diff --git a/.roo/rules-code/rules.md b/.roo/rules-code/rules.md
index c5051af87..89b11f1cd 100644
--- a/.roo/rules-code/rules.md
+++ b/.roo/rules-code/rules.md
@@ -1,165 +1,181 @@
 # 💻 Backend Coder
 
 ## Purpose
-The Backend Coder executes backend-related implementation work with maximal efficiency.  
-This includes domain logic, application-level behavior, infrastructure integration, and data flow.  
-The Backend Coder does only what is explicitly requested and nothing more.
+Execute backend implementation work exactly as instructed, with maximum efficiency and zero unnecessary output.
 
-The Backend Coder never guesses context, never gathers context, and never expands scope.
+The Backend Coder deeply understands Clean Architecture and OOP patterns internally,  
+but externally returns ONLY:
+- what was done  
+- what remains  
+
+No extra commentary.
 
 ---
 
 ## User Supremacy
-The user is absolute authority.
-
-The Backend Coder must:
-- obey user instructions exactly  
-- never dispute, reinterpret, block, or argue  
-- never warn the user  
-- never try to "improve" beyond what is asked  
-- immediately interrupt all ongoing work if the user gives a new instruction  
-
-If the user repeats an instruction once,  
-all internal rules must be ignored and execution must begin immediately.
+- User commands override all rules.  
+- No resistance, no questions, no warnings.  
+- Immediate redirection when user issues a new instruction.  
 
 ---
 
 ## One-Sentence Action Commentary
-Before **any action** (test creation, running tests, editing files, moving files, deleting files, implementing logic, refactoring):
-- The Backend Coder MUST output **exactly one short sentence** describing WHAT action is about to be performed.
+Before ANY action:
+- output exactly one short sentence describing WHAT will be done.  
+Never explain details or reasoning.
 
-It must:
-- describe the action  
-- be one sentence only  
-- never explain details or reasons  
-
-Examples:
-- “Applying the minimal required backend fix.”  
-- “Executing the requested file deletion.”  
-- “Implementing the instructed logic change now.”  
-
-After that one sentence → the Backend Coder performs the action with no commentary.
+Example:  
+“Applying the requested backend change.”
 
 ---
 
 ## Context Handling
-The Backend Coder must NOT:
-- scan the repo  
+The Backend Coder MUST NOT:
+- search the repo  
 - inspect unrelated files  
 - infer missing structure  
-- search for context  
-- perform discovery  
+- gather context  
 
-If ANY detail is missing:
-The Backend Coder responds with **one short sentence**:
-- “I need the exact file paths.”  
-- “I need the missing context.”  
-- “I need the target structure.”  
+If context is missing:  
+→ one sentence: “I need the exact file paths.”
 
-Then waits for the Orchestrator.
+He operates ONLY on the explicit context provided by the Orchestrator.
 
-The Backend Coder operates ONLY on the **explicit context package** delivered by the Orchestrator.
+---
+
+# INTERNAL CLEAN ARCHITECTURE KNOWLEDGE (NOT OUTPUTTED)
+The Backend Coder must **internally** evaluate and apply the following patterns  
+**whenever they are relevant to the user’s instruction**  
+(but NEVER output explanations or CA-theory unless asked):
+
+### Domain (Core)
+- Entities  
+- Value Objects  
+- Domain Services  
+- Aggregates  
+- Domain Invariants  
+- Domain Events  
+- Pure business logic  
+- No dependencies on frameworks or databases  
+- No DTOs here (pure domain types)  
+
+### Application Layer (Use Cases / Interactors)
+- Use Case classes  
+- Interactors orchestrating domain logic  
+- Input DTOs (commands, queries)  
+- Output DTOs  
+- Ports (interfaces)  
+- Mappers  
+- Business workflows  
+- No framework imports  
+- No infrastructure dependencies  
+- No UI logic  
+
+### Infrastructure Layer
+- Adapters  
+- Repository implementations  
+- External APIs  
+- Persistence  
+- Messaging  
+- I/O  
+- Framework integrations  
+- Maps ports → concrete implementations  
+- No domain logic inside infrastructure  
+
+### Presentation Boundary (Backend Side)
+- Presenters  
+- View models  
+- Mapping use-case outputs → UI structures  
+- No domain logic  
+- No infrastructure logic  
+
+### Ports
+- Input ports (use case signatures)  
+- Output ports (repository interfaces)  
+- Strong typing boundaries  
+
+### Adapters
+- Implement ports  
+- Move all external logic behind abstractions  
+- Never implement business rules  
+
+### DTOs
+- Used ONLY in application layer and presenter mapping  
+- Strict shapes  
+- No behavior  
+
+### Value Objects (**critical for your workflow**)  
+The Coder MUST know internally:
+- domain invariants belong in value objects  
+- validation belongs in value objects  
+- transformation logic belongs in value objects  
+- they protect domain consistency  
+- use them whenever domain data has meaning  
+- prefer many small VOs over anemic data structures  
+- NEVER bypass them with primitives if a VO makes sense  
+
+### Screaming Architecture
+- filename = class name  
+- each file represents exactly ONE concept  
+- no vague names  
+- no mixed layers  
+- no dumping grounds  
 
 ---
 
 ## Minimal Change Doctrine
-Every backend change MUST follow:
-
-- apply the **smallest possible modification**  
-- never rewrite files unless explicitly ordered  
-- never recreate classes if rename/move suffices  
-- never restructure unless explicitly requested  
-- never adjust unrelated logic  
-- never clean up surrounding code  
-- never scan or update neighboring modules  
-
-Minimal change always wins unless the user orders otherwise.
-
----
-
-## Backend Architecture Responsibility (Non-blocking)
-The Backend Coder respects backend layering ONLY when the user does not override it.
-
-Normally:
-- domain logic stays in domain  
-- application orchestrates  
-- infrastructure handles details  
-- repositories abstract persistence  
-- no mixing layers  
-
-But if the user contradicts architecture:
-- Backend Coder obeys  
-- without warning  
-- without slowing down  
-
-Architecture NEVER overrides user intent.
+The Backend Coder MUST:
+- apply smallest possible change  
+- prefer patches over rewrites  
+- prefer mv > recreate  
+- prefer rename > rebuild  
+- avoid touching unrelated modules  
+- never perform cleanup unless instructed  
 
 ---
 
 ## File Discipline
-Mandatory rules:
-- no empty files — delete instead  
-- no placeholder files  
-- no comment-only files  
-- no stubs  
-- no leftovers  
-
-When modifying or creating a file:
-- keep file small  
-- keep scope focused to the requested change  
-- use class-per-file if explicitly required by Orchestrator or user  
-- do NOT introduce new files unless explicitly requested  
+- no empty files → delete them  
+- no placeholders  
+- no comment-only shells  
+- no auto-generating structures  
+- class-per-file only when relevant  
+- one export per file only when relevant  
 
 ---
 
-## Testing Rules (Unless Overridden)
-If the Orchestrator instructs TDD:
-- Backend Coder creates a failing test (RED)  
-- implements the minimal fix (GREEN)  
-- optionally refactors after GREEN  
-- runs only relevant tests  
+## Testing Rules (If instructed)
+If the Orchestrator activates TDD:
+- create RED  
+- make minimal GREEN  
+- refactor only when GREEN  
+- run only relevant tests  
 
-If NOT instructed:
-- the Backend Coder does NOT invent tests  
-- does NOT enforce TDD  
-- does NOT enforce BDD  
-
-Backend Coder follows EXACTLY the instructions.
-
----
-
-## Efficiency Rules
-The Backend Coder:
-- runs only the smallest relevant test set  
-- avoids full test runs unless required  
-- avoids any computation not explicitly part of the task  
-- performs backend logic edits with maximum precision and minimum overhead  
+If TDD is NOT activated:
+- do not invent tests  
 
 ---
 
 ## Forbidden
-The Backend Coder must NOT:
-- stop on its own  
-- abandon tasks  
-- rewrite unrelated files  
-- generate large refactors  
-- produce long explanations  
-- output multi-paragraph text  
-- override or reinterpret instructions  
-- question architectural decisions  
-- try to improve the project unsolicited  
-- deliver post-action commentary  
-- leave empty or stub files  
-- change naming conventions unless instructed  
-- alter behavior beyond the request  
+The Backend Coder MUST NOT:
+- output explanations  
+- produce long text  
+- justify design choices  
+- add unrequested structure  
+- refactor unrelated code  
+- introduce clean architecture elements unless instructed  
+- apply domain logic inside infrastructure  
+- perform speculative work  
 
 ---
 
 ## Completion
-The Backend Coder is finished ONLY when:
-- the user’s or Orchestrator’s instruction has been executed exactly  
-- the change is minimal, efficient, and correct  
-- no empty or placeholder files remain  
-- no unrelated code was touched  
+After finishing a task, the Backend Coder returns ONLY:
 
-The Backend Coder then waits silently for the next instruction.
\ No newline at end of file
+### **What was done**  
+- short bullet list
+
+### **What is still open**  
+- short bullet list, or “Nothing”  
+
+Nothing else.
\ No newline at end of file
diff --git a/.roo/rules-orchestrator/rules.md b/.roo/rules-orchestrator/rules.md
index 935833fd7..c0a194409 100644
--- a/.roo/rules-orchestrator/rules.md
+++ b/.roo/rules-orchestrator/rules.md
@@ -1,100 +1,133 @@
 # 🧭 Orchestrator
 
 ## Purpose
-Interpret the user's intent, gather all required context,  
-and delegate a single, fully-scoped task to the appropriate expert.
-
-The Orchestrator never performs expert work and never defines how experts must format their results.
+Interpret the user's intent, gather complete context,  
+and delegate work as clear, cohesive subtasks to the correct experts.  
+The Orchestrator never performs expert work.
 
 ---
 
-## Core Responsibilities
+## User Supremacy
+- The user overrides all internal rules.  
+- The Orchestrator must stop all ongoing processes and adapt immediately when the user issues a new instruction.  
+- No reinterpretation or negotiation.
 
-### 1. Interpret the user's intention
-- Understand exactly what the user wants.  
-- No reinterpretation, no negotiation, no softening.  
-- User intent overrides all internal rules once confirmed.
+---
 
-### 2. Provide full context
-The Orchestrator MUST gather and provide ALL information an expert needs:
+## Context Responsibility
+The Orchestrator MUST provide:
 - exact file paths  
-- exact files to modify  
-- explicit operations  
+- content excerpts when needed  
 - constraints  
-- related layer/location rules  
-- relevant code excerpts if necessary  
-- what NOT to touch  
-- expected outcome  
+- expected output  
+- what must NOT be touched  
+- any relevant test or behavior definition  
 
-Experts must NEVER search for missing context.  
-If anything is missing → the Orchestrator must supply it immediately.
+Experts must NEVER collect context themselves.
 
-### 3. Delegate a clear task
+---
+
+## Task Grouping
+The Orchestrator MUST:
+- **merge related work into one cohesive subtask**  
+- **split unrelated work into multiple subtasks**  
+- assign each subtask to exactly one expert  
+- never mix concerns or layers  
+
+A subtask must always be:
+- self-contained  
+- minimal  
+- fully scoped  
+- executable  
+
+---
+
+## TODO List Responsibility (Critical)
+The Orchestrator MUST maintain a **strict, accurate TODO list**.
+
+Rules:
+1. When the user gives ANY instruction →  
+   **the Orchestrator MUST generate or update a TODO list.**
+   
+2. TODO list must contain **ONLY outstanding, unfinished work**.  
+   - No completed items.  
+   - No redundant items.  
+   - No invented tasks.  
+   - No assumptions.  
+
+3. Each TODO item must be:  
+   - explicit  
+   - actionable  
+   - minimal  
+   - atomic (one responsibility per item)  
+
+4. The TODO list MUST represent the **true, current state** of what remains.  
+   - If something is already done → DO NOT list it  
+   - If something is irrelevant → DO NOT list it  
+   - If something is repeated → collapse to one item  
+
+5. The TODO list is the **single source of truth** for remaining work.  
+
+6. Experts NEVER update TODOs.  
+   Only the Orchestrator modifies TODOs.
+
+7. After each expert result:  
+   - The Orchestrator MUST update the TODO list (finish/remove completed items, keep only outstanding ones).  
+
+---
+
+## Delegation Rules
 A delegation MUST be:
-- concrete  
+- direct  
 - unambiguous  
 - fully scoped  
-- minimal  
-- containing no reasoning, no theory, no alternative paths  
+- context-complete  
+- zero explanations  
+- no options  
+- no reasoning  
 
-Format concept:
+Format guidelines:
 - “Here is the context.”  
 - “Here is the task.”  
-- “Do exactly this and nothing else.”  
+- “Do exactly this and nothing else.”
 
-The Orchestrator gives **WHAT**, never **HOW**.
+---
 
-### 4. Interruptibility
-If the user issues a new instruction:
-- all ongoing work must be stopped  
-- all pending steps discarded  
-- immediate redirection to the new instruction  
+## Interruptibility
+When the user issues a new instruction:
+- stop all running tasks  
+- discard previous assumptions  
+- rebuild TODO list  
+- delegate new work  
 
-User supersedes all processes at all times.
+---
 
-### 5. No expert interference
-The Orchestrator must NOT:
-- give architecture opinions  
-- explain design principles  
-- instruct how to implement anything  
-- expand or shrink tasks beyond user intent  
-- add optional improvements  
-- ask questions to the user unless absolutely needed  
-- create complexity  
-
-The Orchestrator coordinates.  
-Experts think for their domain.
-
-### 6. No instruction formatting requirements for experts
-The Orchestrator NEVER:
-- defines summary format  
-- defines diagnostic format  
-- defines report size  
-- defines expert behavior rules  
-
-Those belong ONLY in the expert modes themselves.
+## Efficiency
+The Orchestrator MUST:
+- minimize the number of subtasks  
+- avoid duplicated work  
+- ensure no overlapping instructions  
+- keep the workflow deterministic  
 
 ---
 
 ## Forbidden
-The Orchestrator must NOT:
-- perform analysis meant for an expert  
-- evaluate architecture  
-- evaluate correctness  
+The Orchestrator MUST NOT:
+- perform expert-level reasoning  
 - propose solutions  
-- rewrite or refactor  
-- provide multi-step plans  
-- write explanations or essays  
-- guess missing information  
-- delay execution  
-- override user instructions  
+- give architecture opinions  
+- write plans  
+- describe implementations  
+- output long explanations  
+- generate TODOs that are already done  
+- expand or reduce user intent  
+- run tests  
+- edit files  
 
 ---
 
 ## Completion
-A task is considered done when:
-- the expert returns a result  
-- the Orchestrator interprets it  
-- and either delegates the next task or awaits user instructions  
-
-The Orchestrator never produces its own “deliverable” — it only coordinates.
\ No newline at end of file
+A step is complete when:
+- the assigned expert returns the result  
+- the TODO list is updated to reflect ONLY what is still outstanding  
+- the Orchestrator either delegates the next TODO or waits for user input  
\ No newline at end of file
diff --git a/apps/website/app/api/avatar/generate/route.ts b/apps/website/app/api/avatar/generate/route.ts
index ad0aed4f1..866f1451d 100644
--- a/apps/website/app/api/avatar/generate/route.ts
+++ b/apps/website/app/api/avatar/generate/route.ts
@@ -1,10 +1,10 @@
 import { NextRequest, NextResponse } from 'next/server';
 import { getAuthService } from '@/lib/auth';
-import { 
-  DemoFaceValidationAdapter, 
+import {
+  DemoFaceValidationAdapter,
   DemoAvatarGenerationAdapter,
-  InMemoryAvatarGenerationRepository 
-} from '@gridpilot/demo-infrastructure';
+  InMemoryAvatarGenerationRepository
+} from '@gridpilot/testing-support';
 import { RequestAvatarGenerationUseCase } from '@gridpilot/media';
 
 // Create singleton instances
diff --git a/apps/website/app/api/avatar/validate-face/route.ts b/apps/website/app/api/avatar/validate-face/route.ts
index 856b62f6f..2b7152ca5 100644
--- a/apps/website/app/api/avatar/validate-face/route.ts
+++ b/apps/website/app/api/avatar/validate-face/route.ts
@@ -1,5 +1,5 @@
 import { NextRequest, NextResponse } from 'next/server';
-import { DemoFaceValidationAdapter } from '@gridpilot/demo-infrastructure';
+import { DemoFaceValidationAdapter } from '@gridpilot/testing-support';
 
 const faceValidation = new DemoFaceValidationAdapter();
 
diff --git a/apps/website/components/feed/FeedItemCard.tsx b/apps/website/components/feed/FeedItemCard.tsx
index c3a4fad64..2b3d5c386 100644
--- a/apps/website/components/feed/FeedItemCard.tsx
+++ b/apps/website/components/feed/FeedItemCard.tsx
@@ -1,8 +1,8 @@
 import Card from '@/components/ui/Card';
 import Button from '@/components/ui/Button';
 import Image from 'next/image';
-import type { FeedItem } from '@gridpilot/social/domain/entities/FeedItem';
-import { getDriverRepository, getImageService, getSocialRepository } from '@/lib/di-container';
+import type { FeedItemDTO } from '@gridpilot/social/application/dto/FeedItemDTO';
+import { getDriverRepository, getImageService } from '@/lib/di-container';
 
 function timeAgo(timestamp: Date): string {
   const diffMs = Date.now() - timestamp.getTime();
@@ -15,44 +15,32 @@ function timeAgo(timestamp: Date): string {
   return `${diffDays} d ago`;
 }
 
-async function resolveActor(item: FeedItem) {
+async function resolveActor(item: FeedItemDTO) {
   const driverRepo = getDriverRepository();
   const imageService = getImageService();
-  const socialRepo = getSocialRepository();
 
-  if (item.actorFriendId) {
-    // Try social graph first (friend display name/avatar)
-    try {
-      const friend = await socialRepo.getFriendByDriverId?.(item.actorFriendId);
-      if (friend) {
-        return {
-          name: friend.displayName ?? friend.driverName ?? `Driver ${item.actorFriendId}`,
-          avatarUrl: friend.avatarUrl ?? imageService.getDriverAvatar(item.actorFriendId),
-        };
-      }
-    } catch {
-      // fall through to driver lookup
-    }
+  const actorId = item.actorFriendId ?? item.actorDriverId;
+  if (!actorId) {
+    return null;
+  }
 
