CB-WP-0009-T04: CB-EV-0008 — the gate changes, measured

The windowed budget is confirmed for the failure it was written against
and not for the general claim: a single-pass window reads 0% for
CB-WP-0008 against 50% lifetime, but the trailing-3 window reads 45%
against 50%, inside the refutation band. The prediction was written
before the window size was chosen and did not say which comparison it
meant. Both readings are on record and whether 3 is the right window is
carried as open.

gate-review's first run: 9 gates, 0 due, 2 silent. The silent two are the
chaos roll and gate-review itself, both with dates. A registry where
everything looked productive would have been one written to look good.

D4 holds per pass, not per task: three of four tasks shipped a command,
and the two that did not are the spec change that makes the commands
normative and the evidence file that checks them.

Cost is the honest part. This pass cashed out three commands and ran at
$0.177/response — cheaper than every previous meta pass (0.228, 0.298,
0.362) and still 1.4x the product pass at 0.123. Partial support for D4,
not vindication. Context breached both shape targets because the pass ran
on an already-long session; reported, not gated.

Meta reads 45% of the trailing three against a soft 25%. Nothing was
displaced, but the number is over the line and the next pass should be
product.

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

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

@@ -0,0 +1,134 @@
+# 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).
+
+---
+
+## 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.

workplans/CB-WP-0009-adaptive-gates.md

@@ -2,7 +2,7 @@
 id: CB-WP-0009
 kind: meta
 title: "Make control gates experimental: window them, review them, cash them out"
-status: in_progress
+status: done
 authorized_above_budget: "maintainer, 2026-08-01 — 'improve our policies where it seems promising; we will experiment our way to sensible task- and context-specific control and review gates'. Meta read 59% at the time."
 state_hub_workstream_id: "98c0af4a-415c-4cf5-92d0-a722eb70cb90"
 ---
@@ -120,7 +120,7 @@ started at 399.
 
 ```task
 id: CB-WP-0009-T04
-status: todo
+status: done
 priority: high
 state_hub_task_id: "e06f57fc-147f-4cba-b398-0db6b060381f"
 ```
@@ -139,3 +139,9 @@ answered from output, not argument:
    pass or needs the exception written down.
 4. **Cost**, against the 0.123–0.362 per-response range, and the meta
    share this pass itself consumed — reported under the rule it wrote.
+
+**Done 2026-08-01.** [CB-EV-0008](../evidence/CB-EV-0008-adaptive-gates.md).
+The pass ran at **$0.177/response** — cheaper than every previous meta
+pass and still 1.4× the product pass, which is partial support for D4 and
+is reported as such. Meta share reads **45% over the trailing three**,
+over the line; the next pass should be product.