CB-WP-0019-T05: what the meta budget is for, at 80/20

InnerLoop v1.7. The purpose is written first and the number follows from
it: most spend on the task at hand, some on control, review and
improving the process. make status prints it above the figure, because a
threshold with no stated purpose is what let this number be argued three
times.

Soft 20% over a trailing 5, and the self-test enforces that the ratio and
the window are a PAIR: META_SOFT_PCT == 100 / TRAILING_PASSES. One meta
pass among n at parity cost reads 1/n, so 80/20 is one pass in five at
normal cost -- a five-pass window. The same 20% over three would have
silently also demanded the meta pass be half-price, which makes meta work
rushed rather than rare. Moving the ratio without the window goes red.

The phase setting is declared, argued and expiring in gates.toml, and
reverts on review_by unless re-argued. Verified live at 35%. One with no
reason or no expiry is refused rather than honoured, because a threshold
anyone may move is not a threshold.

Measured: the last five passes read 7% against the new line.

InnerLoop.md crossed the 400-line limit three times while this was
written and was fixed structurally each time -- the arithmetic, the
cost-per-response basis and the two review case studies moved to
InnerLoopReference.md. The limit was not raised.

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

specs/InnerLoop.md

@@ -6,12 +6,23 @@ a breach never blocks its own repair (D1/D2); loop work cashes out into
 something runnable in the pass that invents it (D4); the tier table
 covers changes to the loop's own operation (D5).
 
-> **Meta budget — soft, 25% of the trailing three passes.** Work on the
-> loop's own instruments and process is capped at a quarter of recent
-> spend. Measured by `make status` from each workplan's `kind:`
-> frontmatter (`product` | `meta` | `mixed`), over a **trailing 3-pass
-> window**; the lifetime figure is reported as history and is not the
-> metric (ADR-0006 D1).
+> **What the budget is for (v1.7, CB-WP-0019 T05).** Most of what this
+> project spends should go on **the task at hand**. Some of it must go on
+> **control, review, and improving the process that carries the work
+> forward** — a loop that never inspects itself accumulates exactly the
+> defects this one keeps finding, and a loop that only inspects itself
+> ships nothing. The budget names the split so that neither happens by
+> drift.
+>
+> **Meta budget — soft, 20% of the trailing five passes.** Measured by
+> `make status` from each workplan's `kind:` frontmatter (`product` |
+> `meta` | `mixed`), over a **trailing 5-pass window**; the lifetime
+> figure is reported as history and is not the metric (ADR-0006 D1).
+>
+> **The ratio and the window are a pair** — 20% over five is *one pass in
+> five at normal cost*; the same number over three would mean *one in five
+> and at half price*. `InnerLoopReference.md` §Meta budget has the
+> arithmetic.
 >
 > **Soft on purpose.** A task already started may be finished — stopping
 > mid-task to satisfy a ratio wastes the work and leaves the tree worse
@@ -27,6 +38,13 @@ covers changes to the loop's own operation (D5).
 >    `authorized_above_budget:` in the workplan frontmatter. Undocumented
 >    above-line meta work is a violation the evidence file must report.
 >
+> **The phase setting is not a dial.** The split may move for a phase, but
+> only **declared, argued, and expiring** — `meta_phase = { pct, reason,
+> review_by }` in `gates.toml`, reverting to 20 on `review_by` unless
+> re-argued. A setting with no reason or no expiry fails
+> `status.py --self-test`, so the line cannot be raised quietly to pass a
+> breach.
+>
 > A pass that exceeds it **says so in its evidence file and names the
 > product work displaced**. That is the whole enforcement: a reporting
 > budget, not a gate, for the same reason the session-shape budget is —
@@ -36,12 +54,8 @@ covers changes to the loop's own operation (D5).
 > least one executable check, command, or gate. Findings that stay prose
 > are recorded as findings and do **not** count as delivery.
 >
-> Measured basis: cost per response across five passes ran 0.123, 0.228,
-> 0.362, 0.298, 0.123 dollars, and the reading that survived the data is
-> that **cost tracks distance from a runnable check** — the passes that
-> shipped a command were cheap, the passes that argued about what a
-> number means were not (CB-EV-0007 §5). **Refuted if** a prose-only meta
-> pass lowers cost per response or catches a class no command could.
+> Measured basis and its falsifier: `InnerLoopReference.md` §Loop work
+> cashes out — **cost tracks distance from a runnable check**.
 