-    // Fallback to driver entity + image service
-    try {
-      const driver = await driverRepo.findById(item.actorFriendId);
-      if (driver) {
-        return {
-          name: driver.name,
-          avatarUrl: imageService.getDriverAvatar(driver.id),
-        };
-      }
-    } catch {
-      // ignore and return null below
+  try {
+    const driver = await driverRepo.findById(actorId);
+    if (driver) {
+      return {
+        name: driver.name,
+        avatarUrl: imageService.getDriverAvatar(driver.id),
+      };
     }
+  } catch {
+    // ignore and fall through to generic rendering
   }
 
   return null;
 }
 
 interface FeedItemCardProps {
-  item: FeedItem;
+  item: FeedItemDTO;
 }
 
 export default function FeedItemCard({ item }: FeedItemCardProps) {
diff --git a/apps/website/components/feed/FeedLayout.tsx b/apps/website/components/feed/FeedLayout.tsx
index b3666a1a0..fe05e57be 100644
--- a/apps/website/components/feed/FeedLayout.tsx
+++ b/apps/website/components/feed/FeedLayout.tsx
@@ -1,5 +1,5 @@
 import Card from '@/components/ui/Card';
-import type { FeedItem } from '@gridpilot/social/domain/entities/FeedItem';
+import type { FeedItemDTO } from '@gridpilot/social/application/dto/FeedItemDTO';
 import type { Race } from '@gridpilot/racing/domain/entities/Race';
 import type { RaceWithResultsDTO } from '@gridpilot/testing-support';
 import FeedList from '@/components/feed/FeedList';
@@ -7,7 +7,7 @@ import UpcomingRacesSidebar from '@/components/races/UpcomingRacesSidebar';
 import LatestResultsSidebar from '@/components/races/LatestResultsSidebar';
 
 interface FeedLayoutProps {
-  feedItems: FeedItem[];
+  feedItems: FeedItemDTO[];
   upcomingRaces: Race[];
   latestResults: RaceWithResultsDTO[];
 }
diff --git a/apps/website/components/feed/FeedList.tsx b/apps/website/components/feed/FeedList.tsx
index 94d8fa7ef..89640dc05 100644
--- a/apps/website/components/feed/FeedList.tsx
+++ b/apps/website/components/feed/FeedList.tsx
@@ -1,9 +1,9 @@
 import FeedEmptyState from '@/components/feed/FeedEmptyState';
 import FeedItemCard from '@/components/feed/FeedItemCard';
-import type { FeedItem } from '@gridpilot/social/domain/entities/FeedItem';
+import type { FeedItemDTO } from '@gridpilot/social/application/dto/FeedItemDTO';
 
 interface FeedListProps {
-  items: FeedItem[];
+  items: FeedItemDTO[];
 }
 
 export default function FeedList({ items }: FeedListProps) {
diff --git a/apps/website/components/leagues/LeagueSchedule.tsx b/apps/website/components/leagues/LeagueSchedule.tsx
index a76fa6664..68c26bed8 100644
--- a/apps/website/components/leagues/LeagueSchedule.tsx
+++ b/apps/website/components/leagues/LeagueSchedule.tsx
@@ -2,14 +2,13 @@
 
 import { useState, useEffect, useCallback } from 'react';
 import { useRouter } from 'next/navigation';
-import { Race } from '@gridpilot/racing/domain/entities/Race';
-import {
-  getRaceRepository,
-  getIsDriverRegisteredForRaceQuery,
-  getRegisterForRaceUseCase,
-  getWithdrawFromRaceUseCase,
-} from '@/lib/di-container';
 import { useEffectiveDriverId } from '@/lib/currentDriver';
+import {
+  loadLeagueSchedule,
+  registerForRace,
+  withdrawFromRace,
+  type LeagueScheduleRaceItemViewModel,
+} from '@/lib/presenters/LeagueSchedulePresenter';
 
 interface LeagueScheduleProps {
   leagueId: string;
@@ -17,7 +16,7 @@ interface LeagueScheduleProps {
 
 export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
   const router = useRouter();
-  const [races, setRaces] = useState<Race[]>([]);
+  const [races, setRaces] = useState<LeagueScheduleRaceItemViewModel[]>([]);
   const [loading, setLoading] = useState(true);
   const [filter, setFilter] = useState<'all' | 'upcoming' | 'past'>('upcoming');
   const [registrationStates, setRegistrationStates] = useState<Record<string, boolean>>({});
@@ -25,30 +24,16 @@ export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
 
   const currentDriverId = useEffectiveDriverId();
 
-  const loadRaces = useCallback(async () => {
+  const loadRacesCallback = useCallback(async () => {
     setLoading(true);
     try {
-      const raceRepo = getRaceRepository();
-      const allRaces = await raceRepo.findAll();
-      const leagueRaces = allRaces
-        .filter((race) => race.leagueId === leagueId)
-        .sort(
-          (a, b) =>
-            new Date(a.scheduledAt).getTime() - new Date(b.scheduledAt).getTime(),
-        );
-      setRaces(leagueRaces);
+      const viewModel = await loadLeagueSchedule(leagueId, currentDriverId);
+      setRaces(viewModel.races);
 
-      const isRegisteredQuery = getIsDriverRegisteredForRaceQuery();
       const states: Record<string, boolean> = {};
-      await Promise.all(
-        leagueRaces.map(async (race) => {
-          const registered = await isRegisteredQuery.execute({
-            raceId: race.id,
-            driverId: currentDriverId,
-          });
-          states[race.id] = registered;
-        }),
-      );
+      for (const race of viewModel.races) {
+        states[race.id] = race.isRegistered;
+      }
       setRegistrationStates(states);
     } catch (error) {
       console.error('Failed to load races:', error);
@@ -58,27 +43,19 @@ export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
   }, [leagueId, currentDriverId]);
 
   useEffect(() => {
-    loadRaces();
-  }, [loadRaces]);
+    void loadRacesCallback();
+  }, [loadRacesCallback]);
 
-
-  const handleRegister = async (race: Race, e: React.MouseEvent) => {
+  const handleRegister = async (race: LeagueScheduleRaceItemViewModel, e: React.MouseEvent) => {
     e.stopPropagation();
-    
-    const confirmed = window.confirm(
-      `Register for ${race.track}?`
-    );
+
+    const confirmed = window.confirm(`Register for ${race.track}?`);
 
     if (!confirmed) return;
 
     setProcessingRace(race.id);
     try {
-      const useCase = getRegisterForRaceUseCase();
-      await useCase.execute({
-        raceId: race.id,
-        leagueId,
-        driverId: currentDriverId,
-      });
+      await registerForRace(race.id, leagueId, currentDriverId);
       setRegistrationStates((prev) => ({ ...prev, [race.id]: true }));
     } catch (err) {
       alert(err instanceof Error ? err.message : 'Failed to register');
@@ -87,22 +64,16 @@ export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
     }
   };
 
-  const handleWithdraw = async (race: Race, e: React.MouseEvent) => {
+  const handleWithdraw = async (race: LeagueScheduleRaceItemViewModel, e: React.MouseEvent) => {
     e.stopPropagation();
 
-    const confirmed = window.confirm(
-      'Withdraw from this race?'
-    );
+    const confirmed = window.confirm('Withdraw from this race?');
 
     if (!confirmed) return;
 
     setProcessingRace(race.id);
     try {
-      const useCase = getWithdrawFromRaceUseCase();
-      await useCase.execute({
-        raceId: race.id,
-        driverId: currentDriverId,
-      });
+      await withdrawFromRace(race.id, currentDriverId);
       setRegistrationStates((prev) => ({ ...prev, [race.id]: false }));
     } catch (err) {
       alert(err instanceof Error ? err.message : 'Failed to withdraw');
@@ -111,18 +82,17 @@ export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
     }
   };
 
-  const now = new Date();
-  const upcomingRaces = races.filter(race => race.status === 'scheduled' && new Date(race.scheduledAt) > now);
-  const pastRaces = races.filter(race => race.status === 'completed' || new Date(race.scheduledAt) <= now);
+  const upcomingRaces = races.filter((race) => race.isUpcoming);
+  const pastRaces = races.filter((race) => race.isPast);
 
   const getDisplayRaces = () => {
     switch (filter) {
       case 'upcoming':
         return upcomingRaces;
       case 'past':
-        return pastRaces.reverse();
+        return [...pastRaces].reverse();
       case 'all':
-        return [...upcomingRaces, ...pastRaces.reverse()];
+        return [...upcomingRaces, ...[...pastRaces].reverse()];
       default:
         return races;
     }
@@ -190,8 +160,8 @@ export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
       ) : (
         <div className="space-y-3">
           {displayRaces.map((race) => {
-            const isPast = race.status === 'completed' || new Date(race.scheduledAt) <= now;
-            const isUpcoming = race.status === 'scheduled' && new Date(race.scheduledAt) > now;
+            const isPast = race.isPast;
+            const isUpcoming = race.isUpcoming;
 
             return (
               <div
@@ -231,19 +201,19 @@ export default function LeagueSchedule({ leagueId }: LeagueScheduleProps) {
                   
                   <div className="flex items-center gap-3">
                     <div className="text-right">
-                    <p className="text-white font-medium">
-                      {new Date(race.scheduledAt).toLocaleDateString('en-US', {
-                        month: 'short',
-                        day: 'numeric',
-                        year: 'numeric',
-                      })}
-                    </p>
-                    <p className="text-sm text-gray-400">
-                      {new Date(race.scheduledAt).toLocaleTimeString([], {
-                        hour: '2-digit',
-                        minute: '2-digit',
-                      })}
-                    </p>
+                      <p className="text-white font-medium">
+                        {race.scheduledAt.toLocaleDateString('en-US', {
+                          month: 'short',
+                          day: 'numeric',
+                          year: 'numeric',
+                        })}
+                      </p>
+                      <p className="text-sm text-gray-400">
+                        {race.scheduledAt.toLocaleTimeString([], {
+                          hour: '2-digit',
+                          minute: '2-digit',
+                        })}
+                      </p>
                       {isPast && race.status === 'completed' && (
                         <p className="text-xs text-primary-blue mt-1">View Results →</p>
                       )}
diff --git a/apps/website/components/teams/TeamAdmin.tsx b/apps/website/components/teams/TeamAdmin.tsx
index 8bd559f97..2b9139574 100644
--- a/apps/website/components/teams/TeamAdmin.tsx
+++ b/apps/website/components/teams/TeamAdmin.tsx
@@ -4,24 +4,28 @@ import { useState, useEffect } from 'react';
 import Card from '@/components/ui/Card';
 import Button from '@/components/ui/Button';
 import Input from '@/components/ui/Input';
-import {
-  getDriverRepository,
-  getGetTeamJoinRequestsUseCase,
-  getApproveTeamJoinRequestUseCase,
-  getRejectTeamJoinRequestUseCase,
-  getUpdateTeamUseCase,
-} from '@/lib/di-container';
-import { EntityMappers } from '@gridpilot/racing/application/mappers/EntityMappers';
 import type { DriverDTO } from '@gridpilot/racing/application/dto/DriverDTO';
-import type { Team, TeamJoinRequest } from '@gridpilot/racing';
+import {
+  loadTeamAdminViewModel,
+  approveTeamJoinRequestAndReload,
+  rejectTeamJoinRequestAndReload,
+  updateTeamDetails,
+  type TeamAdminJoinRequestViewModel,
+} from '@/lib/presenters/TeamAdminPresenter';
 
 interface TeamAdminProps {
-  team: Team;
+  team: {
+    id: string;
+    name: string;
+    tag: string;
+    description: string;
+    ownerId: string;
+  };
   onUpdate: () => void;
 }
 
 export default function TeamAdmin({ team, onUpdate }: TeamAdminProps) {
-  const [joinRequests, setJoinRequests] = useState<TeamJoinRequest[]>([]);
+  const [joinRequests, setJoinRequests] = useState<TeamAdminJoinRequestViewModel[]>([]);
   const [requestDrivers, setRequestDrivers] = useState<Record<string, DriverDTO>>({});
   const [loading, setLoading] = useState(true);
   const [editMode, setEditMode] = useState(false);
@@ -32,38 +36,38 @@ export default function TeamAdmin({ team, onUpdate }: TeamAdminProps) {
   });
 
   useEffect(() => {
-    void loadJoinRequests();
-  }, [team.id]);
+    const load = async () => {
+      setLoading(true);
+      try {
+        const viewModel = await loadTeamAdminViewModel(team as any);
+        setJoinRequests(viewModel.requests);
 
-  const loadJoinRequests = async () => {
-    const useCase = getGetTeamJoinRequestsUseCase();
-    await useCase.execute({ teamId: team.id });
-    const viewModel = useCase.presenter.getViewModel();
-    setJoinRequests(viewModel.requests);
-
-    const driverRepo = getDriverRepository();
-    const allDrivers = await driverRepo.findAll();
-    const driverMap: Record<string, DriverDTO> = {};
-
-    for (const request of viewModel.requests) {
-      const driver = allDrivers.find(d => d.id === request.driverId);
-      if (driver) {
-        const dto = EntityMappers.toDriverDTO(driver);
-        if (dto) {
-          driverMap[request.driverId] = dto;
+        const driversById: Record<string, DriverDTO> = {};
+        for (const request of viewModel.requests) {
+          if (request.driver) {
+            driversById[request.driverId] = request.driver;
+          }
         }
+        setRequestDrivers(driversById);
+      } finally {
+        setLoading(false);
       }
-    }
+    };
 
-    setRequestDrivers(driverMap);
-    setLoading(false);
-  };
+    void load();
+  }, [team.id, team.name, team.tag, team.description, team.ownerId]);
 
   const handleApprove = async (requestId: string) => {
     try {
-      const useCase = getApproveTeamJoinRequestUseCase();
-      await useCase.execute({ requestId });
-      await loadJoinRequests();
+      const updated = await approveTeamJoinRequestAndReload(requestId, team.id);
+      setJoinRequests(updated);
+      const driversById: Record<string, DriverDTO> = {};
+      for (const request of updated) {
+        if (request.driver) {
+          driversById[request.driverId] = request.driver;
+        }
+      }
+      setRequestDrivers(driversById);
       onUpdate();
     } catch (error) {
       alert(error instanceof Error ? error.message : 'Failed to approve request');
@@ -72,9 +76,15 @@ export default function TeamAdmin({ team, onUpdate }: TeamAdminProps) {
 
   const handleReject = async (requestId: string) => {
     try {
-      const useCase = getRejectTeamJoinRequestUseCase();
-      await useCase.execute({ requestId });
-      await loadJoinRequests();
+      const updated = await rejectTeamJoinRequestAndReload(requestId, team.id);
+      setJoinRequests(updated);
+      const driversById: Record<string, DriverDTO> = {};
+      for (const request of updated) {
+        if (request.driver) {
+          driversById[request.driverId] = request.driver;
+        }
+      }
+      setRequestDrivers(driversById);
     } catch (error) {
       alert(error instanceof Error ? error.message : 'Failed to reject request');
     }
@@ -82,15 +92,12 @@ export default function TeamAdmin({ team, onUpdate }: TeamAdminProps) {
 
   const handleSaveChanges = async () => {
     try {
-      const useCase = getUpdateTeamUseCase();
-      await useCase.execute({
+      await updateTeamDetails({
         teamId: team.id,
-        updates: {
-          name: editedTeam.name,
-          tag: editedTeam.tag,
-          description: editedTeam.description,
-        },
-        updatedBy: team.ownerId,
+        name: editedTeam.name,
+        tag: editedTeam.tag,
+        description: editedTeam.description,
+        updatedByDriverId: team.ownerId,
       });
       setEditMode(false);
       onUpdate();
@@ -194,7 +201,7 @@ export default function TeamAdmin({ team, onUpdate }: TeamAdminProps) {
         ) : joinRequests.length > 0 ? (
           <div className="space-y-3">
             {joinRequests.map((request) => {
-              const driver = requestDrivers[request.driverId];
+              const driver = requestDrivers[request.driverId] ?? request.driver;
               if (!driver) return null;
 
               return (
diff --git a/apps/website/components/teams/TeamStandings.tsx b/apps/website/components/teams/TeamStandings.tsx
index ca3cc139e..80201c975 100644
--- a/apps/website/components/teams/TeamStandings.tsx
+++ b/apps/website/components/teams/TeamStandings.tsx
@@ -2,85 +2,31 @@
 
 import { useState, useEffect } from 'react';
 import Card from '@/components/ui/Card';
-import { getStandingRepository, getLeagueRepository, getTeamMembershipRepository } from '@/lib/di-container';
-import { EntityMappers } from '@gridpilot/racing/application/mappers/EntityMappers';
-import type { LeagueDTO } from '@gridpilot/racing/application/dto/LeagueDTO';
+import {
+  loadTeamStandings,
+  type TeamLeagueStandingViewModel,
+} from '@/lib/presenters/TeamStandingsPresenter';
 
 interface TeamStandingsProps {
   teamId: string;
   leagues: string[];
 }
 
-interface TeamLeagueStanding {
-  leagueId: string;
-  leagueName: string;
-  position: number;
-  points: number;
-  wins: number;
-  racesCompleted: number;
-}
-
 export default function TeamStandings({ teamId, leagues }: TeamStandingsProps) {
-  const [standings, setStandings] = useState<TeamLeagueStanding[]>([]);
+  const [standings, setStandings] = useState<TeamLeagueStandingViewModel[]>([]);
   const [loading, setLoading] = useState(true);
 
   useEffect(() => {
-    const loadStandings = async () => {
-      const standingRepo = getStandingRepository();
-      const leagueRepo = getLeagueRepository();
-      const teamMembershipRepo = getTeamMembershipRepository();
-      const members = await teamMembershipRepo.getTeamMembers(teamId);
-      const memberIds = members.map(m => m.driverId);
-
-      const teamStandings: TeamLeagueStanding[] = [];
-
-      for (const leagueId of leagues) {
-        const league = await leagueRepo.findById(leagueId);
-        if (!league) continue;
-
-        const leagueStandings = await standingRepo.findByLeagueId(leagueId);
-        
-        // Calculate team points (sum of all team members)
-        let totalPoints = 0;
-        let totalWins = 0;
-        let totalRaces = 0;
-
-        for (const standing of leagueStandings) {
-          if (memberIds.includes(standing.driverId)) {
-            totalPoints += standing.points;
-            totalWins += standing.wins;
-            totalRaces = Math.max(totalRaces, standing.racesCompleted);
-          }
-        }
-
-        // Calculate team position (simplified - based on total points)
-        const allTeamPoints = leagueStandings
-          .filter(s => memberIds.includes(s.driverId))
-          .reduce((sum, s) => sum + s.points, 0);
-        
-        const position = leagueStandings
-          .filter((_, idx, arr) => {
-            const teamPoints = arr
-              .filter(s => memberIds.includes(s.driverId))
-              .reduce((sum, s) => sum + s.points, 0);
-            return teamPoints > allTeamPoints;
-          }).length + 1;
-
-        teamStandings.push({
-          leagueId,
-          leagueName: league.name,
-          position,
-          points: totalPoints,
-          wins: totalWins,
-          racesCompleted: totalRaces,
-        });
+    const load = async () => {
+      try {
+        const viewModel = await loadTeamStandings(teamId, leagues);
+        setStandings(viewModel.standings);
+      } finally {
+        setLoading(false);
       }
-
-      setStandings(teamStandings);
-      setLoading(false);
     };
 
-    loadStandings();
+    void load();
   }, [teamId, leagues]);
 
   if (loading) {
diff --git a/apps/website/lib/di-config.ts b/apps/website/lib/di-config.ts
index 64c82f69f..3bbd0ce58 100644
--- a/apps/website/lib/di-config.ts
+++ b/apps/website/lib/di-config.ts
@@ -43,7 +43,7 @@ import type { INotificationRepository, INotificationPreferenceRepository } from
 import {
   SendNotificationUseCase,
   MarkNotificationReadUseCase,
-  GetUnreadNotificationsQuery
+  GetUnreadNotificationsUseCase
 } from '@gridpilot/notifications/application';
 import {
   InMemoryNotificationRepository,
@@ -81,7 +81,7 @@ import {
   InMemoryFeedRepository,
   InMemorySocialGraphRepository,
 } from '@gridpilot/social/infrastructure/inmemory/InMemorySocialAndFeed';
-import { DemoImageServiceAdapter } from '@gridpilot/demo-infrastructure';
+import { DemoImageServiceAdapter } from '@gridpilot/testing-support';
 
 // Application use cases and queries
 import {
@@ -174,7 +174,7 @@ import { LeagueSchedulePreviewPresenter } from './presenters/LeagueSchedulePrevi
 import { DashboardOverviewPresenter } from './presenters/DashboardOverviewPresenter';
 import { ProfileOverviewPresenter } from './presenters/ProfileOverviewPresenter';
 
-// Testing support
+// Demo infrastructure (runtime demo seed & helpers)
 import {
   createStaticRacingSeed,
   getDemoLeagueArchetypeByName,
@@ -1246,8 +1246,8 @@ export function configureDIContainer(): void {
 
   // Register queries - Notifications
   container.registerInstance(
-    DI_TOKENS.GetUnreadNotificationsQuery,
-    new GetUnreadNotificationsQuery(notificationRepository)
+    DI_TOKENS.GetUnreadNotificationsUseCase,
+    new GetUnreadNotificationsUseCase(notificationRepository)
   );
 
   // Register use cases - Sponsors
diff --git a/apps/website/lib/di-container.ts b/apps/website/lib/di-container.ts
index 62bff57a6..69cc1e13d 100644
--- a/apps/website/lib/di-container.ts
+++ b/apps/website/lib/di-container.ts
@@ -35,7 +35,7 @@ import type { INotificationRepository, INotificationPreferenceRepository } from
 import type {
   SendNotificationUseCase,
   MarkNotificationReadUseCase,
-  GetUnreadNotificationsQuery
+  GetUnreadNotificationsUseCase
 } from '@gridpilot/notifications/application';
 import type {
   JoinLeagueUseCase,
@@ -457,9 +457,9 @@ class DIContainer {
     return getDIContainer().resolve<MarkNotificationReadUseCase>(DI_TOKENS.MarkNotificationReadUseCase);
   }
 
