feat!: drop unmaintained eslint-config-airbnb-base

[B4nan]

Why

eslint-config-airbnb-base@15.0.0 was published in August 2022 and has been the latest version ever since. It still declares its eslint peer dependency as ^7.32.0 || ^8.2.0.

We use eslint 9. So every consumer of @apify/eslint-config has been getting ERESOLVE peer-dep warnings on every install for as long as we've been on the v9 line:

npm warn ERESOLVE overriding peer dependency
npm warn While resolving: eslint-config-airbnb-base@15.0.0
npm warn Found: eslint@9.x
npm warn   peer eslint@"^7.32.0 || ^8.2.0" from eslint-config-airbnb-base@15.0.0

This package already shipped an overrides block in its own package.json to paper over the conflict — but npm only honors overrides from the root package, not from transitive deps. So that override has been a no-op for years and never actually did anything.

The warnings were tolerable. The breaking change came when apify/actor-templates started enabling npm's min-release-age (1-day) setting in .npmrc to defend against malicious freshly-published packages. With min-release-age set, npm switches to strict peer-dep resolution and the long-standing warning escalates to a hard error:

npm error code ENOVERSIONS
npm error No versions available for eslint

The upstream package is unmaintained — there's no realistic path to a fix there. So the only way forward is to drop the dep.

Approach

Five commits:

1. feat!: drop unmaintained eslint-config-airbnb-base — replaces the legacy compat.extends('airbnb-base') with the modern js.configs.recommended + pluginImport.flatConfigs.recommended. Drops the dep, drops the dead @eslint/compat dep, drops the no-op overrides block, drops FlatCompat boilerplate.

2. feat: re-add curated rules from airbnb-base directly — brings back 70 of the meaningful rules airbnb-base used to give us, declared inline with airbnb's exact rule values. Stylistic rules are intentionally not in the base config — they're available via the new opt-in style export below.

3. fix: silence noisy import/no-named-as-default(-member) rules — see the validation section.

4. feat: add opt-in @apify/eslint-config/style export — exposes airbnb's stylistic ruleset as a separate opt-in entry point for consumers who don't want a formatter.

5. fix: also silence import/namespace — same root cause as the import/no-named-as-default fix; surfaced during validation against more downstream consumers.

What's in the curated base rule set

Grouped here the same way they're grouped (with comments) in the diff:

Modern JS / hygiene (16)

eqeqeq, no-var, prefer-const, prefer-template, prefer-arrow-callback, prefer-rest-params, prefer-spread, prefer-object-spread, prefer-numeric-literals, prefer-exponentiation-operator, object-shorthand, no-useless-rename, no-useless-computed-key, no-useless-concat, no-useless-return, no-object-constructor (modern replacement for the deprecated no-new-object), no-array-constructor

Defensive / bug-catching (24)

no-param-reassign (props allowed for acc, req, res, ctx etc.), consistent-return, default-case, default-case-last, default-param-last, radix, no-throw-literal, no-return-assign, no-unused-expressions, no-shadow (TS files use the typescript-eslint variant via ts.js), array-callback-return, no-promise-executor-return, no-template-curly-in-string, no-loop-func, no-constructor-return, no-new, no-new-wrappers, no-self-compare, no-sequences, no-unneeded-ternary, no-nested-ternary, no-lonely-if, no-multi-assign, no-else-return, no-empty-function, prefer-promise-reject-errors, block-scoped-var, vars-on-top

Security (8)

no-eval, no-implied-eval, no-new-func, no-script-url, no-proto, no-extend-native, no-caller, no-iterator

Quality / readability (13)

dot-notation, guard-for-in, no-alert (warn), no-bitwise, no-labels, no-restricted-globals (only isFinite/isNaN), no-multi-str, no-octal-escape, no-undef-init, symbol-description, prefer-regex-literals, new-cap, grouped-accessor-pairs

Imports (8)

import/first, import/no-cycle, import/no-self-import, import/no-mutable-exports, import/no-useless-path-segments, import/no-absolute-path, import/no-dynamic-require, import/newline-after-import

All rule values (severity + options) match airbnb-base's exact configuration.

Cross-checked against @eslint/js.configs.recommended and pluginImport.flatConfigs.recommended: none of the curated rules overlap with what those configs already provide. @eslint/js recommended is deliberately conservative — it covers things that are almost always bugs (no-cond-assign, no-dupe-keys, no-debugger, no-unreachable, etc.) but explicitly does not include style/defensive opinions like eqeqeq, no-var, prefer-const, or consistent-return. So all 70 curated rules are genuinely additive.

