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+# Component Override System: Feasibility Report
+
+**Date:** 2026-02-09  
+**Author:** Razor (Code Review Agent)  
+**Status:** Research Complete
+
+---
+
+## Executive Summary
+
+**Verdict:** Moderate effort. The codebase already has excellent extension foundations through registries, hooks, and the pane app system. Component override capability can be implemented with **~400-600 LOC** across 4-6 files.
+
+**Key Findings:**
+- ✅ Registry pattern exists and is battle-tested (`_registry.ts`)
+- ✅ Hook/filter system is mature and type-safe
+- ✅ Custom pane apps already support component replacement
+- ⚠️ Core components (ChatContainer, ModelSelect, PromptEditor, ModelCatalog) are hardcoded in PageShell.vue
+- ⚠️ No component override registry exists yet
+
+**Recommended Approach:**
+1. Create `ComponentOverrideRegistry` using existing `createRegistry<T>` pattern
+2. Add `useComponentOverride()` composable for resolution with fallback
+3. Wrap hardcoded component imports in registry lookups
+4. Document override contract and props interface
+
+**Estimated Effort:** 4-6 hours for implementation + tests + docs
+
+---
+
+## 1. Existing Extension Mechanisms (Already in Place)
+
+### 1.1 Registry System (`app/composables/_registry.ts`)
+
+**Status:** ✅ Production-ready, HMR-safe, reactive
+
+```typescript
+export interface RegistryItem {
+    id: string;
+    order?: number;
+}
+
+export interface RegistryApi<T extends RegistryItem> {
+    register(item: T): void;
+    unregister(id: string): void;
+    listIds(): string[];
+    snapshot(): T[];
+    useItems(): ComputedRef<readonly T[]>;
+}
+```
+
+**Features:**
+- Global storage via `globalThis` with typed keys
+- Automatic sorting by `order` field (default 200)
+- Vue reactivity via `ShallowRef`
+- Dev warnings on duplicate IDs
+- Object freezing for immutability
+
+**Current Usage:**
+- Storage providers (`app/core/storage/provider-registry.ts`)
+- Workspace APIs (`app/core/workspace/registry.ts`)
+- Auth UI adapters (`app/core/auth-ui/registry.ts`)
+- AI tools (`app/utils/chat/tool-registry.ts`)
+- Custom pane apps (`app/composables/core/usePaneApps.ts`)
+
+### 1.2 Hook System (`app/core/hooks/`)
+
+**Status:** ✅ Comprehensive, type-safe, priority-based
+
+**Files:**
+- Core: `app/core/hooks/hooks.ts`
+- Types: `app/core/hooks/hook-types.ts`
+- Composable: `app/composables/core/useHookEffect.ts`
+
+**Capabilities:**
+- **Actions** (fire-and-forget): `doAction(name, ...args)`
+- **Filters** (value transformation): `applyFilters(name, value, ...args)`
+- **Priority-based execution** (default 10, lower = earlier)
+- **Wildcard pattern matching**: `ui.*:action:after`
+- **Lifecycle-safe**: `useHookEffect()` auto-cleans on unmount
+- **SSR/HMR safe**: Singleton on client, fresh per-request on server
+
+**Hook Categories:**
+- Chat/AI: `ai.send:action:before`, `ai.send:action:after`
+- UI Pane: `ui.pane.*:action:*`, `ui.pane.thread:action:changed`
+- Sync: `sync.bootstrap:action:*`, `sync.pull:action:*`
+- DB: Template literal support for dynamic table names
+
+### 1.3 Custom Pane Apps System
+
+**Status:** ✅ Fully functional plugin ecosystem
+
+**File:** `app/composables/core/usePaneApps.ts`
+
+**Interface:**
+```typescript
+export interface PaneAppDef {
+    id: string;