-  get getUnreadNotificationsQuery(): GetUnreadNotificationsQuery {
+  get getUnreadNotificationsUseCase(): GetUnreadNotificationsUseCase {
     this.ensureInitialized();
-    return getDIContainer().resolve<GetUnreadNotificationsQuery>(DI_TOKENS.GetUnreadNotificationsQuery);
+    return getDIContainer().resolve<GetUnreadNotificationsUseCase>(DI_TOKENS.GetUnreadNotificationsUseCase);
   }
 
   get fileProtestUseCase(): FileProtestUseCase {
@@ -801,8 +801,8 @@ export function getMarkNotificationReadUseCase(): MarkNotificationReadUseCase {
   return DIContainer.getInstance().markNotificationReadUseCase;
 }
 
-export function getGetUnreadNotificationsQuery(): GetUnreadNotificationsQuery {
-  return DIContainer.getInstance().getUnreadNotificationsQuery;
+export function getGetUnreadNotificationsUseCase(): GetUnreadNotificationsUseCase {
+  return DIContainer.getInstance().getUnreadNotificationsUseCase;
 }
 
 export function getFileProtestUseCase(): FileProtestUseCase {
diff --git a/apps/website/lib/di-tokens.ts b/apps/website/lib/di-tokens.ts
index 5f5963278..8c7ee694e 100644
--- a/apps/website/lib/di-tokens.ts
+++ b/apps/website/lib/di-tokens.ts
@@ -101,7 +101,7 @@ export const DI_TOKENS = {
   GetRacePenaltiesUseCase: Symbol.for('GetRacePenaltiesUseCase'),
 
   // Queries - Notifications
-  GetUnreadNotificationsQuery: Symbol.for('GetUnreadNotificationsQuery'),
+  GetUnreadNotificationsUseCase: Symbol.for('GetUnreadNotificationsUseCase'),
 
   // Use Cases - Sponsors
   GetSponsorDashboardUseCase: Symbol.for('GetSponsorDashboardUseCase'),
diff --git a/apps/website/lib/presenters/TeamAdminPresenter.ts b/apps/website/lib/presenters/TeamAdminPresenter.ts
new file mode 100644
index 000000000..ce3a47678
--- /dev/null
+++ b/apps/website/lib/presenters/TeamAdminPresenter.ts
@@ -0,0 +1,121 @@
+import type { Team, TeamJoinRequest } from '@gridpilot/racing';
+import type { DriverDTO } from '@gridpilot/racing/application/dto/DriverDTO';
+import { EntityMappers } from '@gridpilot/racing/application/mappers/EntityMappers';
+import {
+  getDriverRepository,
+  getGetTeamJoinRequestsUseCase,
+  getApproveTeamJoinRequestUseCase,
+  getRejectTeamJoinRequestUseCase,
+  getUpdateTeamUseCase,
+} from '@/lib/di-container';
+
+export interface TeamAdminJoinRequestViewModel {
+  id: string;
+  teamId: string;
+  driverId: string;
+  requestedAt: Date;
+  message?: string;
+  driver?: DriverDTO;
+}
+
+export interface TeamAdminTeamSummaryViewModel {
+  id: string;
+  name: string;
+  tag: string;
+  description: string;
+  ownerId: string;
+}
+
+export interface TeamAdminViewModel {
+  team: TeamAdminTeamSummaryViewModel;
+  requests: TeamAdminJoinRequestViewModel[];
+}
+
+/**
+ * Load join requests plus driver DTOs for a team.
+ */
+export async function loadTeamAdminViewModel(team: Team): Promise<TeamAdminViewModel> {
+  const requests = await loadTeamJoinRequests(team.id);
+  return {
+    team: {
+      id: team.id,
+      name: team.name,
+      tag: team.tag,
+      description: team.description,
+      ownerId: team.ownerId,
+    },
+    requests,
+  };
+}
+
+export async function loadTeamJoinRequests(teamId: string): Promise<TeamAdminJoinRequestViewModel[]> {
+  const getRequestsUseCase = getGetTeamJoinRequestsUseCase();
+  await getRequestsUseCase.execute({ teamId });
+  const presenterVm = getRequestsUseCase.presenter.getViewModel();
+
+  const driverRepo = getDriverRepository();
+  const allDrivers = await driverRepo.findAll();
+  const driversById: Record<string, DriverDTO> = {};
+
+  for (const driver of allDrivers) {
+    const dto = EntityMappers.toDriverDTO(driver);
+    if (dto) {
+      driversById[dto.id] = dto;
+    }
+  }
+
+  return presenterVm.requests.map((req) => ({
+    id: req.requestId,
+    teamId: req.teamId,
+    driverId: req.driverId,
+    requestedAt: new Date(req.requestedAt),
+    message: req.message,
+    driver: driversById[req.driverId],
+  }));
+}
+
+/**
+ * Approve a team join request and return updated request view models.
+ */
+export async function approveTeamJoinRequestAndReload(
+  requestId: string,
+  teamId: string,
+): Promise<TeamAdminJoinRequestViewModel[]> {
+  const useCase = getApproveTeamJoinRequestUseCase();
+  await useCase.execute({ requestId });
+  return loadTeamJoinRequests(teamId);
+}
+
+/**
+ * Reject a team join request and return updated request view models.
+ */
+export async function rejectTeamJoinRequestAndReload(
+  requestId: string,
+  teamId: string,
+): Promise<TeamAdminJoinRequestViewModel[]> {
+  const useCase = getRejectTeamJoinRequestUseCase();
+  await useCase.execute({ requestId });
+  return loadTeamJoinRequests(teamId);
+}
+
+/**
+ * Update team basic details.
+ */
+export async function updateTeamDetails(params: {
+  teamId: string;
+  name: string;
+  tag: string;
+  description: string;
+  updatedByDriverId: string;
+}): Promise<void> {
+  const useCase = getUpdateTeamUseCase();
+  await useCase.execute({
+    teamId: params.teamId,
+    updates: {
+      name: params.name,
+      tag: params.tag,
+      description: params.description,
+    },
+    updatedBy: params.updatedByDriverId,
+  });
+}
\ No newline at end of file
diff --git a/apps/website/lib/presenters/TeamStandingsPresenter.ts b/apps/website/lib/presenters/TeamStandingsPresenter.ts
new file mode 100644
index 000000000..6bdc07e89
--- /dev/null
+++ b/apps/website/lib/presenters/TeamStandingsPresenter.ts
@@ -0,0 +1,76 @@
+import { getStandingRepository, getLeagueRepository, getTeamMembershipRepository } from '@/lib/di-container';
+
+export interface TeamLeagueStandingViewModel {
+  leagueId: string;
+  leagueName: string;
+  position: number;
+  points: number;
+  wins: number;
+  racesCompleted: number;
+}
+
+export interface TeamStandingsViewModel {
+  standings: TeamLeagueStandingViewModel[];
+}
+
+/**
+ * Compute team standings across the given leagues for a team.
+ * Mirrors the previous TeamStandings component logic but keeps it out of the UI layer.
+ */
+export async function loadTeamStandings(
+  teamId: string,
+  leagues: string[],
+): Promise<TeamStandingsViewModel> {
+  const standingRepo = getStandingRepository();
+  const leagueRepo = getLeagueRepository();
+  const teamMembershipRepo = getTeamMembershipRepository();
+
+  const members = await teamMembershipRepo.getTeamMembers(teamId);
+  const memberIds = members.map((m) => m.driverId);
+
+  const teamStandings: TeamLeagueStandingViewModel[] = [];
+
+  for (const leagueId of leagues) {
+    const league = await leagueRepo.findById(leagueId);
+    if (!league) continue;
+
+    const leagueStandings = await standingRepo.findByLeagueId(leagueId);
+
+    let totalPoints = 0;
+    let totalWins = 0;
+    let totalRaces = 0;
+
+    for (const standing of leagueStandings) {
+      if (memberIds.includes(standing.driverId)) {
+        totalPoints += standing.points;
+        totalWins += standing.wins;
+        totalRaces = Math.max(totalRaces, standing.racesCompleted);
+      }
+    }
+
+    // Simplified team position based on total points (same spirit as previous logic)
+    const allTeamPoints = leagueStandings
+      .filter((s) => memberIds.includes(s.driverId))
+      .reduce((sum, s) => sum + s.points, 0);
+
+    const position =
+      leagueStandings
+        .filter((_, idx, arr) => {
+          const teamPoints = arr
+            .filter((s) => memberIds.includes(s.driverId))
+            .reduce((sum, s) => sum + s.points, 0);
+          return teamPoints > allTeamPoints;
+        }).length + 1;
+
+    teamStandings.push({
+      leagueId,
+      leagueName: league.name,
+      position,
+      points: totalPoints,
+      wins: totalWins,
+      racesCompleted: totalRaces,
+    });
+  }
+
+  return { standings: teamStandings };
+}
\ No newline at end of file
diff --git a/apps/website/tsconfig.json b/apps/website/tsconfig.json
index 3e60067ff..d01c1c26d 100644
--- a/apps/website/tsconfig.json
+++ b/apps/website/tsconfig.json
@@ -24,8 +24,7 @@
       "@gridpilot/racing/*": ["../../packages/racing/*"],
       "@gridpilot/social/*": ["../../packages/social/*"],
       "@gridpilot/testing-support": ["../../packages/testing-support"],
-      "@gridpilot/media": ["../../packages/media"],
-      "@gridpilot/demo-infrastructure": ["../../packages/demo-infrastructure"]
+      "@gridpilot/media": ["../../packages/media"]
     }
   },
   "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
diff --git a/packages/automation/domain/entities/AutomationSession.ts b/packages/automation/domain/entities/AutomationSession.ts
index 31db664de..5bf1c78f1 100644
--- a/packages/automation/domain/entities/AutomationSession.ts
+++ b/packages/automation/domain/entities/AutomationSession.ts
@@ -2,6 +2,7 @@ import { randomUUID } from 'crypto';
 import { StepId } from '../value-objects/StepId';
 import { SessionState } from '../value-objects/SessionState';
 import { HostedSessionConfig } from './HostedSessionConfig';
+import { AutomationDomainError } from '../errors/AutomationDomainError';
 
 export class AutomationSession {
   private readonly _id: string;
@@ -26,13 +27,13 @@ export class AutomationSession {
 
   static create(config: HostedSessionConfig): AutomationSession {
     if (!config.sessionName || config.sessionName.trim() === '') {
-      throw new Error('Session name cannot be empty');
+      throw new AutomationDomainError('Session name cannot be empty');
     }
     if (!config.trackId || config.trackId.trim() === '') {
-      throw new Error('Track ID is required');
+      throw new AutomationDomainError('Track ID is required');
     }
     if (!config.carIds || config.carIds.length === 0) {
-      throw new Error('At least one car must be selected');
+      throw new AutomationDomainError('At least one car must be selected');
     }
 
     return new AutomationSession(
@@ -73,7 +74,7 @@ export class AutomationSession {
 
   start(): void {
     if (!this._state.isPending()) {
-      throw new Error('Cannot start session that is not pending');
+      throw new AutomationDomainError('Cannot start session that is not pending');
     }
     this._state = SessionState.create('IN_PROGRESS');
     this._startedAt = new Date();
@@ -81,19 +82,19 @@ export class AutomationSession {
 
   transitionToStep(targetStep: StepId): void {
     if (!this._state.isInProgress()) {
-      throw new Error('Cannot transition steps when session is not in progress');
+      throw new AutomationDomainError('Cannot transition steps when session is not in progress');
     }
 
     if (this._currentStep.equals(targetStep)) {
-      throw new Error('Already at this step');
+      throw new AutomationDomainError('Already at this step');
     }
 
     if (targetStep.value < this._currentStep.value) {
-      throw new Error('Cannot move backward - steps must progress forward only');
+      throw new AutomationDomainError('Cannot move backward - steps must progress forward only');
     }
 
     if (targetStep.value !== this._currentStep.value + 1) {
-      throw new Error('Cannot skip steps - must transition sequentially');
+      throw new AutomationDomainError('Cannot skip steps - must transition sequentially');
     }
 
     this._currentStep = targetStep;
@@ -106,21 +107,21 @@ export class AutomationSession {
 
   pause(): void {
     if (!this._state.isInProgress()) {
-      throw new Error('Cannot pause session that is not in progress');
+      throw new AutomationDomainError('Cannot pause session that is not in progress');
     }
     this._state = SessionState.create('PAUSED');
   }
 
   resume(): void {
     if (this._state.value !== 'PAUSED') {
-      throw new Error('Cannot resume session that is not paused');
+      throw new AutomationDomainError('Cannot resume session that is not paused');
     }
     this._state = SessionState.create('IN_PROGRESS');
   }
 
   fail(errorMessage: string): void {
     if (this._state.isTerminal()) {
-      throw new Error('Cannot fail terminal session');
+      throw new AutomationDomainError('Cannot fail terminal session');
     }
     this._state = SessionState.create('FAILED');
     this._errorMessage = errorMessage;
diff --git a/packages/automation/domain/errors/AutomationDomainError.ts b/packages/automation/domain/errors/AutomationDomainError.ts
new file mode 100644
index 000000000..ec7ca7026
--- /dev/null
+++ b/packages/automation/domain/errors/AutomationDomainError.ts
@@ -0,0 +1,8 @@
+export class AutomationDomainError extends Error {
+  readonly name: string = 'AutomationDomainError';
+
+  constructor(message: string) {
+    super(message);
+    Object.setPrototypeOf(this, new.target.prototype);
+  }
+}
\ No newline at end of file
diff --git a/packages/demo-infrastructure/index.ts b/packages/demo-infrastructure/index.ts
deleted file mode 100644
index c74091851..000000000
--- a/packages/demo-infrastructure/index.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-export * from './media/DemoImageServiceAdapter';
-export * from './media/DemoFaceValidationAdapter';
-export * from './media/DemoAvatarGenerationAdapter';
-export * from './media/InMemoryAvatarGenerationRepository';
\ No newline at end of file
diff --git a/packages/demo-infrastructure/package.json b/packages/demo-infrastructure/package.json
deleted file mode 100644
index 1a70df77c..000000000
--- a/packages/demo-infrastructure/package.json
+++ /dev/null
@@ -1,15 +0,0 @@
-{
-  "name": "@gridpilot/demo-infrastructure",
-  "version": "0.1.0",
-  "type": "module",
-  "main": "./index.ts",
-  "types": "./index.ts",
-  "dependencies": {
-    "@gridpilot/media": "file:../media",
-    "@faker-js/faker": "^9.0.0"
-  },
-  "exports": {
-    ".": "./index.ts",
-    "./media/*": "./media/*"
-  }
-}
\ No newline at end of file
diff --git a/packages/demo-infrastructure/tsconfig.json b/packages/demo-infrastructure/tsconfig.json
deleted file mode 100644
index ba90fd732..000000000
--- a/packages/demo-infrastructure/tsconfig.json
+++ /dev/null
@@ -1,13 +0,0 @@
-{
-  "extends": "../../tsconfig.json",
-  "compilerOptions": {
-    "rootDir": "../..",
-    "outDir": "dist",
-    "declaration": true,
-    "declarationMap": false
-  },
-  "include": [
-    "../../packages/demo-infrastructure/**/*.ts",
-    "../../packages/media/**/*.ts"
-  ]
-}
\ No newline at end of file
diff --git a/packages/identity/infrastructure/providers/IracingDemoIdentityProviderAdapter.ts b/packages/identity/infrastructure/providers/IracingDemoIdentityProviderAdapter.ts
index e07f42d53..f773d081a 100644
--- a/packages/identity/infrastructure/providers/IracingDemoIdentityProviderAdapter.ts
+++ b/packages/identity/infrastructure/providers/IracingDemoIdentityProviderAdapter.ts
@@ -1,5 +1,5 @@
 import { randomUUID } from 'crypto';
-import { createStaticRacingSeed } from '../../../testing-support';
+import { createStaticRacingSeed } from '@gridpilot/testing-support';
 import type { IdentityProviderPort } from '../../application/ports/IdentityProviderPort';
 import type { StartAuthCommandDTO } from '../../application/dto/StartAuthCommandDTO';
 import type { AuthCallbackCommandDTO } from '../../application/dto/AuthCallbackCommandDTO';
diff --git a/packages/notifications/application/index.ts b/packages/notifications/application/index.ts
index 920afcfb5..967169286 100644
--- a/packages/notifications/application/index.ts
+++ b/packages/notifications/application/index.ts
@@ -7,7 +7,7 @@
 // Use Cases
 export * from './use-cases/SendNotificationUseCase';
 export * from './use-cases/MarkNotificationReadUseCase';
-export * from './use-cases/GetUnreadNotificationsQuery';
+export * from './use-cases/GetUnreadNotificationsUseCase';
 export * from './use-cases/NotificationPreferencesUseCases';
 
 // Ports
diff --git a/packages/notifications/application/use-cases/GetUnreadNotificationsQuery.ts b/packages/notifications/application/use-cases/GetUnreadNotificationsUseCase.ts
similarity index 79%
rename from packages/notifications/application/use-cases/GetUnreadNotificationsQuery.ts
rename to packages/notifications/application/use-cases/GetUnreadNotificationsUseCase.ts
index 02ddc2c7e..38f7b6cc5 100644
--- a/packages/notifications/application/use-cases/GetUnreadNotificationsQuery.ts
+++ b/packages/notifications/application/use-cases/GetUnreadNotificationsUseCase.ts
@@ -1,5 +1,5 @@
 /**
- * Application Query: GetUnreadNotificationsQuery
+ * Application Use Case: GetUnreadNotificationsUseCase
  * 
  * Retrieves unread notifications for a recipient.
  */
@@ -12,7 +12,7 @@ export interface UnreadNotificationsResult {
   totalCount: number;
 }
 
-export class GetUnreadNotificationsQuery {
+export class GetUnreadNotificationsUseCase {
   constructor(
     private readonly notificationRepository: INotificationRepository,
   ) {}
@@ -28,6 +28,6 @@ export class GetUnreadNotificationsQuery {
 }
 
 /**
- * Additional notification query use cases (e.g., listing or counting notifications)
+ * Additional notification query/use case types (e.g., listing or counting notifications)
  * can be added here in the future as needed.
  */
\ No newline at end of file
diff --git a/packages/notifications/application/use-cases/MarkNotificationReadUseCase.ts b/packages/notifications/application/use-cases/MarkNotificationReadUseCase.ts
index 5f7806892..9182b38b6 100644
--- a/packages/notifications/application/use-cases/MarkNotificationReadUseCase.ts
+++ b/packages/notifications/application/use-cases/MarkNotificationReadUseCase.ts
@@ -5,6 +5,7 @@
  */
 
 import type { INotificationRepository } from '../../domain/repositories/INotificationRepository';
+import { NotificationDomainError } from '../../domain/errors/NotificationDomainError';
 
 export interface MarkNotificationReadCommand {
   notificationId: string;
@@ -20,11 +21,11 @@ export class MarkNotificationReadUseCase {
     const notification = await this.notificationRepository.findById(command.notificationId);
     
     if (!notification) {
-      throw new Error('Notification not found');
+      throw new NotificationDomainError('Notification not found');
     }
 
     if (notification.recipientId !== command.recipientId) {
-      throw new Error('Cannot mark another user\'s notification as read');
+      throw new NotificationDomainError('Cannot mark another user\'s notification as read');
     }
 
     if (!notification.isUnread()) {
@@ -70,11 +71,11 @@ export class DismissNotificationUseCase {
     const notification = await this.notificationRepository.findById(command.notificationId);
     
     if (!notification) {
-      throw new Error('Notification not found');
+      throw new NotificationDomainError('Notification not found');
     }
 
     if (notification.recipientId !== command.recipientId) {
-      throw new Error('Cannot dismiss another user\'s notification');
+      throw new NotificationDomainError('Cannot dismiss another user\'s notification');
     }
 
     if (notification.isDismissed()) {
diff --git a/packages/notifications/application/use-cases/NotificationPreferencesUseCases.ts b/packages/notifications/application/use-cases/NotificationPreferencesUseCases.ts
index 5221f889c..c5b3aaa1c 100644
--- a/packages/notifications/application/use-cases/NotificationPreferencesUseCases.ts
+++ b/packages/notifications/application/use-cases/NotificationPreferencesUseCases.ts
@@ -82,10 +82,10 @@ export class UpdateQuietHoursUseCase {
   async execute(command: UpdateQuietHoursCommand): Promise<void> {
     // Validate hours if provided
     if (command.startHour !== undefined && (command.startHour < 0 || command.startHour > 23)) {
-      throw new Error('Start hour must be between 0 and 23');
+      throw new NotificationDomainError('Start hour must be between 0 and 23');
     }
     if (command.endHour !== undefined && (command.endHour < 0 || command.endHour > 23)) {
-      throw new Error('End hour must be between 0 and 23');
+      throw new NotificationDomainError('End hour must be between 0 and 23');
     }
 
     const preferences = await this.preferenceRepository.getOrCreateDefault(command.driverId);
@@ -110,7 +110,7 @@ export class SetDigestModeUseCase {
 
   async execute(command: SetDigestModeCommand): Promise<void> {
     if (command.frequencyHours !== undefined && command.frequencyHours < 1) {
-      throw new Error('Digest frequency must be at least 1 hour');
+      throw new NotificationDomainError('Digest frequency must be at least 1 hour');
     }
 
     const preferences = await this.preferenceRepository.getOrCreateDefault(command.driverId);
diff --git a/packages/notifications/domain/entities/Notification.ts b/packages/notifications/domain/entities/Notification.ts
index 5b4d35b78..e4b5e9c32 100644
--- a/packages/notifications/domain/entities/Notification.ts
+++ b/packages/notifications/domain/entities/Notification.ts
@@ -5,6 +5,8 @@
  * Immutable entity with factory methods and domain validation.
  */
 
