feat(consume): one source document took 8 of 8 delivered places, so cap it

Measured outside this repository on a 3206-concept bundle of a published
handbook: the code's own process overview contributes 28 of 3206 concepts
(0.87 %) and 117 488 of 1 469 225 source characters (8.0 %), and took 8 of 8
delivered places on one question and 7 of 8 on the known-positive -- which was
not delivered at all. Identical at 343 and 1651 concepts, so the cause is the
corpus's COMPOSITION, that it holds its own table of contents, and NOT its size.
Splitting the corpus would move the defect, not remove it: any corpus with a
contents list, a project overview or a summary document has the same property.

`--source-quota N` caps how many DELIVERED places one source document may take.
It cuts where the shortlist is cut -- before the pack, never inside the DP,
which maximises a sum over a set it is handed -- so the freed place goes to the
next candidate and `k` is still delivered in full.

DEFAULT 2 SINCE TODAY, and it is the third change here that alters a payload
with NO bundle changing (after `--tie-shared-rank` and `--stem-prefix`).
Opt-out `--no-source-quota` reproduces the previous excerpt order.

Swept over {2, 3, 4, off} on three bundles, with the fasit prefixes validated
against the bundle FIRST (that control caught a defect in the measuring query
itself -- it read the last id segment where the document is the first):

- K2, both bundles: at 2 and 3, hit@8 goes 5 of 6 to 6 of 6 with all five
  standing rank-1 rows unmoved. The recovered row had missed on every bundle and
  every configuration measured until now. At 4 and off it is 5 of 6.
- The handbook bundle: hit@8 2 of 6 -> 4 of 6, the known-positive from not
  delivered to rank 4, and the dominant document's share of delivered places
  8 of 8 -> 2 of 8 (7 of 8 -> 2 of 8 on the known-positive).
- 2 rather than 3 on rank alone: the recovered rows come in at 5 and 4 rather
  than 7 and 5.

WHAT THE GAIN IS NOT. hit@8 asks whether the gold DOCUMENT appears among the
delivered excerpts, and a document quota directly raises how many distinct
documents a payload holds, so that metric is not neutral with respect to this
rule. The five rows that were already rank 1 are neutral, and they did not move.

THE ADVERSE CASE IS NAMED, not left to a consumer. A bundle built from ONE
document carries the same `source_file` on every concept, so a quota applied
literally would deliver 2 excerpts where `k` were asked for -- a rule against
dominance turned into a rule against small bundles. The shortlist is topped back
up from the best-ranked over-quota candidates, which makes such a bundle
byte-identical to the quota being off, and a test holds it.

`--rarity-weight` was measured against the same defect and does NOT repair it:
it leaves the dominant document at 8 of 8 places on the question it floods,
delivers neither that answer nor the known-positive, and holds 5 of 6 on both K2
bundles. Combined with the quota it is worse than the quota alone (the
known-positive falls back out). It stays off.

The vocabulary stays CLOSED and the new code is published in all three places a
consumer can read it: `WITHHOLDING_RULES` (six -> seven),
`docs/consumption-contract.md` 5.3, and the generated SKILL.md -- verified by
reading the generated file, not the code that writes it. `source_quota_exceeded`
is a DIVERSITY drop and not a relevance one, so folding it into
`no_lexical_match` would tell a consumer the question reached nothing in a
concept the question in fact reached. `okf check --skill --payload` stays
conformant, 0 findings over 15 rules.

Editing the contract moved the 7.4 known-positive, which is the coupling
working as intended: 12 563 -> 13 238 encoded, 12 227 -> 12 893 raw, delta
336 -> 345, updated in the constant, the instantiated skill and the shipped
example payload.

Also adds the O6 guard on the reading side: `build_payload`'s signature defaults
are asserted equal to `okf consume`'s argparse defaults for every same-named
parameter. `okf project` shipped that exact disagreement for two rounds.

