-- Regression test: pgmnemo.recency_weight GUC (v0.1.1)
-- Verifies γ=0.0 collapses recency contribution to zero and
-- γ=0.5 produces a measurable spread between old and new lessons.
-- Setup: two lessons with identical embeddings and importance but different ages
CREATE TEMPORARY TABLE _rw_lessons AS
SELECT
    0                                    AS importance,
    NOW() - INTERVAL '1 day'            AS new_created_at,
    NOW() - INTERVAL '89 days'          AS old_created_at;
-- Compute recency term directly (avoids recall_lessons() embedding requirement)
-- γ=0.0: both recency terms must be 0.0
SET pgmnemo.recency_weight = '0.0';
SELECT
    round(
        0.0 * GREATEST(0.0, 1.0 - LEAST(1  / 90.0, 1.0))::numeric, 6
    ) AS new_recency_gamma0,
    round(
        0.0 * GREATEST(0.0, 1.0 - LEAST(89 / 90.0, 1.0))::numeric, 6
    ) AS old_recency_gamma0;
 new_recency_gamma0 | old_recency_gamma0 
--------------------+--------------------
           0.000000 |           0.000000
(1 row)

-- γ=0.5: new lesson should score higher than old
SET pgmnemo.recency_weight = '0.5';
SELECT
    round(
        0.5 * GREATEST(0.0, 1.0 - LEAST(1  / 90.0, 1.0))::numeric, 6
    ) AS new_recency_gamma05,
    round(
        0.5 * GREATEST(0.0, 1.0 - LEAST(89 / 90.0, 1.0))::numeric, 6
    ) AS old_recency_gamma05,
    (0.5 * GREATEST(0.0, 1.0 - LEAST(1  / 90.0, 1.0))) >
    (0.5 * GREATEST(0.0, 1.0 - LEAST(89 / 90.0, 1.0))) AS new_beats_old;
 new_recency_gamma05 | old_recency_gamma05 | new_beats_old 
---------------------+---------------------+---------------
            0.494444 |            0.005556 | t
(1 row)

-- Reset to default
RESET pgmnemo.recency_weight;
DROP TABLE _rw_lessons;