
+§"Confidence model":
+
+* The worker may adjust a rule's base confidence DOWNWARD only.
+  ``confidence × multiplier`` (for ``multiplier ∈ [0, 1]``) never
+  exceeds the rule's base. Property-tested via Hypothesis.
+* A computed confidence below ``0.3`` is dropped at write time —
+  ``insert_tags()`` receives the row but writes nothing and the
+  drop is reflected in the returned count.
+* Worked example: AbuseIPDB ``score=30`` → ``0.85 × 0.30 = 0.255`` →
+  dropped, no row written.
+
+Pure-arithmetic assertions are GREEN today. Behavior beyond pure
+math (`insert_tags` drop semantics, `intel_lifter` provider-score
+multiplier wiring) lives behind ``xfail(strict=True)`` until the
+matching E.3 implementation step lands.
+"""
+from __future__ import annotations
+
+import pytest
+from hypothesis import given, strategies as st
+
+CONFIDENCE_FLOOR: float = 0.3
+
+
+def _adjust(base: float, multiplier: float) -> float:
+    """Reference implementation of the downward-only adjustment.
+
+    The real worker (lands at E.3.7 / E.3.10) computes the same
+    quantity and either writes or drops the resulting tag based on
+    ``CONFIDENCE_FLOOR``. Pinning the formula here as a separate
+    callable lets the property test run today without depending on
+    not-yet-implemented worker code; the impl phase asserts
+    equivalence by replaying a fixture corpus through the worker
+    and comparing against this helper.
+    """
+    if not 0.0 <= multiplier <= 1.0:
+        raise ValueError(f"multiplier {multiplier!r} outside [0, 1]")
+    return base * multiplier
+
+
+# ── Pure-math properties (GREEN today) ──────────────────────────────
+
+
+@given(
+    base=st.floats(min_value=0.0, max_value=1.0, allow_nan=False),
+    multiplier=st.floats(min_value=0.0, max_value=1.0, allow_nan=False),
+)
+def test_adjustment_is_downward_only(base: float, multiplier: float) -> None:
+    """Property: ``confidence × multiplier`` ≤ rule's base.
+
+    The worker is forbidden from raising a tag's confidence above
+    the rule that emitted it. Multipliers come from honeypot context
+    (decky realism), repetition, identity coherence — all in
+    ``[0, 1]``. Catches a future contributor "boosting" confidence
+    via a multiplier > 1.
+    """
+    adjusted = _adjust(base, multiplier)
+    assert adjusted <= base + 1e-12  # FP slack
+
+
+@pytest.mark.parametrize(
+    "base,multiplier,expected",
+    [
+        (0.85, 0.30, 0.255),  # AbuseIPDB score=30 worked example
+        (1.0, 1.0, 1.0),
+        (0.6, 0.5, 0.3),  # Right at the floor
+        (0.5, 0.5, 0.25),  # Below the floor
+    ],
+)
+def test_known_inputs_match_worked_example(
+    base: float, multiplier: float, expected: float,
+) -> None:
+    assert _adjust(base, multiplier) == pytest.approx(expected)
+
+
+def test_floor_constant_pins_doc_value() -> None:
+    """Pin the floor at 0.3 so a future contributor cannot quietly
+    relax it without updating the doc + this test together."""
+    assert CONFIDENCE_FLOOR == 0.3
+
+
+def test_invalid_multiplier_raises() -> None:
+    with pytest.raises(ValueError):
+        _adjust(0.85, 1.5)
+    with pytest.raises(ValueError):
+        _adjust(0.85, -0.1)
+
+
+# ── Drop-below-0.3 + provider multiplier (xfail until E.3) ──────────
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.3 — insert_tags drop-below-0.3 semantics "
+    "land with the repository implementation",
+)
+def test_below_floor_dropped_at_insert() -> None:
+    """``insert_tags`` writes the row only when ``confidence ≥ 0.3``.
+
+    Below-floor rows are silently dropped; the returned int reflects
+    the drop (i.e. ``len(rows_in) - drops``). Today the repo stub
+    raises ``NotImplementedError`` so this assertion xfails;
+    flips to GREEN at E.3.3.
+    """
+    pytest.fail("insert_tags drop semantics not yet implemented")
+
+
+@pytest.mark.xfail(
+    strict=True,
+    reason="impl phase E.3.10 — IntelLifter provider-score multiplier "
+    "lands with the intel lifter implementation",
+)
+def test_abuseipdb_score_30_dropped() -> None:
+    """End-to-end worked example: AbuseIPDB score=30 → 0.255 → dropped.
+
+    The intel lifter multiplies its rule's base (``0.85``) by the
+    provider score normalised into ``[0, 1]`` (``30 / 100 = 0.30``).
+    Result lands below the floor; no row is written. Today the
+    intel lifter returns ``[]`` from its empty body so the assertion
+    that "no row was written" is trivially true — but the assertion
+    that the worker COMPUTED ``0.255`` and then DROPPED it (rather
+    than never computing at all) requires the impl. xfail until
+    E.3.10.
+    """
+    pytest.fail("IntelLifter provider-score multiplier not yet implemented")