fix(fleet): harden #791 upgrade rollback against find/reset failures

Second- and third-round independent-review reliability fixes on the keep-mode
upgrade rollback path, plus accurate abort messaging. All fixed red-first with
self-verifying controls in the rollback gate.

Round 2 (blockers A/B, should-fix C):
- install.sh: `trap 'restore_snapshot; exit 1' ERR INT TERM` so an INT/TERM
  mid-sync terminates instead of resuming past the interrupt and reporting
  success (a bash signal handler that only returns does not terminate).
- manifest.{ts,sh}: reject a degenerate [framework] section whose entries are
  all empty or bare-dot (`/`, `./`, `.`, `..`) — it passed the non-empty guard
  yet yielded zero usable globs, silently resolving everything to operator.
  Parity via a shared `[^/.]` usable-glob test; TS throws ManifestError.
- finalize.ts: classify the sync-abort message — a ManifestError is a pre-sync
  validation abort ("no files were changed"); any other error may be partial.

Round 3 (blockers D1, D2):
- install.sh: enumerate framework files with a checked temp file (_scan_or_die)
  instead of `< <(find …)` — process substitution discards find's exit status,
  so an EACCES/I/O failure mid-scan would truncate the file list yet leave the
  loop exiting 0, committing a partial upgrade as success (ERR trap never fires).
- install.sh: guard the `rm -rf; mkdir -p` target reset inside restore_snapshot
  — a bare reset failing under set -e exits silently after partial deletion,
  never printing the snapshot-recovery pointer. Now checked like the cp -a
  restore: on failure it preserves the snapshot and tells the operator where.

Tests: rollback gate 14→28 (Parts C/D/E with disabled-guard controls);
new finalize-sync-abort.spec.ts (3). No secret value is ever emitted; snapshots
stay 0700. Gates green: typecheck, lint, format:check, full mosaic vitest 1094,
HARD GATE 193, rollback 28, migration 21.

Refs #791

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/mosaic/framework/tools/quality/scripts/test-upgrade-manifest-guard.sh

@@ -9,8 +9,16 @@
 # must still update, and a retired framework file inside a shipped subtree must
 # still be pruned. No operator secret value may appear in installer output.
 #
-# Runs the whole matrix twice: once with rsync available, once forcing the
-# cp-based fallback (both destructive paths in install.sh must obey the manifest).
+# Keep mode is a SINGLE code path (sync_framework_keep, a manifest-driven cp
+# overlay + scoped prune — no rsync). The matrix still runs twice, once with
+# rsync on PATH and once with it hidden, to prove the keep path is genuinely
+# rsync-independent: it must obey the manifest identically whether or not rsync
+# happens to be installed (rsync --delete is only ever used by overwrite mode,
+# which has no operator state to protect).
+#
+# It also runs a fail-closed matrix (#791 B2/B3): an empty, operator-only,
+# malformed, or missing manifest must ABORT the upgrade loudly and leave every
+# operator path untouched — never silently no-op to "complete".
 #
 # Usage:  bash test-upgrade-manifest-guard.sh
 set -uo pipefail
@@ -131,6 +139,59 @@ run_matrix() {
   rm -rf "$H" "$E" "$OUT"
 }
 
