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Native rule packs are complete, Fensu-shipped policies for a particular framework or architecture. They run in Rust like core rules, but stay out of the catalogue until a repository explicitly activates them. Use a native pack when Fensu ships an architecture policy that should replace the generic core policy for that kind of repository. Packs can combine framework-specific rules with transparent aliases of compatible core or pack rules, presenting one coherent namespace for selection, diagnostics, and generated skills.

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Activation and selection

Pack activation and rule selection are separate:
  • rule_packs controls which shipped catalogues are available.
  • select, warn, and ignore assign available pack identities to policy tiers.
  • Activating a pack does not select it.
  • A pack selector matches no identities until its pack is activated.
  • Pack names must be registered and unique.
This separation lets a repository activate a catalogue while selecting one rule, one family of aliases, or the complete policy. The exact selectors belong to each pack’s reference page.

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Codes and namespaces

Fensu reserves FP for shipped native packs. Each pack owns a namespace beneath that prefix. The Dagster, Rust, TypeScript, and SvelteKit packs own FPDG, FPRS, FPTS, and FPSK. Pack-native rules append their numeric identity directly, such as FPDG022. Retained core aliases preserve the core family and number after the pack namespace: FFA001 becomes FPDGA001 in the Dagster pack. Pack-to-pack aliases follow the same rule: FPTSA001 becomes FPSKA001 in the standalone SvelteKit pack. An alias executes the canonical native implementation while diagnostics retain the selected pack identity and disclose provenance:
The canonical code and its alias cannot occupy the same tier because that would select one implementation twice. Fensu rejects the overlap instead of emitting duplicate diagnostics.

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Native execution

Pack-native rules and retained aliases execute without starting Python. They use the same deterministic discovery, caching, warning, ignore, exception, and output machinery as core rules. Activating a native pack by itself does not require a Python interpreter. A project that also configures rule_paths, rule_modules, or custom-rule options still uses the custom-rule metadata host for those custom rules. fensu rule shows Kind: pack, the owning pack, and any canonical alias target for an activated identity.

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Available packs

Dagster

A standalone Dagster repository architecture with 23 native policies and 101 retained core aliases.

TypeScript and SvelteKit

Framework-independent TypeScript policy and a standalone SvelteKit policy with transparent TypeScript aliases.

Rust

Native Cargo workspace analysis with 117 layout, dependency, naming, shape, hygiene, and test-convention rules.