The metric six evidence files reported as 0.0% was never measured.
--shape-budget windows since the last commit, and it is read while
writing the evidence file — right after a commit, when the window holds
one or two responses. SH-1/SH-2 are location statistics and survive n=2.
SH-3 is a rate: at n=2 its only possible values are 0%, 50%, 100%.
cb-cost.py gains sh3_line(), which below a minimum sample prints
"insufficient sample" and no verdict. The floor is derived: if the true
rate were exactly the 20% target, P(zero batched in n) = 0.8^n, and at
n=14 that is 4.4% — so "0 batched in 14" rules out a target-meeting rate
at ~95%. Below that the tool has nothing to say and now says so.
The window was kept rather than split. SH-3 could have been given a
per-pass window, but the budget's purpose is the open remainder since
the last commit, and giving one of three metrics a different window
makes "the window" ambiguous in a tool three specs cite.
Four controls, three mutations, each red for its stated reason —
including the one the evidence files actually hit, where a refusal is
printed as a measured zero.
SessionShape.md §4 carries the correction with the real per-pass figures
(1.1%-6.3%), beside the eighth trusted-arithmetic instance. This is the
ninth, and the second in this same metric. It also shows what the frozen
0.0% hid: against the pinned 7.8%-8.6%, batching has got worse, and six
passes reported a breach that was moving underneath them.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Declaration 8 of 12. Structural tier M (changes how the loop constrains
its own operation — a budget instrument and a gate floor); d4 = 3, no
override. Meta budget reads 0% of the trailing three, so this is in
budget without the ADR-0006 D2 repair exemption.
The SH-3 half is larger than CB-WP-0012 filed it as. "SH-3 has read
0.0% for six consecutive passes" is an artifact: --shape-budget measures
the window since the last commit, and it is read while writing the
evidence file, immediately after a commit, when that window holds one or
two responses. SH-1 and SH-2 are location statistics and survive n=2;
SH-3 is a rate, and at n=2 its only possible values are 0%, 50%, 100%.
Measured over real per-pass windows it is 1.1%-6.3%, not 0.0%. Which
exposes what the artifact hid: the pinned historical rate is 7.8%-8.6%,
so batching has got WORSE, and a metric stuck at a constant could not
have shown it.
That is the ninth recorded instance of the trusted-arithmetic class, and
the second one in this same metric — SessionShape.md §4 already records
"0 of 330 tool calls were batched" as the eighth.
Also owed: AM-4a counts proc-macro crates that never reach a binary
(89,048 lines, 36.2%). The task is explicit that the target must move
down with the instrument, or the pass must argue why 89,048 lines of
unearned headroom are legitimate.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