+    label: string;
+    icon?: string;
+    component: Component | (() => Promise<Component>);
+    postType?: string;
+    createInitialRecord?: (ctx: { app: PaneAppDef }) => Promise<{ id: string } | null>;
+    order?: number;
+}
+```
+
+**Features:**
+- Async component support
+- Zod validation at registration
+- Integration with Pane Plugin API
+- Global API exposure (`globalThis.__or3PanePluginApi`)
+
+**Current Pane Resolution Logic** (`PageShell.vue:576-620`):
+```typescript
+function resolvePaneComponent(pane: PaneState): Component {
+    if (pane.mode === 'chat') return ChatContainer;
+    if (pane.mode === 'doc') return DocumentEditorAsync;
+    
+    const app = getPaneApp(pane.mode);
+    if (app?.component) return app.component as Component;
+    
+    return PaneUnknown;
+}
+```
+
+---
+
+## 2. Components Worth Overriding (Priority Ranking)
+
+### 2.1 High Value (Core User Flows)
+
+#### A. **ModelSelect** (`app/components/chat/ModelSelect.vue`)
+**Why:** Central to chat UX, frequently customized for org-specific models
+
+**Current Usage:**
+- `ChatInputDropper.vue` (inline model picker)
+- `ChatSettingsPopover.vue` (settings modal)
+- Used as `LazyChatModelSelect` (auto-imported)
+
+**Props Contract:**
+```typescript
+interface Props {
+    model?: string;
+    loading?: boolean;
+}
+
+interface Emits {
+    (e: 'update:model', value: string): void;
+    (e: 'change', value: string): void;
+}
+```
+
+**Composables Used:**
+- `useModelStore()` (favorite models)
+- `useThemeOverrides()` (styling)
+- `useIcon()` (iconography)
+
+**Override Complexity:** Low (clear contract, no deep state coupling)
+
+---
+
+#### B. **ModelCatalog** (`app/components/modal/ModelCatalog.vue`)
+**Why:** Model discovery/management, orgs may want custom catalogs
+
+**Current Usage:**
+- Opened via modal system
+- Used in Dashboard AI page
+
+**Props Contract:**
+```typescript
+// Modal-based, uses v-model:open
+interface Props {
+    open?: boolean;
+}
+```
+
+**Composables Used:**
+- `useModelStore()` (favorites, catalog data)
+- `useOramaModelSearch()` (search indexing)
+- `useThemeOverrides()` (styling)
+
+**Override Complexity:** Medium (search integration, virtual scrolling)
+
+---
+
+#### C. **PromptEditor** (`app/components/prompts/PromptEditor.vue`)
+**Why:** Content editing, orgs may want custom editors (Markdown, plain text)
+
+**Current Usage:**
+- Direct import in pane rendering (not currently abstracted)
+
+**Props Contract:**
+```typescript
+interface Props {
+    promptId: string;
+}
+
+interface Emits {
+    (e: 'back'): void;
+}
+```
+
+**Composables Used:**
+- `getPrompt()`, `updatePrompt()` (DB operations)
+- `useThemeOverrides()` (styling)
+- TipTap editor (heavy dependency)
+
+**Override Complexity:** Medium (editor integration, autosave logic)
+
+---
+
+#### D. **DocumentEditor** (`app/components/documents/DocumentEditor.vue`)
+**Why:** Primary content editor, alternative editors (Monaco, Codemirror)
+
+**Current Usage:**
+- Pane mode `doc` via `DocumentEditorAsync` (lazy loaded)
+
+**Props Contract:**
+```typescript
+interface Props {
+    documentId?: string;
+}
+```
+
+**Composables Used:**
+- `useDocumentsStore()` (state management)
+- TipTap editor via `LazyEditorHost.vue`
+
+**Override Complexity:** High (async loading, search panel, toolbar, autosave)