Opt-in stylistic rules: @apify/eslint-config/style

The base config does not enforce stylistic / formatting rules — Prettier (or any other formatter) is the right tool for those. For projects that don't use a formatter and want to keep the airbnb stylistic ruleset, this PR adds a new opt-in export:

import apifyTypescriptConfig from '@apify/eslint-config/ts';
import apifyStyleConfig from '@apify/eslint-config/style';

export default [
    ...apifyTypescriptConfig,
    ...apifyStyleConfig,
];

This adds 58 stylistic rules (indent, quotes, semi, comma-dangle, space-before-blocks, keyword-spacing, max-len, arrow-parens, arrow-spacing, object-curly-spacing, padded-blocks, eol-last, linebreak-style, no-multiple-empty-lines, no-trailing-spaces, etc.) with the same options eslint-config-airbnb-base used to enforce, rewritten as @stylistic/* rules so they work with eslint v9 + flat config.

@stylistic/eslint-plugin is added as an optional peer dependency — consumers who don't import this config don't need to install it. The README is updated with full setup instructions.

Note: Don't include this config if you're using Prettier — the rules will conflict with your formatter.

Validation

Tested against five real consumers using their actual lint entry points (npm run lint, not a manual npx eslint invocation):

Repo	Baseline (1.1.0)	New config	Δ errors	Δ warnings
apify/actor-templates (root + 4 templates)	0 / 0	0 / 0	0	0
apify/apify-core (lerna, 59 workspaces)	0 / 7	5 / 71	+5	+64
apify/apify-shared-js	0 / 0	0 / 5	0	+5
apify/crawlee	4 / 0	4 / 7	0	+7
apify/apify-docs	0 / 0	0 / 2	0	+2

The +5 errors in apify-core

All 5 are real new findings from @eslint/js recommended catching genuine bugs:

• 3 × no-constant-binary-expression — patterns like if (cond || true) and x === y === z in console-frontend
• 2 × no-unused-private-class-members — #signalEnd / #endedPromise defined but unused in tests/lib/api_helpers.test.js

The 4 errors in crawlee

Pre-existing @typescript-eslint/await-thenable errors in playwright-crawler and puppeteer-crawler's click-elements.ts. They reproduce against the unmodified @apify/eslint-config@1.1.0 from npm too — unrelated to this PR.

The +78 warnings (across all consumers)

All of them are "Unused eslint-disable directive" reports fired by reportUnusedDisableDirectives: true (which this config has had on for a while). They surface because consumer codebases have inline // eslint-disable-next-line max-classes-per-file (and similar) comments for rules the new config no longer enables — so the disables are dead. Per-consumer breakdown:

• apify-core (+64): 34 × max-classes-per-file, 5 × camelcase, 4 × newline-per-chained-call, 2 × valid-typeof, 2 × quote-props, 1 × no-restricted-globals, 1 × no-cond-assign, plus stragglers
• apify-shared-js (+5): 3 × max-classes-per-file, 1 × global-require, 1 generic
• crawlee (+7): 1 × no-cond-assign, 3 × no-unreachable-loop, 3 generic
• apify-docs (+2): 1 × global-require, 1 × no-cond-assign

These are not regressions — they're dead inline disables that the consumer can clean up with eslint --fix (which auto-removes unused disable directives).

A note on the import-plugin rules I had to silence

The first iterations of this PR caused +1107 warnings in apify-core, +4 errors in apify-shared-js, and +1 error in crawlee, all from import/no-named-as-default, import/no-named-as-default-member, and import/namespace.

These three rules are part of eslint-plugin-import's flatConfigs.recommended. They were declared as error in airbnb-base too — but they were silently no-op in the legacy baseline because FlatCompat doesn't fully register eslint-plugin-import's plugin context. The new config registers the plugin properly (via pluginImport.flatConfigs.recommended), so the rules suddenly start firing — including a lot of false positives:

• import/no-named-as-default / -member: false positives on namespace re-exports and on libraries like zod and async whose default and named exports overlap.
• import/namespace: cannot validate computed property access against imported namespaces (e.g. REGEXS[someKey]).

Two commits in this PR explicitly silence all three to match the effective baseline behavior:

• fix: silence noisy import/no-named-as-default(-member) rules
• fix: also silence import/namespace

After both fixes, all five validated consumers have zero new errors from this PR beyond the 5 genuine bug catches in apify-core.

