docs: comprehensive documentation - README, specs, architecture, API reference, UI/UX flow, dev guide

README.md

@@ -1,36 +1,148 @@
-This is a [Next.js](https://nextjs.org) project bootstrapped with [`create-next-app`](https://nextjs.org/docs/app/api-reference/cli/create-next-app).
+# ComparAIson
 
-## Getting Started
+**AI-Powered Deep Research Comparison Platform**
 
-First, run the development server:
+Compare anything with intelligent, multi-dimensional analysis. ComparAIson uses LLM-powered research to generate comprehensive, visual comparisons — then saves them as shareable posts on your profile.
+
+## Features
+
+- **Deep Research Engine** — Multi-provider LLM pipeline (Tavily search → Perplexity/OpenAI synthesis) with automatic fallback
+- **Interactive Visualizations** — Radar charts, grouped bar charts, feature comparison tables, score cards, pros/cons breakdowns
+- **Real-Time Streaming** — Watch research progress live via Server-Sent Events
+- **User Profiles** — Save comparisons to your profile, browse a public feed
+- **Self-Hosted** — Docker Compose deployment, runs on a Raspberry Pi
+
+## Tech Stack
+
+| Layer | Technology |
+|---|---|
+| Framework | Next.js 15 (App Router, Server Components, Server Actions) |
+| Language | TypeScript |
+| Database | PostgreSQL 16 |
+| ORM | Drizzle ORM |
+| Auth | Better Auth (email + password) |
+| UI | Tailwind CSS + shadcn/ui |
+| Charts | Recharts |
+| LLM | OpenAI GPT-4o-mini + Tavily Search + Perplexity Sonar |
+| Deployment | Docker Compose + Traefik reverse proxy |
+
+## Quick Start
+
+### Prerequisites
+
+- Node.js 20+
+- PostgreSQL 16+ (or Docker)
+- At least one LLM API key
+
+### 1. Clone & Install
+
+```bash
+git clone https://gitea.tophermayor.com/TopherMayor/comparaison.git
+cd comparaison
+npm install
+```
+
+### 2. Configure Environment
+
+```bash
+cp .env.example .env.local
+# Edit .env.local with your API keys and database URL
+```
+
+Required environment variables:
+
+| Variable | Description | Required |
+|---|---|---|
+| `DATABASE_URL` | PostgreSQL connection string | Yes |
+| `BETTER_AUTH_SECRET` | Random secret for session signing | Yes |
+| `OPENAI_API_KEY` | OpenAI API key (GPT-4o-mini) | Yes* |
+| `TAVILY_API_KEY` | Tavily search API key | Recommended |
+| `PERPLEXITY_API_KEY` | Perplexity Sonar API key | Optional |
+| `NEXT_PUBLIC_APP_URL` | Public URL of the app | Yes |
+
+*At minimum, one LLM provider key is required. OpenAI works standalone; Tavily adds web search; Perplexity adds cheaper synthesis.
+
+### 3. Database Setup
+
+```bash
+# Generate migration
+npx drizzle-kit generate
+
+# Run migration
+npx drizzle-kit migrate
+```
+
+### 4. Development
 
 ```bash
 npm run dev
-# or
+# App runs at http://localhost:3000
-yarn dev
-# or
-pnpm dev
-# or
-bun dev
 ```
 
-Open [http://localhost:3000](http://localhost:3000) with your browser to see the result.
+### 5. Docker Deployment
 
-You can start editing the page by modifying `app/page.tsx`. The page auto-updates as you edit the file.
+```bash
+docker compose up -d
+```
 
-This project uses [`next/font`](https://nextjs.org/docs/app/building-your-application/optimizing/fonts) to automatically optimize and load [Geist](https://vercel.com/font), a new font family for Vercel.
+## Project Structure
 
-## Learn More
+```
+src/
+├── app/
+│   ├── (auth)/              # Auth route group
+│   │   ├── sign-in/         # Sign in page
+│   │   └── sign-up/         # Sign up page
+│   ├── (main)/              # Main app route group (with nav)
+│   │   ├── compare/         # Comparison input + results
+│   │   ├── explore/         # Public comparisons feed
+│   │   └── profile/         # User profile + saved comparisons
+│   ├── api/
+│   │   ├── auth/[...all]/   # Better Auth catch-all
+│   │   └── compare/         # SSE streaming research endpoint
+│   ├── layout.tsx           # Root layout
+│   └── page.tsx             # Landing page
+├── components/
+│   ├── comparison/          # Visualization components
+│   │   ├── radar-chart.tsx
+│   │   ├── bar-chart.tsx
+│   │   ├── comparison-table.tsx
+│   │   ├── score-card.tsx
+│   │   └── pros-cons-card.tsx
+│   └── ui/                  # shadcn/ui components
+├── hooks/
+│   └── use-comparison-stream.ts  # SSE streaming hook
+├── lib/
+│   ├── auth.ts              # Better Auth server config
+│   ├── auth-client.ts       # Better Auth client
+│   ├── db/
+│   │   ├── index.ts         # Drizzle client
+│   │   └── schema.ts        # Database schema
+│   ├── llm/
+│   │   ├── index.ts         # Research pipeline orchestrator
+│   │   ├── types.ts         # LLM type definitions
+│   │   └── providers/
+│   │       ├── index.ts     # Provider fallback chain
+│   │       ├── openai.ts    # OpenAI GPT-4o-mini provider
+│   │       ├── tavily.ts    # Tavily search provider
+│   │       └── perplexity.ts # Perplexity Sonar provider
+│   ├── types.ts             # Shared type definitions
+│   └── utils.ts             # Utility functions
+└── middleware.ts             # Auth middleware + route protection
+```
 
-To learn more about Next.js, take a look at the following resources:
+## Architecture
 
-- [Next.js Documentation](https://nextjs.org/docs) - learn about Next.js features and API.
+See [docs/architecture.md](docs/architecture.md) for detailed architecture documentation.
-- [Learn Next.js](https://nextjs.org/learn) - an interactive Next.js tutorial.
 
-You can check out [the Next.js GitHub repository](https://github.com/vercel/next.js) - your feedback and contributions are welcome!
+## API Reference
 
-## Deploy on Vercel
+See [docs/api-reference.md](docs/api-reference.md) for endpoint documentation.
 
-The easiest way to deploy your Next.js app is to use the [Vercel Platform](https://vercel.com/new?utm_medium=default-template&filter=next.js&utm_source=create-next-app&utm_campaign=create-next-app-readme) from the creators of Next.js.
+## UI/UX Flow
 
