fix(hooks): give guard-shared-stash's split_segments() the backslash branch #11131 closed next door

.claude/hooks/guard-shared-stash.selftest.sh

@@ -85,6 +85,28 @@ expect allow 'grep -rn "cd x && git stash pop" .claude/'
 expect allow 'echo "never run git stash pop in a shared checkout"'
 expect allow 'git grep -n "git stash"'
 
+echo "== an UNQUOTED \\\" opens no quote, so the stash behind it is still seen (#11738) =="
+# The measured hole: segmentation read the escaped `"` as OPENING a quoted region that never
+# closed. Every separator behind it went inert, the whole command collapsed into a single
+# `echo` segment, and the real `git stash pop` was just another argument. Same repair
+# guard-main-checkout-bash.sh's split_segments() took in #11131. Every case below was
+# ALLOWED before that branch existed; the bare forms next door are the controls that say
+# the guard was reached at all.
+expect block 'echo \" ; git stash'
+expect block 'echo \" ; git stash pop'
+expect block 'echo \" && git stash pop'
+expect block 'printf \" ; git stash drop'
+expect block 'echo \" ; git -C ../objectstack-issue-11738 stash pop'
+expect block "$(printf 'echo \\"\ngit stash pop\n')"
+# Precision twins: the escape must not manufacture a block where nothing touches the stack,
+# and the read-only and SHA-pinned forms stay allowed behind one.
+expect allow 'echo \" ; echo hello'
+expect allow 'echo \" ; git status'
+expect allow 'echo \" ; git stash list'
+expect allow 'echo \" ; git stash apply abc1234'
+expect allow 'echo a\ b'
+expect allow 'echo \\ ; git status'
+
 echo "== escape hatch =="
 expect allow 'git stash pop' OS_ALLOW_STASH=1
 

.claude/hooks/guard-shared-stash.sh

@@ -63,7 +63,7 @@
 # for anyone who means it. Widening it to string-match anywhere in the command would block
 # every `grep "git stash"` run against this very file.
 #
-# Self-test (32 cases, no network, no build): .claude/hooks/guard-shared-stash.selftest.sh
+# Self-test (44 cases, no network, no build): .claude/hooks/guard-shared-stash.selftest.sh
 
 set -uo pipefail
 
@@ -89,6 +89,18 @@ fi
 # A separator inside '…' or "…" does NOT split, so writing *about* the ban is never caught
 # by the ban: `grep -n "cd x && git stash pop" AGENTS.md` stays one segment whose first
 # word is grep. (objectstack#4890's lesson — the PR writing a rule must not trip it.)
+#
+# OUTSIDE quotes a backslash escapes the NEXT character, so an escaped `\"` opens no quoted
+# region at all. Without that branch this pass read the `"` as opening a region that never
+# closed, went inert for every separator behind it, collapsed the whole command into one
+# segment whose head word was the harmless one, and let a real `git stash pop` ride through
+# as a mere argument of `echo` (#11738). Measured on this repo's copy before the fix:
+# `echo \" ; git stash pop` was ALLOWED while a bare `git stash pop` was blocked.
+#
+# This is the same repair guard-main-checkout-bash.sh's split_segments() took in #11131,
+# in the same shape; that guard's `word` bookkeeping has no analogue here because this pass
+# has no comment rule to track word starts for. Both characters are kept verbatim — this
+# pass only SPLITS, and check_segment() re-reads the words afterwards.
 segments=()
 split_segments() {
  local s="$1" seg="" q="" ch i n=${#1}
@@ -100,6 +112,10 @@ split_segments() {
  continue
  fi
  case "$ch" in
+ '\')
+ seg+="$ch"
+ if [ $((i + 1)) -lt "$n" ]; then i=$((i + 1)) ; seg+="${s:i:1}" ; fi
+ ;;
  "'" | '"') q="$ch" ; seg+="$ch" ;;
  ';' | '|' | '&' | '(' | ')' | '{' | '}' | $'\n') segments+=("$seg") ; seg="" ;;
  *) seg+="$ch" ;;