Sibling to ADR-0048's DEFINITION/RECALL pack-grounded surface for
the COMPARISON intent. `pack_grounded_comparison_surface(a, b)` in
`chat/pack_grounding.py` composes a deterministic side-by-side
surface from both lemmas' pack `semantic_domains`, joined by the
fixed connective "contrasts with":
"{a} (d_a1; d_a2) contrasts with {b} (d_b1; d_b2) — pack-grounded
({pack_id}). No session evidence yet."
`chat/runtime.py:_maybe_pack_grounded_surface` gains a COMPARISON
branch that runs before the DEFINITION/RECALL check. Engages only
when both `intent.subject` and `intent.secondary_subject` are pack
lemmas and differ (identical-lemma comparison defers to disclosure).
Order-sensitive by design — matches the graph-layer's directional
CONTRAST edge.
Cognition eval (13-case public split):
surface_groundedness 61.5% → 69.2% (+7.7 pp)
term_capture_rate 50.0% → 58.3% (+8.3 pp)
intent_accuracy 100.0% (=)
versor_closure_rate 100.0% (=)
Case lifted: comparison_memory_recall_030 ("Compare memory and
recall"). Remaining unlift cases (CAUSE×2, VERIFICATION×1,
CORRECTION×1) need teaching-store chains or operator-driven
inference — pack lookup cannot supply causal explanations,
verifications, or corrections without fabrication.
Tests: tests/test_pack_grounded_comparison.py (15 tests).
Lanes green: smoke (67), cognition (121), runtime (19), algebra
(132), teaching (17), packs (6).