+
+---
+
+#### E. **ChatContainer** (`app/components/chat/ChatContainer.vue`)
+**Why:** Core chat orchestration, custom chat UIs
+
+**Current Usage:**
+- Pane mode `chat` in `PageShell.vue:582`
+
+**Props Contract:**
+```typescript
+interface Props {
+    messageHistory?: string;
+    threadId?: string;
+    paneId?: string;
+}
+```
+
+**Composables Used:**
+- `useAi()` (message sending, streaming)
+- `useMessageStore()` (persistence)
+- `useThreadsStore()` (thread management)
+- `useHookEffect()` (pane change hooks)
+
+**Override Complexity:** Very High (complex state orchestration, many integrations)
+
+---
+
+### 2.2 Medium Value (Settings/Configuration)
+
+#### F. **SystemPromptsModal** (`app/components/chat/SystemPromptsModal.vue`)
+**Current Usage:** Modal for system prompt management  
+**Override Complexity:** Low (simple modal with list)
+
+#### G. **DashboardThemeSelector** (`app/components/dashboard/DashboardThemeSelector.vue`)
+**Current Usage:** Theme customization UI  
+**Override Complexity:** Low (isolated component)
+
+---
+
+### 2.3 Low Value (Better Served by Hooks)
+
+- **ChatMessage** - Use `ai.send:action:after` hook instead
+- **MessageEditor** - Use `ai.send:action:before` for input manipulation
+- **WorkflowChatMessage** - Workflow-specific, edge case
+- **NotificationBell** - Use notification hooks
+
+---
+
+## 3. Proposed Implementation
+
+### 3.1 New Files Required
+
+1. **`app/composables/core/useComponentOverride.ts`** (120 LOC)
+2. **`app/core/components/registry.ts`** (80 LOC)
+3. **`app/types/component-override.ts`** (40 LOC)
+4. **`app/plugins/00-component-registry.client.ts`** (30 LOC)
+
+### 3.2 Modified Files
+
+1. **`app/components/PageShell.vue`** (~20 LOC changes)
+2. **`app/components/chat/ChatInputDropper.vue`** (~10 LOC changes)
+3. **`app/components/chat/ChatSettingsPopover.vue`** (~10 LOC changes)
+4. **Documentation** (`docs/component-overrides.md`) (200 LOC)
+
+---
+
+## 4. Architecture Design
+
+### 4.1 Registry Interface
+
+**File:** `app/core/components/registry.ts`
+
+```typescript
+import { createRegistry } from '~/composables/_registry';
+import type { Component } from 'vue';
+
+export interface ComponentOverride {
+    id: string;
+    component: Component | (() => Promise<Component>);
+    order?: number;
+    displayName?: string;
+}
+
+const registry = createRegistry<ComponentOverride>('__or3_component_overrides');
+
+export function registerComponentOverride(override: ComponentOverride): void {
+    registry.register(override);
+}
+
+export function unregisterComponentOverride(id: string): void {
+    registry.unregister(id);
+}
+
+export function getComponentOverride(id: string): ComponentOverride | undefined {
+    return registry.snapshot().find(o => o.id === id);
+}
+```
+
+### 4.2 Composable Interface
+
+**File:** `app/composables/core/useComponentOverride.ts`
+
+```typescript
+import { markRaw, type Component } from 'vue';
+import { getComponentOverride } from '~/core/components/registry';
+
+interface ResolveOptions {
+    fallback: Component;
+    props?: Record<string, any>;
+    mode?: 'exact' | 'prefix';
+}
+
+export function useComponentOverride() {
+    /**
+     * Resolve a component by ID with fallback.
+     * Returns override if registered, otherwise returns fallback.
