polyglot-core-standardlisted

# Polyglot Core Standard This skill is the guiding standard for **any repo where one shared core is called from more than one language**. Apply it by default; don't wait to be asked. Its spine: **trust is placed not in any one language's checker, but in the machine-checkable contract at every seam between languages.** Each per-language standard (rust/swift/python-project-standard) already secures its own sub-tree; that is necessary but not sufficient. A polyglot repo fails at the *seams the single-language checkers cannot see*: the core and a host drift apart, the same struct is hand-copied into four languages and three of them rot, a Rust `panic!` unwinds across an FFI boundary into undefined behavior, "the build is green" means one language's build while another's binding is stale. So the job here is to (a) collapse shared truth to **one canonical core** and **derive** every binding rather than hand-mirror it, (b) make the **FFI boundary itself typed, fallible, and abort-safe**, (c) **drift-guard** every generated artifact, and (d) compose the per-language gates into **one gate that crosses every seam**. The repo's correctness ceiling equals the tightness of its **weakest seam**, not its strongest sub-tree. This standard is a **meta-standard**: it governs the seams and **delegates each language's internals** to `rust-project-standard` (the core), `swift-project-standard`, `python-project-standard`, and their siblings. It does not restate their rules — it composes them an