-Check out our [Next.js deployment documentation](https://nextjs.org/docs/app/building-your-application/deploying) for more details.
+See [docs/ui-ux-flow.md](docs/ui-ux-flow.md) for user journey and wireframe descriptions.
+
+## License
+
+MIT

docs/api-reference.md

@@ -0,0 +1,204 @@
+# ComparAIson — API Reference
+
+## Base URL
+
+```
+Development: http://localhost:3000
+Production:  https://comparaison.tophermayor.com
+```
+
+---
+
+## Authentication
+
+All authenticated endpoints use Better Auth session cookies.
+
+### POST `/api/auth/sign-up`
+Create a new account.
+
+**Request:**
+```json
+{
+  "name": "Alex Johnson",
+  "email": "alex@example.com",
+  "password": "securepassword123"
+}
+```
+
+**Response:** `200 OK` — Sets session cookie, returns user object
+
+### POST `/api/auth/sign-in`
+Sign in to existing account.
+
+**Request:**
+```json
+{
+  "email": "alex@example.com",
+  "password": "securepassword123"
+}
+```
+
+**Response:** `200 OK` — Sets session cookie, redirects to callbackUrl
+
+### POST `/api/auth/sign-out`
+Sign out, clears session.
+
+**Response:** `200 OK` — Redirects to `/`
+
+---
+
+## Comparison Endpoints
+
+### POST `/api/compare`
+Start a new comparison research. Returns a Server-Sent Events stream.
+
+**Authentication:** Required
+
+**Request:**
+```json
+{
+  "query": "for modern web development",
+  "items": ["React", "Vue", "Svelte"],
+  "dimensions": ["Performance", "Developer Experience"]
+}
+```
+
+| Field | Type | Required | Description |
+|---|---|---|---|
+| `query` | string | No | Context/focus for the comparison |
+| `items` | string[] | Yes | Items to compare (2-10) |
+| `dimensions` | string[] | No | Optional dimension hints |
+
+**Response:** `200 OK` — `text/event-stream`
+
+SSE event format:
+```
+event: progress
+data: {"status":"researching","message":"Analyzing comparison request...","itemsCompleted":0,"totalItems":3,"currentStep":"Analyzing comparison request..."}
+
+event: progress
+data: {"status":"researching","message":"Researching React...","itemsCompleted":1,"totalItems":3,"currentStep":"Analyzing React"}
+
+event: progress
+data: {"status":"completed","message":"Research complete!","itemsCompleted":3,"totalItems":3,"currentStep":"Done"}
+
+event: done
+data: {"id":"clx123abc","slug":"react-vs-vue-vs-svelte-clx123","data":{...full comparison data...}}
+```
+
+**Error Response:** `400 Bad Request`
+```json
+{ "error": "At least 2 items are required" }
+```
+
+---
+
+## Page Routes
+
+### `GET /`
+Landing page. Public. Shows hero, example comparisons, features.
+
+### `GET /sign-in`
+Sign in form. Public. Redirects to `/compare` on success.
+
+### `GET /sign-up`
+Sign up form. Public. Redirects to `/compare` on success.
+
+### `GET /compare`
+Comparison creation page. **Protected.** Shows item input form + streaming progress.
+
+### `GET /compare/[slug]`
+Comparison results page. Public (if comparison is public). Shows tabbed visualization layout.
+
+**URL format:** `/compare/react-vs-vue-vs-svelte-clx123a`
+
+### `GET /explore`
+Public comparisons feed. Public. Grid layout with search + category filter.
+
+### `GET /profile`
+User profile page. **Protected.** Shows user info, stats, and saved comparisons.
+
+---
+
+## TypeScript Types
+
+### ComparisonRequest
+```typescript
+interface ComparisonRequest {
+  query: string;
+  items: string[];
+  dimensions?: string[];
+}
+```
+
+### ComparisonResult
+```typescript
+interface ComparisonResult {
+  items: ItemResearch[];
+  dimensions: string[];
+  summary: string;
+  recommendation: string;
+}
+```
+
+### ItemResearch
+```typescript
+interface ItemResearch {
+  name: string;
+  description: string;
+  overallScore: number;
+  dimensions: Record<string, DimensionResult>;
+  pros: string[];
+  cons: string[];
+  sources: { title: string; url: string; snippet: string }[];
+}
+```
+
+### DimensionResult
+```typescript
+interface DimensionResult {
+  score: number;       // 1-10
+  summary: string;
+  details: string;
+  pros: string[];
+  cons: string[];
+}
+```
+
+### ResearchProgress (SSE)
+```typescript
+type ResearchProgress =
+  | { stage: "parsing"; message: string }
+  | { stage: "searching"; item: string; results: number }
+  | { stage: "researching"; item: string; progress: number }
+  | { stage: "synthesizing"; message: string }
+  | { stage: "complete"; result: ComparisonResult }
+  | { stage: "error"; error: string };
+```
+
+### ComparisonData (Frontend)
+```typescript
+interface ComparisonData {
+  id: string;
+  userId: string;
+  title: string;
+  query: string;
+  slug: string;
+  status: "researching" | "completed" | "failed";
+  summary: string;
+  items: {
+    name: string;
+    description: string;
+    overallScore: number;
+    dimensions: Record<string, DimensionResult>;
+    pros: string[];
+    cons: string[];
+  }[];
+  dimensions: string[];
+  tags: string[];
+  isPublic: boolean;
+  viewCount: number;
+  createdAt: string;
+  updatedAt: string;
+}
+```

docs/architecture.md

@@ -0,0 +1,129 @@
+# ComparAIson — Architecture
+
+## System Overview
+
+```
+┌─────────────┐     ┌──────────────┐     ┌─────────────┐
+│   Browser    │────▶│   Traefik    │────▶│   Next.js   │
+│  (React SPA) │◀────│  (Reverse    │◀────│  (Port 3000)│
+│              │     │   Proxy)     │     │             │
+└─────────────┘     └──────────────┘     └──────┬──────┘
+                                                  │
+                                    ┌─────────────┼─────────────┐
+                                    ▼             ▼             ▼
+                              ┌──────────┐ ┌──────────┐ ┌──────────┐
+                              │PostgreSQL│ │  Tavily  │ │  OpenAI  │
+                              │  (DB)    │ │ (Search) │ │  (LLM)   │
+                              └──────────┘ └──────────┘ └──────────┘
+                                                        ┌──────────┐
+                                                        │Perplexity│
+                                                        │ (LLM)    │
+                                                        └──────────┘
+```
+
+## Component Architecture
+
+### Frontend (Next.js App Router)
+
+```
+Route Groups:
+├── (auth)/          — Unauthenticated pages (sign-in, sign-up)
+├── (main)/          — Authenticated pages with shared nav layout
+│   ├── compare/     — Comparison creation + results viewing
+│   ├── explore/     — Public feed browsing
+│   └── profile/     — User profile + comparison history
+└── api/             — Server-side API routes
+    ├── auth/        — Better Auth endpoints
+    └── compare/     — SSE research streaming endpoint
+```
+
+**Key patterns:**
+- **Server Components** for data-fetching pages (profile, explore)
+- **Client Components** for interactive UI (compare input, charts, streaming)
+- **Server Actions** for mutations (save comparison, update profile)
+- **SSE streaming** for real-time research progress
+
+### Backend Services
+
+#### Research Pipeline (`src/lib/llm/`)
+Orchestrates the multi-stage research process:
+1. **Input parsing** — Validate items, extract dimensions
+2. **Provider detection** — Check available API keys, select best provider chain
+3. **Web search** — Tavily API searches per item
+4. **LLM synthesis** — Structured JSON generation via Perplexity or OpenAI
+5. **Validation** — Runtime type checking of LLM output
+6. **Persistence** — Store results in PostgreSQL via Drizzle ORM
+
+#### Auth System (`src/lib/auth.ts`)
+- Better Auth with Drizzle adapter
+- Email + password authentication
+- 7-day session expiry
+- Middleware-based route protection
+
+#### Database (`src/lib/db/`)
+- Drizzle ORM with PostgreSQL
+- 5 tables: users, sessions, comparisons, comparison_items, comparison_dimensions
+- JSONB columns for flexible research data storage
+- Indexed on userId, slug, status for query performance
+
+## Data Flow
+
+### Comparison Creation Flow
+
+```
+1. User enters items + query on /compare
+2. Client calls POST /api/compare with { items, query, dimensions }
+3. Server creates comparison record (status: "researching")
+4. Server opens SSE stream to client
+5. Research pipeline runs:
+   a. Parsing → emits SSE "parsing" event
+   b. For each item:
+      - Tavily search → emits SSE "searching" event
+      - Process results → emits SSE "researching" event with progress %
+   c. Synthesize all data → emits SSE "synthesizing" event
+   d. Validate + structure → emits SSE "complete" event with full data
+6. Server persists results to comparisons + comparison_items tables
+7. Client renders visualization components with result data
+8. User redirected to /compare/[slug] with full results
+```
+
+### Comparison Viewing Flow
+
+```
+1. User navigates to /compare/[slug]
+2. Server component fetches comparison from DB by slug
+3. If status === "researching": show streaming progress UI
+4. If status === "completed": render full results with all viz components
+5. If status === "failed": show error with retry option
+6. Increment viewCount on each visit
+```
+
+## Deployment Architecture
+
+### Docker Compose
+
+```yaml
+services:
+  app:        # Next.js standalone (~150-300MB RAM)
+  db:         # PostgreSQL 16 Alpine (~200-400MB RAM)
+```
+
+Total estimated RAM: **400-800MB** — fits comfortably on an 8GB Raspberry Pi.
+
+### Traefik Integration
+
+The app is exposed via Traefik reverse proxy with:
+- HTTPS termination
+- Domain routing (e.g., `comparaison.tophermayor.com`)
+- Automatic SSL certificate management
+
+## Error Handling
+
+| Layer | Strategy |
+|---|---|
+| LLM API failures | 3x retry with exponential backoff |
+| Provider unavailable | Automatic fallback to next provider in chain |
+| Invalid LLM output | Runtime validation + retry with new prompt |
+| Database errors | Transaction rollback, error logged, user sees "failed" status |
+| SSE connection lost | Client auto-reconnects, polls comparison status from DB |
+| Auth failures | Redirect to sign-in with callback URL |