 > **Every gate is an experiment (v1.6, ADR-0006 D3).** Each standing
 > control gate has an entry in `gates.toml` naming what it has caught, a
@@ -194,20 +208,9 @@ sampling. So:
 > red. Re-running the command that prints a number satisfies "reproduce
 > independently" and finds nothing of this class.
 >
-> *(v1.4, from CB-WP-0005: `evidence/CB-EV-0001` reported `AM-7 replay |
-> met, 2,290×` for a clause that asserts nothing — the hash reaches only a
-> `println!`. The reviewer found it by opening a test out of curiosity and
-> said so; no systematic step pointed there. Mutating it settled it in one
-> command. This is the second verification step to inherit the author's
-> blindness — the first was CB-WP-0002's dedup sample — and both fixes
-> replace re-derivation with **adversarial execution**.)*
-
-*(v1.1, from CB-WP-0002: the dedup invariant was verified on the main
-transcript by the survey — 206/206 groups — and independently re-verified
-by the reviewer, who used the same transcript. It is false in the
-8-response `subagents/` tree neither examined. Two independent checks,
-one blind spot, because both sampled the same way. Only an assertion
-running over all the data at execution time caught it.)*
+*Both cases that produced these rules — CB-WP-0005's inert `AM-7 replay`
+clause and CB-WP-0002's same-sample dedup blind spot — are in
+`InnerLoopReference.md` §Why review is adversarial execution.*
 
 **What review demonstrably does do.** Measured across two passes:
 **$0.66** and **$1.11**, roughly 1% of each pass, each finding

specs/InnerLoopReference.md

@@ -227,3 +227,73 @@ So window 2 carries a falsifier: **if it produces no override at all, that
 is evidence the rate went too far**, not evidence the mechanism is
 healthy. A window that cannot fire cannot be evaluated, which is the exact
 failure d10 had.
+
+## Meta budget — why 20% goes with a five-pass window
+
+*(CB-WP-0019 T05, 2026-08-03, at the maintainer's instruction: "the main
+budget should be spent on the task at hand while some of the budget should
+be spent on control, review and improvement… 80/20 to start with".)*
+
+The ratio and the window are a pair. With one meta pass among `n` at the
+same cost `P` as each product pass, the measured share is `P / (n·P)`, so:
+
+| window | one meta pass at parity reads | what a 20% line then demands |
+|---:|---:|---|
+| 3 | 33% | the meta pass must cost **half** a product pass |
+| 4 | 25% | ~80% of one |
+| **5** | **20%** | **parity — one pass in five, normal cost** |
+| 6 | 17% | 20% is slack |
+
+So 80/20 over a **trailing 5** is the literal reading of the instruction:
+one pass in five is meta, and it may cost what a pass costs. The same 20%
+over a trailing 3 would silently also require it to be half-price, which
+does not make meta work rarer — it makes it rushed, and this project's
+meta passes are where its instruments get repaired.
+
+**Why not simply keep 25% over three?** Because 25% over three is *"one in
+four at three-quarters cost"*, which is a ratio nobody chose; it was
+inherited from ADR-0006 without the window being considered alongside it.
+Stating the pair is the correction.
+
+**The phase setting.** `meta_phase` in `gates.toml` carries `pct`,
+`reason`, and `review_by`. It exists because stage 0 and a stabilisation
+phase do not deserve the same ratio — but it expires, because a threshold
+anyone may move is not a threshold. The failure it guards against is the
+one this project has refused four times: raising a limit to pass a breach
+rather than fixing the breach.
+
+## Loop work cashes out — the measured basis
+
+*(ADR-0006 D4, moved out of `InnerLoop.md` by CB-WP-0019 T05 when that file
+crossed the loadability limit. Limits get fixed structurally here.)*
+
+Cost per response across five passes ran **0.123, 0.228, 0.362, 0.298,
+0.123** dollars. The reading that survived the data is that **cost tracks
+distance from a runnable check**: the passes that shipped a command were
+cheap; the passes that argued about what a number means were not
+(CB-EV-0007 §5).
+
+**Refuted if** a prose-only meta pass lowers cost per response, or catches
+a class no command could.
+
+## Why review is adversarial execution, not re-derivation
+
+*(Moved out of `InnerLoop.md` by CB-WP-0019 T05 at the loadability limit.
+Two cases, three passes apart, with the same shape.)*
+
+**v1.1, from CB-WP-0002 — the same-sample blind spot (SSB).** The dedup
+invariant was verified on the main transcript by the survey (206/206
+groups) and independently re-verified by the reviewer, who used the same
+transcript. It is **false** in the 8-response `subagents/` tree neither
+examined. Two independent checks, one blind spot, because both sampled the
+same way. Only an assertion running over all the data at execution time
+caught it.
+
+**v1.4, from CB-WP-0005 — re-derivation is not enough.**
+`evidence/CB-EV-0001` reported `AM-7 replay | met, 2,290×` for a clause
+that asserts nothing: the hash reaches only a `println!`. The reviewer
+found it by opening a test out of curiosity and said so; **no systematic
+step pointed there.** Mutating it settled it in one command.
+
+Both are verification steps that inherited the author's blindness, and
+both fixes replace re-derivation with **adversarial execution**.