chore: unify TypeScript on 6.0.3 across all five packages

client/package.json

@@ -91,8 +91,8 @@
     "@types/react-dom": "^18.0.0",
     "@types/react-syntax-highlighter": "^13.5.2",
     "@types/react-table": "^7.7.5",
-    "@typescript-eslint/eslint-plugin": "^8.57.2",
-    "@typescript-eslint/parser": "^8.57.2",
+    "@typescript-eslint/eslint-plugin": "^8.64.0",
+    "@typescript-eslint/parser": "^8.64.0",
     "@vitejs/plugin-react": "^5.1.4",
     "autoprefixer": "^10.4.7",
     "eslint": "^9.39.4",
@@ -106,7 +106,7 @@
     "source-map-explorer": "^2.5.3",
     "storybook": "^9.1.20",
     "tailwindcss": "^3.4.19",
-    "typescript": "^5.3.2",
+    "typescript": "^6.0.3",
     "vite": "^7.3.5",
     "vite-plugin-commonjs": "^0.10.4",
     "vite-plugin-svgr": "^4.5.0",

client/src/utils/collections.ts

@@ -22,6 +22,13 @@ export function filterNullOrUndefined<T>(
   return array.filter((it) => it !== null && it !== undefined) as T[];
 }
 
+// `Array.isArray` is typed as `arg is any[]`, which can't narrow a
+// `readonly T[]` out of the union — readonly arrays aren't assignable to
+// `any[]`, so they survive into the else branch and widen the return type.
+function isReadonlyArray<T>(value: readonly T[] | T): value is readonly T[] {
+  return Array.isArray(value);
+}
+
 export function arrayFromArrayOrSingleItem<T>(array: readonly T[] | T): T[] {
-  return Array.isArray(array) ? [...array] : [array];
+  return isReadonlyArray(array) ? [...array] : [array];
 }

client/src/webpages/dashboard/investigation/ItemInvestigation.tsx

@@ -403,7 +403,12 @@ export default function ItemInvestigation(props: {
       try {
         return getFieldValueForRole(
           {
-            // eslint-disable-next-line custom-rules/no-casting-in-getFieldValueForRole
+            // The cast is load-bearing under TS 6: `getFieldValueForRole` is
+            // generic, and without it the `ThreadItemType` member of `item.type`
+            // has no overlap with the inferred parameter type. `no-unnecessary-
+            // type-assertion` disagrees because it compares against the
+            // already-inferred contextual type; tsc fails if the cast is removed.
+            // eslint-disable-next-line custom-rules/no-casting-in-getFieldValueForRole, @typescript-eslint/no-unnecessary-type-assertion
             type: item.type as Parameters<
               typeof getFieldValueForRole
             >[0]['type'],

client/src/webpages/dashboard/item_types/ItemTypePreview.tsx

@@ -37,7 +37,7 @@ export default function ItemTypePreview<T extends ItemTypeKind>(props: {
     case 'CONTENT':
       return <ContentTypePreview roles={roles as ItemTypeRoles<'CONTENT'>} />;
     case 'THREAD':
-      return <ThreadTypePreview roles={roles as ItemTypeRoles<'THREAD'>} />;
+      return <ThreadTypePreview roles={roles} />;
     case 'USER':
       return <UserTypePreview roles={roles as ItemTypeRoles<'USER'>} />;
   }

client/src/webpages/dashboard/mrt/manual_review_job/v2/ncmec/NCMECReviewUser.tsx

@@ -447,7 +447,7 @@ export default function NCMECReviewUser(
   }
 
   const {
-    moderatorSafetyBlurLevel = 2 as BlurStrength,
+    moderatorSafetyBlurLevel = 2,
     moderatorSafetyGrayscale = true,
     moderatorSafetyMuteVideo = true,
     moderatorSafetySepia = false,

client/src/webpages/dashboard/rules/rule_form/RuleForm.tsx

@@ -685,7 +685,7 @@ export default function RuleForm() {
     const out: Record<string, Record<string, unknown>> = {};
     for (const action of rule?.actions ?? []) {
       if ('configuredParameters' in action && action.configuredParameters) {
-        out[action.id] = action.configuredParameters as Record<string, unknown>;
+        out[action.id] = action.configuredParameters;
       }
     }
     return out;

client/src/webpages/dashboard/rules/rule_form/RuleFormReducers.test.ts

@@ -7,7 +7,7 @@ import {
   GQLSignalPricingStructureType,
   GQLSignalType,
 } from '../../../../graphql/generated';
-import { RuleFormConditionSet, RuleFormLeafCondition } from '../types';
+import { RuleFormLeafCondition } from '../types';
 import { initialState, RuleFormState } from './RuleForm';
 import { RuleFormReducerActionType, updateInput } from './RuleFormReducers';
 import {
@@ -86,7 +86,7 @@ describe('updateInput signal eligibility', () => {
         conditions: [
           { input: oldInput, signal: custom1, eligibleSignals: [custom1] },
         ],
-      } as RuleFormConditionSet,
+      },
     };
 
     const result = updateInput(state, {
@@ -117,7 +117,7 @@ describe('updateInput signal eligibility', () => {
         conditions: [
           { input: oldInput, signal: custom2, eligibleSignals: [custom2] },
         ],
-      } as RuleFormConditionSet,
+      },
     };
 
     const result = updateInput(state, {

client/tsconfig.json

@@ -12,11 +12,10 @@
     "allowJs": true,
     "allowSyntheticDefaultImports": true,
     "noFallthroughCasesInSwitch": true,
-    "moduleResolution": "node",
+    "moduleResolution": "bundler",
     "resolveJsonModule": true,
     "isolatedModules": true,
     "noEmit": true,
-    "downlevelIteration": true,
     "paths": {
       "@/*": ["./src/*"]
     }

package.json

@@ -49,6 +49,6 @@
     "prettier": "^3.8.3",
     "@parcel/watcher": "^2.5.6",
     "ts-node": "^10.9.2",
-    "typescript": "^5.9.0"
+    "typescript": "^6.0.3"
   }
 }