GeezerVison

Purpose

Turn the existing raw text-signature/result-persistence follow-up into a real CI regression gate, without another RustPython build or scanner pass. This remains separate from the merged non-raw reporting prerequisite (#9726).

Rebased onto main b66534d448. Current head 9671f56cee.

Changes

• Keep native raw __text_signature__ observations independent of inspect.signature comparisons; preserve type-document and unknown distinctions.
• Reuse the existing three-OS scan. Compare exact individual observed failures and selected-scope fingerprints against platform-specific baselines.
• Reject new/changed failures, unknown/coverage regressions, missing required observation metadata, and stale resolved exceptions. Requiring resolved exceptions to disappear prevents later reintroduction under an old allowance.
• Preserve full scan/context artifacts even if the gate fails. Pin the CPython oracle through .python-version; check exact OS/architecture/version/build-feature context.
• Keep the baseline generation command explicit and outside CI.

Baseline provenance and remaining work

The initial three baselines were generated from the existing verified Linux/macOS/Windows artifacts of CI run 42421287760, merge 5da7d5b1d1d56467fb60997bbdb66676e0c6c33d, CPython 3.15.0. Downloaded ZIP SHA256 values match GitHub's artifact metadata.

Baseline refresh completed: exact-head run 42491705325, head 4a6ddde862, merge 3b4735987efcc7ba59d454a1f6cf9d667a631778, produced all three platform artifacts. Removed 30 resolved observations on Linux/macOS and 28 on Windows; reviewed retained pre-existing main differences. Normalized only process addresses in exception repr diagnostics, not raw signatures or default literals. The gate now runs immediately after the existing build to avoid expensive tests after a detected signature regression.

Final-head validation passed: CI run 42496222992 passed on head 9671f56cee21682a26cc4c52f44924cb72114c5b, including the signature gate and native tests on Linux, Windows and macOS. This PR remains draft for maintainer review. Do not interpret old green CI or self-comparison as validation of current main. This gate is an observed-surface ratchet, not a claim of zero signature mismatches, complete discovery, argument behavior parity or CPython compatibility. Unknowns remain unverified. No runtime/Lib changes are included.

Validation

• 59 focused whatsleft and gate tests pass under CPython 3.15.1.
• All three current hosted platform artifacts pass the refreshed checker and matching-context CLI; deliberate reintroduction of a resolved queue mismatch fails on every platform.
• Independent review reproduced the important negative paths: missing provenance is rejected; resolved exceptions require deletion; unchanged observations pass.
• Repository hooks and git diff --check pass after rebase.
• Previous head hosted CI passed Rust/C API tests, Clippy, WASI, lint, and native snippets/CPython tests on all three OSes; only the expected baseline gate failed. Final-head changes are checker/tests/baselines and step ordering only. Final-head hosted integration subsequently passed (run 42496222992), including all three signature gates, native tests, Rust tests, Clippy, WASI and lint; no additional local Rust build was performed.

AI assistance

Implementation and independent review assisted by dot; exact model version unavailable in this runtime.