+# Fail-closed matrix (#791 B2/B3 + blocker-1): run install.sh from a COPY of the
+# framework so the shipped manifest can be corrupted. Every corruption must abort
+# the upgrade non-zero with a manifest error, leaving all operator sentinels
+# byte-identical AND on the SAME inode. The inode check is the load-bearing part:
+# manifest validation is hoisted BEFORE make_snapshot/the restore trap, so a bad
+# manifest must abort without ever snapshotting, deleting, and restoring the
+# target. Were validation still armed under the ERR trap, restore_snapshot would
+# rm -rf + rebuild the target — same bytes but a NEW inode (broken hard links,
+# changed ctime), which a content-only hash would miss (#791 blocker-1).
+run_failclosed() {
+  local label="$1" mutate="$2"
+  local SRC H E OUT rc rel before_hash after_hash before_ino after_ino key
+  SRC=$(mktemp -d); H=$(mktemp -d); E=$(mktemp -d); OUT=$(mktemp)
+  cp -a "$FW/." "$SRC/"
+  case "$mutate" in
+    empty)         : > "$SRC/framework-manifest.txt" ;;
+    operator-only) printf '[operator]\nSOUL.md\n*.local.md\n' > "$SRC/framework-manifest.txt" ;;
+    malformed)     printf 'stray.md\n[framework]\nguides/**\n' > "$SRC/framework-manifest.txt" ;;
+    degenerate)    printf '[framework]\n/\n./\n[operator]\nSOUL.md\n' > "$SRC/framework-manifest.txt" ;;
+    missing)       rm -f "$SRC/framework-manifest.txt" ;;
+  esac
+
+  seed_home "$H"
+  for rel in "${OPERATOR_SENTINELS[@]}"; do
+    key=$(echo "$rel" | tr / _)
+    sha256sum "$H/$rel" | awk '{print $1}' > "$E/$key.hash"
+    stat -c '%i' "$H/$rel" > "$E/$key.ino"
+  done
+
+  MOSAIC_HOME="$H" MOSAIC_INSTALL_MODE=keep MOSAIC_SYNC_ONLY=1 bash "$SRC/install.sh" >"$OUT" 2>&1
+  rc=$?
+
+  chk "[fail-closed:$label] upgrade aborts non-zero" "[ '$rc' -ne 0 ]"
+  chk "[fail-closed:$label] refuses loudly with a manifest error" \
+    "grep -qi 'manifest' '$OUT'"
+  for rel in "${OPERATOR_SENTINELS[@]}"; do
+    key=$(echo "$rel" | tr / _)
+    before_hash=$(cat "$E/$key.hash")
+    after_hash=$(sha256sum "$H/$rel" 2>/dev/null | awk '{print $1}')
+    chk "[fail-closed:$label] operator sentinel untouched: $rel" \
+      "[ -n '$after_hash' ] && [ '$before_hash' = '$after_hash' ]"
+    before_ino=$(cat "$E/$key.ino")
+    after_ino=$(stat -c '%i' "$H/$rel" 2>/dev/null)
+    chk "[fail-closed:$label] operator sentinel not deleted/recreated (inode stable): $rel" \
+      "[ -n '$after_ino' ] && [ '$before_ino' = '$after_ino' ]"
+  done
+  chk "[fail-closed:$label] operator secret value absent from output" \
+    "! grep -q '$SECRET' '$OUT'"
+
+  chmod -R u+w "$SRC" "$H" 2>/dev/null || true
+  rm -rf "$SRC" "$H" "$E" "$OUT"
+}
+
 echo "#791 upgrade manifest guard (HARD GATE):"
 
 # 1) rsync path (if available on this host).
@@ -140,15 +201,24 @@ else
   echo "  · rsync not installed — skipping rsync-path matrix"
 fi
 
-# 2) cp fallback path — hide rsync behind a scratch PATH so install.sh takes the
-#    find/rm+cp branch. Provide the coreutils the fallback needs.
+# 2) rsync-absent path — hide rsync behind a scratch PATH. Keep mode never calls
+#    rsync, so this must resolve identically to run (1); it proves the keep path
+#    does not silently depend on rsync being installed. (Provide the coreutils the
+#    installer needs on the stripped PATH.)
 FBIN=$(mktemp -d)
 for t in bash cp find mktemp rm mkdir chmod cmp sed grep cat dirname basename stat sha256sum awk tr; do
   p=$(command -v "$t" 2>/dev/null) && ln -s "$p" "$FBIN/$t"
 done
-run_matrix "cp-fallback" env "PATH=$FBIN"
+run_matrix "rsync-absent" env "PATH=$FBIN"
 rm -rf "$FBIN"
 
+# 3) fail-closed matrix (#791 B2/B3) — corrupt the shipped manifest four ways.
+run_failclosed "empty-manifest"       empty
+run_failclosed "operator-only"        operator-only
+run_failclosed "malformed-manifest"   malformed
+run_failclosed "degenerate-framework" degenerate
+run_failclosed "missing-manifest"     missing
+
 echo
 echo "RESULT: $pass passed, $fail failed"
 [ "$fail" -eq 0 ]