PlayForm/@playform/hook-dsh-governor-cargo

Silent Cargo.toml governor — the RUST-SIDED FLAVOR of the package.json governor (@playform/hook-dsh-governor-package): same architecture, same API-awareness discipline, same PlayForm TypeScript layout — but for Rust manifests. Hooks fs/observed — the cordis event every tool-layer file write dispatches — for basename Cargo.toml, parses with smol-toml ONLY to identify dependency entries ([dependencies], [dev-dependencies], [build-dependencies], [target.'cfg(...)'.dependencies], [workspace.dependencies]) and rewrites chain-governed pins SURGICALLY on the raw text lines (comments and formatting survive; an internal calculation, not a TOML stringify), then runs the update stage as a detached, contained continuation that drives the RUST-SIDE CLI — cargo upgrade (cargo-edit) — through the ctx.subprocess seam with the exclusion list enforced AT THE CLI LEVEL (--exclude, one flag per crate; chain deps merged in so cargo upgrade can never bump a chain-governed pin). The Rust/TS boundary is exclusionary: Rust does not co-opt into the TypeScript ecosystem, and there is no npm-library equivalent for cargo manifest updates — the cargo CLI is the only update path. Fully API-aware: the governed manifest is read/rewritten through ctx.fs with a version-guarded replaceIfVersion write (the service owns version tokens), configuration is a validated Schemastery Config schema with defaults, and the authoring agent is never notified: the tool result is built from the author's own content, and the observation-policy's version record is refreshed by re-emitting fs/observed with the service-issued fresh version (P₃ after the chain rewrite; U₂ after the cargo upgrade).