helix-skills-dir-env-var-enables-portable-lint-execution

The fusion-invariants-lint.py script supports a HELIX_SKILLS_DIR environment variable override so it runs correctly when the Helix repo is cloned to any path. Without this override, the script defaults to /root/.claude/skills/ (the VPS live runtime path). When running lint against the GitHub-cloned repo, set HELIX_SKILLS_DIR=/path/to/helix/skills python3 scripts/fusion-invariants-lint.py. Both modes should pass 71/71 PASS 0/0 as the benchmark.