docs/development.md

@@ -0,0 +1,86 @@
+# ComparAIson — Development Guide
+
+## Getting Started
+
+```bash
+# Clone
+git clone https://gitea.tophermayor.com/TopherMayor/comparaison.git
+cd comparaison
+
+# Install
+npm install
+
+# Environment
+cp .env.example .env.local
+# Edit .env.local with your keys
+
+# Database
+docker compose up db -d  # Start just PostgreSQL
+npx drizzle-kit generate  # Generate migrations
+npx drizzle-kit migrate   # Apply migrations
+
+# Dev server
+npm run dev
+```
+
+## Commands
+
+| Command | Description |
+|---|---|
+| `npm run dev` | Start dev server (port 3000) |
+| `npm run build` | Production build (standalone output) |
+| `npm run start` | Start production server |
+| `npm run lint` | ESLint check |
+| `npx tsc --noEmit` | Type check without building |
+| `npx drizzle-kit generate` | Generate DB migrations from schema |
+| `npx drizzle-kit migrate` | Apply migrations to database |
+| `npx drizzle-kit studio` | Open Drizzle Studio (DB browser) |
+
+## Branch Strategy
+
+| Branch | Purpose |
+|---|---|
+| `main` | Stable, deployable code |
+| `feat/backend` | DB schema, auth, Docker, config changes |
+| `feat/llm-engine` | LLM provider changes, research pipeline |
+| `feat/frontend` | UI components, pages, layouts |
+
+Worktrees are used for parallel development:
+```bash
+git worktree add ../comparaison-backend -b feat/backend main
+```
+
+## Database Schema Changes
+
+1. Edit `src/lib/db/schema.ts`
+2. Run `npx drizzle-kit generate` to create migration SQL
+3. Run `npx drizzle-kit migrate` to apply
+4. Commit both schema.ts and the generated SQL in `drizzle/`
+
+## Adding a New LLM Provider
+
+1. Create `src/lib/llm/providers/your-provider.ts`
+2. Implement the provider function matching the `Provider` interface:
+   ```typescript
+   export async function synthesize(
+     request: ComparisonRequest,
+     searchResults: Record<string, SearchResult[]>
+   ): Promise<ComparisonResult>
+   ```
+3. Register in `src/lib/llm/providers/index.ts` — add to the fallback chain
+4. Add API key to `.env.example` and document in README
+
+## Adding a New Visualization
+
+1. Create `src/components/comparison/your-chart.tsx`
+2. Accept `ComparisonData` as props (or relevant subset)
+3. Use Recharts for chart components
+4. Import and add to the tab layout in `results-client.tsx`
+
+## Key Conventions
+
+- **Server Components** by default, `"use client"` only when needed (hooks, interactivity)
+- **Drizzle ORM** for all database queries — no raw SQL
+- **shadcn/ui** for UI components — no external component libraries
+- **Tailwind** for styling — no CSS modules or styled-components
+- **TypeScript strict mode** — no `any` types

