# typescript-eslint Parity Tracker

This page tracks the native rule set against typescript-eslint (and its native companion surface, tsgolint/internal/rules, which is the exact 59-rule target the plugin ships). Every rule listed here:

• is implemented in Rust (corsa_core::lint) and exposed as an Oxlint plugin rule under the typescript/ namespace,
• receives its full documented fact vocabulary from the JS bridge (type facts come from the pinned Corsa checker — none of the decision inputs are synthesized only in tests),
• has Rust unit tests over its decision logic and a RuleTester valid/invalid suite that runs against the real pinned Corsa binary in CI (real-corsa-smoke).

# Column legend

• Options — parity with the upstream typescript-eslint option schema. full means every documented option is honored. TypeOrValueSpecifier entries (allow, allowForKnownSafePromises, …) are matched by type/value name (array sugar included); the from: package/file domain is not derivable over the stdio API, so a name match is honored for every domain, which errs toward silence.
• Messages — whether the rule's message IDs mirror upstream typescript-eslint (upstream) or use a legacy local catalog (local). Local IDs are kept where they predate this tracker; migrating them is a breaking change for messageId matchers and is done rule by rule (no-floating-promises and only-throw-error migrated in 1.13).
• Notes — residual, deliberate divergences. "conservative" means the rule stays silent where a fact cannot be proven over the upstream API (the documented degradation contract) instead of guessing.

# Rules

¹ allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing is intentionally a no-op: the native lane reads strictNullChecks from the project's compiler options and emits the upstream noStrictNullCheck diagnostic where the rule defines one, but it never hard-errors the whole run the way typescript-eslint does, so there is nothing for the escape hatch to bypass.

# Beyond the tsgolint surface

typescript-eslint ships more rules than the type-checked surface tracked here. The rest fall into two groups:

• Syntax-only rules (ban-ts-comment, array-type, naming-convention's syntactic core, …) — these need no checker and belong to Oxlint's own native rule set, not to this plugin.
• Type-aware extension candidates not yet in tsgolint/internal/rules (e.g. the type-aware half of naming-convention). These enter this tracker when the upstream parity target adopts them.

# Known engineering trade-offs

Two implementation strategies in the native lane are deliberate and worth understanding before filing parity bugs:

1. Rendered-type-text analysis. Rules like no-unsafe-assignment detect unsafe any flow by parsing the checker's rendered generic type texts (Set<any> → Set<string>) instead of walking live checker type objects. The upstream API resolves types per request over stdio; a recursive structural walk would multiply round trips per node, and the checker's isTypeAssignableTo cannot answer "unsafe any flow" (any is assignable to everything). The text walk mirrors the same structure the upstream Go rule walks, at zero additional round trips.
2. Position-based lookups. The upstream API addresses types by file position (the touching token). Call results, await unwrapping, and construct results resolve through callee signatures instead; anonymous function literals have no addressable type at all, so their facts derive from the literal's AST. This is why a handful of notes above say "conservative": where neither a position nor a signature reaches the needed type, the rule prefers silence over guessing.

# How this page stays honest

• implementedNativeRuleNames + pendingNativeRuleNames is asserted against the upstream tsgolint/internal/rules directory listing in native_rules.test.ts; the surface cannot silently drift.
• Every rule's RuleTester suite runs against the real pinned binary in the real-corsa-smoke CI job (CORSA_REQUIRE_INTEGRATION=1 turns a missing runtime into a hard failure).
• The fact vocabulary consumed by the Rust rules is cross-checked against what the bridge produces; a fact consumed but never produced is a bug, not a degradation.

# See also

• Native rules — the rule catalog and bridge design
• Type-aware Oxlint — authoring model and configuration