fix(gate,propose): okf build runs a real guard; a code fence declares no structure

Two defects reported from outside by claude-code-llm-wiki (order
20260915T202332Z-228694739), both reproduced against this tree before
anything moved.

F1 -- the packaged CLI never ran the guard. corpus.measure wired an
unconditional approve-everything stub into process_inbox and 0 of 90
add_argument calls named a gate, so the one path most people use screened
nothing while pyproject.toml made the guard a mandatory runtime dependency
and the README recommended a composition the command line could not reach.

  --gate takes guard-trusted-source (default), guard-user-upload or none.
  corpus.resolve_gate is the one name->callable map, with the guard imported
  lazily so importing the package still does not pull it in; an unknown name
  RAISES rather than falling back, because a fallback reproduces the defect
  with an extra step. The gate's NAME goes into the section 9 log.md -- a
  stub is only dangerous when nothing downstream can see it -- and --gate
  none renders NOTHING WAS SCREENED.

  The default was chosen on a measurement: over the 453 concept bodies of
  the pinned reference bundle, PRESET_TRUSTED_SOURCE persists 453 of 453 and
  PRESET_USER_UPLOAD holds 1, costing that concept's whole source document.
  Neither tier waves anything through -- an invisible carrier and a CRITICAL
  finding fail secure at both. Door B's library default is UNCHANGED at
  PRESET_USER_UPLOAD: an inbox drop is an untrusted upload, an operator
  pointing this command at their own folder is not. The second tier ships as
  guard_adapter.inbox_gate_trusted_source, the three-line adapter that
  module's docstring already described, never a preset parameter.

  process_inbox(segmentations=..., gate=inbox_gate) now has a test. Before
  this, `grep -rl inbox_gate tests/` gave 1 file with 0 occurrences of
  `segment` -- the recommended composition was untested, which is how the
  defect survived.

F2 -- a fenced code block declared structure. `# Use the opus[1m] alias`
inside a ```bash fence became a level-1 ATX heading: the document was
refused entirely where the line carried [ or ] (5 of 191 pages of the
reporter's corpus), and the concept TITLE came from somebody's shell session
on 62 of 191 (32.5 %). The fix is in the proposer and never in Door B's
title rule -- that rule is right, and a heading that was never a heading is
what has to stop being proposed. propose.fenced_lines is computed once per
text and no rule reads a fenced line, including Arm D's outline RUN, which
selects from the whole line list. Backtick and tilde fences, three leading
spaces, a closing fence at least as long as its opener, and no backtick in a
backtick fence's info string -- that last one keeps a line holding only
`okf build` from silencing a document.

MEASURED ON THE BYTES, and this is the number that decides: the 43-document
reference corpus built at b6da09c (from git archive, never the editable
tree) and rebuilt at the shipped defaults differ in log.md alone, by the one
added bullet. 865 concept files on both sides, every concept byte-identical.

Found by that control and NOT caused by this work: the pinned artifact
K2-bundle-default-20260912 was written 2026-09-09, two days before ed0418f
changed title: quoting, so it differs from what HEAD produces on 42 concept
files. test_default_bundle_pin stays green because it pins the count and the
hit@8 ranks, not the bytes. Re-pinning is the operator's call.

Suite 1896 passed / 1 skipped (+27 from 1869). ruff, ruff format and mypy
--strict clean. No version bump, no tag, no push.

Report: docs/2026-09-15-f1-f2-gaten-og-kodefencen.md

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

tests/test_docs_promises.py

@@ -280,3 +280,40 @@ def test_the_threshold_document_carries_the_boundary_bar_and_its_single_corpus()
     assert f"`{BOUNDARY_THRESHOLD.metric}` | **2 759/2 761**" in text
     assert "1 corpus" in text
     assert BOUNDARY_THRESHOLD.corpora == 1
+
+
+# --- the CLI's default persist gate ----------------------------------------
+#
+# F1 (reported 2026-09-15): `okf build` injected a permissive stub and no
+# argument in the package named a gate, so the command screened nothing while
+# the guard was a mandatory runtime dependency and the README recommended a
+# composition the command line could not reach. What made that survivable for
+# months is that nothing tied the README's claim to the code's behaviour. This
+# does. A published promise is a test obligation.
+
+_GATE_LINE = re.compile(r"^<!-- cli-default-gate: (.+) -->$", re.MULTILINE)
+
+
+def test_the_readme_names_the_gate_the_build_command_actually_defaults_to() -> None:
+    from llm_ingestion_okf import cli
+
+    match = _GATE_LINE.search(README.read_text(encoding="utf-8"))
+    assert match is not None, (
+        "README.md carries no `<!-- cli-default-gate: ... -->` marker; without it "
+        "the documented default can drift from the one the command applies, which "
+        "is exactly how F1 survived"
+    )
+    assert match.group(1).strip() == cli.DEFAULT_GATE
+
+
+def test_the_readme_names_every_gate_the_command_accepts() -> None:
+    """A tier reachable but undocumented is a tier nobody can choose.
+
+    The stricter one matters most: a caller whose folder IS an untrusted drop
+    has to be able to find `guard-user-upload` without reading the source.
+    """
+    from llm_ingestion_okf.corpus import GATE_NAMES
+
+    text = README.read_text(encoding="utf-8")
+    for name in GATE_NAMES:
+        assert f"`{name}`" in text, f"README does not name the gate {name}"