fix(git): push-guard harness — resolve three re-review blockers + two corrections

Authored by installer-7; committed by mos-claude (no credential for this remote).
push-guard.sh and test-push-guard.sh are BYTE-IDENTICAL to the previously cleared
versions — every change this round is in the harness, confirming the reviewer's
framing that none of the three blockers was in the guard itself.

B1 verify-clean-clone.sh could not verify the artifact in its real monorepo location:
  it resolved ROOT but kept artifacts as bare basenames, so running it in place
  reported all artifacts NOT TRACKED. Its own suite missed this because every
  fixture installed artifacts at fixture ROOT — a fixture encoding a layout the
  real subject does not have. PREFIX now comes from 'git rev-parse --show-prefix'
  and is threaded through the ls-tree pathspec, the cloned stat, and the suite cwd;
  the verifier PRINTS the prefix. Three needles: nested-layout pass, prefix-reported
  (else a green only means the prefix was ignored harmlessly), and mode-needle-still-
  bites-nested (a prefix threaded into the clone but not ls-tree would silently stop
  checking modes).
B2 the generator reported full coverage and exited 0 on a RED baseline — any
  pre-existing failure marked every mutant killed. Now refuses unless baseline is
  exit 0 with zero failures, prints the actual tally on refusal, emits no table, and
  scores kills by NAMED DELTA rather than a raw red count.
B3 the generator mutated the reviewed source in place; SIGKILL stranded a mutant and
  contaminated a following run. Guard and suite are now copied into a temp dir and
  mutations apply to that copy — no restore step to fail. The author's first control
  for this was itself vacuous (a 3s kill lands during baseline, before any mutation,
  so it passed against the unfixed mechanism too); the real control drives the kill
  from inside the run on the second suite invocation, plus a needle proving the
  reconstructed pre-fix mechanism DOES strand.
Corrections: 'shellcheck clean' had been measured at -S warning and published
  unqualified — a filtered measurement stated as an unfiltered claim. Now clean at
  DEFAULT severity across six files with one scoped, documented SC2016 disable.
  ARTIFACTS extended five -> six so the test files no longer omit themselves.

Verified before commit: six files sha256-matched to the author's hashes; shellcheck
exit 0 at default severity; push-guard 46/46 and verifier 9/9 run directly; the
in-place verifier resolved the real nested prefix against this tree.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YKj59Qadrb2WBLaePvkM7H

packages/mosaic/framework/tools/git/verify-clean-clone.sh

@@ -51,7 +51,9 @@ done
 HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 [[ -n "$REPO" ]] || REPO="$HERE"
 
-ARTIFACTS=(push-guard.sh test-push-guard.sh verify-clean-clone.sh mutate-push-guard.sh)
+ARTIFACTS=(push-guard.sh test-push-guard.sh verify-clean-clone.sh mutate-push-guard.sh
+           test-mutate-push-guard.sh
+           test-verify-clean-clone.sh)
 SUITE="test-push-guard.sh"
 
 # --- the subject must be a real repository, or there is nothing to verify -----
@@ -66,8 +68,26 @@ if ! REV_SHA="$(git -C "$ROOT" rev-parse --verify --quiet "${REV}^{commit}")"; t
     exit "$EX_FAIL"
 fi
 
+# --- THE ARTIFACT'S COMMITTED PATH, NOT ITS BASENAME -------------------------
+# v2 asserted `git ls-tree HEAD -- push-guard.sh`, which is a ROOT-RELATIVE
+# pathspec. These files really live several directories down. Run in place and
+# every artifact came back "NOT TRACKED" -- the verifier built to stop packaging
+# false-greens could not verify the tree that ships it.
+#
+# The tests missed it because EVERY FIXTURE INSTALLED THE ARTIFACTS AT THE
+# FIXTURE ROOT. 6/6 green proved flat-layout operation and nothing about the
+# deployed path. THAT IS THE THIRD TIME ON THIS TOOL THAT A CONTROL VALIDATED A
+# MODEL INSTEAD OF THE SUBJECT: v1 measured a cp'd scratch repo, and then v2's
+# own tests measured a layout that does not exist. A fixture is a claim about
+# the world, and an untested fixture is an unreviewed one.
+#
+# --show-prefix answers "where is this directory inside its repository", so the
+# same prefix drives ls-tree, the cloned stat, and the suite's working dir.
+PREFIX="$(git -C "$REPO" rev-parse --show-prefix)"
+
 printf '=== subject ===\n'
-printf '  repo %s\n  rev  %s (%s)\n\n' "$ROOT" "$REV" "$REV_SHA"
+printf '  repo   %s\n  rev    %s (%s)\n  prefix %s\n\n' \
+    "$ROOT" "$REV" "$REV_SHA" "${PREFIX:-<repository root>}"
 
 # --- 1. MODE, FROM THE COMMITTED TREE OF THE SUBJECT -------------------------
 # git ls-tree reports what the COMMIT records. Nothing on my filesystem can
@@ -75,7 +95,7 @@ printf '  repo %s\n  rev  %s (%s)\n\n' "$ROOT" "$REV" "$REV_SHA"
 printf '=== committed modes (git ls-tree %s) ===\n' "$REV"
 rc=0
 for f in "${ARTIFACTS[@]}"; do
-    entry="$(git -C "$ROOT" ls-tree "$REV_SHA" -- "$f")"
+    entry="$(git -C "$ROOT" ls-tree "$REV_SHA" -- "${PREFIX}${f}")"
     if [[ -z "$entry" ]]; then
         printf '  FAIL  %s is NOT TRACKED at %s -- nothing committed to verify\n' "$f" "$REV"
         rc=1; continue
@@ -111,14 +131,14 @@ git clone -q --no-local --no-hardlinks "$ROOT" "$WORK/clone"
 git -C "$WORK/clone" -c advice.detachedHead=false checkout -q "$REV_SHA"
 
 for f in "${ARTIFACTS[@]}"; do
-    printf '  clone disk mode: %s %s\n' "$(stat -c '%a' "$WORK/clone/$f")" "$f"
+    printf '  clone disk mode: %s %s\n' "$(stat -c '%a' "$WORK/clone/${PREFIX}${f}")" "${PREFIX}${f}"
 done
 
 printf '\n=== executing DIRECTLY (./%s), not via "bash %s" ===\n' "$SUITE" "$SUITE"
 # Invoking the interpreter explicitly masks a missing exec bit completely -- it
 # is how the original green was obtained. Direct execution is the thing under
 # test, so the mode has to be real for this line to succeed.
-cd "$WORK/clone"
+cd "$WORK/clone/${PREFIX}"
 if ! "./$SUITE"; then
     printf '\nCLEAN-CLONE RUN FAILED.\n'
     exit "$EX_FAIL"