Speed up viewer and frontend eslint: local cache + drop slow rule

frontend/.gitignore

@@ -3,6 +3,7 @@ node_modules
 /build
 /.svelte-kit
 /package
+.eslintcache
 vite.config.js.timestamp-*
 vite.config.ts.timestamp-*
 /src/lib/gql/generated

frontend/eslint.config.js

@@ -4,7 +4,6 @@ import js from '@eslint/js';
 import path from 'path';
 import stylistic from '@stylistic/eslint-plugin';
 import svelte from 'eslint-plugin-svelte';
-import svelteConfig from './svelte.config.js';
 import svelteParser from 'svelte-eslint-parser';
 import tsParser from '@typescript-eslint/parser';
 import typescript from 'typescript-eslint';
@@ -48,6 +47,10 @@ export default [
   ...svelte.configs.recommended,
   {
     rules: {
+      // Low-value type-aware rule disabled for lint performance/consistency with the
+      // sibling viewer package, where it dominated lint time. (Here its cost is small;
+      // this package's hot rule is no-misused-promises — see the lint perf notes.)
+      '@typescript-eslint/no-duplicate-type-constituents': 'off',
       // https://typescript-eslint.io/rules/
       '@typescript-eslint/naming-convention': [
         'error',
@@ -123,7 +126,9 @@ export default [
         project: true,
         tsconfigRootDir: __dirname,
         extraFileExtensions: ['.svelte'], // Yes, TS-Parser, relax when you're fed svelte files
-        svelteConfig: svelteConfig,
+        // svelteConfig is intentionally NOT passed here: svelte-eslint-parser auto-loads
+        // svelte.config.js from disk, and passing it inline would embed its warningFilter/
+        // onwarn functions in the ESLint config, breaking --cache (config must serialize).
       },
       globals: {
         ...globals.browser,

frontend/package.json

@@ -23,7 +23,7 @@
     "check": "svelte-kit sync && svelte-check",
     "check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch",
     "test:unit": "vitest",
-    "lint": "svelte-kit sync && eslint .",
+    "lint": "svelte-kit sync && eslint . --cache",
     "lint:report": "svelte-kit sync && eslint-output",
     "format": "eslint . --fix",
     "clean": "pnpm dlx rimraf node_modules .svelte-kit"

frontend/viewer/.gitignore

@@ -29,4 +29,5 @@ storybook-static
 screenshots/
 __screenshots__/
 eslint_report.json
+.eslintcache
 **/*-html-report

frontend/viewer/eslint.config.js

@@ -51,6 +51,11 @@ export default [
   ...svelte.configs.prettier,
   {
     rules: {
+      // Disabled for performance: this single type-aware rule accounted for ~60% of
+      // total lint time (~15s of a ~73s run) and flagged nothing in this codebase. It
+      // does expensive type-relation checks on every union/intersection, which blows up
+      // against our large generated dotnet-types unions. See TIMING=25 profiling.
+      '@typescript-eslint/no-duplicate-type-constituents': 'off',
       // https://typescript-eslint.io/rules/
       '@typescript-eslint/naming-convention': [
         'error',

frontend/viewer/package.json

@@ -27,7 +27,7 @@
     "check": "svelte-check",
     "format": "prettier --write .",
     "format:check": "prettier --check .",
-    "lint": "eslint",
+    "lint": "eslint --cache",
     "lint:report": "eslint-output",
     "i18n:extract": "node extract-i18n-preserve-comments.js",
     "generate-icon-types": "node ./generate-icon-types.js",