chore: Migrate to eslint 10

[TimothyJones]

Migrates the workspace to ESLint 10: the shared eslint-config-case-maintainer package, and each of the 18 packages that consume it.

The blocker: eslint-plugin-import

[email protected] cannot run under ESLint 10. import/order calls SourceCode#getTokenOrCommentBefore/After, which v10 removed, and that rule is error in our config — so it crashes rather than merely warning about peer ranges. Upstream support was merged in June 2026 but is still unreleased.

This PR moves to eslint-plugin-import-x@4, which declares ESLint 10 support and has all 44 import/* rules we use. Every rule and settings key becomes import-x/*, in the config and in eslint-disable comments. no-cycle's disableScc option isn't in import-x's schema; it defaulted to false, so dropping it changes nothing.

If eslint-plugin-import does ship v10 support later, moving back is a mechanical rename plus restoring disableScc — but import-x is actively maintained and already there, so there's no pressure to.

Config changes

• Dropped @eslint/eslintrc/FlatCompat — the eslintrc format is gone in v10. The two compat.extends() calls now use native flat configs: import-x's flatConfigs.typescript and jest's flat/recommended. We take only settings and rules from the former, since it registers import-x itself and v10 rejects a redefinition.
• jest is now registered alongside the other plugins, so eslint-disable jest/* comments still resolve in every file the way the global plugin:jest/recommended extend allowed.
• Bumped @eslint/js to ^10, @typescript-eslint/* to ^8.70, eslint-plugin-jest to ^29.
• Added globals as an explicit dependency — it had been arriving transitively via @eslint/eslintrc.
• Added eslint: ^10 as a peer dependency; engines.node → >=22.13.0 to match ESLint 10's floor. CI already runs 22.x/24.x/26.x.
• Deleted the root .eslintrc.json, dead since the flat-config move and unreadable by v10 regardless.

Source fixes

Four, each a real finding rather than a silencing:

1. no-useless-assignment (new in v10's recommended set) correctly flags let content = '' in readContract — the initialiser is never read.
2. import-x/no-named-as-default: import supportsColor from 'supports-color' shadowed that module's own named export. Renamed the binding rather than switching import style, since forceColour depends on load order.
3. jest/no-export on case-core's jest test helper. Upstream change, not ours: plugin v29 broadened the rule to trigger on describe, where v28 only triggered on test. Added the same file-level disable the sibling helper in contract-case-jest already carries.
4. case-connector-proto/src/index.d.ts: import-x resolves the barrel to the generated .d.ts files and then reports the export type * lines as duplicate exports missing an extension — neither of which eslint-plugin-import did. Scoped both rules off for that one file rather than change a published package's type surface, since a297ce9 added those lines deliberately.

Verification

• nx run-many -t lint — 18/18 projects pass
• nx run-many -t build — 20/20 pass
• nx run-many -t test — full suite passes
• nx run-many -t format:check — clean

To be sure the migration adds no new lint output, I ran ESLint 9 against a worktree of clean main and compared. The remaining warnings — 1 jest/expect-expect, 1 jest/no-disabled-tests, 8 unused-disable-directives — are present in that baseline at identical counts. That baseline is also how finding 3 was confirmed as upstream rather than a side effect of restructuring the jest config.

Generated docs examples are unaffected: the extractor strips eslint-disable comments, so no regeneration is needed.

🤖 Generated with Claude Code