docs/specs.md

@@ -0,0 +1,163 @@
+# ComparAIson — Product Specification
+
+## 1. Product Overview
+
+**ComparAIson** is a self-hosted web application that enables users to compare two or more items using AI-powered deep research. The system performs multi-source research, generates structured comparison data, and presents results through interactive visualizations. Completed comparisons are saved as posts on user profiles, creating a browsable library of research.
+
+## 2. Problem Statement
+
+Comparing products, technologies, or services requires gathering data from multiple sources, synthesizing findings, and presenting them clearly. This is time-consuming and often produces inconsistent results. ComparAIson automates this process with LLM-powered research that produces structured, visual, and comparable outputs.
+
+## 3. Target Users
+
+- **Developers** comparing frameworks, tools, cloud services
+- **Consumers** comparing products before purchase
+- **Researchers** comparing methodologies, papers, or approaches
+- **Teams** evaluating options for technical decisions
+
+## 4. Core Features
+
+### 4.1 AI Research Engine
+- Multi-item comparison (2-10 items)
+- Multi-dimensional scoring (5-8 dimensions per comparison)
+- Web search integration via Tavily API
+- LLM synthesis via OpenAI GPT-4o-mini or Perplexity Sonar
+- Automatic provider fallback chain
+- Structured JSON output with validation
+- Server-Sent Events for real-time progress
+
+### 4.2 Interactive Visualizations
+- **Radar/Spider Chart** — Multi-dimensional overlay showing all items
+- **Grouped Bar Chart** — Side-by-side metric comparison
+- **Comparison Table** — Feature matrix with color-coded cells
+- **Score Cards** — Animated progress bars with overall + per-dimension scores
+- **Pros/Cons Cards** — Expandable per-item breakdown
+
+### 4.3 User System
+- Email + password authentication (Better Auth)
+- Session management (7-day expiry)
+- Protected routes for compare/profile actions
+- Public profile pages with comparison history
+
+### 4.4 Social/Feed Features
+- Public comparisons feed (Explore page)
+- Per-comparison view count tracking
+- Tag-based categorization and filtering
+- Search across public comparisons
+- Shareable URLs for each comparison
+
+## 5. Technical Constraints
+
+| Constraint | Value |
+|---|---|
+| Deployment target | Raspberry Pi ARM64, 8GB RAM |
+| Concurrent users | Low (homelab, <20) |
+| Total RAM budget | ~500MB-1GB (app + DB + reverse proxy) |
+| Cost target | Minimal (free tier APIs where possible) |
+| Network | Behind Traefik reverse proxy with HTTPS |
+
+## 6. Data Model
+
+### 6.1 Users (Better Auth managed)
+```
+users: id, name, email, emailVerified, image, createdAt, updatedAt
+sessions: id, userId (FK), token, expiresAt, createdAt, updatedAt
+```
+
+### 6.2 Comparisons
+```
+comparisons: id, userId (FK), title, query, slug, status (researching|completed|failed),
+             summary, overallData (JSONB), tags[], isPublic, viewCount, createdAt, updatedAt
+```
+
+### 6.3 Comparison Items
+```
+comparison_items: id, comparisonId (FK), name, description, imageUrl,
+                  researchData (JSONB), scores (JSONB), pros[], cons[], order
+```
+
+### 6.4 Comparison Dimensions
+```
+comparison_dimensions: id, comparisonId (FK), name, description, weight, order
+```
+
+### 6.5 JSONB Schemas
+
+**overallData (on comparisons):**
+```json
+{
+  "title": "React vs Vue vs Svelte",
+  "query": "for modern web development",
+  "status": "completed",
+  "summary": "...",
+  "items": [
+    {
+      "name": "React",
+      "description": "...",
+      "overallScore": 8.5,
+      "dimensions": {
+        "Performance": { "score": 8, "summary": "...", "details": "...", "pros": [], "cons": [] }
+      },
+      "pros": ["..."],
+      "cons": ["..."]
+    }
+  ],
+  "dimensions": ["Performance", "Developer Experience", "Ecosystem", ...]
+}
+```
+
+**researchData (on comparison_items):**
+Full `ItemResearch` object including dimensions, sources, and scores.
+
+## 7. LLM Research Pipeline
+
+### 7.1 Flow
+```
+User submits query
+  → Parse request (validate items ≥ 2)
+  → Detect available providers (Tavily? Perplexity? OpenAI?)
+  → If Tavily available: search each item individually
+  → Synthesize via best available provider:
+      Priority 1: Tavily search + Perplexity synthesis
+      Priority 2: Tavily search + OpenAI synthesis
+      Priority 3: OpenAI only (no web search)
+  → Validate structured JSON output
+  → Persist to database
+  → Stream results to client
+```
+
+### 7.2 Provider Details
+
+| Provider | Role | Model | Cost |
+|---|---|---|---|
+| Tavily | Web search | Search API | ~$0.005/search |
+| Perplexity | Synthesis | Sonar | ~$0.002/query |
+| OpenAI | Synthesis | GPT-4o-mini | ~$0.15/1M tokens |
+
+### 7.3 Progress Stages (SSE)
+1. `parsing` — Validating query and extracting items
+2. `searching` — Running web search for each item (Tavily only)
+3. `researching` — Processing research per item
+4. `synthesizing` — LLM generating structured comparison
+5. `complete` — Final result with all data
+6. `error` — Failure with error message
+
+## 8. Security Considerations
+
+- Auth middleware protects `/compare` and `/profile` routes
+- Session tokens stored in HTTP-only cookies
+- API keys never exposed to client (server-only LLM calls)
+- Input validation on all API endpoints (min 2 items, max 10)
+- SQL injection prevented via Drizzle ORM parameterized queries
+- CSRF protection via Better Auth
+- Rate limiting placeholder in compare API route
+
+## 9. Future Considerations
+
+- [ ] OAuth providers (Google, GitHub)
+- [ ] Comparison comments/likes
+- [ ] Export to PDF/image
+- [ ] Embeddable comparison widgets
+- [ ] Comparison templates
+- [ ] Batch comparison queue for heavy loads
+- [ ] Local Ollama fallback for offline operation

