CB-WP-0006 T04: withdraw AM-4c; and fix where AM-6 is measured

AM-4c is withdrawn from the acceptance table and retained as a reported
diagnostic. GameKernel §5a carries the argument.

The ratio has no monotone better direction. INTENT's rule is "own the
semantics, assimilate the implementation": rising can mean owning
semantics properly or reimplementing what should have been assimilated;
falling can mean leverage or dependency bloat. A target requires knowing
which way is better. It is also redundant — AM-4a/AM-4b bound the
denominator and AM-2 bounds own-source density, so AM-4c is a ratio of two
already-targeted quantities.

Measured at withdrawal: 1,426 own lines per 100k third-party (shipped),
1,107 (dev). make dep-weight now prints both, labelled diagnostic — the
row was never actually reported before.

M-D1-MUT keeps AM-4c in its denominator on purpose and says so in the
output. Dropping it would move the score 7/14 -> 7/13 without enforcing
anything: a score improved by deleting the question.

Decided before Phase B deliberately, since ADR-0005 predicts own-source
growth that will move this ratio; deciding after would be the retarget
§Step 4 forbids.

A T01 correction found here. The AM-6 gate failed inside `make all` at
38,753 ev/s against 341,280 in isolation — a 9x drop, because cargo test
runs binaries and threads concurrently. A throughput assertion inside a
parallel harness measures contention, not throughput. T01's measurement
was valid; its gate placement was not.

Fixed by running it only where valid — #[ignore] plus `make am6` in
release with --test-threads=1, now 2.0M ev/s at 20.2x headroom — and not
by lowering the target, which T01 forbade. My first attempt did drift that
way, adding a debug "sanity floor" of 50,000, and was backed out: a second
threshold is still a second chance to tune.

The mutation then went SURVIVED on the first run after the move. 4,000
black_box iterations were calibrated against debug's 3.4x headroom and are
invisible against release's 20x. Raised to 100,000; back to red. A weak
mutation is not a fixed property of a row — it can become weak when the
row's measurement conditions change.

Tier S (amends one row, creates no capability), chaos d4=2, no override.

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

tools/dep-weight.py

@@ -186,6 +186,14 @@ def main():
                 f"{r['third_party_loc']:>9,} lines third-party  "
                 f"[{mark} target {limit:,}]"
             )
+        # AM-4c: own source per 100k third-party lines. A DIAGNOSTIC, not a
+        # target — see specs/GameKernel.md §5 and CB-WP-0006 T04. The ratio
+        # has no monotone better direction, so it cannot carry a threshold.
+        for label in CONFIGS:
+            tp = report[label]["third_party_loc"]
+            if tp:
+                print(f"  AM-4c {label:<18}{own / (tp / 100_000):>9,.0f} own "
+                      f"lines per 100k third-party   (diagnostic, not targeted)")
         delta = (
             report["dev-toolchain"]["third_party_loc"]
             - report["shipped-runtime"]["third_party_loc"]

tools/mutation-check.py

@@ -125,12 +125,22 @@ def rows():
             mutate=("tools/dep-weight.py",
                     '"dev-toolchain": 350_000,', '"dev-toolchain": 1_000,')),
 
+        # Deliberately RETAINED in this denominator after its withdrawal
+        # from the acceptance table. Dropping it would move M-D1-MUT from
+        # 7/14 to 7/13 without enforcing anything — a score improved by
+        # deleting the question.
         Row("AM-4c", "own source per third-party 100k lines",
-            unmutatable="declared `reported, not targeted` in the spec. "
-                        "There is no threshold, so there is no property to "
-                        "invert. Counts against the metric by ADR-0005 §1, "
-                        "which is the honest treatment: an untargeted number "
-                        "cannot fail."),
+            unmutatable="WITHDRAWN from the acceptance table 2026-08-01 "
+                        "(CB-WP-0006 T04, GameKernel §5a) and retained here "
+                        "as a diagnostic. The ratio has no monotone better "
+                        "direction — rising can mean owning semantics or "
+                        "reimplementing what should be assimilated; falling "
+                        "can mean leverage or dependency bloat — so it "
+                        "cannot carry a threshold. It is also redundant: "
+                        "AM-4a/AM-4b bound the denominator and AM-2 bounds "
+                        "own-source density. Kept in this denominator on "
+                        "purpose, so the metric cannot be improved by "
+                        "deleting rows."),
 
         Row("AM-5", "clean release build <= 60 s",
             unmutatable="now RECORDED (`make build-time`) and **breaching**: "
@@ -144,8 +154,12 @@ def rows():
                         "itself."),
 
         Row("AM-6", ">= 100,000 applied events/s",
-            verify=CARGO + ["test", "-p", "games-ground", "--all-features",
-                            "am6_throughput"],
+            # Release: the gate runs where headroom is ~24x. In debug the
+            # test only asserts a sanity floor, so a debug mutation run
+            # would need a far larger slowdown to register.
+            verify=CARGO + ["test", "--release", "-p", "games-ground",
+                            "--all-features", "am6_throughput", "--",
+                            "--ignored", "--test-threads=1"],
             # A PROPERTY mutation, not a threshold tweak: slow the fold hot
             # path and require the gate to notice. Raising the target
             # instead would only prove the comparison runs.
@@ -153,7 +167,7 @@ def rows():
                     "    fn fold(&mut self, event: &Self::Event) {\n"
                     "        match event {",
                     "    fn fold(&mut self, event: &Self::Event) {\n"
-                    "        for _ in 0..4000 { std::hint::black_box(0u8); }\n"
+                    "        for _ in 0..100_000 { std::hint::black_box(0u8); }\n"
                     "        match event {"),
             expect="AM-6 UNMET"),
 
@@ -339,7 +353,12 @@ def report(only=None):
 
     red = tally.get("red", 0)
     total = len(rs)
+    withdrawn = sum(1 for r in rs if "WITHDRAWN" in (r.unmutatable or ""))
     print(f"\n  M-D1-MUT: {red}/{total} rows enforced")
+    if withdrawn:
+        print(f"    ({withdrawn} withdrawn row(s) retained in the denominator "
+              f"on purpose — a score\n     improved by deleting the question "
+              f"is not an improvement)")
     for k in ("PARTIAL", "SURVIVED", "WRONG-REASON", "unmutatable",
               "inconclusive"):
         if tally.get(k):