diff --git a/frontend/eslint.config.mjs b/frontend/eslint.config.mjs
index ee266a20e0dc..8e9338969001 100644
--- a/frontend/eslint.config.mjs
+++ b/frontend/eslint.config.mjs
@@ -218,14 +218,21 @@ export default defineConfig([
     rules: {
       ...vitest.configs.recommended.rules,
 
-      // vitest expect(...) is always any
-      '@typescript-eslint/no-unsafe-member-access': 'off',
-      '@typescript-eslint/no-unsafe-call': 'off',
-
       // Allow more than one class definitions per file (test components)
       'max-classes-per-file': 'off',
     },
   },
+  {
+    files: ['**/*.spec.ts', '**/testing/**/*.ts', 'src/stimulus/test-helpers.ts', 'src/test-*.ts'],
+    rules: {
+      '@typescript-eslint/no-explicit-any': 'off',
+      '@typescript-eslint/no-unsafe-argument': 'off',
+      '@typescript-eslint/no-unsafe-assignment': 'off',
+      '@typescript-eslint/no-unsafe-call': 'off',
+      '@typescript-eslint/no-unsafe-member-access': 'off',
+      '@typescript-eslint/no-unsafe-return': 'off',
+    },
+  },
   {
     // esbuild follows imports past the tsconfig exclude, so the import site
     // is the boundary keeping test helpers out of the production bundle.
diff --git a/frontend/src/app/core/current-project/current-project.service.spec.ts b/frontend/src/app/core/current-project/current-project.service.spec.ts
index 6db59e0f76ba..5661fe258745 100644
--- a/frontend/src/app/core/current-project/current-project.service.spec.ts
+++ b/frontend/src/app/core/current-project/current-project.service.spec.ts
@@ -46,7 +46,6 @@ describe('currentProject service', () => {
       providers: [
         CurrentProjectService,
         PathHelperService,
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
         { provide: ApiV3Service, useValue: apiV3Stub },
       ],
     });
diff --git a/frontend/src/app/features/plugins/hook-service.spec.ts b/frontend/src/app/features/plugins/hook-service.spec.ts
index 59d90d27796c..1be9dda6c7ef 100644
--- a/frontend/src/app/features/plugins/hook-service.spec.ts
+++ b/frontend/src/app/features/plugins/hook-service.spec.ts
@@ -156,4 +156,16 @@ describe('HookService', () => {
       shouldBehaveLikeResultWithElements(validId, 2);
     });
   });
+
+  describe('known hooks', () => {
+    it('rejects callbacks and arguments that break the hook signature', () => {
+      // @ts-expect-error gridWidgets callbacks return widget registrations
+      service.register('gridWidgets', () => 123);
+
+      // @ts-expect-error prependedAttributeGroups is called with a work package
+      service.call('prependedAttributeGroups', 'not a work package');
+
+      expect(service.call('gridWidgets')).toEqual([123]);
+    });
+  });
 });
diff --git a/frontend/src/app/features/plugins/hook-service.ts b/frontend/src/app/features/plugins/hook-service.ts
index 7c5971862439..5c28c263b7e6 100644
--- a/frontend/src/app/features/plugins/hook-service.ts
+++ b/frontend/src/app/features/plugins/hook-service.ts
@@ -26,15 +26,43 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-import { Injectable } from '@angular/core';
+import { Injectable, Type } from '@angular/core';
+import type { HalResource } from 'core-app/features/hal/resources/hal-resource';
+import type { WorkPackageResource } from 'core-app/features/hal/resources/work-package-resource';
+import type { WorkPackageChangeset } from 'core-app/features/work-packages/components/wp-edit/work-package-changeset';
+import type { GroupDescriptor } from 'core-app/features/work-packages/components/wp-single-view/wp-single-view.component';
+import type { WorkPackageAction } from 'core-app/features/work-packages/components/wp-table/context-menu-helper/wp-context-menu-helper.service';
+import type { ResourceChangeset } from 'core-app/shared/components/fields/changeset/resource-changeset';
+import type { WidgetRegistration } from 'core-app/shared/components/grids/grid/grid.component';
+
+type ResourceChangesetClass = new (...params:ConstructorParameters<typeof ResourceChangeset>) => ResourceChangeset;
+
+export interface HookSignatures {
+  attributeGroupComponent:(group:GroupDescriptor, workPackage:WorkPackageResource) => Type<unknown>|null;
+  gridWidgets:() => WidgetRegistration[];
+  halResourceChangesetClass:(resource:HalResource) => ResourceChangesetClass|null;
+  prependedAttributeGroups:(workPackage:WorkPackageResource) => Type<unknown>|undefined;
+  workPackageAttachmentListComponent:(workPackage:WorkPackageResource) => Type<unknown>;
+  workPackageAttachmentUploadComponent:(workPackage:WorkPackageResource) => Type<unknown>;
+  workPackageBulkContextMenu:() => WorkPackageAction;
+  workPackageNewInitialization:(change:WorkPackageChangeset) => void;
+  workPackageSingleContextMenu:() => WorkPackageAction;
+  workPackageTableContextMenu:() => WorkPackageAction;
+}
+
+type HookCallback = (...params:never[]) => unknown;
+
+type CustomHookId<K extends string> = K extends keyof HookSignatures ? never : K;
 
