test(accounting): N101's prefixed tags are counted in the test (red)

The known-negative for stripping a namespace prefix -- "N101 ships 574 `tbx:`
tags, and not one of their local names is a role" -- was published in four
docstrings (CLAUDE.md, tools/okf_witness.py, this file, the round's report)
and asserted nowhere. A measurement presented as a fact, with nothing that
could turn red when it stopped being true.

The walk is written HERE rather than taken from `okf_witness`: the witness's
own reader is what this known-negative judges, so counting through it would
make the two agree by construction.

RED on the claim, not on an import:

    assert sum(tbx.values()) == 574
    AssertionError: assert 568 == 574
      where 568 = sum(dict_values([94, 94, 94, 94, 94, 94, 1, 1, 1, 1]))

Three independent counts of the delivery agree on 568 -- raw `tbx:` substring,
regex over `"tag": "tbx:`, and node traversal -- against 574 in the tree.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_accounting_gate.py

@@ -377,6 +377,46 @@ def test_a_prefixed_tag_that_names_no_role_stays_uncounted() -> None:
         assert witness._sts_role_json(witness._local(tag), "sec", "body") is None
 
 
+N101_DELIVERY = gate.N200_DEFAULT.parent / "N101-2025-860031.json"
+
+
+def _tags_of(payload: bytes) -> dict[str, int]:
+    """Every `tag` string in a delivery, counted by a walk written HERE.
+
+    The witness's own reader is what the known-negative below judges, so
+    counting through it would make the two agree by construction.
+    """
+    names: dict[str, int] = {}
+
+    def walk(node: Any) -> None:
+        if isinstance(node, dict):
+            tag = node.get("tag")
+            if isinstance(tag, str):
+                names[tag] = names.get(tag, 0) + 1
+            for value in node.values():
+                walk(value)
+        elif isinstance(node, list):
+            for value in node:
+                walk(value)
+
+    walk(json.loads(payload.decode("utf-8")))
+    return names
+
+
+@pytest.mark.skipif(not N101_DELIVERY.is_file(), reason="N101 is not on this machine")
+def test_n101s_own_prefixed_tags_are_counted_here_and_name_no_role() -> None:
+    """The published number for that known-negative was a measurement nothing
+    could falsify: it lived in four docstrings and in no assertion, and it was
+    wrong. The count is made HERE, over the delivery itself, so the sentence
+    four files publish is red when it stops being true."""
+    names = _tags_of(N101_DELIVERY.read_bytes())
+    assert sum(names.values()) > 0, "the walk found no tag at all"
+    tbx = {tag: n for tag, n in names.items() if tag.startswith("tbx:")}
+    assert sum(tbx.values()) == 574
+    for tag in sorted(tbx):
+        assert witness._sts_role_json(witness._local(tag), "sec", "body") is None, tag
+
+
 @pytest.mark.skipif(not gate.N200_DEFAULT.is_file(), reason="N200 is not on this machine")
 def test_the_json_role_map_counts_n200s_own_formulas_and_figure_captions() -> None:
     """The same defect on the delivery it was found in, with PM's numbers.