Restore ten guarded C API test modules with explicit updater import bindings - #9505

Summary

Restore ten whole test_capi modules from pinned CPython 3.15 (d220409a13b77de7a6c30abe16ea90db01528edc) through the actual scripts/update_lib migrate command:

• Canonical byte-identical: test_file, test_object, test_run, test_set, test_slots, test_tuple, test_complex, test_float.
• test_codecs: use the existing optional import helper for _testcapi before the unchanged _testlimitedcapi gate.
• test_getargs: bind the genuinely required getargs_keywords and getargs_keyword_only through existing support.get_attribute. A partial fixture such as Add a _testcapi module #9143 lacks these APIs; this raises a real capability skip rather than an import failure. The unchanged complex/float sibling imports propagate that skip.

All class/function bodies, decorators and assertions remain canonical. No new skip decorators, xfails, fake fixtures or global test-disable switches are introduced. This is source restoration, not implementation of these C API fixtures. The package still has 22 missing canonical files afterward.

Generic updater extension

Add explicitly declared import_binding_rewrites to the already landed new-file adaptation mechanism. Only exact, same-name import-to-canonical-helper bindings are admitted, with module/name/alias/order/provenance and scope-shadow checks. Validated groups retain their position among protected statements. Existing default migrations, source-hash/path/block/overlap/overwrite protections and class/function AST checks remain unchanged. Relative/dotted/star imports and unsupported rewrite forms fail closed.

#9498 and #9501 have landed. This diff contains only the new tooling extension and ten module additions; no duplicated parent code or synthetic dependency commit.

Validation

• Reproduced on main 88f373357f40923c7b1bb533072e7962790e2663; all 17 original parent-file bytes were checked against their PR heads.
• Host updater suite: 241 tests passed, independently rechecked with Python 3.13 and 3.12.
• Actual candidate updater generated all ten modules. Eight canonical byte identities, two exact reviewed metadata adaptations, and full class/function/decorator/assertion AST equality were verified.
• Normal configured commit hooks passed; final 13-file hashes and reviewed diff were unchanged afterward.
• Following an execution-environment reset, the private reviewed patch and metadata were recovered byte-for-byte from preserved artifacts. The newly generated files exactly match the historical Python 3.15 migration output hashes. Current selected-source parsing/tooling checks used Python 3.13; no fresh Python 3.15 runtime or full dependency-graph validation is claimed.

Limits and future activation

No C API test module was imported or executed locally, and no Rust/native build or full interpreter suite was run for this source-only cohort. Missing-fixture skips in ordinary builds are not C API behavioral passes or complete CPython compatibility.

If a future _testcapi provides both getargs entry points, re-review the subsequent constants, eager class-body getargs_positional_only_and_keywords import and remaining parser APIs before activation. Introducing _testlimitedcapi similarly requires separate review of NULL/invalid arguments, refcounts, mutation, GC/finalizer and subprocess paths. Existing bodies are preserved, not claimed safe or supported by module presence alone.

AI assistance

OpenAI Codex assisted source investigation, updater implementation, migration, recovery and validation, with independent agent review. The runtime model version is unavailable. This reports tool/source evidence, not human manual validation or unexecuted native compatibility checks.