+     */
+    function resolve(id: string, options: ResolveOptions): Component {
+        const override = getComponentOverride(id);
+        
+        if (override?.component) {
+            if (import.meta.dev) {
+                console.debug('[ComponentOverride] Using override for', id);
+            }
+            return markRaw(
+                typeof override.component === 'function'
+                    ? override.component
+                    : markRaw(override.component)
+            );
+        }
+        
+        if (import.meta.dev) {
+            console.debug('[ComponentOverride] Using fallback for', id);
+        }
+        return markRaw(options.fallback);
+    }
+    
+    return { resolve };
+}
+```
+
+### 4.3 Type Definitions
+
+**File:** `app/types/component-override.ts`
+
+```typescript
+import type { Component } from 'vue';
+
+/**
+ * Standard component IDs for overridable components.
+ * Use these constants to ensure consistency across the codebase.
+ */
+export const COMPONENT_IDS = {
+    CHAT_CONTAINER: 'chat.container',
+    MODEL_SELECT: 'chat.model-select',
+    MODEL_CATALOG: 'modal.model-catalog',
+    PROMPT_EDITOR: 'prompts.editor',
+    DOCUMENT_EDITOR: 'documents.editor',
+    SYSTEM_PROMPTS_MODAL: 'chat.system-prompts-modal',
+    DASHBOARD_THEME_SELECTOR: 'dashboard.theme-selector',
+} as const;
+
+export type ComponentId = (typeof COMPONENT_IDS)[keyof typeof COMPONENT_IDS];
+
+/**
+ * Props contracts for overridable components.
+ * Override implementations must accept these props.
+ */
+export interface ComponentPropsMap {
+    [COMPONENT_IDS.CHAT_CONTAINER]: {
+        messageHistory?: string;
+        threadId?: string;
+        paneId?: string;
+    };
+    [COMPONENT_IDS.MODEL_SELECT]: {
+        model?: string;
+        loading?: boolean;
+    };
+    [COMPONENT_IDS.MODEL_CATALOG]: {
+        open?: boolean;
+    };
+    [COMPONENT_IDS.PROMPT_EDITOR]: {
+        promptId: string;
+    };
+    [COMPONENT_IDS.DOCUMENT_EDITOR]: {
+        documentId?: string;
+    };
+    [COMPONENT_IDS.SYSTEM_PROMPTS_MODAL]: {
+        open?: boolean;
+    };
+    [COMPONENT_IDS.DASHBOARD_THEME_SELECTOR]: {
+        // No required props
+    };
+}
+
+/**
+ * Type-safe component override definition.
+ */
+export interface TypedComponentOverride<T extends ComponentId> {
+    id: T;
+    component: Component<ComponentPropsMap[T]>;
+    order?: number;
+    displayName?: string;
+}
+```
+
+### 4.4 Example Usage (Plugin)
+
+**File:** `app/plugins/00-component-registry.client.ts`
+
+```typescript
+export default defineNuxtPlugin(() => {
+    // Plugin authors can register overrides here
+    // Example: Custom model selector
+    /*
+    const { registerComponentOverride } = useComponentOverride();
+    registerComponentOverride({
+        id: COMPONENT_IDS.MODEL_SELECT,
+        component: () => import('~/components/custom/CustomModelSelect.vue'),
+        order: 10, // Lower order = higher priority
+        displayName: 'Custom Model Selector',
+    });
+    */
+});
+```
+
+### 4.5 Integration Example (PageShell.vue)
+
+**Before:**
+```typescript
+function resolvePaneComponent(pane: PaneState): Component {
+    if (pane.mode === 'chat') return ChatContainer;
+    if (pane.mode === 'doc') return DocumentEditorAsync;
+    // ...
+}
+```
+
+**After:**
+```typescript
+import { useComponentOverride } from '~/composables/core/useComponentOverride';
+import { COMPONENT_IDS } from '~/types/component-override';
+
+const { resolve } = useComponentOverride();
+
+function resolvePaneComponent(pane: PaneState): Component {
+    if (pane.mode === 'chat') {
+        return resolve(COMPONENT_IDS.CHAT_CONTAINER, {
+            fallback: ChatContainer,
+        });
+    }
+    if (pane.mode === 'doc') {
+        return resolve(COMPONENT_IDS.DOCUMENT_EDITOR, {
+            fallback: DocumentEditorAsync,
+        });
+    }
+    // ...