docs/ui-ux-flow.md

@@ -0,0 +1,343 @@
+# ComparAIson — UI/UX Flow
+
+## User Journeys
+
+### Journey 1: New User Discovers → Signs Up → First Comparison
+
+```
+Landing Page (/)
+    │
+    ▼ "Start Comparing" CTA or /compare URL
+Sign In Page (/sign-in)
+    │ ─── "Don't have an account? Sign up"
+    ▼
+Sign Up Page (/sign-up)
+    │ User enters: name, email, password
+    │ On success → redirect to /compare
+    ▼
+Compare Page (/compare)
+    │ User enters items (2-10) + query
+    │ Clicks "Start Research"
+    ▼
+Streaming Progress
+    │ Progress bar + current step label
+    │ Steps: "Analyzing..." → "Searching React..." → "Synthesizing..."
+    ▼
+Results Page (/compare/[slug])
+    │ Tab layout: Overview | Charts | Table | Details
+    │ User explores visualizations
+    │ Comparison auto-saved to profile
+    ▼
+Profile Page (/profile)
+    │ Sees their first comparison in the grid
+    └── Can click to view again
+```
+
+### Journey 2: Returning User Quick Compare
+
+```
+Home (/) → already logged in
+    │
+    ▼ Click "Compare" in nav
+Compare Page (/compare)
+    │ Enter items + query → "Start Research"
+    ▼
+Results Page (/compare/[slug])
+    │ Review results, share URL
+    └── Return to profile or start new compare
+```
+
+### Journey 3: Anonymous User Browses Public Comparisons
+
+```
+Landing Page (/)
+    │
+    ▼ "Explore" in nav or example comparison card
+Explore Page (/explore)
+    │ Grid of public comparisons
+    │ Filter by category tags
+    │ Search by keyword
+    ▼ Click a comparison card
+Results Page (/compare/[slug])
+    │ View full results (read-only)
+    │ "Start Your Own Comparison" CTA if not logged in
+    └── Sign up flow from Journey 1
+```
+
+---
+
+## Page Descriptions
+
+### 1. Landing Page (`/`)
+**Purpose:** First impression, explain the product, drive sign-ups
+
+**Layout:**
+```
+┌─────────────────────────────────────────────┐
+│  Header: Logo "ComparAIson" | [Sign In]     │
+├─────────────────────────────────────────────┤
+│                                             │
+│     ✨ AI-Powered Research                  │
+│                                             │
+│  Compare Anything with                      │
+│  AI-Powered Deep Research                   │
+│                                             │
+│  [🚀 Start Comparing]  [Explore Examples]   │
+│                                             │
+├─────────────────────────────────────────────┤
+│  Example Comparisons (2x2 grid)             │
+│  ┌──────────────┐  ┌──────────────┐         │
+│  │ React vs Vue │  │ GPT-4 vs     │         │
+│  │ vs Svelte    │  │ Claude vs    │         │
+│  │ ⭐ 8.5       │  │ Gemini ⭐ 8.8│         │
+│  └──────────────┘  └──────────────┘         │
+│  ┌──────────────┐  ┌──────────────┐         │
+│  │ Notion vs    │  │ AWS vs GCP   │         │
+│  │ Obsidian     │  │ vs Azure     │         │
+│  └──────────────┘  └──────────────┘         │
+├─────────────────────────────────────────────┤
+│  Features (3 columns)                       │
+│  📊 Rich Viz  🔍 Deep Research  🔗 Share   │
+├─────────────────────────────────────────────┤
+│  Footer                                     │
+└─────────────────────────────────────────────┘
+```
+
+### 2. Sign In Page (`/sign-in`)
+**Purpose:** Authenticate existing users
+
+**Layout:**
+```
+Centered card, max-w-md:
+┌─────────────────────────────┐
+│     Sign In                  │
+│     Welcome back             │
+│                              │
+│  Email    [______________]   │
+│  Password [______________]   │
+│                              │
+│  [    Sign In    ]           │
+│                              │
+│  Don't have an account?      │
+│  [Sign Up]                   │
+└─────────────────────────────┘
+```
+
+- Error state: Red text below form on invalid credentials
+- Loading state: Spinner on button, disabled inputs
+- Success: Redirect to callbackUrl or /compare
+
+### 3. Sign Up Page (`/sign-up`)
+**Purpose:** Register new users
+
+**Layout:** Same as sign in but with Name field added
+```
+Name     [______________]
+Email    [______________]
+Password [______________]
+[    Create Account    ]
+Already have an account? [Sign In]
+```
+
+### 4. Compare Page (`/compare`)
+**Purpose:** Main comparison creation interface
+
+**Layout:**
+```
+Centered card, max-w-2xl:
+┌─────────────────────────────────────────┐
+│  ✨ Start a Comparison                  │
+│  Enter items to compare and let AI      │
+│  do deep research for you.              │
+│                                          │
+│  What would you like to compare?         │
+│  [________________________________]      │
+│  (textarea for natural language query)   │
+│                                          │
+│  Items to compare (min 2, max 10)        │
+│  [React ×] [Vue ×] [Svelte ×] [+ Add]  │
+│  [________________________] [Add]        │
+│                                          │
+│  Comparison dimensions (optional)        │
+│  [________________________________]      │
+│  (comma-separated hints)                 │
+│                                          │
+│  [🚀 Start Research]                     │
+│                                          │
+│  ┌─ Progress (shown during research) ──┐ │
+│  │ [████████████░░░░░░░] 60%           │ │
+│  │ 🔍 Researching Svelte...            │ │
+│  └─────────────────────────────────────┘ │
+└─────────────────────────────────────────┘
+```
+
+**Interactions:**
+- Tag-style item input: type + Enter to add, X to remove
+- Minimum 2 items required to start
+- Progress bar appears after "Start Research" clicked
+- Cancel button during research
+- Auto-redirect to results on completion
+
+### 5. Results Page (`/compare/[slug]`)
+**Purpose:** Display completed comparison with visualizations
+
+**Layout:**
+```
+┌─────────────────────────────────────────────────┐
+│ ← Back    React vs Vue vs Svelte    [Share]     │
+│ Overall: React ⭐ 8.5 | Vue ⭐ 7.8 | Svelte ⭐ 8.2│
+├─────────────────────────────────────────────────┤
+│ [Overview] [Charts] [Table] [Details]           │
+├─────────────────────────────────────────────────┤
+│                                                  │
+│  ┌── Overview Tab ─────────────────────────────┐ │
+│  │                                              │ │
+│  │  Summary text from AI                        │ │
+│  │  "React excels in ecosystem size..."         │ │
+│  │                                              │ │
+│  │  ┌─ Score Cards ────────────────────────┐   │ │
+│  │  │ React: ⭐ 8.5                        │   │ │
+│  │  │ [█████████░] Performance: 8/10       │   │ │
+│  │  │ [████████░░] DX: 9/10               │   │ │
+│  │  │ ...                                  │   │ │
+│  │  └──────────────────────────────────────┘   │ │
+│  │                                              │ │
+│  │  🏆 Recommendation: "For most projects..."  │ │
+│  └──────────────────────────────────────────────┘ │
+│                                                  │
+│  ┌── Charts Tab ──────────────────────────────┐  │
+│  │                                              │  │
+│  │  Radar Chart          Bar Chart              │  │
+│  │  ┌─────────────┐     ┌──────────────┐       │  │
+│  │  │  ╱  React ╲  │     │ ▓ ▓ ▓        │       │  │
+│  │  │ │  Vue   │  │     │ ▓ ▓ ▓        │       │  │
+│  │  │  ╲Svelte╱   │     │ ▓ ▓ ▓        │       │  │
+│  │  └─────────────┘     └──────────────┘       │  │
+│  │                                              │  │
+│  └──────────────────────────────────────────────┘ │
+│                                                  │
+│  ┌── Table Tab ───────────────────────────────┐  │
+│  │            │ React │ Vue  │ Svelte │        │  │
+│  │ Performance│  8    │  7   │   9    │        │  │
+│  │ DX         │  9    │  8   │   8    │        │  │
+│  │ Ecosystem  │  10   │  7   │   6    │        │  │
+│  │ Price      │  9    │  9   │   10   │        │  │
+│  └──────────────────────────────────────────────┘  │
+│                                                    │
+│  ┌── Details Tab ─────────────────────────────┐   │
+│  │ Per-item expandable deep dives              │   │
+│  │ ▶ React - Performance (8/10)                │   │
+│  │   Pros: Virtual DOM, concurrent mode...     │   │
+│  │   Cons: Bundle size can grow...             │   │
+│  │ ▶ Vue - Performance (7/10)                  │   │
+│  │ ...                                          │   │
+│  └──────────────────────────────────────────────┘   │
+└─────────────────────────────────────────────────────┘
+```
+
+**Interactions:**
+- Tab switching between Overview/Charts/Table/Details
+- Hover tooltips on all charts
+- Click legend items to toggle visibility on radar/bar charts
+- Expandable rows in table for detailed breakdowns
+- Share button copies URL to clipboard
+- Trophy icon highlights the winner
+
+### 6. Profile Page (`/profile`)
+**Purpose:** User's personal comparison library
+
+**Layout:**
+```
+┌─────────────────────────────────────────────┐
+│  [Avatar]  Alex Johnson                     │
+│            alex@example.com                  │
+│                                             │
+│  ┌─ Stats ─────────┐  ┌─ Stats ──────────┐ │
+│  │ 12               │  │ 8.2K              │ │
+│  │ Total Comparisons│  │ Total Views       │ │
+│  └──────────────────┘  └───────────────────┘ │
+│                                             │
+│  My Comparisons                             │
+│  ┌──────────────┐  ┌──────────────┐         │
+│  │ React vs Vue │  │ GPT-4 vs     │         │
+│  │ vs Svelte    │  │ Claude       │         │
+│  │ ⭐ 8.5 | 👁 1.2K│  │ ⭐ 8.8 | 👁 3.9K│   │
+│  │ Jan 15, 2024 │  │ Jan 10, 2024 │        │
+│  └──────────────┘  └──────────────┘         │
+│                                             │
+│  [+ New Comparison]                         │
+└─────────────────────────────────────────────┘
+```
+
+### 7. Explore Page (`/explore`)
+**Purpose:** Browse public comparisons from all users
+
+**Layout:**
+```
+┌─────────────────────────────────────────────────┐
+│  Explore Comparisons                             │
+│  [🔍 Search comparisons...]                     │
+│                                                  │
+│  [All] [Tech] [Products] [AI] [Cloud] [Prod.]   │
+│                                                  │
+│  ┌─────────┐ ┌─────────┐ ┌─────────┐           │
+│  │React vs │ │GPT-4 vs │ │iPhone vs│           │
+│  │Vue vs   │ │Claude vs │ │Samsung  │           │
+│  │Svelte   │ │Gemini   │ │S24 Ultra│           │
+│  │⭐8.5 👁1.2K│ │⭐8.8 👁3.9K│ │⭐8.2 👁3.4K│    │
+│  │by Alex  │ │by Sarah │ │by James │           │
+│  └─────────┘ └─────────┘ └─────────┘           │
+│  ┌─────────┐ ┌─────────┐ ┌─────────┐           │
+│  │AWS vs   │ │Python vs│ │Notion vs│           │
+│  │GCP vs   │ │Rust vs  │ │Obsidian │           │
+│  │Azure    │ │Go       │ │vs Roam  │           │
+│  │⭐9.0 👁2.2K│ │⭐8.4 👁1.9K│ │⭐7.5 👁892 │    │
+│  │by Emma  │ │by Anna  │ │by Mike  │           │
+│  └─────────┘ └─────────┘ └─────────┘           │
+│                                                  │
+│  [Load More]                                     │
+└─────────────────────────────────────────────────┘
+```
+
+---
+
+## Responsive Design
+
+### Desktop (≥768px)
+- Sidebar navigation on the left
+- Full-width comparison tables
+- Side-by-side charts on Charts tab
+- 3-column grid on Explore page
+
+### Mobile (<768px)
+- Bottom navigation bar (fixed)
+- Stacked charts (full width each)
+- Single column cards on Explore
+- Collapsible navigation menu
+
+---
+
+## Loading & Error States
+
+### Research Progress
+```
+┌─ Research in Progress ──────────────┐
+│ [████████████░░░░░░░░░] 60%         │
+│ 🔍 Researching Svelte...            │
+│                                      │
+│ Items: React ✓  Vue ✓  Svelte ⟳    │
+│                                      │
+│                [Cancel]              │
+└──────────────────────────────────────┘
+```
+
+### Skeleton Loaders
+- Used on results page while data loads
+- Shimmer effect on card placeholders
+- Chart skeleton rectangles
+
+### Error States
+- **API error:** Red banner with error message + "Try Again" button
+- **Auth required:** Redirect to sign-in with callback
+- **Not found:** 404 page with "Browse comparisons" link
+- **Network error:** Toast notification + retry prompt