 @Injectable({
   providedIn: 'root',
 })
 export class HookService {
-  private hooks:Record<string, Function[]> = {};
+  private hooks:Record<string, HookCallback[]> = {};
 
-  public register(id:string, callback:Function) {
+  public register<K extends keyof HookSignatures>(id:K, callback:HookSignatures[K]):void;
+  public register<K extends string>(id:CustomHookId<K>, callback:HookCallback):void;
+  public register(id:string, callback:HookCallback) {
     if (!callback) {
       return;
     }
@@ -46,12 +74,18 @@ export class HookService {
     this.hooks[id].push(callback);
   }
 
-  public call(id:string, ...params:any[]):any[] {
+  public call<K extends keyof HookSignatures>(
+    id:K,
+    ...params:Parameters<HookSignatures[K]>
+  ):NonNullable<ReturnType<HookSignatures[K]>>[];
+
+  public call<K extends string>(id:CustomHookId<K>, ...params:unknown[]):unknown[];
+  public call(id:string, ...params:unknown[]):unknown[] {
     const results = [];
 
     if (this.hooks[id]) {
-      for (let x = 0; x < this.hooks[id].length; x++) {
-        const result = this.hooks[id][x](...params);
+      for (const hook of this.hooks[id] as ((...params:unknown[]) => unknown)[]) {
+        const result = hook(...params);
 
         if (result) {
           results.push(result);
diff --git a/frontend/src/app/features/work-packages/components/wp-list/wp-list-checksum.service.ts b/frontend/src/app/features/work-packages/components/wp-list/wp-list-checksum.service.ts
index 805ef8378c5a..a17899f6320f 100644
--- a/frontend/src/app/features/work-packages/components/wp-list/wp-list-checksum.service.ts
+++ b/frontend/src/app/features/work-packages/components/wp-list/wp-list-checksum.service.ts
@@ -116,7 +116,7 @@ export class WorkPackagesListChecksumService {
 
   public executeIfOutdated(newId:string|null,
     newChecksum:string|null,
-    callback:Function) {
+    callback:() => void) {
     if (this.isUninitialized() || this.isOutdated(newId, newChecksum)) {
       this.set(newId, newChecksum);
 
diff --git a/frontend/src/app/features/work-packages/components/wp-query/url-params-helper.spec.ts b/frontend/src/app/features/work-packages/components/wp-query/url-params-helper.spec.ts
index 133c917211ff..0742e265499a 100644
--- a/frontend/src/app/features/work-packages/components/wp-query/url-params-helper.spec.ts
+++ b/frontend/src/app/features/work-packages/components/wp-query/url-params-helper.spec.ts
@@ -40,7 +40,6 @@ describe('UrlParamsHelper', () => {
     TestBed.configureTestingModule({
       providers: [
         UrlParamsHelperService,
-        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
         { provide: PaginationService, useValue: paginationStub },
       ],
     });
diff --git a/frontend/src/app/features/work-packages/components/wp-single-view-tabs/keep-tab/keep-tab.service.spec.ts b/frontend/src/app/features/work-packages/components/wp-single-view-tabs/keep-tab/keep-tab.service.spec.ts
index a74513355449..bc8813b97e2c 100644
--- a/frontend/src/app/features/work-packages/components/wp-single-view-tabs/keep-tab/keep-tab.service.spec.ts
+++ b/frontend/src/app/features/work-packages/components/wp-single-view-tabs/keep-tab/keep-tab.service.spec.ts
@@ -44,10 +44,8 @@ describe('keepTab service', () => {
     TestBed.configureTestingModule({
       providers: [
         KeepTabService,
-        /* eslint-disable @typescript-eslint/no-unsafe-assignment */
         { provide: PathHelperService, useValue: pathHelper },
         { provide: CurrentProjectService, useValue: currentProject },
-        /* eslint-enable @typescript-eslint/no-unsafe-assignment */
       ],
     });
 
