Regression stage of QP — re-executes a previous run's test cases unchanged, computes surface_reach (how many TCs left the entry screen, as a ratio over ALL TCs), and reports the per-TC delta against the earlier run so a "no change" claim is per case, not an aggregate.
Install
npx skills add chrono-meta/forge-harness --skill qp-regressnpx skills add chrono-meta/forge-harness --skill qp-regress -a claude-code -gnpx skills add chrono-meta/forge-harness --skill qp-regress -a codex -ggemini skills install https://github.com/chrono-meta/forge-harness.git --path plugins/fh-qp/skills/qp-regressgh skill install chrono-meta/forge-harness qp-regressgit clone --depth 1 https://github.com/chrono-meta/forge-harness /tmp/chrono-meta__forge-harness
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/chrono-meta__forge-harness/plugins/fh-qp/skills/qp-regress ~/.claude/skills/qp-regress # Claude Code
cp -R /tmp/chrono-meta__forge-harness/plugins/fh-qp/skills/qp-regress ~/.agents/skills/qp-regress # Codex, Cursor, Gemini CLI, Copilot, OpenCode