src/app/(main)/explore/page.tsx

@@ -0,0 +1,216 @@
+"use client"
+
+import { useState } from "react"
+import { Input } from "@/components/ui/input"
+import { Button } from "@/components/ui/button"
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
+import { Badge } from "@/components/ui/badge"
+import { Avatar, AvatarFallback } from "@/components/ui/avatar"
+import { Search, Eye, BarChart3, Filter, X, Loader2 } from "lucide-react"
+import Link from "next/link"
+
+const allComparisons = [
+  {
+    id: "1",
+    title: "React vs Vue vs Svelte",
+    description: "Frontend framework comparison for modern web development",
+    items: ["React", "Vue", "Svelte"],
+    tags: ["Tech", "JavaScript"],
+    author: "Alex Johnson",
+    overallScore: 8.5,
+    views: 1247,
+  },
+  {
+    id: "2",
+    title: "GPT-4 vs Claude vs Gemini",
+    description: "Comparing top AI language models for reasoning tasks",
+    items: ["GPT-4", "Claude 3", "Gemini Pro"],
+    tags: ["AI", "Products"],
+    author: "Sarah Chen",
+    overallScore: 8.8,
+    views: 3891,
+  },
+  {
+    id: "3",
+    title: "Notion vs Obsidian vs Roam",
+    description: "Knowledge management tools for productivity",
+    items: ["Notion", "Obsidian", "Roam Research"],
+    tags: ["Productivity", "Tools"],
+    author: "Mike Peters",
+    overallScore: 7.5,
+    views: 892,
+  },
+  {
+    id: "4",
+    title: "AWS vs GCP vs Azure",
+    description: "Cloud platform comparison for enterprise infrastructure",
+    items: ["AWS", "Google Cloud", "Microsoft Azure"],
+    tags: ["Tech", "Cloud"],
+    author: "Emma Wilson",
+    overallScore: 9.0,
+    views: 2156,
+  },
+  {
+    id: "5",
+    title: "iPhone 15 Pro vs Samsung S24 Ultra",
+    description: "Flagship smartphone comparison with camera and performance benchmarks",
+    items: ["iPhone 15 Pro", "Samsung S24 Ultra"],
+    tags: ["Products", "Mobile"],
+    author: "James Lee",
+    overallScore: 8.2,
+    views: 3421,
+  },
+  {
+    id: "6",
+    title: "Python vs Rust vs Go",
+    description: "Systems programming languages compared for performance and productivity",
+    items: ["Python", "Rust", "Go"],
+    tags: ["Tech", "Programming"],
+    author: "Anna Kim",
+    overallScore: 8.4,
+    views: 1873,
+  },
+]
+
+const categories = ["All", "Tech", "Products", "AI", "Cloud", "Productivity"]
+
+export default function ExplorePage() {
+  const [searchQuery, setSearchQuery] = useState("")
+  const [selectedCategory, setSelectedCategory] = useState("All")
+  const [loading, setLoading] = useState(false)
+
+  const filteredComparisons = allComparisons.filter((comparison) => {
+    const matchesSearch =
+      searchQuery === "" ||
+      comparison.title.toLowerCase().includes(searchQuery.toLowerCase()) ||
+      comparison.items.some((item) =>
+        item.toLowerCase().includes(searchQuery.toLowerCase())
+      )
+    const matchesCategory =
+      selectedCategory === "All" ||
+      comparison.tags.some((tag) => tag.toLowerCase() === selectedCategory.toLowerCase())
+    return matchesSearch && matchesCategory
+  })
+
+  return (
+    <div className="max-w-6xl mx-auto p-4 sm:p-6 space-y-6">
+      <div className="space-y-4">
+        <h1 className="text-2xl font-bold">Explore Comparisons</h1>
+
+        <div className="flex flex-col sm:flex-row gap-4">
+          <div className="relative flex-1">
+            <Search className="absolute left-3 top-1/2 -translate-y-1/2 size-4 text-muted-foreground" />
+            <Input
+              type="search"
+              placeholder="Search comparisons..."
+              value={searchQuery}
+              onChange={(e) => setSearchQuery(e.target.value)}
+              className="pl-9"
+            />
+          </div>
+        </div>
+
+        <div className="flex flex-wrap gap-2">
+          {categories.map((category) => (
+            <Button
+              key={category}
+              variant={selectedCategory === category ? "default" : "outline"}
+              size="sm"
+              onClick={() => setSelectedCategory(category)}
+              className="rounded-full"
+            >
+              {category}
+            </Button>
+          ))}
+        </div>
+      </div>
+
+      {loading ? (
+        <div className="flex items-center justify-center py-12">
+          <Loader2 className="size-8 animate-spin text-primary" />
+        </div>
+      ) : filteredComparisons.length > 0 ? (
+        <div className="grid gap-6 sm:grid-cols-2 lg:grid-cols-3">
+          {filteredComparisons.map((comparison) => (
+            <Link key={comparison.id} href={`/compare/${comparison.id}`}>
+              <Card className="h-full transition-all hover:border-primary hover:shadow-md">
+                <CardHeader className="pb-3">
+                  <div className="flex items-start justify-between gap-2">
+                    <CardTitle className="text-base line-clamp-1 flex-1">
+                      {comparison.title}
+                    </CardTitle>
+                  </div>
+                  <CardDescription className="text-sm line-clamp-2">
+                    {comparison.description}
+                  </CardDescription>
+                </CardHeader>
+                <CardContent className="space-y-3">
+                  <div className="flex flex-wrap gap-1.5">
+                    {comparison.tags.map((tag) => (
+                      <Badge key={tag} variant="secondary" className="text-xs">
+                        {tag}
+                      </Badge>
+                    ))}
+                  </div>
+
+                  <div className="flex items-center gap-2 text-sm text-muted-foreground">
+                    <Avatar className="size-6">
+                      <AvatarFallback className="text-[10px]">
+                        {comparison.author.split(" ").map((n) => n[0]).join("")}
+                      </AvatarFallback>
+                    </Avatar>
+                    <span className="text-xs">{comparison.author}</span>
+                  </div>
+
+                  <div className="flex items-center justify-between pt-2 border-t">
+                    <span className="text-sm text-muted-foreground">
+                      {comparison.items.join(" vs ")}
+                    </span>
+                    <div className="flex items-center gap-3 text-sm">
+                      <span className="flex items-center gap-1 text-muted-foreground">
+                        <Eye className="size-3.5" />
+                        {comparison.views.toLocaleString()}
+                      </span>
+                      <span className="font-semibold text-foreground bg-primary/10 px-2 py-0.5 rounded">
+                        {comparison.overallScore}/10
+                      </span>
+                    </div>
+                  </div>
+                </CardContent>
+              </Card>
+            </Link>
+          ))}
+        </div>
+      ) : (
+        <Card className="p-8 text-center">
+          <div className="flex flex-col items-center gap-4">
+            <div className="size-12 rounded-full bg-muted flex items-center justify-center">
+              <Search className="size-6 text-muted-foreground" />
+            </div>
+            <div>
+              <p className="font-medium">No comparisons found</p>
+              <p className="text-sm text-muted-foreground">
+                Try adjusting your search or filters
+              </p>
+            </div>
+            <Button
+              variant="outline"
+              onClick={() => {
+                setSearchQuery("")
+                setSelectedCategory("All")
+              }}
+            >
+              Clear Filters
+            </Button>
+          </div>
+        </Card>
+      )}
+
+      <div className="flex justify-center">
+        <Button variant="outline" className="gap-2">
+          Load More
+        </Button>
+      </div>
+    </div>
+  )
+}