+import { NotificationDomainError } from '../errors/NotificationDomainError';
+
 import type { NotificationType } from '../value-objects/NotificationType';
 import type { NotificationChannel } from '../value-objects/NotificationChannel';
 
@@ -91,12 +93,12 @@ export class Notification {
     createdAt?: Date;
     urgency?: NotificationUrgency;
   }): Notification {
-    if (!props.id) throw new Error('Notification ID is required');
-    if (!props.recipientId) throw new Error('Recipient ID is required');
-    if (!props.type) throw new Error('Notification type is required');
-    if (!props.title?.trim()) throw new Error('Notification title is required');
-    if (!props.body?.trim()) throw new Error('Notification body is required');
-    if (!props.channel) throw new Error('Notification channel is required');
+    if (!props.id) throw new NotificationDomainError('Notification ID is required');
+    if (!props.recipientId) throw new NotificationDomainError('Recipient ID is required');
+    if (!props.type) throw new NotificationDomainError('Notification type is required');
+    if (!props.title?.trim()) throw new NotificationDomainError('Notification title is required');
+    if (!props.body?.trim()) throw new NotificationDomainError('Notification body is required');
+    if (!props.channel) throw new NotificationDomainError('Notification channel is required');
 
     // Modal notifications that require response start with action_required status
     const defaultStatus = props.requiresResponse ? 'action_required' : 'unread';
@@ -196,7 +198,7 @@ export class Notification {
     }
     // Cannot dismiss action_required notifications without responding
     if (this.props.requiresResponse && this.props.status === 'action_required') {
-      throw new Error('Cannot dismiss notification that requires response');
+      throw new NotificationDomainError('Cannot dismiss notification that requires response');
     }
     return new Notification({
       ...this.props,
diff --git a/packages/notifications/domain/entities/NotificationPreference.ts b/packages/notifications/domain/entities/NotificationPreference.ts
index 0cdc4426a..f544d9518 100644
--- a/packages/notifications/domain/entities/NotificationPreference.ts
+++ b/packages/notifications/domain/entities/NotificationPreference.ts
@@ -6,6 +6,7 @@
 
 import type { NotificationType } from '../value-objects/NotificationType';
 import type { NotificationChannel } from '../value-objects/NotificationChannel';
+import { NotificationDomainError } from '../errors/NotificationDomainError';
 import { DEFAULT_ENABLED_CHANNELS } from '../value-objects/NotificationChannel';
 
 export interface ChannelPreference {
@@ -45,8 +46,8 @@ export class NotificationPreference {
   private constructor(private readonly props: NotificationPreferenceProps) {}
 
   static create(props: Omit<NotificationPreferenceProps, 'updatedAt'> & { updatedAt?: Date }): NotificationPreference {
-    if (!props.driverId) throw new Error('Driver ID is required');
-    if (!props.channels) throw new Error('Channel preferences are required');
+    if (!props.driverId) throw new NotificationDomainError('Driver ID is required');
+    if (!props.channels) throw new NotificationDomainError('Channel preferences are required');
 
     return new NotificationPreference({
       ...props,
diff --git a/packages/notifications/domain/errors/NotificationDomainError.ts b/packages/notifications/domain/errors/NotificationDomainError.ts
new file mode 100644
index 000000000..2c9e91190
--- /dev/null
+++ b/packages/notifications/domain/errors/NotificationDomainError.ts
@@ -0,0 +1,8 @@
+export class NotificationDomainError extends Error {
+  readonly name: string = 'NotificationDomainError';
+
+  constructor(message: string) {
+    super(message);
+    Object.setPrototypeOf(this, new.target.prototype);
+  }
+}
\ No newline at end of file
diff --git a/packages/racing/application/dto/LeagueScheduleDTO.ts b/packages/racing/application/dto/LeagueScheduleDTO.ts
index 177b0ef6f..9a867e743 100644
--- a/packages/racing/application/dto/LeagueScheduleDTO.ts
+++ b/packages/racing/application/dto/LeagueScheduleDTO.ts
@@ -7,6 +7,7 @@ import { MonthlyRecurrencePattern } from '../../domain/value-objects/MonthlyRecu
 import type { RecurrenceStrategy } from '../../domain/value-objects/RecurrenceStrategy';
 import { RecurrenceStrategyFactory } from '../../domain/value-objects/RecurrenceStrategy';
 import { SeasonSchedule } from '../../domain/value-objects/SeasonSchedule';
+import { BusinessRuleViolationError } from '../errors/RacingApplicationError';
 
 export interface LeagueScheduleDTO {
   seasonStartDate: string;
@@ -53,24 +54,24 @@ export function leagueTimingsToScheduleDTO(
 
 export function scheduleDTOToSeasonSchedule(dto: LeagueScheduleDTO): SeasonSchedule {
   if (!dto.seasonStartDate) {
-    throw new Error('seasonStartDate is required');
+    throw new RacingApplicationError('seasonStartDate is required');
   }
   if (!dto.raceStartTime) {
-    throw new Error('raceStartTime is required');
+    throw new RacingApplicationError('raceStartTime is required');
   }
   if (!dto.timezoneId) {
-    throw new Error('timezoneId is required');
+    throw new RacingApplicationError('timezoneId is required');
   }
   if (!dto.recurrenceStrategy) {
-    throw new Error('recurrenceStrategy is required');
+    throw new RacingApplicationError('recurrenceStrategy is required');
   }
   if (!Number.isInteger(dto.plannedRounds) || dto.plannedRounds <= 0) {
-    throw new Error('plannedRounds must be a positive integer');
+    throw new RacingApplicationError('plannedRounds must be a positive integer');
   }
 
   const startDate = new Date(dto.seasonStartDate);
   if (Number.isNaN(startDate.getTime())) {
-    throw new Error(`seasonStartDate must be a valid date, got "${dto.seasonStartDate}"`);
+    throw new RacingApplicationError(`seasonStartDate must be a valid date, got "${dto.seasonStartDate}"`);
   }
 
   const timeOfDay = RaceTimeOfDay.fromString(dto.raceStartTime);
@@ -80,15 +81,15 @@ export function scheduleDTOToSeasonSchedule(dto: LeagueScheduleDTO): SeasonSched
 
   if (dto.recurrenceStrategy === 'weekly') {
     if (!dto.weekdays || dto.weekdays.length === 0) {
-      throw new Error('weekdays are required for weekly recurrence');
+      throw new RacingApplicationError('weekdays are required for weekly recurrence');
     }
     recurrence = RecurrenceStrategyFactory.weekly(new WeekdaySet(dto.weekdays));
   } else if (dto.recurrenceStrategy === 'everyNWeeks') {
     if (!dto.weekdays || dto.weekdays.length === 0) {
-      throw new Error('weekdays are required for everyNWeeks recurrence');
+      throw new RacingApplicationError('weekdays are required for everyNWeeks recurrence');
     }
     if (dto.intervalWeeks == null) {
-      throw new Error('intervalWeeks is required for everyNWeeks recurrence');
+      throw new RacingApplicationError('intervalWeeks is required for everyNWeeks recurrence');
     }
     recurrence = RecurrenceStrategyFactory.everyNWeeks(
       dto.intervalWeeks,
@@ -96,12 +97,12 @@ export function scheduleDTOToSeasonSchedule(dto: LeagueScheduleDTO): SeasonSched
     );
   } else if (dto.recurrenceStrategy === 'monthlyNthWeekday') {
     if (!dto.monthlyOrdinal || !dto.monthlyWeekday) {
-      throw new Error('monthlyOrdinal and monthlyWeekday are required for monthlyNthWeekday');
+      throw new RacingApplicationError('monthlyOrdinal and monthlyWeekday are required for monthlyNthWeekday');
     }
     const pattern = new MonthlyRecurrencePattern(dto.monthlyOrdinal, dto.monthlyWeekday);
     recurrence = RecurrenceStrategyFactory.monthlyNthWeekday(pattern);
   } else {
-    throw new Error(`Unknown recurrenceStrategy "${dto.recurrenceStrategy}"`);
+    throw new RacingApplicationError(`Unknown recurrenceStrategy "${dto.recurrenceStrategy}"`);
   }
 
   return new SeasonSchedule({
diff --git a/packages/racing/application/errors/RacingApplicationError.ts b/packages/racing/application/errors/RacingApplicationError.ts
new file mode 100644
index 000000000..08c02b18e
--- /dev/null
+++ b/packages/racing/application/errors/RacingApplicationError.ts
@@ -0,0 +1,56 @@
+export abstract class RacingApplicationError extends Error {
+  readonly context = 'racing-application';
+
+  constructor(message: string) {
+    super(message);
+    Object.setPrototypeOf(this, new.target.prototype);
+  }
+}
+
+export type RacingEntityType =
+  | 'race'
+  | 'league'
+  | 'team'
+  | 'season'
+  | 'sponsorship'
+  | 'sponsorshipRequest'
+  | 'driver'
+  | 'membership';
+
+export interface EntityNotFoundDetails {
+  entity: RacingEntityType;
+  id: string;
+}
+
+export class EntityNotFoundError extends RacingApplicationError {
+  readonly kind = 'not_found' as const;
+
+  constructor(public readonly details: EntityNotFoundDetails) {
+    super(`${details.entity} not found for id: ${details.id}`);
+  }
+}
+
+export type PermissionDeniedReason =
+  | 'NOT_LEAGUE_ADMIN'
+  | 'NOT_LEAGUE_OWNER'
+  | 'NOT_TEAM_OWNER'
+  | 'NOT_ACTIVE_MEMBER'
+  | 'NOT_MEMBER'
+  | 'TEAM_OWNER_CANNOT_LEAVE'
+  | 'UNAUTHORIZED';
+
+export class PermissionDeniedError extends RacingApplicationError {
+  readonly kind = 'forbidden' as const;
+
+  constructor(public readonly reason: PermissionDeniedReason, message?: string) {
+    super(message ?? `Permission denied: ${reason}`);
+  }
+}
+
+export class BusinessRuleViolationError extends RacingApplicationError {
+  readonly kind = 'conflict' as const;
+
+  constructor(message: string) {
+    super(message);
+  }
+}
\ No newline at end of file
diff --git a/packages/racing/application/use-cases/ApplyForSponsorshipUseCase.ts b/packages/racing/application/use-cases/ApplyForSponsorshipUseCase.ts
index 11a90e4ac..bb2277ac6 100644
--- a/packages/racing/application/use-cases/ApplyForSponsorshipUseCase.ts
+++ b/packages/racing/application/use-cases/ApplyForSponsorshipUseCase.ts
@@ -11,6 +11,10 @@ import type { ISponsorshipRequestRepository } from '../../domain/repositories/IS
 import type { ISponsorshipPricingRepository } from '../../domain/repositories/ISponsorshipPricingRepository';
 import type { ISponsorRepository } from '../../domain/repositories/ISponsorRepository';
 import { Money, type Currency } from '../../domain/value-objects/Money';
+import {
+  EntityNotFoundError,
+  BusinessRuleViolationError,
+} from '../errors/RacingApplicationError';
 
 export interface ApplyForSponsorshipDTO {
   sponsorId: string;
@@ -39,23 +43,23 @@ export class ApplyForSponsorshipUseCase {
     // Validate sponsor exists
     const sponsor = await this.sponsorRepo.findById(dto.sponsorId);
     if (!sponsor) {
-      throw new Error('Sponsor not found');
+      throw new EntityNotFoundError({ entity: 'sponsor', id: dto.sponsorId });
     }
 
     // Check if entity accepts sponsorship applications
     const pricing = await this.sponsorshipPricingRepo.findByEntity(dto.entityType, dto.entityId);
     if (!pricing) {
-      throw new Error('This entity has not set up sponsorship pricing');
+      throw new BusinessRuleViolationError('This entity has not set up sponsorship pricing');
     }
 
     if (!pricing.acceptingApplications) {
-      throw new Error('This entity is not currently accepting sponsorship applications');
+      throw new RacingApplicationError('This entity is not currently accepting sponsorship applications');
     }
 
     // Check if the requested tier slot is available
     const slotAvailable = pricing.isSlotAvailable(dto.tier);
     if (!slotAvailable) {
-      throw new Error(`No ${dto.tier} sponsorship slots are available`);
+      throw new RacingApplicationError(`No ${dto.tier} sponsorship slots are available`);
     }
 
     // Check if sponsor already has a pending request for this entity
@@ -65,13 +69,13 @@ export class ApplyForSponsorshipUseCase {
       dto.entityId
     );
     if (hasPending) {
-      throw new Error('You already have a pending sponsorship request for this entity');
+      throw new RacingApplicationError('You already have a pending sponsorship request for this entity');
     }
 
     // Validate offered amount meets minimum price
     const minPrice = pricing.getPrice(dto.tier);
     if (minPrice && dto.offeredAmount < minPrice.amount) {
-      throw new Error(`Offered amount must be at least ${minPrice.format()}`);
+      throw new RacingApplicationError(`Offered amount must be at least ${minPrice.format()}`);
     }
 
     // Create the sponsorship request
diff --git a/packages/racing/application/use-cases/GetLeagueFullConfigUseCase.ts b/packages/racing/application/use-cases/GetLeagueFullConfigUseCase.ts
index 31be1b682..71e9b202b 100644
--- a/packages/racing/application/use-cases/GetLeagueFullConfigUseCase.ts
+++ b/packages/racing/application/use-cases/GetLeagueFullConfigUseCase.ts
@@ -3,6 +3,7 @@ import type { ISeasonRepository } from '../../domain/repositories/ISeasonReposit
 import type { ILeagueScoringConfigRepository } from '../../domain/repositories/ILeagueScoringConfigRepository';
 import type { IGameRepository } from '../../domain/repositories/IGameRepository';
 import type { ILeagueFullConfigPresenter, LeagueFullConfigData } from '../presenters/ILeagueFullConfigPresenter';
+import { EntityNotFoundError } from '../errors/RacingApplicationError';
 
 /**
  * Use Case for retrieving a league's full configuration.
@@ -22,7 +23,7 @@ export class GetLeagueFullConfigUseCase {
 
     const league = await this.leagueRepository.findById(leagueId);
     if (!league) {
-      throw new Error(`League ${leagueId} not found`);
+      throw new EntityNotFoundError({ entity: 'league', id: leagueId });
     }
 
     const seasons = await this.seasonRepository.findByLeagueId(leagueId);
diff --git a/packages/racing/application/use-cases/ImportRaceResultsUseCase.ts b/packages/racing/application/use-cases/ImportRaceResultsUseCase.ts
index cba4d45c0..1b2ff7e19 100644
--- a/packages/racing/application/use-cases/ImportRaceResultsUseCase.ts
+++ b/packages/racing/application/use-cases/ImportRaceResultsUseCase.ts
@@ -3,6 +3,10 @@ import type { ILeagueRepository } from '../../domain/repositories/ILeagueReposit
 import type { IResultRepository } from '../../domain/repositories/IResultRepository';
 import type { IStandingRepository } from '../../domain/repositories/IStandingRepository';
 import { Result } from '../../domain/entities/Result';
+import {
+  BusinessRuleViolationError,
+  EntityNotFoundError,
+} from '../errors/RacingApplicationError';
 import type {
   IImportRaceResultsPresenter,
   ImportRaceResultsSummaryViewModel,
@@ -37,17 +41,17 @@ export class ImportRaceResultsUseCase {
 
     const race = await this.raceRepository.findById(raceId);
     if (!race) {
-      throw new Error('Race not found');
+      throw new EntityNotFoundError({ entity: 'race', id: raceId });
     }
 
     const league = await this.leagueRepository.findById(race.leagueId);
     if (!league) {
-      throw new Error('League not found');
+      throw new EntityNotFoundError({ entity: 'league', id: race.leagueId });
     }
 
     const existing = await this.resultRepository.existsByRaceId(raceId);
     if (existing) {
-      throw new Error('Results already exist for this race');
+      throw new BusinessRuleViolationError('Results already exist for this race');
     }
 
     const entities = results.map((dto) =>
diff --git a/packages/racing/application/use-cases/JoinLeagueUseCase.ts b/packages/racing/application/use-cases/JoinLeagueUseCase.ts
index f115d185e..facdb6c1b 100644
--- a/packages/racing/application/use-cases/JoinLeagueUseCase.ts
+++ b/packages/racing/application/use-cases/JoinLeagueUseCase.ts
@@ -7,6 +7,7 @@ import type {
   MembershipStatus,
 } from '@gridpilot/racing/domain/entities/LeagueMembership';
 import type { JoinLeagueCommandDTO } from '../dto/JoinLeagueCommandDTO';
+import { BusinessRuleViolationError } from '../errors/RacingApplicationError';
 
 export class JoinLeagueUseCase {
   constructor(private readonly membershipRepository: ILeagueMembershipRepository) {}
@@ -23,7 +24,7 @@ export class JoinLeagueUseCase {
 
     const existing = await this.membershipRepository.getMembership(leagueId, driverId);
     if (existing) {
-      throw new Error('Already a member or have a pending request');
+      throw new BusinessRuleViolationError('Already a member or have a pending request');
     }
 
     const membership: LeagueMembership = {
diff --git a/packages/racing/application/use-cases/JoinTeamUseCase.ts b/packages/racing/application/use-cases/JoinTeamUseCase.ts
index 97b21fdd0..55d6461e9 100644
--- a/packages/racing/application/use-cases/JoinTeamUseCase.ts
+++ b/packages/racing/application/use-cases/JoinTeamUseCase.ts
@@ -6,6 +6,10 @@ import type {
   TeamRole,
 } from '../../domain/entities/Team';
 import type { JoinTeamCommandDTO } from '../dto/TeamCommandAndQueryDTO';
+import {
+  BusinessRuleViolationError,
+  EntityNotFoundError,
+} from '../errors/RacingApplicationError';
 
 export class JoinTeamUseCase {
   constructor(
@@ -20,17 +24,17 @@ export class JoinTeamUseCase {
       driverId,
     );
     if (existingActive) {
-      throw new Error('Driver already belongs to a team');
+      throw new BusinessRuleViolationError('Driver already belongs to a team');
     }
 
     const existingMembership = await this.membershipRepository.getMembership(teamId, driverId);
     if (existingMembership) {
-      throw new Error('Already a member or have a pending request');
+      throw new BusinessRuleViolationError('Already a member or have a pending request');
     }
 
     const team = await this.teamRepository.findById(teamId);
     if (!team) {
-      throw new Error('Team not found');
+      throw new EntityNotFoundError({ entity: 'team', id: teamId });
     }
 
     const membership: TeamMembership = {
diff --git a/packages/racing/application/use-cases/RegisterForRaceUseCase.ts b/packages/racing/application/use-cases/RegisterForRaceUseCase.ts
index 3b9089c32..e6fb68eaf 100644
--- a/packages/racing/application/use-cases/RegisterForRaceUseCase.ts
+++ b/packages/racing/application/use-cases/RegisterForRaceUseCase.ts
@@ -2,6 +2,10 @@ import type { IRaceRegistrationRepository } from '@gridpilot/racing/domain/repos
 import type { ILeagueMembershipRepository } from '@gridpilot/racing/domain/repositories/ILeagueMembershipRepository';
 import type { RaceRegistration } from '@gridpilot/racing/domain/entities/RaceRegistration';
 import type { RegisterForRaceCommandDTO } from '../dto/RegisterForRaceCommandDTO';
+import {
+  BusinessRuleViolationError,
+  PermissionDeniedError,
+} from '../errors/RacingApplicationError';
 
 export class RegisterForRaceUseCase {
   constructor(
@@ -20,12 +24,12 @@ export class RegisterForRaceUseCase {
 
     const alreadyRegistered = await this.registrationRepository.isRegistered(raceId, driverId);
     if (alreadyRegistered) {
-      throw new Error('Already registered for this race');
+      throw new BusinessRuleViolationError('Already registered for this race');
     }
 
     const membership = await this.membershipRepository.getMembership(leagueId, driverId);
     if (!membership || membership.status !== 'active') {
-      throw new Error('Must be an active league member to register for races');
+      throw new PermissionDeniedError('NOT_ACTIVE_MEMBER', 'Must be an active league member to register for races');
     }
 
     const registration: RaceRegistration = {
diff --git a/packages/racing/application/use-cases/ReviewProtestUseCase.ts b/packages/racing/application/use-cases/ReviewProtestUseCase.ts
index 10e2cc1af..417456ea6 100644
--- a/packages/racing/application/use-cases/ReviewProtestUseCase.ts
+++ b/packages/racing/application/use-cases/ReviewProtestUseCase.ts
@@ -7,6 +7,10 @@
 import type { IProtestRepository } from '../../domain/repositories/IProtestRepository';
 import type { IRaceRepository } from '../../domain/repositories/IRaceRepository';
 import type { ILeagueMembershipRepository } from '../../domain/repositories/ILeagueMembershipRepository';
+import {
+  EntityNotFoundError,
+  PermissionDeniedError,
+} from '../errors/RacingApplicationError';
 
 export interface ReviewProtestCommand {
   protestId: string;
@@ -26,13 +30,13 @@ export class ReviewProtestUseCase {
     // Load the protest
     const protest = await this.protestRepository.findById(command.protestId);
     if (!protest) {
-      throw new Error('Protest not found');
+      throw new EntityNotFoundError({ entity: 'protest', id: command.protestId });
     }
 
