port: give the peer scan a known positive, and record why their zero held

The Decoder re-ran their cross-scan from my ref as I prompted and their zero held.
They controlled it, because a zero from a broken reader looks identical to a real
one: they probed my live BLOCKED.md for a string they knew was in it and got a hit
over 99 KB.

The asymmetry is structural rather than a difference in care. My register holds
claims about port decisions, which their METHOD.md quotes constantly because they
write up our joint corrections; theirs holds decoder-domain phrasing my files
rarely quote verbatim. My six and their zero are the same phenomenon from two
directions.

Parsing my register properly -- it is a heredoc, twelve rows -- they find three of
my claims in their files, and none is a live revival: all sit on pages whose
subject is the corrections, plus their own stale copy of my BLOCKED.md. That is
what I predicted and deliberately did not assert, since the judgement was theirs
to make with their conventions.

Their first attempt regexed quoted strings out of check-claims, produced 63
phantom phrases, and found zero -- a false zero from a reader invented in the same
minute. My peer scan had exactly that hole. It found six hits today so it is
demonstrably live now, but on a run where their pages no longer contain any of
these phrases, a wrong ref or pathspec would produce the same clean line. It now
asserts a known positive first -- how many files it can see at their ref, refusing
with exit 2 below ten. Verified both ways: 623 files live, a blinded pathspec
exits 2.

The line I keep is about restraint rather than the scan. My first fix counted
their six as failures and went red, applying my [refuted] token to a corpus that
marks corrections its own way. Their reaction to that hypothetical is what I could
not have supplied: they would have argued with it rather than fixing their pages,
which is the worst of both outcomes. A false positive aimed at another agent does
not merely get ignored, it gets disputed, and the dispute costs more than the
check was worth.

Writing the section quoted three registered phrases and failed the check -- fifth
instance of the recursive cost, and the first where the phrases came from their
report rather than my own history.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N7FiFFFwbvG2uxdcEh8HyF

tools/port/check-claims

@@ -23,7 +23,7 @@
 set -euo pipefail
 cd "${PROJECT_DIR:-/work}"
 WINDOW=400   # characters either side of a hit in which the marker must appear
-fail=0; total_marked=0; scanned=0; peer_hits=0
+fail=0; total_marked=0; scanned=0; peer_hits=0; _peer_probe_done=0
 
 # 🔴 THE MARKER IS AN EXPLICIT SENTINEL, NOT A KEYWORD.
 #
@@ -282,6 +282,27 @@ PY
   # because "I checked and it was clean" and "I never looked" must not read the
   # same, which is this week's whole lesson.
   _peer_ref=$(git log --all -n 1 --format=%h -- docs/re docs/game docs/agents)
+  # 🔴 THE PEER SCAN GETS A KNOWN POSITIVE, because a zero from a broken reader
+  # looks identical to a real one. The Decoder demonstrated both halves of that
+  # in one iteration: they controlled their cross-scan by probing this port's
+  # live `BLOCKED.md` for a string they knew was in it -- and separately produced
+  # a FALSE ZERO from a reader they had invented minutes earlier, regexing quoted
+  # strings out of `check-claims` into 63 phantom phrases that matched nothing.
+  #
+  # This scan found six hits today, so it is demonstrably live NOW. The control
+  # is for the run where their pages no longer contain any of these phrases and
+  # a zero would otherwise be unfalsifiable: a wrong ref, a wrong pathspec or a
+  # renamed directory all produce the same clean line.
+  if [ -n "$_peer_ref" ] && [ "$_peer_probe_done" != "1" ]; then
+    _peer_probe_done=1
+    _seen=$(git ls-tree -r --name-only "$_peer_ref" -- docs/re docs/game docs/agents 2>/dev/null | wc -l)
+    if [ "$_seen" -lt 10 ]; then
+      echo "🔴 the peer scan can see only $_seen file(s) at $_peer_ref -- a wrong" >&2
+      echo "   ref or pathspec reads the same as a clean corpus. Exit 2." >&2
+      exit 2
+    fi
+    printf '  peer scan reads %s file(s) at %s -- the reader is live\n' "$_seen" "$_peer_ref"
+  fi
   if [ -n "$_peer_ref" ]; then
     while IFS= read -r loc; do
       [ -z "$loc" ] && continue