fix(shapes): the capped meaning pass reads new shapes first, and its miss withdraws an early flag (#4208)

Measured on the first live refresh after 91cde6c deployed: the version bump
queued 1,533 rows for the semantic arm, the cap read 150 of them in row
order, and all six shapes new since the previous refresh - the only rows
flag_divergence acts on, and the highest ids - were flagged before the arm
reached them. The gate silenced nothing because it never got to look, and
since a flag persists until judged, a later conclusive miss could not take
it back.

- propose_for_repo sorts the semantic todo by _semantic_priority:
  unclassified before scoped, newest first.
- flag_divergence withdraws a standing flag when the row now carries a
  conclusive miss; that evidence alone withdraws one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

tests/test_divergence_meaning_gate.py

@@ -180,3 +180,33 @@ def test_the_miss_basis_is_not_one_of_the_proposal_bases(value: str) -> None:
     filters BY basis, and a collision there would mean confirming a miss as
     though it were a match."""
     assert BASIS_NO_SEMANTIC_MATCH != value
+
+
+# ── the cap spends itself on the rows its verdict can act on ─────────────
+
+
+class _AgedRow:
+    def __init__(self, name: str, status: str, created) -> None:
+        self.name, self.status, self.created_at = name, status, created
+
+
+def test_the_capped_pass_reads_new_shapes_first() -> None:
+    """Measured on the first live refresh after the gate shipped: a version
+    bump queued 1,533 rows, the cap read 150 of them in row order, and every
+    shape NEW since the previous refresh — the only rows `flag_divergence`
+    acts on, and the highest ids — was flagged before the arm reached it. The
+    gate silenced nothing because it never got to look."""
+    from datetime import datetime, timedelta, timezone
+
+    from scribe.services.shape_ledger import _semantic_priority
+
+    t = datetime(2026, 9, 22, tzinfo=timezone.utc)
+    rows = [
+        _AgedRow("scoped_new", "scoped", t),
+        _AgedRow("old", "unclassified", t - timedelta(days=30)),
+        _AgedRow("undated", "unclassified", None),
+        _AgedRow("new", "unclassified", t),
+        _AgedRow("scoped_old", "scoped", t - timedelta(days=30)),
+    ]
+    order = [r.name for r in sorted(rows, key=_semantic_priority)]
+    assert order == ["new", "old", "undated", "scoped_new", "scoped_old"]