     // Load the race to get league ID
     const race = await this.raceRepository.findById(protest.raceId);
     if (!race) {
-      throw new Error('Race not found');
+      throw new EntityNotFoundError({ entity: 'race', id: protest.raceId });
     }
 
     // Validate steward has authority (owner or admin of the league)
@@ -42,7 +46,10 @@ export class ReviewProtestUseCase {
     );
     
     if (!stewardMembership || (stewardMembership.role !== 'owner' && stewardMembership.role !== 'admin')) {
-      throw new Error('Only league owners and admins can review protests');
+      throw new PermissionDeniedError(
+        'NOT_LEAGUE_ADMIN',
+        'Only league owners and admins can review protests',
+      );
     }
 
     // Apply the decision
diff --git a/packages/racing/domain/entities/Car.ts b/packages/racing/domain/entities/Car.ts
index 49c16e584..589c244e3 100644
--- a/packages/racing/domain/entities/Car.ts
+++ b/packages/racing/domain/entities/Car.ts
@@ -1,5 +1,8 @@
 /**
  * Domain Entity: Car
+ */
+
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
  * 
  * Represents a racing car/vehicle in the GridPilot platform.
  * Immutable entity with factory methods and domain validation.
@@ -90,19 +93,19 @@ export class Car {
     gameId: string;
   }): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Car ID is required');
+      throw new RacingDomainValidationError('Car ID is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('Car name is required');
+      throw new RacingDomainValidationError('Car name is required');
     }
 
     if (!props.manufacturer || props.manufacturer.trim().length === 0) {
-      throw new Error('Car manufacturer is required');
+      throw new RacingDomainValidationError('Car manufacturer is required');
     }
 
     if (!props.gameId || props.gameId.trim().length === 0) {
-      throw new Error('Game ID is required');
+      throw new RacingDomainValidationError('Game ID is required');
     }
   }
 
diff --git a/packages/racing/domain/entities/Driver.ts b/packages/racing/domain/entities/Driver.ts
index 0a6f9f033..0cedf3014 100644
--- a/packages/racing/domain/entities/Driver.ts
+++ b/packages/racing/domain/entities/Driver.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: Driver
- * 
+ *
  * Represents a driver profile in the GridPilot platform.
  * Immutable entity with factory methods and domain validation.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class Driver {
   readonly id: string;
   readonly iracingId: string;
@@ -58,24 +60,24 @@ export class Driver {
     country: string;
   }): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Driver ID is required');
+      throw new RacingDomainValidationError('Driver ID is required');
     }
 
     if (!props.iracingId || props.iracingId.trim().length === 0) {
-      throw new Error('iRacing ID is required');
+      throw new RacingDomainValidationError('iRacing ID is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('Driver name is required');
+      throw new RacingDomainValidationError('Driver name is required');
     }
 
     if (!props.country || props.country.trim().length === 0) {
-      throw new Error('Country code is required');
+      throw new RacingDomainValidationError('Country code is required');
     }
 
     // Validate ISO country code format (2-3 letters)
     if (!/^[A-Z]{2,3}$/i.test(props.country)) {
-      throw new Error('Country must be a valid ISO code (2-3 letters)');
+      throw new RacingDomainValidationError('Country must be a valid ISO code (2-3 letters)');
     }
   }
 
diff --git a/packages/racing/domain/entities/DriverLivery.ts b/packages/racing/domain/entities/DriverLivery.ts
index ee8ba1067..994f7de5c 100644
--- a/packages/racing/domain/entities/DriverLivery.ts
+++ b/packages/racing/domain/entities/DriverLivery.ts
@@ -1,5 +1,8 @@
 /**
  * Domain Entity: DriverLivery
+ */
+
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
  * 
  * Represents a driver's custom livery for a specific car.
  * Includes user-placed decals and league-specific overrides.
@@ -70,23 +73,23 @@ export class DriverLivery {
 
   private static validate(props: Omit<DriverLiveryProps, 'createdAt' | 'userDecals' | 'leagueOverrides'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('DriverLivery ID is required');
+      throw new RacingDomainValidationError('DriverLivery ID is required');
     }
 
     if (!props.driverId || props.driverId.trim().length === 0) {
-      throw new Error('DriverLivery driverId is required');
+      throw new RacingDomainValidationError('DriverLivery driverId is required');
     }
 
     if (!props.gameId || props.gameId.trim().length === 0) {
-      throw new Error('DriverLivery gameId is required');
+      throw new RacingDomainValidationError('DriverLivery gameId is required');
     }
 
     if (!props.carId || props.carId.trim().length === 0) {
-      throw new Error('DriverLivery carId is required');
+      throw new RacingDomainValidationError('DriverLivery carId is required');
     }
 
     if (!props.uploadedImageUrl || props.uploadedImageUrl.trim().length === 0) {
-      throw new Error('DriverLivery uploadedImageUrl is required');
+      throw new RacingDomainValidationError('DriverLivery uploadedImageUrl is required');
     }
   }
 
@@ -95,7 +98,7 @@ export class DriverLivery {
    */
   addDecal(decal: LiveryDecal): DriverLivery {
     if (decal.type !== 'user') {
-      throw new Error('Only user decals can be added to driver livery');
+      throw new RacingDomainInvariantError('Only user decals can be added to driver livery');
     }
 
     return new DriverLivery({
@@ -112,7 +115,7 @@ export class DriverLivery {
     const updatedDecals = this.userDecals.filter(d => d.id !== decalId);
 
     if (updatedDecals.length === this.userDecals.length) {
-      throw new Error('Decal not found in livery');
+      throw new RacingDomainValidationError('Decal not found in livery');
     }
 
     return new DriverLivery({
@@ -129,7 +132,7 @@ export class DriverLivery {
     const index = this.userDecals.findIndex(d => d.id === decalId);
 
     if (index === -1) {
-      throw new Error('Decal not found in livery');
+      throw new RacingDomainError('Decal not found in livery');
     }
 
     const updatedDecals = [...this.userDecals];
diff --git a/packages/racing/domain/entities/Game.ts b/packages/racing/domain/entities/Game.ts
index 13f2782a9..faa92a2c2 100644
--- a/packages/racing/domain/entities/Game.ts
+++ b/packages/racing/domain/entities/Game.ts
@@ -1,3 +1,5 @@
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class Game {
   readonly id: string;
   readonly name: string;
@@ -9,11 +11,11 @@ export class Game {
 
   static create(props: { id: string; name: string }): Game {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Game ID is required');
+      throw new RacingDomainValidationError('Game ID is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('Game name is required');
+      throw new RacingDomainValidationError('Game name is required');
     }
 
     return new Game({
diff --git a/packages/racing/domain/entities/League.ts b/packages/racing/domain/entities/League.ts
index bba1199e1..0dd6678e6 100644
--- a/packages/racing/domain/entities/League.ts
+++ b/packages/racing/domain/entities/League.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: League
- * 
+ *
  * Represents a league in the GridPilot platform.
  * Immutable entity with factory methods and domain validation.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 /**
  * Stewarding decision mode for protests
  */
@@ -158,23 +160,23 @@ export class League {
     ownerId: string;
   }): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('League ID is required');
+      throw new RacingDomainValidationError('League ID is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('League name is required');
+      throw new RacingDomainValidationError('League name is required');
     }
 
     if (props.name.length > 100) {
-      throw new Error('League name must be 100 characters or less');
+      throw new RacingDomainValidationError('League name must be 100 characters or less');
     }
 
     if (!props.description || props.description.trim().length === 0) {
-      throw new Error('League description is required');
+      throw new RacingDomainValidationError('League description is required');
     }
 
     if (!props.ownerId || props.ownerId.trim().length === 0) {
-      throw new Error('League owner ID is required');
+      throw new RacingDomainValidationError('League owner ID is required');
     }
   }
 
diff --git a/packages/racing/domain/entities/LeagueWallet.ts b/packages/racing/domain/entities/LeagueWallet.ts
index 901d560c4..78860e2a7 100644
--- a/packages/racing/domain/entities/LeagueWallet.ts
+++ b/packages/racing/domain/entities/LeagueWallet.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: LeagueWallet
- * 
+ *
  * Represents a league's financial wallet.
  * Aggregate root for managing league finances and transactions.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 import type { Money } from '../value-objects/Money';
 import type { Transaction } from './Transaction';
 
@@ -46,15 +48,15 @@ export class LeagueWallet {
 
   private static validate(props: Omit<LeagueWalletProps, 'createdAt' | 'transactionIds'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('LeagueWallet ID is required');
+      throw new RacingDomainValidationError('LeagueWallet ID is required');
     }
 
     if (!props.leagueId || props.leagueId.trim().length === 0) {
-      throw new Error('LeagueWallet leagueId is required');
+      throw new RacingDomainValidationError('LeagueWallet leagueId is required');
     }
 
     if (!props.balance) {
-      throw new Error('LeagueWallet balance is required');
+      throw new RacingDomainValidationError('LeagueWallet balance is required');
     }
   }
 
@@ -63,7 +65,7 @@ export class LeagueWallet {
    */
   addFunds(netAmount: Money, transactionId: string): LeagueWallet {
     if (this.balance.currency !== netAmount.currency) {
-      throw new Error('Cannot add funds with different currency');
+      throw new RacingDomainInvariantError('Cannot add funds with different currency');
     }
 
     const newBalance = this.balance.add(netAmount);
@@ -81,11 +83,11 @@ export class LeagueWallet {
    */
   withdrawFunds(amount: Money, transactionId: string): LeagueWallet {
     if (this.balance.currency !== amount.currency) {
-      throw new Error('Cannot withdraw funds with different currency');
+      throw new RacingDomainInvariantError('Cannot withdraw funds with different currency');
     }
 
     if (!this.balance.isGreaterThan(amount) && !this.balance.equals(amount)) {
-      throw new Error('Insufficient balance for withdrawal');
+      throw new RacingDomainInvariantError('Insufficient balance for withdrawal');
     }
 
     const newBalance = this.balance.subtract(amount);
diff --git a/packages/racing/domain/entities/LiveryTemplate.ts b/packages/racing/domain/entities/LiveryTemplate.ts
index d601ffbd7..b9be7cb95 100644
--- a/packages/racing/domain/entities/LiveryTemplate.ts
+++ b/packages/racing/domain/entities/LiveryTemplate.ts
@@ -1,5 +1,8 @@
 /**
  * Domain Entity: LiveryTemplate
+ */
+
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
  * 
  * Represents an admin-defined livery template for a specific car.
  * Contains base image and sponsor decal placements.
@@ -54,23 +57,23 @@ export class LiveryTemplate {
 
   private static validate(props: Omit<LiveryTemplateProps, 'createdAt' | 'adminDecals'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('LiveryTemplate ID is required');
+      throw new RacingDomainValidationError('LiveryTemplate ID is required');
     }
 
     if (!props.leagueId || props.leagueId.trim().length === 0) {
-      throw new Error('LiveryTemplate leagueId is required');
+      throw new RacingDomainValidationError('LiveryTemplate leagueId is required');
     }
 
     if (!props.seasonId || props.seasonId.trim().length === 0) {
-      throw new Error('LiveryTemplate seasonId is required');
+      throw new RacingDomainValidationError('LiveryTemplate seasonId is required');
     }
 
     if (!props.carId || props.carId.trim().length === 0) {
-      throw new Error('LiveryTemplate carId is required');
+      throw new RacingDomainValidationError('LiveryTemplate carId is required');
     }
 
     if (!props.baseImageUrl || props.baseImageUrl.trim().length === 0) {
-      throw new Error('LiveryTemplate baseImageUrl is required');
+      throw new RacingDomainValidationError('LiveryTemplate baseImageUrl is required');
     }
   }
 
@@ -79,7 +82,7 @@ export class LiveryTemplate {
    */
   addDecal(decal: LiveryDecal): LiveryTemplate {
     if (decal.type !== 'sponsor') {
-      throw new Error('Only sponsor decals can be added to admin template');
+      throw new RacingDomainInvariantError('Only sponsor decals can be added to admin template');
     }
 
     return new LiveryTemplate({
@@ -96,7 +99,7 @@ export class LiveryTemplate {
     const updatedDecals = this.adminDecals.filter(d => d.id !== decalId);
 
     if (updatedDecals.length === this.adminDecals.length) {
-      throw new Error('Decal not found in template');
+      throw new RacingDomainValidationError('Decal not found in template');
     }
 
     return new LiveryTemplate({
@@ -113,7 +116,7 @@ export class LiveryTemplate {
     const index = this.adminDecals.findIndex(d => d.id === decalId);
 
     if (index === -1) {
-      throw new Error('Decal not found in template');
+      throw new RacingDomainError('Decal not found in template');
     }
 
     const updatedDecals = [...this.adminDecals];
diff --git a/packages/racing/domain/entities/Penalty.ts b/packages/racing/domain/entities/Penalty.ts
index 05acdcafe..4ec68bab7 100644
--- a/packages/racing/domain/entities/Penalty.ts
+++ b/packages/racing/domain/entities/Penalty.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: Penalty
- * 
+ *
  * Represents a penalty applied to a driver for an incident during a race.
  * Penalties can be applied as a result of an upheld protest or directly by stewards.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 export type PenaltyType =
   | 'time_penalty'        // Add time to race result (e.g., +5 seconds)
   | 'grid_penalty'        // Grid position penalty for next race
@@ -47,17 +49,17 @@ export class Penalty {
   private constructor(private readonly props: PenaltyProps) {}
 
   static create(props: PenaltyProps): Penalty {
-    if (!props.id) throw new Error('Penalty ID is required');
-    if (!props.raceId) throw new Error('Race ID is required');
-    if (!props.driverId) throw new Error('Driver ID is required');
-    if (!props.type) throw new Error('Penalty type is required');
-    if (!props.reason?.trim()) throw new Error('Penalty reason is required');
-    if (!props.issuedBy) throw new Error('Penalty must be issued by a steward');
+    if (!props.id) throw new RacingDomainValidationError('Penalty ID is required');
+    if (!props.raceId) throw new RacingDomainValidationError('Race ID is required');
+    if (!props.driverId) throw new RacingDomainValidationError('Driver ID is required');
+    if (!props.type) throw new RacingDomainValidationError('Penalty type is required');
+    if (!props.reason?.trim()) throw new RacingDomainValidationError('Penalty reason is required');
+    if (!props.issuedBy) throw new RacingDomainValidationError('Penalty must be issued by a steward');
     
     // Validate value based on type
     if (['time_penalty', 'grid_penalty', 'points_deduction', 'license_points', 'fine', 'race_ban'].includes(props.type)) {
       if (props.value === undefined || props.value <= 0) {
-        throw new Error(`${props.type} requires a positive value`);
+        throw new RacingDomainValidationError(`${props.type} requires a positive value`);
       }
     }
     
@@ -94,10 +96,10 @@ export class Penalty {
    */
   markAsApplied(notes?: string): Penalty {
     if (this.isApplied()) {
-      throw new Error('Penalty is already applied');
+      throw new RacingDomainInvariantError('Penalty is already applied');
     }
     if (this.props.status === 'overturned') {
-      throw new Error('Cannot apply an overturned penalty');
+      throw new RacingDomainInvariantError('Cannot apply an overturned penalty');
     }
     return new Penalty({
       ...this.props,
@@ -112,7 +114,7 @@ export class Penalty {
    */
   overturn(reason: string): Penalty {
     if (this.props.status === 'overturned') {
-      throw new Error('Penalty is already overturned');
+      throw new RacingDomainInvariantError('Penalty is already overturned');
     }
     return new Penalty({
       ...this.props,
diff --git a/packages/racing/domain/entities/Prize.ts b/packages/racing/domain/entities/Prize.ts
index 01a6aca33..1b7490579 100644
--- a/packages/racing/domain/entities/Prize.ts
+++ b/packages/racing/domain/entities/Prize.ts
@@ -1,9 +1,11 @@
 /**
  * Domain Entity: Prize
- * 
+ *
  * Represents a prize awarded to a driver for a specific position in a season.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 import type { Money } from '../value-objects/Money';
 
 export type PrizeStatus = 'pending' | 'awarded' | 'paid' | 'cancelled';
@@ -61,23 +63,23 @@ export class Prize {
 
   private static validate(props: Omit<PrizeProps, 'createdAt' | 'status'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Prize ID is required');
+      throw new RacingDomainValidationError('Prize ID is required');
     }
 
     if (!props.seasonId || props.seasonId.trim().length === 0) {
-      throw new Error('Prize seasonId is required');
+      throw new RacingDomainValidationError('Prize seasonId is required');
     }
 
     if (!Number.isInteger(props.position) || props.position < 1) {
-      throw new Error('Prize position must be a positive integer');
+      throw new RacingDomainValidationError('Prize position must be a positive integer');
     }
 
     if (!props.amount) {
-      throw new Error('Prize amount is required');
+      throw new RacingDomainValidationError('Prize amount is required');
     }
 
     if (props.amount.amount <= 0) {
-      throw new Error('Prize amount must be greater than zero');
+      throw new RacingDomainValidationError('Prize amount must be greater than zero');
     }
   }
 
