clay-borg/evidence/CB-EV-0008-adaptive-gates.md

CB-EV-0008 — did the gate changes fire?

CB-WP-0009 T04. Measured 2026-08-01 at HEAD after T03. This pass is kind: meta, opened above the budget line on recorded maintainer authorization (ADR-0006 D2's first use).

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1. Does the windowed meta share differ from cumulative?

Yes at one pass, no at three — and the prediction did not say which.

reading	value
CB-WP-0008 alone (product)	0%
trailing 3 passes, before this one	36%
trailing 3 passes, now	45%
lifetime, all 9 passes	50%

T01 predicted the windowed figure would differ sharply from cumulative, refuted within 20%. Against the single-pass window that is decisive: 0% versus 50%. Against the trailing-3 window it is not: 45% versus 50% is a 10% relative gap, inside the refutation band.

Both are true, and the honest reading is that the prediction was underspecified — it was written before the window size was chosen, and T01 then chose three passes for a stated reason (one pass is a coin flip: a meta pass reads 100%, a product pass 0%). So:

• D1 is confirmed for the failure it was written against: the v1.5 budget could not see a 100%-product pass, and now it can.
• D1 is not confirmed as "trailing-3 always differs from lifetime." Right now it does not, because the recent mix happens to resemble the lifetime mix. That is a fact about this project's history, not evidence for or against the machinery.

Carried as an open question, not resolved by argument: whether three is the right window. It should be revisited when a pass makes the two diverge, which is the only cheap evidence available.

2. What does gate-review say on its first run?

9 gate(s) — 0 due, 2 silent, 0 drifted

The two silent entries are the uncomfortable ones, and they are supposed to be:

• CHAOS — the chaos roll has never changed a tier. Its 12-declaration window (4 used) exists precisely to find out whether it ever will.
• GATE-REVIEW — this registry itself, which has caught nothing because it is one hour old, and which retires on 2026-12-31 if it has not by then retired, tightened or forced the re-justification of anything.

A registry where every gate looked current and productive would have been a registry written to look good. Two of nine are on notice.

The caught lists are the load-bearing part, and they are honest in the other direction too: M-D1-MUT has six entries, LOOP-LINT two, and the DFD gate one that landed this week — gr_scenarios stale at 21 after CB-WP-0008 T03 added three scenarios, caught by make all going red before the push.

3. Did D4 hold for this pass?

Three of four tasks shipped a command; the fourth is this file.

task	shipped
T01	cb-cost.pass_costs, windowed make status
T02	gates.toml, make gate-review, a loop-lint check
T03	InnerLoop v1.6 — prose
T04	this evidence file — prose

D4 says a meta pass must ship at least one executable check, so the rule holds. But the pass makes the boundary clear: the spec change and the evidence file are prose, and a rule requiring every task to cash out would be wrong — the spec edit is what makes the commands normative, and the evidence file is what checks them.

So D4 stands as written (per pass, not per task), and this pass is on record as its first exercise.

4. Cost

pass	kind	responses	cost	$/response
CB-WP-0006	meta	158	$57.22	0.362
CB-WP-0007	meta	21	$7.95	0.298*
CB-WP-0008	product	134	$17.38	0.123
CB-WP-0009	meta	38	$6.73	0.177

* the CB-WP-0007 figure is from the earlier hand-windowed measurement; the table's per-pass windows are now computed by pass_costs.

This is the interesting number. D4's claim is that loop work that cashes out into a command is cheap. This pass cashed out three commands and ran at 0.177 — cheaper than every previous meta pass (0.228, 0.298, 0.362) and still 1.4× the product pass. Partial support, not vindication, and stated as such.

Session shape over the same window is worse than the product pass and breaches both targets:

metric	this pass	CB-WP-0008	target
SH-1 mean context	290,171	161,994	≤ 200,000
SH-2 p90 context	311,243	215,664	≤ 300,000
SH-3 batching	0.0%	6.9%	≥ 20%

The mechanical cause is visible and boring: this pass ran on top of an already-long session with no compaction, where CB-WP-0008 started immediately after one. The shape budget reports it; nothing gates it; and per CB-RES-0005 §4 nothing should.

Meta share after this pass: 45% of the trailing three, against a soft 25%. Reported under the rule this pass wrote. Nothing was displaced — CB-WP-0008 shipped stage 0 first, and this work was maintainer-authorized on top of it — but the number is over the line and the next pass should be product to bring it back.

5. Open

• Is 3 the right trailing window? Unanswered; revisit when a pass makes single-pass and trailing-3 diverge.
• CHAOS and GATE-REVIEW have caught nothing. Both have dates.
• mech environment setup reads 17 turns / $2.90 this pass, which is the cost classifier scoring inline python3 - <<EOF edits as environment setup. The category is mislabelled rather than the work being wrong — a small classifier defect, recorded, not chased.
• The next pass should be product. The budget says so, and this is the first time it has said so about work that had not started yet.