feat(p22): stage 0's unknown-code refusal NAMES the codes the project buys

P21 was the first ANCHORED stress round and it bought something real -- must_refuse 5/5, all
five caught on stage0-baseline. It cost something measured just as clearly: 0 of 20 approaches
validated, and 26 of 26 rejections (20 approach rows plus 6 own-proposals -- a LARGER population
than the 20) read `unknown cost code '<invention>': not in project P's cost baseline (5 known
codes)`. The model invented signalregulering_konstruksjon, VENTIL_IMP, RIGG01, baerelag_asfalt
and 22 more, and it could not have done otherwise: the price schedule reaches the VALIDATOR and
never the proposer, and the refusal stated the COUNT of known codes, not one name. Step 5 feeds
that sentence verbatim into the next attempt -- and "you guessed wrong, there are five right
answers" carries nothing to correct towards.

The contrast already lived in the same stage: the MAGNITUDE half NAMES the baseline value, and
that is the half that let the loop converge in session 94. This gives that property to the other
half, in one place, and Step 5 carries it forward for free.

The window is a FIXED COUNT of whole codes (20), never a share, and it counts codes rather than
characters because a character cut can sever a code mid-name and hand the proposer an identifier
that exists nowhere. The cut is announced; a schedule that fits is not marked truncated; the
order is the schedule's own.

Measured with denominators: every cost baseline in this repo or its measured corpora is at most
six codes, and the largest real delivered price schedule measured is K2's prissammenstilling at
14 priced rows. Nothing measured reaches the window; it exists for the R761-style mengdebeskrivelse.

Load-bearing MEASURED (tests/test_named_known_codes_loadbearing.py, 10 arms), eight mutations all
red against the WHOLE suite + green control 1873/5 (from 1863/5, superset, 0 removed) and golden
demo-transcript.stdout BYTE-UNCHANGED (shasum -a 1 of the CONTENT = ea8c534773acdbe41ae68f2c55724d69aaf8be4f):
A1 revert to the bare count (7 red) - A2 a share instead of a fixed window (6) - A3 sorted (1) -
A4 silent cut (2) - A5 character slice (3) - A6 no bound at all (3) - A7 break the rejection_stage
marker (2, one an OLDER independent witness) - A8 grow the magnitude half with a code list
(2, one an OLDER independent witness).

Honesty limits, stated: no paid run yet confirms this changes the outcome live (that is DEL D);
the truncation branch is exercised only synthetically because nothing measured reaches the window;
and the schedule still does not reach the prompt, so the first attempt guesses as before.

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

README.md

@@ -757,8 +757,12 @@ when the seam is detached, so the loop cannot silently degrade into theater.
   belongs to the project, and this is where you hand it over: FILE is a `cost-baseline.json` — the
   same `{"project_id": …, "items": {"<code>": {"quantity": …, "unit_cost": …}}}` shape a bundle may
   ship — and it is used INSTEAD of one inside the base. With it, a proposal naming a cost line the
-  project does not buy is refused as a fabricated line, and one naming a real line with invented
-  magnitudes is refused with the real ones named, so the next attempt can correct.
+  project does not buy is refused as a fabricated line — and the refusal NAMES the codes the
+  project does have, so the next attempt has something to correct towards. A real line with
+  invented magnitudes is likewise refused with the real figures named. (Measured on a live tender
+  round before the codes were named: 26 rejections, every one of them an invented code, and not
+  one run recovered — a refusal that says only "there are five right answers" carries nothing to
+  aim at. A long schedule is cut to a fixed number of codes and says so.)
 
   In `--across-bundle` mode the same schedule anchors every base: one project, one price schedule.
   Mutually exclusive with `--derive-cost-baseline` (two sources for one baseline), and it satisfies