@codacy/tools-eslint-9

Table of Contents

• Overview
• Updating patterns
• Updating the ESLint version
• Development
• Notes for maintainers

Overview

JavaScript/TypeScript linter using ESLint 9 with the flat config format. Uses the Library execution strategy — calls the ESLint API directly rather than spawning a subprocess.

| Property | Value | |----------|-------| | Tool ID | ESLint9 | | Codacy UUID | 2a30ab97-477f-4769-8b88-af596ce7a94c | | Strategy | Library | | Languages | JavaScript, TypeScript | | Dependency | eslint npm package (v9.x) + 68 plugin packages | | Patterns | 2900 (292 core + 2608 plugin) | | File patterns | **/*.js, **/*.jsx, **/*.ts, **/*.tsx |

Updating patterns

# Re-fetch pattern metadata from the Codacy API
pnpm prefetch

# Commit the result
git add src/patterns.json

Pattern IDs use the codacy-eslint9 encoding: _ → __, / → _. Examples:

• ESLint9_no-unused-vars (core rule)
• ESLint9_@typescript-eslint_no-unused-vars (scoped plugin)
• ESLint9_react_jsx-no-target-blank (non-scoped plugin)

Updating the ESLint version

1. Update eslint and related packages in package.json
2. Run pnpm install
3. Run pnpm prefetch to check for new/removed rules
4. Run pnpm test to verify compatibility
5. If the major version changes, create a new adapter package (eslint-10/)

Development

pnpm build    # Build with tsup
pnpm test     # Run tests

Notes for maintainers

• ESLint 9 uses the flat config format exclusively. The adapter generates flat config arrays when building from Codacy patterns.
• Pattern IDs use the same encoding as the codacy-eslint9 wrapper: _ → __ then / → _ (encode), reverse for decode. This means _ in rule names is escaped as __.
• The blacklist.ts file contains 30+ rules known to crash ESLint or produce severe false positives, sourced from the codacy-eslint9 wrapper. The isBlacklisted() function also checks regex patterns (e.g. unused-imports/*-ts).
• The plugin-registry.ts handles lazy loading of all 68 ESLint plugin packages. Plugins are only loaded when rules from that plugin are in the active pattern selection.
• The config-builder.ts generates flat config objects from Codacy patterns, grouping rules by plugin and setting up appropriate parsers. TypeScript files get @typescript-eslint/parser; Vue/Svelte/JSONC/YML files get appropriate file globs.
• When no config or patterns are provided, the adapter falls back to @eslint/js recommended config.
• checkAvailability imports the ESLint class and returns ESLint.version.
• install is a no-op — the npm dependency handles installation.
• Peer dependency warnings from plugins not yet updated for ESLint 9 are expected and match the codacy-eslint9 wrapper behavior.