+}
+```
+
+---
+
+## 5. Component Override Contract
+
+### 5.1 Props Requirement
+
+Override components **must** accept the same props as the original component. Type checking enforced via `ComponentPropsMap`.
+
+### 5.2 Emits Requirement
+
+Override components **should** emit the same events for backward compatibility. Not enforced at compile-time but documented.
+
+### 5.3 Composable Access
+
+Override components **can** use the same composables as originals:
+- `useModelStore()` - Model management
+- `useThreadsStore()` - Thread state
+- `useDocumentsStore()` - Document state
+- `useHookEffect()` - Hook subscriptions
+- `useThemeOverrides()` - Styling
+
+### 5.4 Global API Access
+
+Override components **can** access:
+- `globalThis.__or3PanePluginApi` - Pane operations
+- `globalThis.__or3MultiPaneApi` - Multi-pane management
+
+---
+
+## 6. Testing Strategy
+
+### 6.1 Unit Tests
+
+**File:** `app/composables/core/__tests__/useComponentOverride.test.ts`
+
+```typescript
+import { describe, it, expect, vi } from 'vitest';
+import { useComponentOverride } from '../useComponentOverride';
+import { COMPONENT_IDS } from '~/types/component-override';
+
+describe('useComponentOverride', () => {
+    it('returns fallback when no override registered', () => {
+        const { resolve } = useComponentOverride();
+        const fallback = { name: 'Fallback' };
+        const result = resolve(COMPONENT_IDS.MODEL_SELECT, { fallback });
+        expect(result).toBe(fallback);
+    });
+    
+    it('returns override when registered', () => {
+        const override = { name: 'Override' };
+        registerComponentOverride({
+            id: COMPONENT_IDS.MODEL_SELECT,
+            component: override,
+        });
+        
+        const { resolve } = useComponentOverride();
+        const result = resolve(COMPONENT_IDS.MODEL_SELECT, { 
+            fallback: { name: 'Fallback' } 
+        });
+        expect(result).toBe(override);
+    });
+    
+    it('respects order priority', () => {
+        // Lower order = higher priority
+        registerComponentOverride({
+            id: COMPONENT_IDS.MODEL_SELECT,
+            component: { name: 'Low' },
+            order: 100,
+        });
+        registerComponentOverride({
+            id: COMPONENT_IDS.MODEL_SELECT,
+            component: { name: 'High' },
+            order: 10,
+        });
+        
+        const { resolve } = useComponentOverride();
+        const result = resolve(COMPONENT_IDS.MODEL_SELECT, {
+            fallback: { name: 'Fallback' },
+        });
+        expect(result.name).toBe('High');
+    });
+});
+```
+
+### 6.2 Integration Tests
+
+**File:** `app/components/__tests__/ComponentOverride.integration.test.ts`
+
+Test that PageShell.vue correctly resolves overrides for panes.