diff --git a/frontend/src/app/features/work-packages/components/wp-table/context-menu-helper/wp-context-menu-helper.service.ts b/frontend/src/app/features/work-packages/components/wp-table/context-menu-helper/wp-context-menu-helper.service.ts
index 68d82621f843..15438eccfc9d 100644
--- a/frontend/src/app/features/work-packages/components/wp-table/context-menu-helper/wp-context-menu-helper.service.ts
+++ b/frontend/src/app/features/work-packages/components/wp-table/context-menu-helper/wp-context-menu-helper.service.ts
@@ -56,7 +56,7 @@ export class WorkPackageContextMenuHelperService {
   private wpViewIndent = inject(WorkPackageViewHierarchyIdentationService);
   private PathHelper = inject(PathHelperService);
 
-  private BULK_ACTIONS = [
+  private BULK_ACTIONS:WorkPackageAction[] = [
     {
       text: I18n.t('js.work_packages.bulk_actions.edit'),
       key: 'edit',
diff --git a/frontend/src/app/features/work-packages/routing/partitioned-query-space-page/partitioned-query-space-page.component.ts b/frontend/src/app/features/work-packages/routing/partitioned-query-space-page/partitioned-query-space-page.component.ts
index 755f6119a5a9..e9ad9b1086d4 100644
--- a/frontend/src/app/features/work-packages/routing/partitioned-query-space-page/partitioned-query-space-page.component.ts
+++ b/frontend/src/app/features/work-packages/routing/partitioned-query-space-page/partitioned-query-space-page.component.ts
@@ -49,11 +49,12 @@ import { firstValueFrom } from 'rxjs';
 import { PathHelperService } from 'core-app/core/path-helper/path-helper.service';
 import { CurrentProjectService } from 'core-app/core/current-project/current-project.service';
 import { UrlParamsService } from 'core-app/core/navigation/url-params.service';
+import { EventHandler } from 'ng-dynamic-component';
 
 export interface DynamicComponentDefinition {
   component:ComponentType<any>;
   inputs?:Record<string, any>;
-  outputs?:Record<string, Function>;
+  outputs?:Record<string, EventHandler>;
 }
 
 export interface ToolbarButtonComponentDefinition extends DynamicComponentDefinition {
diff --git a/frontend/src/app/features/work-packages/routing/wp-view-base/view-services/wp-view-order.service.spec.ts b/frontend/src/app/features/work-packages/routing/wp-view-base/view-services/wp-view-order.service.spec.ts
index 2c336a81a827..19fc98658d05 100644
--- a/frontend/src/app/features/work-packages/routing/wp-view-base/view-services/wp-view-order.service.spec.ts
+++ b/frontend/src/app/features/work-packages/routing/wp-view-base/view-services/wp-view-order.service.spec.ts
@@ -85,7 +85,6 @@ describe('WorkPackageViewOrderService', () => {
       id: '123',
       _links: { self: { href: 'test' } },
     } as Record<string, unknown>;
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-argument
     querySpace.query.putValue(mockQuery as any);
   });
 
@@ -103,12 +102,10 @@ describe('WorkPackageViewOrderService', () => {
       const order = ['1', '2', '3'];
       const wpId = '2';
 
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
       vi.spyOn(service as any, 'update');
 
       service.remove(order, wpId);
 
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
       expect((service as any).update).toHaveBeenCalledWith({ [wpId]: -1 });
     });
   });
diff --git a/frontend/src/app/shared/components/fields/edit/field-types/select-edit-field/select-edit-field.component.ts b/frontend/src/app/shared/components/fields/edit/field-types/select-edit-field/select-edit-field.component.ts
index 7a30c6b1eadf..34ef43e5c462 100644
--- a/frontend/src/app/shared/components/fields/edit/field-types/select-edit-field/select-edit-field.component.ts
+++ b/frontend/src/app/shared/components/fields/edit/field-types/select-edit-field/select-edit-field.component.ts
@@ -42,6 +42,7 @@ import { HalResourceNotificationService } from 'core-app/features/hal/services/h
 import { HalResourceSortingService } from 'core-app/features/hal/services/hal-resource-sorting.service';
 import { EditFieldComponent } from '../../edit-field.component';
 import { HalLink } from 'core-app/features/hal/hal-link/hal-link';
+import { EventHandler } from 'ng-dynamic-component';
 
 export interface ValueOption {
   name:string;
@@ -66,7 +67,7 @@ export class SelectEditFieldComponent extends EditFieldComponent implements OnIn
 
   public appendTo:any = null;
 
