fix(installer): close detector false-pass gaps

tools/install-next-lane.test.sh

@@ -201,6 +201,9 @@ if [[ -z "$dest" ]]; then
   exit 1
 fi
 mkdir -p "$dest/stack/packages/mosaic/framework" "$dest/stack/apps/gateway"
+if [[ "${MOSAIC_TEST_EXTRA_ARCHIVE_ROOT:-0}" == "1" ]]; then
+  mkdir -p "$dest/unexpected-second-root"
+fi
 cat > "$dest/stack/packages/mosaic/framework/install.sh" <<'FRAMEWORK'
 #!/usr/bin/env bash
 set -euo pipefail
@@ -384,6 +387,29 @@ set -e
 grep -qF 'archive safety/integrity check failed' <<<"$OUTPUT"
 [[ "$(node -p "require('$ACTIVE').status")" == "rolled-back" ]]
 
+reset_state
+echo "[test] source archive with multiple extracted roots fails instead of selecting by find order"
+before_prefix="$(prefix_fingerprint)"
+set +e
+OUTPUT="$(
+  HOME="$HOME_DIR" \
+  MOSAIC_HOME="$MOSAIC_HOME" \
+  MOSAIC_PREFIX="$PREFIX" \
+  MOSAIC_NO_COLOR=1 \
+  MOSAIC_TEST_NPM_LOG="$LOG" \
+  MOSAIC_TEST_STATE="$STATE" \
+  MOSAIC_TEST_FAIL_NEXT_GATEWAY_INSTALL=1 \
+  MOSAIC_TEST_EXTRA_ARCHIVE_ROOT=1 \
+  PATH="$FAKE_BIN:$PATH" \
+  bash "$ROOT/tools/install.sh" --cli --next --yes --no-auto-launch 2>&1
+)"
+FAIL_STATUS=$?
+set -e
+[[ "$FAIL_STATUS" -ne 0 ]]
+[[ "$(prefix_fingerprint)" == "$before_prefix" ]]
+grep -qF 'expected exactly one extracted source root' <<<"$OUTPUT"
+[[ "$(node -p "require('$ACTIVE').status")" == "rolled-back" ]]
+
 reset_state
 echo "[test] --dev source install does not require registry version resolution"
 OUTPUT="$(