+
+---
+
+## 7. Migration Path (Backward Compatibility)
+
+### Phase 1: Registry Foundation (Week 1)
+- Implement `ComponentOverrideRegistry`
+- Implement `useComponentOverride()` composable
+- Add type definitions
+- Write unit tests
+- No breaking changes (all fallbacks to existing components)
+
+### Phase 2: Core Integration (Week 1-2)
+- Integrate into `PageShell.vue` (ChatContainer, DocumentEditor)
+- Integrate into `ChatInputDropper.vue` (ModelSelect)
+- Integrate into `ChatSettingsPopover.vue` (ModelSelect)
+- Integration tests
+
+### Phase 3: Catalog/Modal Integration (Week 2)
+- Integrate into modal system (ModelCatalog, SystemPromptsModal)
+- Document override contracts
+- Add examples to docs
+
+### Phase 4: Community Feedback (Week 3+)
+- Gather feedback from plugin authors
+- Refine contracts based on real-world usage
+- Add more override points as requested
+
+---
+
+## 8. Documentation Requirements
+
+### 8.1 Developer Guide
+
+**File:** `docs/component-overrides.md`
+
+**Sections:**
+1. Overview and rationale
+2. Available override points (component ID catalog)
+3. Props/emits contracts for each component
+4. Registration API (how to register overrides)
+5. Resolution behavior (order, fallback)
+6. Example: Custom model selector
+7. Example: Custom chat UI
+8. Testing overrides
+9. Troubleshooting
+
+### 8.2 API Reference
+
+**File:** `docs/api/component-override-api.md`
+
+**Sections:**
+1. `registerComponentOverride()`
+2. `unregisterComponentOverride()`
+3. `useComponentOverride()`
+4. `COMPONENT_IDS` constants
+5. Type definitions
+
+---
+
+## 9. Edge Cases & Considerations
+
+### 9.1 Async Component Loading
+
+**Problem:** Override may be async, fallback may be sync  
+**Solution:** Both wrapped in `markRaw()`, Vue handles async resolution
+
+### 9.2 HMR (Hot Module Replacement)
+
+**Problem:** Component registry must survive HMR  
+**Solution:** Use `globalThis` storage pattern (already proven in `_registry.ts`)
+
+### 9.3 SSR vs Client
+
+**Problem:** Some components are client-only  
+**Solution:** Registry is client-only (`.client.ts` plugin), matches existing pattern
+
+### 9.4 Multiple Overrides for Same ID
+
+**Problem:** Two plugins register same override  
+**Solution:** Last registration wins, dev warning emitted (matches existing registry behavior)
+
+### 9.5 Props Incompatibility
+
+**Problem:** Override component has different props  
+**Solution:** TypeScript enforces props via `ComponentPropsMap`, runtime validation optional
+
+### 9.6 Performance Impact
+
+**Problem:** Registry lookup on every render  
+**Solution:** Lookup is O(1) Map access, result can be cached per pane
+
+---
+
+## 10. Alternative Approaches (Considered & Rejected)
+
+### 10.1 Hook-Based Component Rendering
+
+**Approach:** Use `applyFilters('ui.component.resolve', defaultComponent, id)`
+
+**Pros:** Reuses existing hook system  
+**Cons:** 
+- Filters not designed for component resolution
+- No type safety for props/emits
+- No ordering guarantees
+- Harder to debug
+
+**Verdict:** Registry pattern is cleaner for static component replacement
+
+### 10.2 Dynamic Component with Slot Props
+
+**Approach:** Use `<component :is="resolved">` with scoped slots
+
+**Pros:** More flexible rendering  
+**Cons:**
+- Slot API is harder to document
+- Breaks existing component contracts
+- More refactoring required
+
+**Verdict:** Direct component replacement is simpler
+
+### 10.3 Wrapper Components
+
+**Approach:** Create `<OverridableModelSelect>` wrapper for each component
+
+**Pros:** Explicit override points  
+**Cons:**
+- Duplicates every overridable component
+- Import path changes required
+- More boilerplate
+
+**Verdict:** Composable pattern is more idiomatic
+
+---
+
+## 11. Risk Assessment
+
+### 11.1 Low Risk
+
+- **Registry pattern** - Already proven in production
+- **TypeScript safety** - Strong types prevent prop mismatches
+- **Backward compatibility** - All fallbacks to existing components
+- **Testing** - Can be thoroughly unit/integration tested
+
+### 11.2 Medium Risk
+
+- **Component contract drift** - Original components may add props/emits