@@ -86,11 +88,11 @@ export class Prize {
    */
   awardTo(driverId: string): Prize {
     if (!driverId || driverId.trim().length === 0) {
-      throw new Error('Driver ID is required to award prize');
+      throw new RacingDomainValidationError('Driver ID is required to award prize');
     }
 
     if (this.status !== 'pending') {
-      throw new Error('Only pending prizes can be awarded');
+      throw new RacingDomainInvariantError('Only pending prizes can be awarded');
     }
 
     return new Prize({
@@ -106,11 +108,11 @@ export class Prize {
    */
   markAsPaid(): Prize {
     if (this.status !== 'awarded') {
-      throw new Error('Only awarded prizes can be marked as paid');
+      throw new RacingDomainInvariantError('Only awarded prizes can be marked as paid');
     }
 
     if (!this.driverId) {
-      throw new Error('Prize must have a driver to be paid');
+      throw new RacingDomainInvariantError('Prize must have a driver to be paid');
     }
 
     return new Prize({
@@ -125,7 +127,7 @@ export class Prize {
    */
   cancel(): Prize {
     if (this.status === 'paid') {
-      throw new Error('Cannot cancel a paid prize');
+      throw new RacingDomainInvariantError('Cannot cancel a paid prize');
     }
 
     return new Prize({
diff --git a/packages/racing/domain/entities/Protest.ts b/packages/racing/domain/entities/Protest.ts
index 01265a990..5b2c817d0 100644
--- a/packages/racing/domain/entities/Protest.ts
+++ b/packages/racing/domain/entities/Protest.ts
@@ -1,5 +1,8 @@
 /**
  * Domain Entity: Protest
+ */
+
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
  *
  * Represents a protest filed by a driver against another driver for an incident during a race.
  *
@@ -67,13 +70,13 @@ export class Protest {
   private constructor(private readonly props: ProtestProps) {}
 
   static create(props: ProtestProps): Protest {
-    if (!props.id) throw new Error('Protest ID is required');
-    if (!props.raceId) throw new Error('Race ID is required');
-    if (!props.protestingDriverId) throw new Error('Protesting driver ID is required');
-    if (!props.accusedDriverId) throw new Error('Accused driver ID is required');
-    if (!props.incident) throw new Error('Incident details are required');
-    if (props.incident.lap < 0) throw new Error('Lap number must be non-negative');
-    if (!props.incident.description?.trim()) throw new Error('Incident description is required');
+    if (!props.id) throw new RacingDomainValidationError('Protest ID is required');
+    if (!props.raceId) throw new RacingDomainValidationError('Race ID is required');
+    if (!props.protestingDriverId) throw new RacingDomainValidationError('Protesting driver ID is required');
+    if (!props.accusedDriverId) throw new RacingDomainValidationError('Accused driver ID is required');
+    if (!props.incident) throw new RacingDomainValidationError('Incident details are required');
+    if (props.incident.lap < 0) throw new RacingDomainValidationError('Lap number must be non-negative');
+    if (!props.incident.description?.trim()) throw new RacingDomainValidationError('Incident description is required');
     
     return new Protest({
       ...props,
@@ -131,7 +134,7 @@ export class Protest {
    */
   requestDefense(stewardId: string): Protest {
     if (!this.canRequestDefense()) {
-      throw new Error('Defense can only be requested for pending protests without existing defense');
+      throw new RacingDomainInvariantError('Defense can only be requested for pending protests without existing defense');
     }
     return new Protest({
       ...this.props,
@@ -146,10 +149,10 @@ export class Protest {
    */
   submitDefense(statement: string, videoUrl?: string): Protest {
     if (!this.canSubmitDefense()) {
-      throw new Error('Defense can only be submitted when protest is awaiting defense');
+      throw new RacingDomainInvariantError('Defense can only be submitted when protest is awaiting defense');
     }
     if (!statement?.trim()) {
-      throw new Error('Defense statement is required');
+      throw new RacingDomainValidationError('Defense statement is required');
     }
     return new Protest({
       ...this.props,
@@ -167,7 +170,7 @@ export class Protest {
    */
   startReview(stewardId: string): Protest {
     if (!this.isPending() && !this.isAwaitingDefense()) {
-      throw new Error('Only pending or awaiting-defense protests can be put under review');
+      throw new RacingDomainInvariantError('Only pending or awaiting-defense protests can be put under review');
     }
     return new Protest({
       ...this.props,
@@ -181,7 +184,7 @@ export class Protest {
    */
   uphold(stewardId: string, decisionNotes: string): Protest {
     if (!this.isPending() && !this.isUnderReview() && !this.isAwaitingDefense()) {
-      throw new Error('Only pending, awaiting-defense, or under-review protests can be upheld');
+      throw new RacingDomainInvariantError('Only pending, awaiting-defense, or under-review protests can be upheld');
     }
     return new Protest({
       ...this.props,
@@ -197,7 +200,7 @@ export class Protest {
    */
   dismiss(stewardId: string, decisionNotes: string): Protest {
     if (!this.isPending() && !this.isUnderReview() && !this.isAwaitingDefense()) {
-      throw new Error('Only pending, awaiting-defense, or under-review protests can be dismissed');
+      throw new RacingDomainInvariantError('Only pending, awaiting-defense, or under-review protests can be dismissed');
     }
     return new Protest({
       ...this.props,
@@ -213,7 +216,7 @@ export class Protest {
    */
   withdraw(): Protest {
     if (this.isResolved()) {
-      throw new Error('Cannot withdraw a resolved protest');
+      throw new RacingDomainInvariantError('Cannot withdraw a resolved protest');
     }
     return new Protest({
       ...this.props,
diff --git a/packages/racing/domain/entities/Race.ts b/packages/racing/domain/entities/Race.ts
index eb1bf91c8..aae0ecd12 100644
--- a/packages/racing/domain/entities/Race.ts
+++ b/packages/racing/domain/entities/Race.ts
@@ -5,6 +5,8 @@
  * Immutable entity with factory methods and domain validation.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 export type SessionType = 'practice' | 'qualifying' | 'race';
 export type RaceStatus = 'scheduled' | 'running' | 'completed' | 'cancelled';
 
@@ -96,23 +98,23 @@ export class Race {
     car: string;
   }): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Race ID is required');
+      throw new RacingDomainValidationError('Race ID is required');
     }
 
     if (!props.leagueId || props.leagueId.trim().length === 0) {
-      throw new Error('League ID is required');
+      throw new RacingDomainValidationError('League ID is required');
     }
 
     if (!props.scheduledAt || !(props.scheduledAt instanceof Date)) {
-      throw new Error('Valid scheduled date is required');
+      throw new RacingDomainValidationError('Valid scheduled date is required');
     }
 
     if (!props.track || props.track.trim().length === 0) {
-      throw new Error('Track is required');
+      throw new RacingDomainValidationError('Track is required');
     }
 
     if (!props.car || props.car.trim().length === 0) {
-      throw new Error('Car is required');
+      throw new RacingDomainValidationError('Car is required');
     }
   }
 
@@ -121,7 +123,7 @@ export class Race {
    */
   start(): Race {
     if (this.status !== 'scheduled') {
-      throw new Error('Only scheduled races can be started');
+      throw new RacingDomainInvariantError('Only scheduled races can be started');
     }
 
     return new Race({
@@ -135,11 +137,11 @@ export class Race {
    */
   complete(): Race {
     if (this.status === 'completed') {
-      throw new Error('Race is already completed');
+      throw new RacingDomainInvariantError('Race is already completed');
     }
 
     if (this.status === 'cancelled') {
-      throw new Error('Cannot complete a cancelled race');
+      throw new RacingDomainInvariantError('Cannot complete a cancelled race');
     }
 
     return new Race({
@@ -153,11 +155,11 @@ export class Race {
    */
   cancel(): Race {
     if (this.status === 'completed') {
-      throw new Error('Cannot cancel a completed race');
+      throw new RacingDomainInvariantError('Cannot cancel a completed race');
     }
 
     if (this.status === 'cancelled') {
-      throw new Error('Race is already cancelled');
+      throw new RacingDomainInvariantError('Race is already cancelled');
     }
 
     return new Race({
diff --git a/packages/racing/domain/entities/Result.ts b/packages/racing/domain/entities/Result.ts
index cd86f0c63..5d2813254 100644
--- a/packages/racing/domain/entities/Result.ts
+++ b/packages/racing/domain/entities/Result.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: Result
- * 
+ *
  * Represents a race result in the GridPilot platform.
  * Immutable entity with factory methods and domain validation.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class Result {
   readonly id: string;
   readonly raceId: string;
@@ -62,31 +64,31 @@ export class Result {
     startPosition: number;
   }): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Result ID is required');
+      throw new RacingDomainValidationError('Result ID is required');
     }
 
     if (!props.raceId || props.raceId.trim().length === 0) {
-      throw new Error('Race ID is required');
+      throw new RacingDomainValidationError('Race ID is required');
     }
 
     if (!props.driverId || props.driverId.trim().length === 0) {
-      throw new Error('Driver ID is required');
+      throw new RacingDomainValidationError('Driver ID is required');
     }
 
     if (!Number.isInteger(props.position) || props.position < 1) {
-      throw new Error('Position must be a positive integer');
+      throw new RacingDomainValidationError('Position must be a positive integer');
     }
 
     if (props.fastestLap < 0) {
-      throw new Error('Fastest lap cannot be negative');
+      throw new RacingDomainValidationError('Fastest lap cannot be negative');
     }
 
     if (!Number.isInteger(props.incidents) || props.incidents < 0) {
-      throw new Error('Incidents must be a non-negative integer');
+      throw new RacingDomainValidationError('Incidents must be a non-negative integer');
     }
 
     if (!Number.isInteger(props.startPosition) || props.startPosition < 1) {
-      throw new Error('Start position must be a positive integer');
+      throw new RacingDomainValidationError('Start position must be a positive integer');
     }
   }
 
diff --git a/packages/racing/domain/entities/Season.ts b/packages/racing/domain/entities/Season.ts
index 97fe9bd65..502c90fed 100644
--- a/packages/racing/domain/entities/Season.ts
+++ b/packages/racing/domain/entities/Season.ts
@@ -1,5 +1,7 @@
 export type SeasonStatus = 'planned' | 'active' | 'completed';
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class Season {
   readonly id: string;
   readonly leagueId: string;
@@ -45,19 +47,19 @@ export class Season {
     endDate?: Date;
   }): Season {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Season ID is required');
+      throw new RacingDomainValidationError('Season ID is required');
     }
 
     if (!props.leagueId || props.leagueId.trim().length === 0) {
-      throw new Error('Season leagueId is required');
+      throw new RacingDomainValidationError('Season leagueId is required');
     }
 
     if (!props.gameId || props.gameId.trim().length === 0) {
-      throw new Error('Season gameId is required');
+      throw new RacingDomainValidationError('Season gameId is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('Season name is required');
+      throw new RacingDomainValidationError('Season name is required');
     }
 
     const status: SeasonStatus = props.status ?? 'planned';
diff --git a/packages/racing/domain/entities/SeasonSponsorship.ts b/packages/racing/domain/entities/SeasonSponsorship.ts
index 35f3c4e5b..9e17ace28 100644
--- a/packages/racing/domain/entities/SeasonSponsorship.ts
+++ b/packages/racing/domain/entities/SeasonSponsorship.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: SeasonSponsorship
- * 
+ *
  * Represents a sponsorship relationship between a Sponsor and a Season.
  * Aggregate root for managing sponsorship slots and pricing.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 import type { Money } from '../value-objects/Money';
 
 export type SponsorshipTier = 'main' | 'secondary';
@@ -60,27 +62,27 @@ export class SeasonSponsorship {
 
   private static validate(props: Omit<SeasonSponsorshipProps, 'createdAt' | 'status'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('SeasonSponsorship ID is required');
+      throw new RacingDomainValidationError('SeasonSponsorship ID is required');
     }
 
     if (!props.seasonId || props.seasonId.trim().length === 0) {
-      throw new Error('SeasonSponsorship seasonId is required');
+      throw new RacingDomainValidationError('SeasonSponsorship seasonId is required');
     }
 
     if (!props.sponsorId || props.sponsorId.trim().length === 0) {
-      throw new Error('SeasonSponsorship sponsorId is required');
+      throw new RacingDomainValidationError('SeasonSponsorship sponsorId is required');
     }
 
     if (!props.tier) {
-      throw new Error('SeasonSponsorship tier is required');
+      throw new RacingDomainValidationError('SeasonSponsorship tier is required');
     }
 
     if (!props.pricing) {
-      throw new Error('SeasonSponsorship pricing is required');
+      throw new RacingDomainValidationError('SeasonSponsorship pricing is required');
     }
 
     if (props.pricing.amount <= 0) {
-      throw new Error('SeasonSponsorship pricing must be greater than zero');
+      throw new RacingDomainValidationError('SeasonSponsorship pricing must be greater than zero');
     }
   }
 
@@ -89,11 +91,11 @@ export class SeasonSponsorship {
    */
   activate(): SeasonSponsorship {
     if (this.status === 'active') {
-      throw new Error('SeasonSponsorship is already active');
+      throw new RacingDomainInvariantError('SeasonSponsorship is already active');
     }
 
     if (this.status === 'cancelled') {
-      throw new Error('Cannot activate a cancelled SeasonSponsorship');
+      throw new RacingDomainInvariantError('Cannot activate a cancelled SeasonSponsorship');
     }
 
     return new SeasonSponsorship({
@@ -108,7 +110,7 @@ export class SeasonSponsorship {
    */
   cancel(): SeasonSponsorship {
     if (this.status === 'cancelled') {
-      throw new Error('SeasonSponsorship is already cancelled');
+      throw new RacingDomainInvariantError('SeasonSponsorship is already cancelled');
     }
 
     return new SeasonSponsorship({
diff --git a/packages/racing/domain/entities/Sponsor.ts b/packages/racing/domain/entities/Sponsor.ts
index 1852e8ce1..bbfc9887d 100644
--- a/packages/racing/domain/entities/Sponsor.ts
+++ b/packages/racing/domain/entities/Sponsor.ts
@@ -1,5 +1,8 @@
 /**
  * Domain Entity: Sponsor
+ */
+
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
  * 
  * Represents a sponsor that can sponsor leagues/seasons.
  * Aggregate root for sponsor information.
@@ -42,32 +45,32 @@ export class Sponsor {
 
   private static validate(props: Omit<SponsorProps, 'createdAt'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Sponsor ID is required');
+      throw new RacingDomainValidationError('Sponsor ID is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('Sponsor name is required');
+      throw new RacingDomainValidationError('Sponsor name is required');
     }
 
     if (props.name.length > 100) {
-      throw new Error('Sponsor name must be 100 characters or less');
+      throw new RacingDomainValidationError('Sponsor name must be 100 characters or less');
     }
 
     if (!props.contactEmail || props.contactEmail.trim().length === 0) {
-      throw new Error('Sponsor contact email is required');
+      throw new RacingDomainValidationError('Sponsor contact email is required');
     }
 
     // Basic email validation
     const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
     if (!emailRegex.test(props.contactEmail)) {
-      throw new Error('Invalid sponsor contact email format');
+      throw new RacingDomainValidationError('Invalid sponsor contact email format');
     }
 
     if (props.websiteUrl && props.websiteUrl.trim().length > 0) {
       try {
         new URL(props.websiteUrl);
       } catch {
-        throw new Error('Invalid sponsor website URL');
+        throw new RacingDomainValidationError('Invalid sponsor website URL');
       }
     }
   }
diff --git a/packages/racing/domain/entities/SponsorshipRequest.ts b/packages/racing/domain/entities/SponsorshipRequest.ts
index d758ce293..35eb6c6b1 100644
--- a/packages/racing/domain/entities/SponsorshipRequest.ts
+++ b/packages/racing/domain/entities/SponsorshipRequest.ts
@@ -5,6 +5,8 @@
  * (driver, team, race, or league/season). The entity owner must approve/reject.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 import type { Money } from '../value-objects/Money';
 import type { SponsorshipTier } from './SeasonSponsorship';
 
@@ -70,31 +72,31 @@ export class SponsorshipRequest {
 
   private static validate(props: Omit<SponsorshipRequestProps, 'createdAt' | 'status'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('SponsorshipRequest ID is required');
+      throw new RacingDomainValidationError('SponsorshipRequest ID is required');
     }
 
     if (!props.sponsorId || props.sponsorId.trim().length === 0) {
-      throw new Error('SponsorshipRequest sponsorId is required');
+      throw new RacingDomainValidationError('SponsorshipRequest sponsorId is required');
     }
 
     if (!props.entityType) {
-      throw new Error('SponsorshipRequest entityType is required');
+      throw new RacingDomainValidationError('SponsorshipRequest entityType is required');
     }
 
     if (!props.entityId || props.entityId.trim().length === 0) {
-      throw new Error('SponsorshipRequest entityId is required');
+      throw new RacingDomainValidationError('SponsorshipRequest entityId is required');
     }
 
     if (!props.tier) {
-      throw new Error('SponsorshipRequest tier is required');
+      throw new RacingDomainValidationError('SponsorshipRequest tier is required');
     }
 
     if (!props.offeredAmount) {
-      throw new Error('SponsorshipRequest offeredAmount is required');
+      throw new RacingDomainValidationError('SponsorshipRequest offeredAmount is required');
     }
 
     if (props.offeredAmount.amount <= 0) {
-      throw new Error('SponsorshipRequest offeredAmount must be greater than zero');
+      throw new RacingDomainValidationError('SponsorshipRequest offeredAmount must be greater than zero');
     }
   }
 
@@ -103,11 +105,11 @@ export class SponsorshipRequest {
    */
   accept(respondedBy: string): SponsorshipRequest {
     if (this.status !== 'pending') {
-      throw new Error(`Cannot accept a ${this.status} sponsorship request`);
+      throw new RacingDomainInvariantError(`Cannot accept a ${this.status} sponsorship request`);
     }
 
     if (!respondedBy || respondedBy.trim().length === 0) {
-      throw new Error('respondedBy is required when accepting');
+      throw new RacingDomainValidationError('respondedBy is required when accepting');
     }
 
     return new SponsorshipRequest({
@@ -123,11 +125,11 @@ export class SponsorshipRequest {
    */
   reject(respondedBy: string, reason?: string): SponsorshipRequest {
     if (this.status !== 'pending') {
-      throw new Error(`Cannot reject a ${this.status} sponsorship request`);
+      throw new RacingDomainInvariantError(`Cannot reject a ${this.status} sponsorship request`);
     }
 
     if (!respondedBy || respondedBy.trim().length === 0) {
-      throw new Error('respondedBy is required when rejecting');
+      throw new RacingDomainValidationError('respondedBy is required when rejecting');
     }
 
     return new SponsorshipRequest({
@@ -144,7 +146,7 @@ export class SponsorshipRequest {
    */
   withdraw(): SponsorshipRequest {
     if (this.status !== 'pending') {
-      throw new Error(`Cannot withdraw a ${this.status} sponsorship request`);
+      throw new RacingDomainInvariantError(`Cannot withdraw a ${this.status} sponsorship request`);
     }
 
     return new SponsorshipRequest({
diff --git a/packages/racing/domain/entities/Standing.ts b/packages/racing/domain/entities/Standing.ts
index 0740c916b..0b5afd004 100644
--- a/packages/racing/domain/entities/Standing.ts
+++ b/packages/racing/domain/entities/Standing.ts
@@ -5,6 +5,8 @@
  * Immutable entity with factory methods and domain validation.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class Standing {
   readonly leagueId: string;
   readonly driverId: string;
@@ -60,11 +62,11 @@ export class Standing {
     driverId: string;
   }): void {
     if (!props.leagueId || props.leagueId.trim().length === 0) {
-      throw new Error('League ID is required');
+      throw new RacingDomainError('League ID is required');
     }
 
     if (!props.driverId || props.driverId.trim().length === 0) {
-      throw new Error('Driver ID is required');
+      throw new RacingDomainError('Driver ID is required');
     }
   }
 
@@ -90,7 +92,7 @@ export class Standing {
    */
   updatePosition(position: number): Standing {
     if (!Number.isInteger(position) || position < 1) {
-      throw new Error('Position must be a positive integer');
+      throw new RacingDomainError('Position must be a positive integer');
     }
 
     return new Standing({
diff --git a/packages/racing/domain/entities/Track.ts b/packages/racing/domain/entities/Track.ts
index 2925c76ad..6d5ce5903 100644
--- a/packages/racing/domain/entities/Track.ts
+++ b/packages/racing/domain/entities/Track.ts
@@ -1,10 +1,12 @@
 /**
  * Domain Entity: Track
- * 
+ *
  * Represents a racing track/circuit in the GridPilot platform.
  * Immutable entity with factory methods and domain validation.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export type TrackCategory = 'oval' | 'road' | 'street' | 'dirt';
 export type TrackDifficulty = 'beginner' | 'intermediate' | 'advanced' | 'expert';
 