src/app/(main)/layout.tsx

@@ -1,50 +1,174 @@
+"use client"
+
 import Link from "next/link"
-import { Sparkles } from "lucide-react"
+import { usePathname } from "next/navigation"
+import { Sparkles, Home, BarChart3, Compass, User, Menu, X, Search } from "lucide-react"
+import { useState } from "react"
+import { Button } from "@/components/ui/button"
+import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar"
+import { DropdownMenu, DropdownMenuContent, DropdownMenuItem, DropdownMenuLabel, DropdownMenuSeparator, DropdownMenuTrigger } from "@/components/ui/dropdown-menu"
+import { Input } from "@/components/ui/input"
+import { cn } from "@/lib/utils"
+
+const navItems = [
+  { href: "/", label: "Home", icon: Home },
+  { href: "/compare", label: "Compare", icon: BarChart3 },
+  { href: "/explore", label: "Explore", icon: Compass },
+  { href: "/profile", label: "Profile", icon: User },
+]
+
+function NavSidebar({ className }: { className?: string }) {
+  const pathname = usePathname()
+
+  return (
+    <nav className={cn("flex flex-col gap-1", className)}>
+      {navItems.map((item) => {
+        const isActive = pathname === item.href || (item.href !== "/" && pathname.startsWith(item.href))
+        return (
+          <Link key={item.href} href={item.href}>
+            <Button
+              variant={isActive ? "secondary" : "ghost"}
+              className={cn(
+                "w-full justify-start gap-2",
+                isActive && "bg-muted text-primary font-medium"
+              )}
+            >
+              <item.icon className="size-4" />
+              {item.label}
+            </Button>
+          </Link>
+        )
+      })}
+    </nav>
+  )
+}
+
+function MobileNav() {
+  const pathname = usePathname()
+
+  return (
+    <nav className="fixed bottom-0 left-0 right-0 z-50 border-t bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60 md:hidden">
+      <div className="flex items-center justify-around h-14">
+        {navItems.map((item) => {
+          const isActive = pathname === item.href || (item.href !== "/" && pathname.startsWith(item.href))
+          return (
+            <Link key={item.href} href={item.href} className="flex flex-col items-center gap-1 py-2 px-3">
+              <item.icon className={cn("size-5", isActive ? "text-primary" : "text-muted-foreground")} />
+              <span className={cn("text-xs", isActive ? "text-primary font-medium" : "text-muted-foreground")}>
+                {item.label}
+              </span>
+            </Link>
+          )
+        })}
+      </div>
+    </nav>
+  )
+}
 
 export default function MainLayout({
   children,
 }: {
   children: React.ReactNode
 }) {
+  const [mobileMenuOpen, setMobileMenuOpen] = useState(false)
+  const [searchQuery, setSearchQuery] = useState("")
+
   return (
     <div className="min-h-screen flex flex-col">
       <header className="sticky top-0 z-50 w-full border-b bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60">
-        <div className="container flex h-14 items-center px-4 mx-auto">
+        <div className="container flex h-14 items-center px-4 mx-auto gap-4">
-          <Link href="/" className="flex items-center gap-2 font-semibold mr-8">
+          <Link href="/" className="flex items-center gap-2 font-semibold shrink-0">
             <Sparkles className="size-5 text-primary" />
-            <span className="text-lg">ComparAIson</span>
+            <span className="text-lg hidden sm:inline">ComparAIson</span>
           </Link>
 
-          <div className="flex-1 max-w-md">
+          <div className="flex-1 max-w-md mx-auto hidden md:block">
             <div className="relative">
-              <input
+              <Search className="absolute left-3 top-1/2 -translate-y-1/2 size-4 text-muted-foreground" />
+              <Input
                 type="search"
                 placeholder="Search comparisons..."
-                className="w-full h-8 rounded-lg border border-input bg-muted/50 px-3 text-sm ring-offset-background placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
+                value={searchQuery}
+                onChange={(e) => setSearchQuery(e.target.value)}
+                className="pl-9 h-9"
               />
             </div>
           </div>
 
-          <div className="flex items-center gap-3 ml-auto">
+          <div className="flex items-center gap-2 ml-auto">
-            <Link href="/compare">
+            <Link href="/compare" className="hidden sm:block">
-              <button className="h-8 px-3 rounded-lg text-sm font-medium bg-primary text-primary-foreground hover:bg-primary/80 transition-colors">
+              <Button size="sm" className="gap-2">
+                <Sparkles className="size-3.5" />
                 New Comparison
-              </button>
+              </Button>
             </Link>
-            <div className="size-8 rounded-full bg-muted flex items-center justify-center text-xs font-medium text-muted-foreground">
+
-              U
+            <DropdownMenu>
-            </div>
+              <DropdownMenuTrigger className="rounded-full">
+                <Avatar className="size-8">
+                  <AvatarImage src="/placeholder-avatar.png" />
+                  <AvatarFallback className="bg-primary/10 text-primary font-medium">U</AvatarFallback>
+                </Avatar>
+              </DropdownMenuTrigger>
+              <DropdownMenuContent align="end" className="w-48">
+                <DropdownMenuLabel>My Account</DropdownMenuLabel>
+                <DropdownMenuSeparator />
+                <DropdownMenuItem>
+                  <Link href="/profile" className="w-full">Profile</Link>
+                </DropdownMenuItem>
+                <DropdownMenuItem>
+                  <Link href="/compare" className="w-full">New Comparison</Link>
+                </DropdownMenuItem>
+                <DropdownMenuSeparator />
+                <DropdownMenuItem>
+                  <Link href="/sign-in" className="w-full">Sign Out</Link>
+                </DropdownMenuItem>
+              </DropdownMenuContent>
+            </DropdownMenu>
+
+            <Button
+              variant="ghost"
+              size="icon"
+              className="md:hidden"
+              onClick={() => setMobileMenuOpen(!mobileMenuOpen)}
+            >
+              {mobileMenuOpen ? <X className="size-5" /> : <Menu className="size-5" />}
+            </Button>
           </div>
         </div>
+
+        {mobileMenuOpen && (
+          <div className="border-t md:hidden bg-background p-4">
+            <div className="relative mb-4">
+              <Search className="absolute left-3 top-1/2 -translate-y-1/2 size-4 text-muted-foreground" />
+              <Input
+                type="search"
+                placeholder="Search comparisons..."
+                value={searchQuery}
+                onChange={(e) => setSearchQuery(e.target.value)}
+                className="pl-9"
+              />
+            </div>
+            <NavSidebar />
+          </div>
+        )}
       </header>
 