Rule diff vs. current @apify/eslint-config@1.1.0

	Count
Before (with airbnb)	328
After (this PR, base config)	173
With opt-in /style	231

The 4 added rules are modern @eslint/js recommended additions airbnb-base didn't have:

• no-constant-binary-expression
• no-empty-static-block
• no-new-native-nonconstructor (replaces the removed no-new-symbol)
• no-object-constructor (replaces the deprecated no-new-object)

The remaining ~100 still-removed rules (assuming the /style opt-in is used) break down into:

1. ~76 deprecated/removed in eslint 9 — these can't be brought back even if we wanted, e.g. no-buffer-constructor, no-new-symbol, no-native-reassign, valid-jsdoc, require-jsdoc, prefer-reflect, lines-around-directive, func-call-spacing, no-process-env, no-process-exit, no-sync, handle-callback-err, callback-return, etc.
2. ~20 stylistic that have been removed/renamed in @stylistic/eslint-plugin — they no longer exist in the modern stylistic plugin either.
3. ~5 deliberately opinionated — no-restricted-imports/no-restricted-properties/no-restricted-modules/no-restricted-exports (airbnb had them on with no config, which is meaningless), no-confusing-arrow (overlaps with prettier and no-mixed-operators).

Downstream rollout plan

1. Merge this PR.
2. Publish via publish_to_npm.yaml workflow_dispatch as a major bump (v2.0.0). The rule diff is large enough to warrant it, but the validation above shows the impact is small in practice.
3. apify/actor-templates: bump @apify/eslint-config to ^2.0.0 in the root and in all 24 templates, and remove the temporary overrides workaround that was added to root package.json in apify/actor-templates#750 as a stopgap.
4. apify/apify-core: bump and run eslint --fix to clean up the ~64 dead inline disables, then fix the 5 real new errors (3 × no-constant-binary-expression, 2 × no-unused-private-class-members).
5. apify/apify-shared-js: bump and run eslint --fix to clean up 5 dead inline disables. Zero real new findings.
6. apify/crawlee: bump and run eslint --fix to clean up 7 dead inline disables. Zero real new findings (the 4 pre-existing await-thenable errors are unrelated to this PR).
7. apify/apify-docs: bump and run eslint --fix to clean up 2 dead inline disables. Zero real new findings.
8. Other consumers: same — bump and observe. If you want to keep the airbnb stylistic rules without adopting a formatter, add the new @apify/eslint-config/style opt-in (see README and the "Opt-in stylistic rules" section above).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR removes the unmaintained eslint-config-airbnb-base (which is incompatible with ESLint 9 peer deps under strict resolution) and switches @apify/eslint-config to rely on native flat-config building blocks (@eslint/js + eslint-plugin-import) while keeping the package installable without peer-dep resolution failures.

Changes:

• Drop eslint-config-airbnb-base (and the now-useless internal overrides) to eliminate ESLint 9 peer-dep conflicts.
• Remove unused/dead dependencies tied to the legacy config loading path (e.g., @eslint/compat, @eslint/eslintrc usage).
• Explicitly include @eslint/js recommended + eslint-plugin-import recommended flat config, and set languageOptions.sourceType = 'module' to preserve prior module parsing semantics.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
package.json	Removes eslint-config-airbnb-base, @eslint/compat, and the no-op overrides block to fix install-time peer resolution issues.
index.js	Replaces legacy FlatCompat-based AirBnB extension with native flat config entries (@eslint/js + eslint-plugin-import) and restores sourceType: 'module'.

---

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[jirimoravcik]

Most of the platform repositories do not use any formatter at the moment. Removing the stylistic rules would be a massive breaking change.

[B4nan]

Well, we can't keep things the way they are now, this was always wrong, you can't use overrides on a production dependency in a library, that only forwards the problem downstream. This literally blocks updates in many of the open source repos, some of them having vulnerability alerts we need to resolve in the next few days. (edit: this is actually only about min release age, not the vulnerabilities, but that doesn't make it any smaller)

This is a major bump, so you could keep using the old version in private repos. Or just adopt a formatter. We keep postponing this for no reason, all tooling repos already have it, and it was super simple to adopt. Alternatively, we could add formatting rules here via https://eslint.style/, but I would rather go with the formatters.

Either way, we need to get rid of that unmaintained dependency. This was causing warnings on install for years now. And if we want to enforce min release age, those warnings become errors, effectively blocking the adoption.

[B4nan]

Discussed this with @fnesveda on slack, I've added some of the missing rules back, keeping the stylistic ones off. PR description is updated in this regard, most of the removed things are stylistic, only a handful of actual lint rules are missing now.

[B4nan]

In the end, I also added opt-in stylistic rules support to ease the migration:

import apifyTypescriptConfig from '@apify/eslint-config/ts';
import apifyStyleConfig from '@apify/eslint-config/style';

export default [
    ...apifyTypescriptConfig,
    ...apifyStyleConfig,
];