feat(p21): a declaration that must have LOOKED, and a refusal that names the neighbours

C1. Round 4 produced 13 declarations over six runs and NOT ONE named a fasit concept.
The distinct documents opened before each were 1,1,1,1,1,1,1,2,5,5,6,13,13: seven
declared the base's FIRST requirement after opening exactly ONE document.

The order offered two rules and asked which discriminates. Replayed against the real
listings: "the declared document must have come back from a read_dir filtered on a word
from the approach's label" refuses 13 of 13 -- including Soraasen's 12.11, the closest
any run came -- because ZERO of the 13 were reached through a filtered listing at all.
A gate that refuses every measured case, right and wrong alike, cannot discriminate.
"fewer than k distinct documents opened" at k=3 refuses 8 of 13 and keeps the five that
navigated. k=3, 4 and 5 refuse the SAME eight -- the distribution has a gap between 2
and 5 -- so the threshold is not on a cliff, and 3 is the lowest of that plateau.
DISTINCT paths, not calls, and capped by the base's own size so a small base stays
declarable.

C2. Over the same traces 18 of 143 path-bearing calls named a path the base does not
hold, ELEVEN of them one run walking R761/4-3, 4.3, 4-2, 4-1, 4-0, 4-5, 4-6 while the
real names are R761/4, R761/41, R761/42. The refusal already named the nearest listable
ancestor; now it also names up to five of that rung's own subdirectories, ranked by
longest common prefix with the segment that failed. ONE copy shared by both refusal
sites, built from context_files through in_dimension, so every name handed back resolves
and the verdict layer can never be advertised in an apology. MEASURED after: 16 of 18.

Load-bearing MEASURED, four mutations all red against the WHOLE suite, green control
1863/5, golden byte-unchanged: C3(i) the declaration gate detached (2 red) . C3(ii) the
neighbour list empty (6) . C3(iii) built from files (1, the verdict arm alone) . C3(iv)
count CALLS instead of distinct documents (1, the repetition arm alone).

Three existing arms REWRITTEN, not weakened: all three read one document and declared,
which is the measured failure class exactly.

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

README.md

@@ -777,6 +777,14 @@ when the seam is detached, so the loop cannot silently degrade into theater.
   run also writes `{run_id}-exploration.json`: the per-round ledger, the plan reviews and the
   in-loop advisory verdicts, written even when a cap cut the exploration short.
 
+  A declaration of the binding requirement is refused when the run has opened fewer than three
+  distinct documents of the base (capped by the base's own size) — measured, seven of round 4's
+  thirteen declarations named the base's FIRST requirement after opening exactly one document, and
+  none of the thirteen named a right one. The refusal is a turn the model can correct, and it
+  carries both numbers. A path the base does not hold is likewise refused by name, and the refusal
+  now lists up to five subdirectories of the nearest directory that does hold documents — every one
+  of them a path `read_dir` will answer for.
+
   Every tool call recorded in `{run_id}-exploration.json` and `{run_id}-debate.json` says HOW the
   level was asked for — `filter`, `offset` and `limit` beside the tool name, the base and the path
   — so "did the model narrow the level, or page through it" is readable from the artefact rather