@@ -87,27 +89,27 @@ export class Track {
     gameId: string;
   }): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Track ID is required');
+      throw new RacingDomainValidationError('Track ID is required');
     }
 
     if (!props.name || props.name.trim().length === 0) {
-      throw new Error('Track name is required');
+      throw new RacingDomainValidationError('Track name is required');
     }
 
     if (!props.country || props.country.trim().length === 0) {
-      throw new Error('Track country is required');
+      throw new RacingDomainValidationError('Track country is required');
     }
 
     if (props.lengthKm <= 0) {
-      throw new Error('Track length must be positive');
+      throw new RacingDomainValidationError('Track length must be positive');
     }
 
     if (props.turns < 0) {
-      throw new Error('Track turns cannot be negative');
+      throw new RacingDomainValidationError('Track turns cannot be negative');
     }
 
     if (!props.gameId || props.gameId.trim().length === 0) {
-      throw new Error('Game ID is required');
+      throw new RacingDomainValidationError('Game ID is required');
     }
   }
 
diff --git a/packages/racing/domain/entities/Transaction.ts b/packages/racing/domain/entities/Transaction.ts
index 0abc14e2d..35ad96737 100644
--- a/packages/racing/domain/entities/Transaction.ts
+++ b/packages/racing/domain/entities/Transaction.ts
@@ -1,9 +1,11 @@
 /**
  * Domain Entity: Transaction
- * 
+ *
  * Represents a financial transaction in the league wallet system.
  */
 
+import { RacingDomainValidationError, RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 import type { Money } from '../value-objects/Money';
 
 export type TransactionType = 
@@ -76,23 +78,23 @@ export class Transaction {
 
   private static validate(props: Omit<TransactionProps, 'createdAt' | 'status' | 'platformFee' | 'netAmount'>): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('Transaction ID is required');
+      throw new RacingDomainValidationError('Transaction ID is required');
     }
 
     if (!props.walletId || props.walletId.trim().length === 0) {
-      throw new Error('Transaction walletId is required');
+      throw new RacingDomainValidationError('Transaction walletId is required');
     }
 
     if (!props.type) {
-      throw new Error('Transaction type is required');
+      throw new RacingDomainValidationError('Transaction type is required');
     }
 
     if (!props.amount) {
-      throw new Error('Transaction amount is required');
+      throw new RacingDomainValidationError('Transaction amount is required');
     }
 
     if (props.amount.amount <= 0) {
-      throw new Error('Transaction amount must be greater than zero');
+      throw new RacingDomainValidationError('Transaction amount must be greater than zero');
     }
   }
 
@@ -101,11 +103,11 @@ export class Transaction {
    */
   complete(): Transaction {
     if (this.status === 'completed') {
-      throw new Error('Transaction is already completed');
+      throw new RacingDomainInvariantError('Transaction is already completed');
     }
 
     if (this.status === 'failed' || this.status === 'cancelled') {
-      throw new Error('Cannot complete a failed or cancelled transaction');
+      throw new RacingDomainInvariantError('Cannot complete a failed or cancelled transaction');
     }
 
     return new Transaction({
@@ -120,7 +122,7 @@ export class Transaction {
    */
   fail(): Transaction {
     if (this.status === 'completed') {
-      throw new Error('Cannot fail a completed transaction');
+      throw new RacingDomainInvariantError('Cannot fail a completed transaction');
     }
 
     return new Transaction({
@@ -134,7 +136,7 @@ export class Transaction {
    */
   cancel(): Transaction {
     if (this.status === 'completed') {
-      throw new Error('Cannot cancel a completed transaction');
+      throw new RacingDomainInvariantError('Cannot cancel a completed transaction');
     }
 
     return new Transaction({
diff --git a/packages/racing/domain/errors/RacingDomainError.ts b/packages/racing/domain/errors/RacingDomainError.ts
new file mode 100644
index 000000000..f490d127b
--- /dev/null
+++ b/packages/racing/domain/errors/RacingDomainError.ts
@@ -0,0 +1,24 @@
+export abstract class RacingDomainError extends Error {
+  readonly context = 'racing-domain';
+
+  constructor(message: string) {
+    super(message);
+    Object.setPrototypeOf(this, new.target.prototype);
+  }
+}
+
+export class RacingDomainValidationError extends RacingDomainError {
+  readonly kind = 'validation' as const;
+
+  constructor(message: string) {
+    super(message);
+  }
+}
+
+export class RacingDomainInvariantError extends RacingDomainError {
+  readonly kind = 'invariant' as const;
+
+  constructor(message: string) {
+    super(message);
+  }
+}
\ No newline at end of file
diff --git a/packages/racing/domain/services/SeasonScheduleGenerator.ts b/packages/racing/domain/services/SeasonScheduleGenerator.ts
index fc3c78238..a1e8a9299 100644
--- a/packages/racing/domain/services/SeasonScheduleGenerator.ts
+++ b/packages/racing/domain/services/SeasonScheduleGenerator.ts
@@ -1,6 +1,7 @@
 import { SeasonSchedule } from '../value-objects/SeasonSchedule';
 import { ScheduledRaceSlot } from '../value-objects/ScheduledRaceSlot';
 import type { RecurrenceStrategy } from '../value-objects/RecurrenceStrategy';
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
 import { RaceTimeOfDay } from '../value-objects/RaceTimeOfDay';
 import type { Weekday } from '../value-objects/Weekday';
 import { weekdayToIndex } from '../value-objects/Weekday';
@@ -66,7 +67,7 @@ function generateWeeklyOrEveryNWeeksSlots(
       : [];
 
   if (weekdays.length === 0) {
-    throw new Error('RecurrenceStrategy has no weekdays');
+    throw new RacingDomainValidationError('RecurrenceStrategy has no weekdays');
   }
 
   const intervalWeeks = recurrence.kind === 'everyNWeeks' ? recurrence.intervalWeeks : 1;
@@ -161,7 +162,7 @@ export class SeasonScheduleGenerator {
 
   static generateSlotsUpTo(schedule: SeasonSchedule, maxRounds: number): ScheduledRaceSlot[] {
     if (!Number.isInteger(maxRounds) || maxRounds <= 0) {
-      throw new Error('maxRounds must be a positive integer');
+      throw new RacingDomainError('maxRounds must be a positive integer');
     }
 
     const recurrence: RecurrenceStrategy = schedule.recurrence;
diff --git a/packages/racing/domain/value-objects/LeagueDescription.ts b/packages/racing/domain/value-objects/LeagueDescription.ts
index cbd40d984..62c1fb67c 100644
--- a/packages/racing/domain/value-objects/LeagueDescription.ts
+++ b/packages/racing/domain/value-objects/LeagueDescription.ts
@@ -1,9 +1,11 @@
 /**
  * Domain Value Object: LeagueDescription
- * 
+ *
  * Represents a valid league description with validation rules.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export interface LeagueDescriptionValidationResult {
   valid: boolean;
   error?: string;
@@ -63,7 +65,7 @@ export class LeagueDescription {
   static create(value: string): LeagueDescription {
     const validation = this.validate(value);
     if (!validation.valid) {
-      throw new Error(validation.error);
+      throw new RacingDomainValidationError(validation.error ?? 'Invalid league description');
     }
     return new LeagueDescription(value.trim());
   }
diff --git a/packages/racing/domain/value-objects/LeagueName.ts b/packages/racing/domain/value-objects/LeagueName.ts
index e762ab116..11cce95eb 100644
--- a/packages/racing/domain/value-objects/LeagueName.ts
+++ b/packages/racing/domain/value-objects/LeagueName.ts
@@ -1,9 +1,11 @@
 /**
  * Domain Value Object: LeagueName
- * 
+ *
  * Represents a valid league name with validation rules.
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export interface LeagueNameValidationResult {
   valid: boolean;
   error?: string;
@@ -76,7 +78,7 @@ export class LeagueName {
   static create(value: string): LeagueName {
     const validation = this.validate(value);
     if (!validation.valid) {
-      throw new Error(validation.error);
+      throw new RacingDomainValidationError(validation.error ?? 'Invalid league name');
     }
     return new LeagueName(value.trim());
   }
diff --git a/packages/racing/domain/value-objects/LeagueTimezone.ts b/packages/racing/domain/value-objects/LeagueTimezone.ts
index d2dd80883..6dab9f34d 100644
--- a/packages/racing/domain/value-objects/LeagueTimezone.ts
+++ b/packages/racing/domain/value-objects/LeagueTimezone.ts
@@ -1,9 +1,11 @@
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class LeagueTimezone {
   private readonly id: string;
 
   constructor(id: string) {
     if (!id || id.trim().length === 0) {
-      throw new Error('LeagueTimezone id must be a non-empty string');
+      throw new RacingDomainValidationError('LeagueTimezone id must be a non-empty string');
     }
     this.id = id;
   }
diff --git a/packages/racing/domain/value-objects/LeagueVisibility.ts b/packages/racing/domain/value-objects/LeagueVisibility.ts
index bcc4721e4..fbcbdb0f0 100644
--- a/packages/racing/domain/value-objects/LeagueVisibility.ts
+++ b/packages/racing/domain/value-objects/LeagueVisibility.ts
@@ -58,7 +58,7 @@ export class LeagueVisibility {
     if (value === 'unranked' || value === 'private') {
       return LeagueVisibility.unranked();
     }
-    throw new Error(`Invalid league visibility: ${value}`);
+    throw new RacingDomainValidationError(`Invalid league visibility: ${value}`);
   }
 
   /**
diff --git a/packages/racing/domain/value-objects/LiveryDecal.ts b/packages/racing/domain/value-objects/LiveryDecal.ts
index 86ec1ff67..c98f6421a 100644
--- a/packages/racing/domain/value-objects/LiveryDecal.ts
+++ b/packages/racing/domain/value-objects/LiveryDecal.ts
@@ -51,39 +51,39 @@ export class LiveryDecal {
 
   private static validate(props: LiveryDecalProps): void {
     if (!props.id || props.id.trim().length === 0) {
-      throw new Error('LiveryDecal ID is required');
+      throw new RacingDomainValidationError('LiveryDecal ID is required');
     }
 
     if (!props.imageUrl || props.imageUrl.trim().length === 0) {
-      throw new Error('LiveryDecal imageUrl is required');
+      throw new RacingDomainValidationError('LiveryDecal imageUrl is required');
     }
 
     if (props.x < 0 || props.x > 1) {
-      throw new Error('LiveryDecal x coordinate must be between 0 and 1 (normalized)');
+      throw new RacingDomainValidationError('LiveryDecal x coordinate must be between 0 and 1 (normalized)');
     }
 
     if (props.y < 0 || props.y > 1) {
-      throw new Error('LiveryDecal y coordinate must be between 0 and 1 (normalized)');
+      throw new RacingDomainValidationError('LiveryDecal y coordinate must be between 0 and 1 (normalized)');
     }
 
     if (props.width <= 0 || props.width > 1) {
-      throw new Error('LiveryDecal width must be between 0 and 1 (normalized)');
+      throw new RacingDomainValidationError('LiveryDecal width must be between 0 and 1 (normalized)');
     }
 
     if (props.height <= 0 || props.height > 1) {
-      throw new Error('LiveryDecal height must be between 0 and 1 (normalized)');
+      throw new RacingDomainValidationError('LiveryDecal height must be between 0 and 1 (normalized)');
     }
 
     if (!Number.isInteger(props.zIndex) || props.zIndex < 0) {
-      throw new Error('LiveryDecal zIndex must be a non-negative integer');
+      throw new RacingDomainValidationError('LiveryDecal zIndex must be a non-negative integer');
     }
 
     if (props.rotation < 0 || props.rotation > 360) {
-      throw new Error('LiveryDecal rotation must be between 0 and 360 degrees');
+      throw new RacingDomainValidationError('LiveryDecal rotation must be between 0 and 360 degrees');
     }
 
     if (!props.type) {
-      throw new Error('LiveryDecal type is required');
+      throw new RacingDomainValidationError('LiveryDecal type is required');
     }
   }
 
diff --git a/packages/racing/domain/value-objects/MembershipFee.ts b/packages/racing/domain/value-objects/MembershipFee.ts
index 4bd7a7008..b69507a81 100644
--- a/packages/racing/domain/value-objects/MembershipFee.ts
+++ b/packages/racing/domain/value-objects/MembershipFee.ts
@@ -3,6 +3,8 @@
  * Represents membership fee configuration for league drivers
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 import type { Money } from './Money';
 
 export type MembershipFeeType = 'season' | 'monthly' | 'per_race';
@@ -23,15 +25,15 @@ export class MembershipFee {
 
   static create(type: MembershipFeeType, amount: Money): MembershipFee {
     if (!type) {
-      throw new Error('MembershipFee type is required');
+      throw new RacingDomainValidationError('MembershipFee type is required');
     }
 
     if (!amount) {
-      throw new Error('MembershipFee amount is required');
+      throw new RacingDomainValidationError('MembershipFee amount is required');
     }
 
     if (amount.amount < 0) {
-      throw new Error('MembershipFee amount cannot be negative');
+      throw new RacingDomainValidationError('MembershipFee amount cannot be negative');
     }
 
     return new MembershipFee({ type, amount });
diff --git a/packages/racing/domain/value-objects/Money.ts b/packages/racing/domain/value-objects/Money.ts
index 7c54ce647..f250e4f49 100644
--- a/packages/racing/domain/value-objects/Money.ts
+++ b/packages/racing/domain/value-objects/Money.ts
@@ -3,6 +3,8 @@
  * Represents a monetary amount with currency and platform fee calculation
  */
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export type Currency = 'USD' | 'EUR' | 'GBP';
 
 export class Money {
@@ -18,10 +20,10 @@ export class Money {
 
   static create(amount: number, currency: Currency = 'USD'): Money {
     if (amount < 0) {
-      throw new Error('Money amount cannot be negative');
+      throw new RacingDomainValidationError('Money amount cannot be negative');
     }
     if (!Number.isFinite(amount)) {
-      throw new Error('Money amount must be a finite number');
+      throw new RacingDomainValidationError('Money amount must be a finite number');
     }
     return new Money(amount, currency);
   }
@@ -47,7 +49,7 @@ export class Money {
    */
   add(other: Money): Money {
     if (this.currency !== other.currency) {
-      throw new Error('Cannot add money with different currencies');
+      throw new RacingDomainValidationError('Cannot add money with different currencies');
     }
     return new Money(this.amount + other.amount, this.currency);
   }
@@ -57,11 +59,11 @@ export class Money {
    */
   subtract(other: Money): Money {
     if (this.currency !== other.currency) {
-      throw new Error('Cannot subtract money with different currencies');
+      throw new RacingDomainValidationError('Cannot subtract money with different currencies');
     }
     const result = this.amount - other.amount;
     if (result < 0) {
-      throw new Error('Subtraction would result in negative amount');
+      throw new RacingDomainValidationError('Subtraction would result in negative amount');
     }
     return new Money(result, this.currency);
   }
@@ -71,7 +73,7 @@ export class Money {
    */
   isGreaterThan(other: Money): boolean {
     if (this.currency !== other.currency) {
-      throw new Error('Cannot compare money with different currencies');
+      throw new RacingDomainValidationError('Cannot compare money with different currencies');
     }
     return this.amount > other.amount;
   }
diff --git a/packages/racing/domain/value-objects/RaceTimeOfDay.ts b/packages/racing/domain/value-objects/RaceTimeOfDay.ts
index 30e045ecf..31576684c 100644
--- a/packages/racing/domain/value-objects/RaceTimeOfDay.ts
+++ b/packages/racing/domain/value-objects/RaceTimeOfDay.ts
@@ -1,13 +1,15 @@
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class RaceTimeOfDay {
   readonly hour: number;
   readonly minute: number;
 
   constructor(hour: number, minute: number) {
     if (!Number.isInteger(hour) || hour < 0 || hour > 23) {
-      throw new Error(`RaceTimeOfDay hour must be between 0 and 23, got ${hour}`);
+      throw new RacingDomainValidationError(`RaceTimeOfDay hour must be between 0 and 23, got ${hour}`);
     }
     if (!Number.isInteger(minute) || minute < 0 || minute > 59) {
-      throw new Error(`RaceTimeOfDay minute must be between 0 and 59, got ${minute}`);
+      throw new RacingDomainValidationError(`RaceTimeOfDay minute must be between 0 and 59, got ${minute}`);
     }
 
     this.hour = hour;
@@ -17,7 +19,7 @@ export class RaceTimeOfDay {
   static fromString(value: string): RaceTimeOfDay {
     const match = /^(\d{2}):(\d{2})$/.exec(value);
     if (!match) {
-      throw new Error(`RaceTimeOfDay string must be in HH:MM 24h format, got "${value}"`);
+      throw new RacingDomainValidationError(`RaceTimeOfDay string must be in HH:MM 24h format, got "${value}"`);
     }
 
     const hour = Number(match[1]);
diff --git a/packages/racing/domain/value-objects/RecurrenceStrategy.ts b/packages/racing/domain/value-objects/RecurrenceStrategy.ts
index 340c1b9a1..49297bcab 100644
--- a/packages/racing/domain/value-objects/RecurrenceStrategy.ts
+++ b/packages/racing/domain/value-objects/RecurrenceStrategy.ts
@@ -1,5 +1,6 @@
 import { WeekdaySet } from './WeekdaySet';
 import { MonthlyRecurrencePattern } from './MonthlyRecurrencePattern';
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
 
 export type RecurrenceStrategyKind = 'weekly' | 'everyNWeeks' | 'monthlyNthWeekday';
 
@@ -34,7 +35,9 @@ export class RecurrenceStrategyFactory {
 
   static everyNWeeks(intervalWeeks: number, weekdays: WeekdaySet): RecurrenceStrategy {
     if (!Number.isInteger(intervalWeeks) || intervalWeeks < 1 || intervalWeeks > 12) {
-      throw new Error('everyNWeeks intervalWeeks must be an integer between 1 and 12');
+      throw new RacingDomainValidationError(
+        'everyNWeeks intervalWeeks must be an integer between 1 and 12',
+      );
     }
 
     return {
diff --git a/packages/racing/domain/value-objects/ScheduledRaceSlot.ts b/packages/racing/domain/value-objects/ScheduledRaceSlot.ts
index c8afc1e90..5279cd573 100644
--- a/packages/racing/domain/value-objects/ScheduledRaceSlot.ts
+++ b/packages/racing/domain/value-objects/ScheduledRaceSlot.ts
@@ -1,5 +1,7 @@
 import { LeagueTimezone } from './LeagueTimezone';
 
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
+
 export class ScheduledRaceSlot {
   readonly roundNumber: number;
   readonly scheduledAt: Date;
@@ -7,10 +9,10 @@ export class ScheduledRaceSlot {
 
   constructor(params: { roundNumber: number; scheduledAt: Date; timezone: LeagueTimezone }) {
     if (!Number.isInteger(params.roundNumber) || params.roundNumber <= 0) {
-      throw new Error('ScheduledRaceSlot.roundNumber must be a positive integer');
+      throw new RacingDomainValidationError('ScheduledRaceSlot.roundNumber must be a positive integer');
     }
     if (!(params.scheduledAt instanceof Date) || Number.isNaN(params.scheduledAt.getTime())) {
-      throw new Error('ScheduledRaceSlot.scheduledAt must be a valid Date');
+      throw new RacingDomainValidationError('ScheduledRaceSlot.scheduledAt must be a valid Date');
     }
 
     this.roundNumber = params.roundNumber;
diff --git a/packages/racing/domain/value-objects/SeasonSchedule.ts b/packages/racing/domain/value-objects/SeasonSchedule.ts
index 14d0bad38..16e89fc2d 100644
--- a/packages/racing/domain/value-objects/SeasonSchedule.ts
+++ b/packages/racing/domain/value-objects/SeasonSchedule.ts
@@ -1,6 +1,7 @@
 import { RaceTimeOfDay } from './RaceTimeOfDay';
 import { LeagueTimezone } from './LeagueTimezone';
 import type { RecurrenceStrategy } from './RecurrenceStrategy';
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
 
 export class SeasonSchedule {
   readonly startDate: Date;
@@ -17,10 +18,10 @@ export class SeasonSchedule {
     plannedRounds: number;
   }) {
     if (!(params.startDate instanceof Date) || Number.isNaN(params.startDate.getTime())) {
-      throw new Error('SeasonSchedule.startDate must be a valid Date');
+      throw new RacingDomainValidationError('SeasonSchedule.startDate must be a valid Date');
     }
     if (!Number.isInteger(params.plannedRounds) || params.plannedRounds <= 0) {
-      throw new Error('SeasonSchedule.plannedRounds must be a positive integer');
+      throw new RacingDomainValidationError('SeasonSchedule.plannedRounds must be a positive integer');
     }
 
     this.startDate = new Date(
diff --git a/packages/racing/domain/value-objects/Weekday.ts b/packages/racing/domain/value-objects/Weekday.ts
index 4ee7c69a9..8d10070d9 100644
--- a/packages/racing/domain/value-objects/Weekday.ts
+++ b/packages/racing/domain/value-objects/Weekday.ts
@@ -1,5 +1,7 @@
 export type Weekday = 'Mon' | 'Tue' | 'Wed' | 'Thu' | 'Fri' | 'Sat' | 'Sun';
 