+  - **Mitigation:** Maintain explicit `ComponentPropsMap`, update docs
+- **Performance** - Registry lookup on every pane render
+  - **Mitigation:** Cache resolved components per pane instance
+
+### 11.3 High Risk
+
+- **None identified** - Pattern is conservative and well-tested
+
+---
+
+## 12. Recommended Next Steps
+
+### 12.1 Immediate Actions (Research Complete)
+
+1. ✅ Reviewed existing extension mechanisms
+2. ✅ Identified high-value override candidates
+3. ✅ Designed architecture with existing patterns
+4. ✅ Documented implementation plan
+5. ⏭️ **Get stakeholder approval on scope**
+
+### 12.2 Implementation Phase 1 (Week 1)
+
+1. Create `app/core/components/registry.ts`
+2. Create `app/composables/core/useComponentOverride.ts`
+3. Create `app/types/component-override.ts`
+4. Write unit tests
+5. Integrate into PageShell.vue (ChatContainer only for validation)
+6. Write integration test
+
+### 12.3 Implementation Phase 2 (Week 1-2)
+
+1. Integrate remaining high-value components:
+   - ModelSelect (ChatInputDropper, ChatSettingsPopover)
+   - DocumentEditor (PageShell)
+   - PromptEditor (if pane-based)
+   - ModelCatalog (modal system)
+2. Update integration tests
+3. Write documentation
+
+### 12.4 Release (Week 2-3)
+
+1. Announce feature in release notes
+2. Publish developer guide
+3. Create example plugin demonstrating override
+4. Gather community feedback
+
+---
+
+## 13. Example: Custom Model Selector Plugin
+
+**File:** `plugins/custom-model-select/index.ts`
+
+```typescript
+import { defineNuxtPlugin } from '#app';
+import { registerComponentOverride } from '~/composables/core/useComponentOverride';
+import { COMPONENT_IDS } from '~/types/component-override';
+
+export default defineNuxtPlugin(() => {
+    // Register custom model selector
+    registerComponentOverride({
+        id: COMPONENT_IDS.MODEL_SELECT,
+        component: () => import('./CustomModelSelect.vue'),
+        order: 10,
+        displayName: 'Custom Model Selector (Org-Specific)',
+    });
+});
+```
+
+**File:** `plugins/custom-model-select/CustomModelSelect.vue`
+
+```vue
+<template>
+    <div class="custom-model-select">
+        <!-- Custom UI here, must accept same props -->
+        <select v-model="internalModel" @change="onChange">
+            <option v-for="m in orgModels" :key="m" :value="m">
+                {{ m }}
+            </option>
+        </select>
+    </div>
+</template>
+
+<script setup lang="ts">
+import { ref, watch } from 'vue';
+
+// Props contract matches original ModelSelect
+const props = defineProps<{
+    model?: string;
+    loading?: boolean;
+}>();
+
+const emit = defineEmits<{
+    (e: 'update:model', value: string): void;
+    (e: 'change', value: string): void;
+}>();
+
+const internalModel = ref(props.model || '');
+
+// Org-specific model list
+const orgModels = [
+    'gpt-4-turbo',
+    'claude-3-opus',
+    'org-custom-model',
+];
+
+function onChange() {
+    emit('update:model', internalModel.value);
+    emit('change', internalModel.value);
+}
+
+watch(() => props.model, (newVal) => {
+    if (newVal !== undefined) internalModel.value = newVal;
+});
+</script>
+```
+
+---
+
+## 14. Effort Estimation
+
+### 14.1 Development Time
+
+| Task | Estimated Hours | Notes |
+|------|----------------|-------|
+| Registry implementation | 2-3 | Reuses `_registry.ts` pattern |
+| Composable implementation | 2-3 | Simple resolution logic |
+| Type definitions | 1-2 | Props mapping, constants |
+| Unit tests | 2-3 | Registry + composable tests |
+| Integration (PageShell) | 1-2 | Small refactor |
+| Integration (other components) | 2-3 | ModelSelect in 2 locations |
+| Integration tests | 2-3 | Pane rendering tests |
+| Documentation | 3-4 | Developer guide + API reference |
+| **Total** | **15-23 hours** | **~2-3 days for one dev** |
+
+### 14.2 Testing Time
+
+| Task | Estimated Hours |
+|------|----------------|
+| Manual QA | 2-3 |
+| Edge case testing | 1-2 |
+| HMR validation | 1 |
+| **Total** | **4-6 hours** |
+
+### 14.3 Grand Total
+
+**20-29 hours (2.5-4 days)** for full implementation, testing, and documentation.