-  public referenceOutputs:Record<string, Function> = {
+  public referenceOutputs:Record<string, EventHandler> = {
     onCreate: (newElement:HalResource) => this.onCreate(newElement),
     onChange: (value:HalResource) => this.onChange(value),
     onAddNew: (value:HalResource) => this.onNewValueAdded(value),
diff --git a/frontend/src/app/shared/components/primer/dynamic-icon.directive.spec.ts b/frontend/src/app/shared/components/primer/dynamic-icon.directive.spec.ts
index 6b601814637d..2999b557a663 100644
--- a/frontend/src/app/shared/components/primer/dynamic-icon.directive.spec.ts
+++ b/frontend/src/app/shared/components/primer/dynamic-icon.directive.spec.ts
@@ -26,8 +26,6 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-/* eslint-disable @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-explicit-any */
-
 import { ChangeDetectionStrategy, Component } from '@angular/core';
 import { ComponentFixture, TestBed } from '@angular/core/testing';
 import { DynamicIconDirective } from './dynamic-icon.directive';
diff --git a/frontend/src/app/shared/components/primer/icon-button.component.spec.ts b/frontend/src/app/shared/components/primer/icon-button.component.spec.ts
index 0f2720b8fbe8..362fc510ab12 100644
--- a/frontend/src/app/shared/components/primer/icon-button.component.spec.ts
+++ b/frontend/src/app/shared/components/primer/icon-button.component.spec.ts
@@ -26,8 +26,6 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-/* eslint-disable @typescript-eslint/no-unsafe-assignment */
-
 import { ComponentFixture, TestBed } from '@angular/core/testing';
 import { PrimerIconButtonComponent } from './icon-button.component';
 
diff --git a/frontend/src/stimulus/controllers/checkable.controller.spec.ts b/frontend/src/stimulus/controllers/checkable.controller.spec.ts
index 473e2081b203..891a796b3b42 100644
--- a/frontend/src/stimulus/controllers/checkable.controller.spec.ts
+++ b/frontend/src/stimulus/controllers/checkable.controller.spec.ts
@@ -26,7 +26,7 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-/* eslint-disable @typescript-eslint/no-empty-function, @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-return */
+/* eslint-disable @typescript-eslint/no-empty-function */
 
 import { ActionEvent } from '@hotwired/stimulus';
 import CheckableController from './checkable.controller';
diff --git a/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.spec.ts b/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.spec.ts
index 1690872b2587..0bc4003eb67c 100644
--- a/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.spec.ts
+++ b/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.spec.ts
@@ -26,8 +26,6 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-/* eslint-disable @typescript-eslint/no-explicit-any */
-
 import PageController from './page.controller';
 
 describe('Reporting PageController serialization', () => {
diff --git a/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.ts b/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.ts
index 73dd9d7267ca..743df61d9a50 100644
--- a/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.ts
+++ b/frontend/src/stimulus/controllers/dynamic/reporting/page.controller.ts
@@ -207,7 +207,6 @@ export default class PageController extends Controller {
     jQuery.metadata = undefined;
 
     // Override the default texts to enable translations
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
     jQuery.tablesorter.language = {
       sortAsc: I18n.t('js.sort.sorted_asc'),
       sortDesc: I18n.t('js.sort.sorted_dsc'),
@@ -218,7 +217,6 @@ export default class PageController extends Controller {
       nextNone: I18n.t('js.sort.activate_no'),
     };
 
-    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
     jQuery('#sortable-table')
       .not('.tablesorter')
       .tablesorter({
diff --git a/frontend/src/stimulus/controllers/expandable-text.controller.spec.ts b/frontend/src/stimulus/controllers/expandable-text.controller.spec.ts
index 69990742f869..35700ed355d2 100644
--- a/frontend/src/stimulus/controllers/expandable-text.controller.spec.ts
+++ b/frontend/src/stimulus/controllers/expandable-text.controller.spec.ts
@@ -26,8 +26,6 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-/* eslint-disable @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-assignment */
-
 import ExpandableTextController from './expandable-text.controller';
 import { setupStimulusTest, type StimulusTestContext } from 'core-stimulus/test-helpers';
 
diff --git a/frontend/src/test-setup.ts b/frontend/src/test-setup.ts
index 2c83fff6175c..824a3b4d93ae 100644
--- a/frontend/src/test-setup.ts
+++ b/frontend/src/test-setup.ts
@@ -43,7 +43,6 @@ afterEach(() => {
   vi.useRealTimers();
 });
 
-// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-member-access
 (window as any).global = window;
 
 window.I18n = new I18n();
@@ -51,9 +50,7 @@ window.I18n = new I18n();
 // jsdom does not implement CSS.escape; production helpers (e.g. getMetaElement)
 // call it unconditionally.
 if (typeof CSS === 'undefined' || typeof CSS.escape !== 'function') {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
   (globalThis as any).CSS = (globalThis as any).CSS || {};
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-member-access
   (globalThis as any).CSS.escape = (value:string) => String(value).replace(/[^a-zA-Z0-9_-]/g, (ch) => `\\${ch}`);
 }
 
@@ -61,7 +58,6 @@ if (typeof CSS === 'undefined' || typeof CSS.escape !== 'function') {
 // constructor signature so static analysis resolving the global to this class
 // still accepts the callback every real call site passes.
 if (typeof (globalThis as any).ResizeObserver === 'undefined') {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
   (globalThis as any).ResizeObserver = class {
     // eslint-disable-next-line @typescript-eslint/no-empty-function
     constructor(_callback:ResizeObserverCallback) {}
@@ -73,7 +69,6 @@ if (typeof (globalThis as any).ResizeObserver === 'undefined') {
 
 // jsdom does not implement HTMLDialogElement.showModal/close.
 if (typeof HTMLDialogElement !== 'undefined') {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const proto = HTMLDialogElement.prototype as any;
   if (typeof proto.showModal !== 'function') {
     proto.showModal = function showModal() { this.open = true; };
diff --git a/frontend/src/turbo/turbo-navigation-patch.spec.ts b/frontend/src/turbo/turbo-navigation-patch.spec.ts
index 432bf784fc7d..5f4a4593370d 100644
--- a/frontend/src/turbo/turbo-navigation-patch.spec.ts
+++ b/frontend/src/turbo/turbo-navigation-patch.spec.ts
@@ -26,7 +26,6 @@
 // See COPYRIGHT and LICENSE files for more details.
 //++
 
-/* eslint-disable @typescript-eslint/no-explicit-any */
 import * as Turbo from '@hotwired/turbo';
 import { applyTurboNavigationPatch } from './turbo-navigation-patch';
 
diff --git a/frontend/src/typings/open-project.typings.d.ts b/frontend/src/typings/open-project.typings.d.ts
index cbffc738fbc8..e5afbccd2d39 100644
--- a/frontend/src/typings/open-project.typings.d.ts
+++ b/frontend/src/typings/open-project.typings.d.ts
@@ -38,24 +38,6 @@ declare namespace api {
    * API v3
    */
   namespace v3 {
-    interface Result {
-      _links:any;
-      _embedded:any;
-      _type:string;
-    }
-
-    interface Collection extends Result {
-      total:number;
-      pageSize:number;
-      count:number;
-      offset:number;
-      groups:any;
-      totalSums:any;
-    }
-
-    interface Duration extends String {
-    }
-
     interface Formattable {
       format?:string;
       raw:string;
@@ -74,15 +56,3 @@ interface Function {
   _type:string;
 }
 
-declare let Factory:any;
-
-declare namespace op {
-  interface QueryParams {
-    offset?:number;
-    pageSize?:number;
-    filters?:any[];
-    groupBy?:string;
-    showSums?:boolean;
-    sortBy?:any[];
-  }
-}
diff --git a/frontend/src/typings/shims.d.ts b/frontend/src/typings/shims.d.ts
index ef00c32df1f8..f223098f11c5 100644
--- a/frontend/src/typings/shims.d.ts
+++ b/frontend/src/typings/shims.d.ts
@@ -69,12 +69,12 @@ declare global {
   }
 
   interface JQuery {
-    tablesorter:any;
+    tablesorter(options:object):JQuery;
   }
 
   interface JQueryStatic {
-    metadata:any;
-    tablesorter:any;
+    metadata:unknown;
+    tablesorter:{ language:Record<string, string> };
   }
 }