feat(propose): --table-grid selects Arm E, absent is off [skip-docs]

The flag threads through `run` and `main` and takes no argument. Arm D's gate
is a run LENGTH where 0 means off; Arm E has no numeric parameter, so a boolean
is the honest shape and an integer would only manufacture a sweepable knob that
means nothing. `run` therefore adds no numeric validation, and the help says
why.

Both prose sites that enumerate the arms `okf build` does not expose are
updated: `src/llm_ingestion_okf/cli.py` and `CLAUDE.md`. The second was found
by review, not by grep of the first -- the same claim lives in two files and
only one of them is code.

The generalised attribution test earned itself in this commit. The first draft
of the Arm E help contained "byte-identical to Arm D -- Arm D rather than Arm
B", and argparse's rendering plus the test's ` --` chunk split meant the
attribution fell OUTSIDE the `table-grid` chunk. The test went red with the
truncated chunk printed, which is exactly the failure it exists to catch: a
whole-output grep would have been satisfied and the attribution would have been
unfindable in the option it belongs to. The clause is now parenthesised.

Arm C's marker check in `tests/test_cli_build.py` gains `rule:table-grid` and
is renamed to speak of all three arms, measured on the artifact rather than on
the flag: a flag `okf build` never passes is not evidence about what it emits.

[skip-docs] is the MEASURED precedent, not a convenience. `grep -c` for
"outline-run", "max-segment-chars", "Arm C" and "Arm D" returns 0 in both
README.md and CHANGELOG.md: an arm flag is documented in its constant's `#:`
comment, in `--help`, and in the round's measurement report, and it is off by
default so it makes no promise to a consumer. `--path-prefix`, which is a real
interface change, does have a CHANGELOG entry. The rule this follows is stated
at docs/2026-09-07-k3-arm-d.md: "interface and behaviour changes yes, arm flags
no." Arm E's report is docs/2026-09-07-k3-arm-e.md, later in this round.

Tests first: 3 red, then green (a fourth, the no-argument test, is honest in
its docstring that it is green before the flag exists too, because argparse
rejects an unknown option with the same code; it becomes evidence only once
the flag is real). 1248 -> 1251.
ruff check: exit 0. ruff format --check: exit 0. mypy --strict src/ tools/:
27 files, Success. pytest -q: exit 0.

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

src/llm_ingestion_okf/cli.py

@@ -36,10 +36,11 @@ time passes one.
 
 ## What it does not decide
 
-Arm C (`--max-segment-chars`) and Arm D (`--outline-run`) are OFF here and are
-not exposed: they are measurement arms, both off by default by operator
-decision, and a build command is not where an unadjudicated segmentation
-heuristic should become one flag away. `tools/` still reaches them.
+Arm C (`--max-segment-chars`), Arm D (`--outline-run`) and Arm E
+(`--table-grid`) are OFF here and are not exposed: they are measurement arms,
+all off by default by operator decision, and a build command is not where an
+unadjudicated segmentation heuristic should become one flag away. `tools/`
+still reaches them.
 """
 
 from __future__ import annotations

src/llm_ingestion_okf/propose.py

@@ -695,6 +695,7 @@ def run(
     path_prefix: str = "",
     max_segment_chars: int = 0,
     outline_run: int = 0,
+    table_grid: bool = False,
 ) -> int:
     if max_segment_chars < 0:
         raise ProposerError(
@@ -745,6 +746,7 @@ def run(
         path_prefix=scope,
         max_segment_chars=max_segment_chars,
         outline_run=outline_run,
+        table_grid=table_grid,
     )
     # Nothing to propose is an OUTCOME, and it is not an artifact. An empty
     # plan cannot be replayed -- `process_inbox` refuses one, because a plan
@@ -822,6 +824,22 @@ def parse_args(argv: list[str] | None) -> argparse.Namespace:
             "the K3 method file does not name it either"
         ),
     )
+    parser.add_argument(
+        "--table-grid",
+        action="store_true",
+        help=(
+            "Arm E: do not let a pandoc grid-table rule line (`+---+---+`, and "
+            "`+===+===+` under a header) close an open table block. The table "
+            "grammar cannot match a rule line, so without this one grid table "
+            "becomes one concept per row group. Absent (the default) is OFF and "
+            "leaves the artifact byte-identical to Arm D (Arm D rather than "
+            "Arm B, because Arm E is defined on top of it). A boolean and not a "
+            "number: the rule has no parameter to sweep. Arm E is the author's "
+            "definition, written for order 20260907T075834Z-18584396-from-.claude; "
+            "it is not defined upstream, and the K3 method file does not name it "
+            "either"
+        ),
+    )
     parser.add_argument(
         "--proposed-at",
         default="1970-01-01T00:00:00Z",
@@ -841,6 +859,7 @@ def main(argv: list[str] | None = None) -> int:
             path_prefix=args.path_prefix,
             max_segment_chars=args.max_segment_chars,
             outline_run=args.outline_run,
+            table_grid=args.table_grid,
         )
     except ProposerError as exc:
         print(f"{PROPOSER_ID}: FAILED - {exc}", file=sys.stderr)