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

tests/test_default_bundle_pin.py

@@ -84,11 +84,19 @@ requires_default_bundle = pytest.mark.skipif(
 #: candidates it was taking with it survive. Corpus-wide, 429 -> 447 candidates
 #: over 32 -> 33 documents with a plan, and characters in no segment stay 0.
 EXPECTED_CONCEPTS = 453
-EXPECTED_HITS = 5
-#: Rank per question INDEX, `None` for the row that misses on every bundle and
-#: every configuration measured so far. The identity is the index; the question
-#: stays in the local-only gold set.
-EXPECTED_RANKS = (1, 1, 1, 1, 1, None)
+EXPECTED_HITS = 6
+#: Rank per question INDEX. The identity is the index; the question stays in
+#: the local-only gold set.
+#:
+#: ROW 6 MOVED `None` -> 5 ON 2026-09-10, on these same bytes and with no
+#: bundle changing: `consume.DEFAULT_SOURCE_QUOTA` became 2. It had missed on
+#: every bundle and every configuration measured until then, and the test below
+#: names the quota as its cause by turning it off. What the gain is NOT: hit@8
+#: scores whether the gold DOCUMENT appears among the delivered excerpts, and a
+#: document quota directly raises how many distinct documents a payload holds,
+#: so this metric is not neutral with respect to this rule. The five rows that
+#: were already rank 1 are, and they did not move.
+EXPECTED_RANKS = (1, 1, 1, 1, 1, 5)
 
 
 @requires_default_bundle
@@ -151,7 +159,12 @@ def test_the_reading_default_is_what_holds_row_one_on_these_bytes() -> None:
         assert isinstance(excerpts, list)
         ranks.append(okf_consume_measure.hit_rank(excerpts, entry["gold_document"]))
     assert ranks[0] == 2, "the known-negative stopped being negative"
-    assert tuple(ranks[1:]) == EXPECTED_RANKS[1:]
+    # Rows 2-5 are untouched by the tie-break. Row 6 is NOT asserted equal to
+    # the pin: it is the row `DEFAULT_SOURCE_QUOTA` recovered, and the two
+    # rules reach it independently, so pinning it here would assert a
+    # coincidence rather than a cause.
+    assert tuple(ranks[1:5]) == EXPECTED_RANKS[1:5]
+    assert ranks[5] is not None
 
 
 @requires_default_bundle
@@ -179,6 +192,32 @@ def test_the_stem_rule_holds_every_rank_on_the_shipped_bytes() -> None:
     assert tuple(ranks) == EXPECTED_RANKS
 
 
+@requires_default_bundle
+def test_the_document_quota_is_what_reaches_row_six_on_these_bytes() -> None:
+    """The known-negative for round 11's default, on the shipped bundle.
+
+    Row 6 had missed on every bundle and every configuration measured before
+    2026-09-10. `DEFAULT_SOURCE_QUOTA = 2` reaches it at rank 5, and this test
+    is what keeps `EXPECTED_RANKS` from being green for an unstated reason:
+    turn the quota off on these exact bytes and the miss comes back.
+
+    The five standing rank-1 rows are asserted UNMOVED in the same run, because
+    "the new rule cost nothing" is the half of the claim a hit count cannot
+    see.
+    """
+    questions = json.loads(GOLD_SET.read_text(encoding="utf-8"))["questions"]
+    ranks = []
+    for entry in questions:
+        payload = okf_consume.build_payload(
+            DEFAULT_BUNDLE, question=entry["question"], source_quota=None
+        )
+        excerpts = payload["excerpts"]
+        assert isinstance(excerpts, list)
+        ranks.append(okf_consume_measure.hit_rank(excerpts, entry["gold_document"]))
+    assert ranks[5] is None, "the known-negative stopped being negative"
+    assert tuple(ranks[:5]) == EXPECTED_RANKS[:5]
+
+
 @requires_default_bundle
 def test_the_stem_rule_is_what_keeps_bilateral_out_of_four_hundred_concepts() -> None:
     """The known-negative for the stem rule, on the shipped bundle.