CB-WP-0006 T07: implement K18, amend K14

Two rules, two different answers, which is the point of a task phrased
"implement, or amend and say why".

K18 is implemented. "Criterion benches driving the same scenario format at
scale" was false — the bench hardcoded its commands and never touched
ScenarioFile, while MetricsAndScenarios §3 pointed at a benchmarks/
directory containing only baselines/. benchmarks/synthetic-3p.yaml now
holds the workload and both the bench and bench_shape read it: the
workload is data, not code.

A second defect surfaced while fixing the first. After the bench switched
to the file, bench_shape still hardcoded the same sequence, so the
workload existed twice — deleting end_round from the YAML broke bench-test
while bench_shape kept passing. Duplicated-fact drift in executable form.
Both now read the same include_str! and deleting a command breaks both.

Explicitly not claimed: this does not unblock AM-3. AM-3's baseline is a
declarative game object — moves, turn order, rules. synthetic-3p.yaml is a
command list; the rules live in games/ground. Marking it as AM-3's subject
would compare a script to a game definition, which is the category error
AM-3 is blocked on. The file says so in its own header, where the next
person will be tempted.

K14 is amended. CommitWindow had zero non-test users and GROUND enforces
the same contract inline. Wiring GROUND through it was rejected: it would
change the serialized shape of `selections`, which four scenario files
assert by dot-path and every state hash depends on, for the sole benefit
of making a sentence literally true.

The deciding argument is INTENT's, not convenience: abstractions are
extracted from working games rather than invented in isolation, and no
concept becomes canonical until it survives a second concrete use.
CommitWindow was invented before any game needed it and has survived none.
Imposing it on GROUND would manufacture the first use rather than discover
it. So K14 states what is actually guaranteed, CommitWindow is marked
provisional in the source, and it carries a delete-by date of 2026-12-31.

Kernel spec->code link 16/18 -> 18/18, stated with the caveat the gate
prints every run: that is about names, not assertions.

Two self-tests broke and both broke correctly. rule-coverage's gate test
hardcoded "unlinked rules exist today" and failed when the last one was
linked; it now computes that and asserts the gate fails iff rules are
unlinked. facts' text check rejected k_unlinked once it became
legitimately empty; empty now renders as "(none)" and the check
distinguishes absent from empty.

M-D1-MUT: 8 of 14, unchanged — K14 and K18 are kernel rules, not
acceptance rows.

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

crates/cb-game-runtime/src/lib.rs

@@ -18,6 +18,17 @@ use std::collections::BTreeMap;
 /// A simultaneous commit window (GameKernel K12): the runtime opens it
 /// naming who must submit; submissions are commitment events hidden from
 /// projections until reveal.
+///
+/// **PROVISIONAL — zero non-test users as of 2026-08-01 (K14, GameKernel
+/// §2.5a).** GROUND implements the same contract inline in its own
+/// aggregate. This type is the *extracted* form, kept because it
+/// documents the seam stage 3 and stage 4 will need — but INTENT says a
+/// concept becomes canonical only *"after surviving a second concrete
+/// use"*, and this has survived none.
+///
+/// **Delete it if no second game uses it by 2026-12-31.** A primitive
+/// with one hypothetical user and a test that exercises only itself is
+/// the AM-11 shape, and this project has paid for that shape twice.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct CommitWindow<C> {
     /// Players who must submit, and their commitment once received.