fmt-workspaces: refuse a package no workspace root reaches (improvise-90ea)

The fixture loop covers every package the fixture has; this covers every
package the tree has. The review's skip-the-root rival now fails the real
repo's own gate (exit 2 naming Cargo.toml), not only the test suite.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

scripts/fmt-workspaces-test.sh

@@ -122,6 +122,32 @@ run_case "a tree with no workspace root is a usage error, not a pass" 2 "$work/e
 
 run_case "--help is a usage error, so a typo cannot pass" 2 "$work/repo" --help
 
+# The loop above covers every package the FIXTURE has; this covers every
+# package the TREE has. A package no root lists is checked by nothing, so the
+# gate must refuse a verdict -- and name the package -- rather than pass.
+scaffold
+mkdir -p "$work/repo/orphan/src"
+printf '[package]\nname = "orphan-pkg"\nversion = "0.1.0"\nedition = "2021"\n' \
+  > "$work/repo/orphan/Cargo.toml"
+printf '%s' "$DIRTY" > "$work/repo/orphan/src/lib.rs"
+cat > "$work/repo/Cargo.toml" <<'EOF'
+[workspace]
+members = ["a"]
+exclude = ["orphan"]
+resolver = "2"
+
+[package]
+name = "root-pkg"
+version = "0.1.0"
+edition = "2021"
+EOF
+if run_case "a package no workspace root reaches is exit 2, not a pass" 2 "$work/repo"; then
+  case "$OUT" in
+    *"no workspace root reaches"*orphan/Cargo.toml*) ok "  and the unreached package is named" ;;
+    *) bad "  and the unreached package is named" "output: ${OUT:0:300}" ;;
+  esac
+fi
+
 # The narrowed contract, pinned so it is not merely prose (ChatGPT Codex on
 # PR #159). rustfmt exits 1 for a source it cannot parse, exactly as for a
 # diff -- so exit 1 is "rustfmt did not certify this root clean", and what