research: add focused portfolio capacity matrix

docs/research/phase-a-matrix.md

@@ -28,6 +28,13 @@ Mechanics guards confirmed before reading results: calendar truncation asserted
 | **Validation** | **1.68** | **0.72** | **41.6%** | **20.9%** | **1.99** | **239** |
 | Full (close-fill) | 1.77 | 0.50 | 48.3% | 21.6% | 2.23 | 472 |
 
+**Capacity correction (2026-08-05):** the full close-fill control also records
+skipped_book_full = 519 versus 472 admitted trades, so the ten-slot book
+refuses 52.4% of admitted+blocked qualified opportunities. The older weekly
+claim that the cap never bound is stale and does not apply to this daily
+gate-reset configuration. Capacity is now isolated in the
+[focused bracket study](portfolio-capacity-bracket.md).
+
 Validation SE ≈ 0.72 — almost no arm clears a 1-SE delta.
 
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