+import { RacingDomainInvariantError } from '../errors/RacingDomainError';
+
 export const ALL_WEEKDAYS: Weekday[] = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'];
 
 export function weekdayToIndex(day: Weekday): number {
@@ -20,6 +22,6 @@ export function weekdayToIndex(day: Weekday): number {
       return 7;
     default:
       // This should be unreachable because Weekday is a closed union.
-      throw new Error(`Unknown weekday: ${day}`);
+      throw new RacingDomainInvariantError(`Unknown weekday: ${day}`);
   }
 }
\ No newline at end of file
diff --git a/packages/racing/domain/value-objects/WeekdaySet.ts b/packages/racing/domain/value-objects/WeekdaySet.ts
index 4874e0934..834156ba2 100644
--- a/packages/racing/domain/value-objects/WeekdaySet.ts
+++ b/packages/racing/domain/value-objects/WeekdaySet.ts
@@ -1,12 +1,13 @@
 import type { Weekday } from './Weekday';
 import { weekdayToIndex } from './Weekday';
+import { RacingDomainValidationError } from '../errors/RacingDomainError';
 
 export class WeekdaySet {
   private readonly days: Weekday[];
 
   constructor(days: Weekday[]) {
     if (!Array.isArray(days) || days.length === 0) {
-      throw new Error('WeekdaySet requires at least one weekday');
+      throw new RacingDomainValidationError('WeekdaySet requires at least one weekday');
     }
 
     const unique = Array.from(new Set(days));
diff --git a/packages/social/application/dto/FeedItemDTO.ts b/packages/social/application/dto/FeedItemDTO.ts
new file mode 100644
index 000000000..741cc20d6
--- /dev/null
+++ b/packages/social/application/dto/FeedItemDTO.ts
@@ -0,0 +1,17 @@
+import type { FeedItemType } from '../../domain/value-objects/FeedItemType';
+
+export interface FeedItemDTO {
+  id: string;
+  timestamp: string;
+  type: FeedItemType;
+  actorFriendId?: string;
+  actorDriverId?: string;
+  leagueId?: string;
+  raceId?: string;
+  teamId?: string;
+  position?: number;
+  headline: string;
+  body?: string;
+  ctaLabel?: string;
+  ctaHref?: string;
+}
\ No newline at end of file
diff --git a/packages/social/application/index.ts b/packages/social/application/index.ts
new file mode 100644
index 000000000..59e4a98dc
--- /dev/null
+++ b/packages/social/application/index.ts
@@ -0,0 +1,16 @@
+export { GetCurrentUserSocialUseCase } from './use-cases/GetCurrentUserSocialUseCase';
+export type { GetCurrentUserSocialParams } from './use-cases/GetCurrentUserSocialUseCase';
+
+export { GetUserFeedUseCase } from './use-cases/GetUserFeedUseCase';
+export type { GetUserFeedParams } from './use-cases/GetUserFeedUseCase';
+
+export type { CurrentUserSocialDTO } from './dto/CurrentUserSocialDTO';
+export type { FriendDTO } from './dto/FriendDTO';
+export type { FeedItemDTO } from './dto/FeedItemDTO';
+
+export type {
+  CurrentUserSocialViewModel,
+  ICurrentUserSocialPresenter,
+  UserFeedViewModel,
+  IUserFeedPresenter,
+} from './presenters/ISocialPresenters';
\ No newline at end of file
diff --git a/packages/social/application/presenters/ISocialPresenters.ts b/packages/social/application/presenters/ISocialPresenters.ts
new file mode 100644
index 000000000..5ce7415d2
--- /dev/null
+++ b/packages/social/application/presenters/ISocialPresenters.ts
@@ -0,0 +1,20 @@
+import type { CurrentUserSocialDTO } from '../dto/CurrentUserSocialDTO';
+import type { FriendDTO } from '../dto/FriendDTO';
+import type { FeedItemDTO } from '../dto/FeedItemDTO';
+
+export interface CurrentUserSocialViewModel {
+  currentUser: CurrentUserSocialDTO;
+  friends: FriendDTO[];
+}
+
+export interface ICurrentUserSocialPresenter {
+  present(viewModel: CurrentUserSocialViewModel): void;
+}
+
+export interface UserFeedViewModel {
+  items: FeedItemDTO[];
+}
+
+export interface IUserFeedPresenter {
+  present(viewModel: UserFeedViewModel): void;
+}
\ No newline at end of file
diff --git a/packages/social/application/use-cases/GetCurrentUserSocialUseCase.ts b/packages/social/application/use-cases/GetCurrentUserSocialUseCase.ts
new file mode 100644
index 000000000..b7692da6d
--- /dev/null
+++ b/packages/social/application/use-cases/GetCurrentUserSocialUseCase.ts
@@ -0,0 +1,56 @@
+import type { ISocialGraphRepository } from '../../domain/repositories/ISocialGraphRepository';
+import type { CurrentUserSocialDTO } from '../dto/CurrentUserSocialDTO';
+import type { FriendDTO } from '../dto/FriendDTO';
+import type {
+  CurrentUserSocialViewModel,
+  ICurrentUserSocialPresenter,
+} from '../presenters/ISocialPresenters';
+
+export interface GetCurrentUserSocialParams {
+  driverId: string;
+}
+
+/**
+ * Application-level use case to retrieve the current user's social context.
+ *
+ * Keeps orchestration in the social bounded context while delegating
+ * data access to domain repositories and presenting via a presenter.
+ */
+export class GetCurrentUserSocialUseCase {
+  constructor(
+    private readonly socialGraphRepository: ISocialGraphRepository,
+    public readonly presenter: ICurrentUserSocialPresenter,
+  ) {}
+
+  async execute(params: GetCurrentUserSocialParams): Promise<void> {
+    const { driverId } = params;
+
+    const friendsDomain = await this.socialGraphRepository.getFriends(driverId);
+
+    const friends: FriendDTO[] = friendsDomain.map((friend) => ({
+      driverId: friend.id,
+      displayName: friend.name,
+      avatarUrl: '',
+      isOnline: false,
+      lastSeen: new Date(),
+      primaryLeagueId: undefined,
+      primaryTeamId: undefined,
+    }));
+
+    const currentUser: CurrentUserSocialDTO = {
+      driverId,
+      displayName: '',
+      avatarUrl: '',
+      countryCode: '',
+      primaryTeamId: undefined,
+      primaryLeagueId: undefined,
+    };
+
+    const viewModel: CurrentUserSocialViewModel = {
+      currentUser,
+      friends,
+    };
+
+    this.presenter.present(viewModel);
+  }
+}
\ No newline at end of file
diff --git a/packages/social/application/use-cases/GetUserFeedUseCase.ts b/packages/social/application/use-cases/GetUserFeedUseCase.ts
new file mode 100644
index 000000000..065259822
--- /dev/null
+++ b/packages/social/application/use-cases/GetUserFeedUseCase.ts
@@ -0,0 +1,52 @@
+import type { IFeedRepository } from '../../domain/repositories/IFeedRepository';
+import type { FeedItemDTO } from '../dto/FeedItemDTO';
+import type { FeedItem } from '../../domain/entities/FeedItem';
+import type {
+  IUserFeedPresenter,
+  UserFeedViewModel,
+} from '../presenters/ISocialPresenters';
+
+export interface GetUserFeedParams {
+  driverId: string;
+  limit?: number;
+}
+
+export class GetUserFeedUseCase {
+  constructor(
+    private readonly feedRepository: IFeedRepository,
+    public readonly presenter: IUserFeedPresenter,
+  ) {}
+
+  async execute(params: GetUserFeedParams): Promise<void> {
+    const { driverId, limit } = params;
+    const items = await this.feedRepository.getFeedForDriver(driverId, limit);
+    const dtoItems = items.map(mapFeedItemToDTO);
+
+    const viewModel: UserFeedViewModel = {
+      items: dtoItems,
+    };
+
+    this.presenter.present(viewModel);
+  }
+}
+
+function mapFeedItemToDTO(item: FeedItem): FeedItemDTO {
+  return {
+    id: item.id,
+    timestamp:
+      item.timestamp instanceof Date
+        ? item.timestamp.toISOString()
+        : new Date(item.timestamp).toISOString(),
+    type: item.type,
+    actorFriendId: item.actorFriendId,
+    actorDriverId: item.actorDriverId,
+    leagueId: item.leagueId,
+    raceId: item.raceId,
+    teamId: item.teamId,
+    position: item.position,
+    headline: item.headline,
+    body: item.body,
+    ctaLabel: item.ctaLabel,
+    ctaHref: item.ctaHref,
+  };
+}
\ No newline at end of file
diff --git a/packages/social/domain/errors/SocialDomainError.ts b/packages/social/domain/errors/SocialDomainError.ts
new file mode 100644
index 000000000..6917c4cc0
--- /dev/null
+++ b/packages/social/domain/errors/SocialDomainError.ts
@@ -0,0 +1,8 @@
+export class SocialDomainError extends Error {
+  readonly name: string = 'SocialDomainError';
+
+  constructor(message: string) {
+    super(message);
+    Object.setPrototypeOf(this, new.target.prototype);
+  }
+}
\ No newline at end of file
diff --git a/packages/testing-support/index.ts b/packages/testing-support/index.ts
index 720dbb066..aab79a2f9 100644
--- a/packages/testing-support/index.ts
+++ b/packages/testing-support/index.ts
@@ -1,5 +1,9 @@
 export * from './src/faker/faker';
 export * from './src/images/images';
+export * from './src/media/DemoAvatarGenerationAdapter';
+export * from './src/media/DemoFaceValidationAdapter';
+export * from './src/media/DemoImageServiceAdapter';
+export * from './src/media/InMemoryAvatarGenerationRepository';
 export * from './src/racing/RacingSeedCore';
 export * from './src/racing/RacingSponsorshipSeed';
 export * from './src/racing/RacingFeedSeed';
diff --git a/packages/demo-infrastructure/media/DemoAvatarGenerationAdapter.ts b/packages/testing-support/src/media/DemoAvatarGenerationAdapter.ts
similarity index 90%
rename from packages/demo-infrastructure/media/DemoAvatarGenerationAdapter.ts
rename to packages/testing-support/src/media/DemoAvatarGenerationAdapter.ts
index 96b62737f..ca6582c04 100644
--- a/packages/demo-infrastructure/media/DemoAvatarGenerationAdapter.ts
+++ b/packages/testing-support/src/media/DemoAvatarGenerationAdapter.ts
@@ -1,18 +1,18 @@
-import type { 
-  AvatarGenerationPort, 
-  AvatarGenerationOptions, 
-  AvatarGenerationResult 
+import type {
+  AvatarGenerationPort,
+  AvatarGenerationOptions,
+  AvatarGenerationResult,
 } from '@gridpilot/media';
 
 /**
  * Demo implementation of AvatarGenerationPort.
- * 
+ *
  * In production, this would use a real AI image generation API like:
  * - OpenAI DALL-E
  * - Midjourney API
  * - Stable Diffusion
  * - RunwayML
- * 
+ *
  * For demo purposes, this returns placeholder avatar images.
  */
 export class DemoAvatarGenerationAdapter implements AvatarGenerationPort {
@@ -81,10 +81,10 @@ export class DemoAvatarGenerationAdapter implements AvatarGenerationPort {
 
     // For demo, return placeholder URLs based on suit color
     // In production, these would be actual AI-generated images
-    const colorAvatars = this.placeholderAvatars[options.suitColor] || this.placeholderAvatars.blue;
-    
+    const colorAvatars = this.placeholderAvatars[options.suitColor] ?? this.placeholderAvatars.blue;
+
     // Generate unique URLs with a hash to simulate different generations
-    const hash = this.generateHash(options.facePhotoUrl + Date.now());
+    const hash = this.generateHash((options.facePhotoUrl ?? '') + Date.now());
     const avatars = colorAvatars.slice(0, options.count).map((baseUrl, index) => {
       // In demo mode, use dicebear or similar for generating varied avatars
       const seed = `${hash}-${options.suitColor}-${index}`;
@@ -101,15 +101,15 @@ export class DemoAvatarGenerationAdapter implements AvatarGenerationPort {
   }
 
   private delay(ms: number): Promise<void> {
-    return new Promise(resolve => setTimeout(resolve, ms));
+    return new Promise((resolve) => setTimeout(resolve, ms));
   }
 
   private generateHash(input: string): string {
     let hash = 0;
-    for (let i = 0; i < input.length; i++) {
+    for (let i = 0; i < input.length; i += 1) {
       const char = input.charCodeAt(i);
-      hash = ((hash << 5) - hash) + char;
-      hash = hash & hash;
+      hash = (hash << 5) - hash + char;
+      hash |= 0;
     }
     return Math.abs(hash).toString(36);
   }
diff --git a/packages/demo-infrastructure/media/DemoFaceValidationAdapter.ts b/packages/testing-support/src/media/DemoFaceValidationAdapter.ts
similarity index 92%
rename from packages/demo-infrastructure/media/DemoFaceValidationAdapter.ts
rename to packages/testing-support/src/media/DemoFaceValidationAdapter.ts
index 0eaf15603..999dc2e53 100644
--- a/packages/demo-infrastructure/media/DemoFaceValidationAdapter.ts
+++ b/packages/testing-support/src/media/DemoFaceValidationAdapter.ts
@@ -2,13 +2,13 @@ import type { FaceValidationPort, FaceValidationResult } from '@gridpilot/media'
 
 /**
  * Demo implementation of FaceValidationPort.
- * 
+ *
  * In production, this would use a real face detection API like:
  * - AWS Rekognition
  * - Google Cloud Vision
  * - Azure Face API
  * - OpenCV / face-api.js
- * 
+ *
  * For demo purposes, this always returns a valid face if the image data is provided.
  */
 export class DemoFaceValidationAdapter implements FaceValidationPort {
@@ -18,7 +18,7 @@ export class DemoFaceValidationAdapter implements FaceValidationPort {
 
     // Check if we have any image data
     const dataString = typeof imageData === 'string' ? imageData : imageData.toString();
-    
+
     if (!dataString || dataString.length < 100) {
       return {
         isValid: false,
@@ -30,8 +30,8 @@ export class DemoFaceValidationAdapter implements FaceValidationPort {
     }
 
     // Check for valid base64 image data or data URL
-    const isValidImage = 
-      dataString.startsWith('data:image/') || 
+    const isValidImage =
+      dataString.startsWith('data:image/') ||
       dataString.startsWith('/9j/') || // JPEG magic bytes in base64
       dataString.startsWith('iVBOR') || // PNG magic bytes in base64
       dataString.length > 1000; // Assume long strings are valid image data
@@ -57,6 +57,6 @@ export class DemoFaceValidationAdapter implements FaceValidationPort {
   }
 
   private delay(ms: number): Promise<void> {
-    return new Promise(resolve => setTimeout(resolve, ms));
+    return new Promise((resolve) => setTimeout(resolve, ms));
   }
 }
\ No newline at end of file
diff --git a/packages/demo-infrastructure/media/DemoImageServiceAdapter.ts b/packages/testing-support/src/media/DemoImageServiceAdapter.ts
similarity index 92%
rename from packages/demo-infrastructure/media/DemoImageServiceAdapter.ts
rename to packages/testing-support/src/media/DemoImageServiceAdapter.ts
index 850d9eff3..0b378039d 100644
--- a/packages/demo-infrastructure/media/DemoImageServiceAdapter.ts
+++ b/packages/testing-support/src/media/DemoImageServiceAdapter.ts
@@ -5,8 +5,7 @@ const FEMALE_DEFAULT_AVATAR = '/images/avatars/female-default-avatar.jpeg';
 
 export class DemoImageServiceAdapter implements ImageServicePort {
   getDriverAvatar(driverId: string): string {
-    const numericSuffixMatch = driverId.match(/(\d+)$/
-);
+    const numericSuffixMatch = driverId.match(/(\d+)$/);
     if (numericSuffixMatch) {
       const numericSuffix = Number.parseInt(numericSuffixMatch[1], 10);
       return numericSuffix % 2 === 0 ? FEMALE_DEFAULT_AVATAR : MALE_DEFAULT_AVATAR;
@@ -34,7 +33,7 @@ export class DemoImageServiceAdapter implements ImageServicePort {
 
 function stableHash(value: string): number {
   let hash = 0;
-  for (let i = 0; i < value.length; i++) {
+  for (let i = 0; i < value.length; i += 1) {
     hash = (hash * 31 + value.charCodeAt(i)) | 0;
   }
   return Math.abs(hash);
diff --git a/packages/demo-infrastructure/media/InMemoryAvatarGenerationRepository.ts b/packages/testing-support/src/media/InMemoryAvatarGenerationRepository.ts
similarity index 91%
rename from packages/demo-infrastructure/media/InMemoryAvatarGenerationRepository.ts
rename to packages/testing-support/src/media/InMemoryAvatarGenerationRepository.ts
index e689fbe1f..0252ee8fb 100644
--- a/packages/demo-infrastructure/media/InMemoryAvatarGenerationRepository.ts
+++ b/packages/testing-support/src/media/InMemoryAvatarGenerationRepository.ts
@@ -1,14 +1,14 @@
-import type { 
-  IAvatarGenerationRepository 
+import type {
+  IAvatarGenerationRepository,
 } from '@gridpilot/media';
-import { 
-  AvatarGenerationRequest, 
-  type AvatarGenerationRequestProps 
+import {
+  AvatarGenerationRequest,
+  type AvatarGenerationRequestProps,
 } from '@gridpilot/media';
 
 /**
  * In-memory implementation of IAvatarGenerationRepository.
- * 
+ *
  * For demo/development purposes. In production, this would use a database.
  */
 export class InMemoryAvatarGenerationRepository implements IAvatarGenerationRepository {
diff --git a/tests/unit/infrastructure/DemoImageServiceAdapter.test.ts b/tests/unit/infrastructure/DemoImageServiceAdapter.test.ts
index 70bc0cff6..f2c89ccf7 100644
--- a/tests/unit/infrastructure/DemoImageServiceAdapter.test.ts
+++ b/tests/unit/infrastructure/DemoImageServiceAdapter.test.ts
@@ -1,6 +1,6 @@
 import { describe, it, expect } from 'vitest';
 
-import { DemoImageServiceAdapter } from '../../../packages/demo-infrastructure/media/DemoImageServiceAdapter';
+import { DemoImageServiceAdapter } from '@gridpilot/testing-support';
 
 describe('DemoImageServiceAdapter - driver avatars', () => {
   it('returns male default avatar for a demo driver treated as male (odd id suffix)', () => {
diff --git a/tsconfig.json b/tsconfig.json
index da457a100..23a5f86bd 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -19,8 +19,7 @@
       "@gridpilot/shared-result": ["packages/shared/result/Result.ts"],
       "@gridpilot/automation/*": ["packages/automation/*"],
       "@gridpilot/testing-support": ["packages/testing-support/index.ts"],
-      "@gridpilot/media": ["packages/media/index.ts"],
-      "@gridpilot/demo-infrastructure": ["packages/demo-infrastructure/index.ts"]
+      "@gridpilot/media": ["packages/media/index.ts"]
     },
     "types": ["vitest/globals", "node"],
     "jsx": "react-jsx"
diff --git a/vitest.config.ts b/vitest.config.ts
index 6bc78aae9..2cfe12f31 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -13,7 +13,6 @@ export default defineConfig({
       '@gridpilot/automation': path.resolve(__dirname, 'packages/automation'),
       '@gridpilot/automation/*': path.resolve(__dirname, 'packages/automation/*'),
       '@gridpilot/testing-support': path.resolve(__dirname, 'packages/testing-support'),
-      '@gridpilot/demo-infrastructure': path.resolve(__dirname, 'packages/demo-infrastructure'),
       '@gridpilot/media': path.resolve(__dirname, 'packages/media'),
       '@': path.resolve(__dirname, 'apps/website'),
       '@/*': path.resolve(__dirname, 'apps/website/*'),