Typed service path inventory

This page inventories the current typed callpaths that can reach parser services or the TypeScript checker.

Source document: docs/internal/typed-paths.md

Guard model

All type-aware rule execution enters through explicit gates:

• createTypedRule(...) short-circuits typed rules (meta.docs.requiresTypeChecking: true) when full type services are unavailable.
• Optional typed flows in non-type-checked rules call hasTypeServices(context) before calling getTypedRuleServices(context).
• Type-dependent helpers no longer discover typed services internally.

Core typed helpers

Path	Typed dependency	Guard entry	Fallback behavior	Max expected expensive calls/file
src/_internal/typed-rule.ts#getTypedRuleServices	parserServices.program, checker	hasTypeServices(context) or typed-rule create short-circuit	Throws if called without program	1 (rule create path)
src/_internal/constrained-type-at-location.ts#getConstrainedTypeAtLocationWithFallback	parserServices, checker	Caller must pass prevalidated checker/parser services	Attempts constrained API first, then checker/node-map fallback	O(number of callsites invoking type resolution)
src/_internal/array-like-expression.ts#createIsArrayLikeExpressionChecker	checker + parser-services node map	Caller must pass typed services object	Returns false on safe operation failure	O(array-like candidate expressions)
src/_internal/typescript-eslint-node-autofix.ts#createTypeScriptEslintNodeExpressionSkipChecker	optional typed services	Caller passes typedServices explicitly (or omits for definition-only mode)	Definition-only path when no typed services are supplied	O(guard candidate expressions)
src/_internal/type-checker-compat.ts helpers	checker compatibility methods	Only called from typed helper/rule paths	Returns undefined when host checker API is unavailable	O(type graph traversal within caller)

Rule callpath inventory

Rules that require type checking (meta.docs.requiresTypeChecking: true)

• src/rules/prefer-ts-extras-array-at.ts
• src/rules/prefer-ts-extras-array-concat.ts
• src/rules/prefer-ts-extras-array-find.ts
• src/rules/prefer-ts-extras-array-find-last.ts
• src/rules/prefer-ts-extras-array-find-last-index.ts
• src/rules/prefer-ts-extras-array-includes.ts
• src/rules/prefer-ts-extras-array-join.ts
• src/rules/prefer-ts-extras-array-first.ts
• src/rules/prefer-ts-extras-array-last.ts
• src/rules/prefer-ts-extras-is-empty.ts
• src/rules/prefer-ts-extras-safe-cast-to.ts
• src/rules/prefer-ts-extras-set-has.ts
• src/rules/prefer-ts-extras-string-split.ts

Rules with optional typed branch (meta.docs.requiresTypeChecking: false)

These rules always run a definition-only check and only run checker-backed logic when services are explicitly prevalidated:

• src/rules/prefer-ts-extras-is-defined.ts
• src/rules/prefer-ts-extras-is-infinite.ts
• src/rules/prefer-ts-extras-is-present.ts

Telemetry counters

Typed hot-path counters are recorded in src/_internal/typed-path-telemetry.ts:

• prefilterChecks
• prefilterHits
• expensiveTypeCalls
• fallbackInvocations

Snapshot API:

• getTypedPathTelemetrySnapshot()
• resetTypedPathTelemetry()

Derived rates included in snapshot totals:

• prefilterHitRate = prefilterHits / prefilterChecks
• fallbackInvocationRate = fallbackInvocations / expensiveTypeCalls
• averageExpensiveCallsPerFile = expensiveTypeCalls / fileCount