GeezerVison

Summary

• Add --json-output PATH to whats_left.py so the complete structured comparison can be preserved while retaining the existing human-readable --signature output.
• Include CPython builtin signature inventory and skipped CPython reference imports in the structured result, so a future gate can detect reference-coverage loss. The new human summary rows count inventory groups and import failures, not signature mismatches.
• Upload the complete JSON and a Python/platform/runner/commit context sidecar from each existing Linux, macOS, and Windows CI job. The GITHUB_SHA in a PR run is a merge commit; establish future baselines from main push runs.
• Fail the scan if its RustPython subprocess exits unsuccessfully, rather than potentially accepting a JSON-looking last line from a failed process.

This is a data-collection step toward a transparent text-signature regression gate, not a gate and not a claim of signature parity. No mismatches or missing/import failures are filtered out. A later check must detect regressions and coverage loss, and eventually require zero mismatches.

Validation

• Focused Python AST-extracted checks verified sample JSON output, failure on a nonzero child, reference-import failure recording, and builtin signature inventory. The script also passed an AST syntax parse.
• git diff --check, the normal commit hook, Ruff formatting and Ruff checks passed. Independent source review checked the structured data path, cross-platform quoting, artifact naming and provenance.
• Full whats_left scans and RustPython workspace/C API tests were not run locally: the coordinated native-execution guard and lock are absent and the offline cache is incomplete. Hosted three-platform scans and the required workflow zizmor scan are pending; no CI pass is claimed.

AI assistance

Implementation and source review were assisted by dot. The runtime does not expose its exact model version.