+
+---
+
+## 15. Success Metrics
+
+### 15.1 Technical Metrics
+
+- ✅ Zero breaking changes to existing components
+- ✅ Zero performance regression (< 1ms overhead per pane render)
+- ✅ 100% type safety for override contracts
+- ✅ 100% test coverage for registry + composable
+
+### 15.2 Developer Experience Metrics
+
+- ✅ Plugin authors can override components in < 20 LOC
+- ✅ Clear error messages when props mismatch
+- ✅ Dev warnings for duplicate registrations
+- ✅ Documentation includes working examples
+
+### 15.3 Adoption Metrics (Post-Release)
+
+- Track number of plugins using component overrides
+- Track GitHub issues related to override API
+- Track community feedback on docs clarity
+
+---
+
+## 16. Conclusion
+
+**Feasibility:** High  
+**Value:** High (enables custom UIs without forking core)  
+**Risk:** Low (pattern is proven, changes are minimal)  
+**Effort:** Moderate (2-4 days)
+
+**Recommendation:** ✅ Proceed with implementation
+
+The codebase is well-positioned for component overrides. The existing registry pattern, hook system, and pane app architecture provide excellent foundations. Implementation is straightforward and low-risk.
+
+**Next Step:** Get stakeholder approval on scope (which components to prioritize) and proceed with Phase 1 implementation.
+
+---
+
+## Appendix A: Component Priority Matrix
+
+| Component | Value | Complexity | Effort (hrs) | Priority |
+|-----------|-------|------------|--------------|----------|
+| ModelSelect | High | Low | 2-3 | **P0** |
+| ModelCatalog | High | Medium | 3-4 | **P0** |
+| ChatContainer | High | Very High | 4-6 | P1 |
+| DocumentEditor | Medium | High | 3-4 | P1 |
+| PromptEditor | Medium | Medium | 2-3 | P1 |
+| SystemPromptsModal | Low | Low | 1-2 | P2 |
+| DashboardThemeSelector | Low | Low | 1-2 | P2 |
+
+**Recommendation:** Start with P0 components (ModelSelect, ModelCatalog) for Phase 1.
+
+---
+
+## Appendix B: Files to Create/Modify
+
+### New Files (4)
+
+1. `app/core/components/registry.ts` (80 LOC)
+2. `app/composables/core/useComponentOverride.ts` (120 LOC)
+3. `app/types/component-override.ts` (40 LOC)
+4. `app/plugins/00-component-registry.client.ts` (30 LOC)
+
+### Modified Files (3)
+
+1. `app/components/PageShell.vue` (~20 LOC changes)
+2. `app/components/chat/ChatInputDropper.vue` (~10 LOC changes)
+3. `app/components/chat/ChatSettingsPopover.vue` (~10 LOC changes)
+
+### Test Files (2)
+
+1. `app/composables/core/__tests__/useComponentOverride.test.ts` (150 LOC)
+2. `app/components/__tests__/ComponentOverride.integration.test.ts` (100 LOC)
+
+### Documentation (2)
+
+1. `docs/component-overrides.md` (500 LOC)
+2. `docs/api/component-override-api.md` (200 LOC)
+
+**Total New/Modified Files:** 11  
+**Total LOC:** ~1,260 LOC (including tests + docs)  
+**Core Implementation LOC:** ~360 LOC
+
+---
+
+**End of Report**