-      <main className="flex-1">{children}</main>
+      <div className="flex flex-1">
+        <aside className="hidden md:block w-52 border-r bg-muted/20 p-4 shrink-0">
+          <NavSidebar />
+        </aside>
 
-      <footer className="border-t py-4">
+        <main className="flex-1 pb-16 md:pb-0">{children}</main>
+      </div>
+
+      <MobileNav />
+
+      <footer className="border-t py-4 hidden md:block">
         <div className="container mx-auto px-4 text-center text-xs text-muted-foreground">
           ComparAIson — AI-powered deep research comparisons
         </div>
       </footer>
     </div>
   )
-}
+}

src/app/(main)/profile/page.tsx

@@ -0,0 +1,157 @@
+"use client"
+
+import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar"
+import { Button } from "@/components/ui/button"
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
+import { Badge } from "@/components/ui/badge"
+import { BarChart3, Eye, Calendar, Plus, ArrowRight } from "lucide-react"
+import Link from "next/link"
+
+const mockUser = {
+  name: "Alex Johnson",
+  email: "alex@example.com",
+  avatar: "/placeholder-avatar.png",
+}
+
+const mockComparisons = [
+  {
+    id: "1",
+    title: "React vs Vue vs Svelte",
+    items: ["React", "Vue", "Svelte"],
+    tags: ["Tech", "JavaScript"],
+    overallScore: 8.5,
+    views: 1247,
+    createdAt: "2024-01-15",
+  },
+  {
+    id: "2",
+    title: "GPT-4 vs Claude vs Gemini",
+    items: ["GPT-4", "Claude 3", "Gemini Pro"],
+    tags: ["AI", "Products"],
+    overallScore: 8.8,
+    views: 3891,
+    createdAt: "2024-01-10",
+  },
+  {
+    id: "3",
+    title: "Notion vs Obsidian vs Roam",
+    items: ["Notion", "Obsidian", "Roam Research"],
+    tags: ["Productivity"],
+    overallScore: 7.5,
+    views: 892,
+    createdAt: "2024-01-05",
+  },
+]
+
+const stats = [
+  { label: "Total Comparisons", value: 12, icon: BarChart3 },
+  { label: "Total Views", value: "8.2K", icon: Eye },
+]
+
+export default function ProfilePage() {
+  return (
+    <div className="max-w-4xl mx-auto p-4 sm:p-6 space-y-8">
+      <div className="flex items-center gap-6">
+        <Avatar className="size-20">
+          <AvatarImage src={mockUser.avatar} />
+          <AvatarFallback className="text-2xl bg-primary/10 text-primary font-semibold">
+            {mockUser.name.split(" ").map((n) => n[0]).join("")}
+          </AvatarFallback>
+        </Avatar>
+        <div className="space-y-1.5">
+          <h1 className="text-2xl font-bold">{mockUser.name}</h1>
+          <p className="text-muted-foreground">{mockUser.email}</p>
+        </div>
+      </div>
+
+      <div className="grid gap-4 sm:grid-cols-2">
+        {stats.map((stat) => (
+          <Card key={stat.label}>
+            <CardContent className="flex items-center gap-4 p-4">
+              <div className="size-10 rounded-lg bg-primary/10 flex items-center justify-center">
+                <stat.icon className="size-5 text-primary" />
+              </div>
+              <div>
+                <p className="text-2xl font-bold">{stat.value}</p>
+                <p className="text-sm text-muted-foreground">{stat.label}</p>
+              </div>
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+
+      <div className="space-y-4">
+        <div className="flex items-center justify-between">
+          <h2 className="text-xl font-semibold">My Comparisons</h2>
+          <Link href="/compare">
+            <Button size="sm" className="gap-2">
+              <Plus className="size-4" />
+              New Comparison
+            </Button>
+          </Link>
+        </div>
+
+        {mockComparisons.length > 0 ? (
+          <div className="grid gap-4 sm:grid-cols-2">
+            {mockComparisons.map((comparison) => (
+              <Link key={comparison.id} href={`/compare/${comparison.id}`}>
+                <Card className="h-full transition-all hover:border-primary hover:shadow-md">
+                  <CardHeader className="pb-3">
+                    <CardTitle className="text-base line-clamp-1">{comparison.title}</CardTitle>
+                    <CardDescription className="flex items-center gap-2 text-xs">
+                      <Calendar className="size-3.5" />
+                      {comparison.createdAt}
+                    </CardDescription>
+                  </CardHeader>
+                  <CardContent className="space-y-3">
+                    <div className="flex flex-wrap gap-1.5">
+                      {comparison.tags.map((tag) => (
+                        <Badge key={tag} variant="secondary" className="text-xs">
+                          {tag}
+                        </Badge>
+                      ))}
+                    </div>
+                    <div className="flex items-center justify-between">
+                      <span className="text-sm text-muted-foreground">
+                        {comparison.items.join(" vs ")}
+                      </span>
+                      <div className="flex items-center gap-3 text-sm text-muted-foreground">
+                        <span className="flex items-center gap-1">
+                          <Eye className="size-3.5" />
+                          {comparison.views.toLocaleString()}
+                        </span>
+                        <span className="font-semibold text-foreground">
+                          {comparison.overallScore}/10
+                        </span>
+                      </div>
+                    </div>
+                  </CardContent>
+                </Card>
+              </Link>
+            ))}
+          </div>
+        ) : (
+          <Card className="p-8 text-center">
+            <div className="flex flex-col items-center gap-4">
+              <div className="size-12 rounded-full bg-muted flex items-center justify-center">
+                <BarChart3 className="size-6 text-muted-foreground" />
+              </div>
+              <div>
+                <p className="font-medium">No comparisons yet</p>
+                <p className="text-sm text-muted-foreground">
+                  Create your first comparison to get started
+                </p>
+              </div>
+              <Link href="/compare">
+                <Button className="gap-2">
+                  <Plus className="size-4" />
+                  Create Comparison
+                </Button>
+              </Link>
+            </div>
+          </Card>
+        )}
+      </div>
+    </div>
+  )
+}

src/app/api/compare/route.ts

@@ -18,6 +18,10 @@ function slugify(text: string): string {
     .slice(0, 200);
 }
 
+// TODO: Implement rate limiting per IP/user
+// Example: Use Upstash Ratelimit or a simple in-memory counter
+// const ratelimit = new Ratelimit({ redis, limiter: slidingWindow(5, "1m") })
+
 export async function POST(request: Request) {
   const body: { query?: string; items?: string[]; dimensions?: string[] } =
     await request.json();
@@ -25,7 +29,21 @@ export async function POST(request: Request) {
 
   if (!items || items.length < 2) {
     return Response.json(
-      { error: "At least 2 items are required" },
+      { error: "At least 2 items are required for comparison" },
+      { status: 400 }
+    );
+  }
+
+  if (items.length > 10) {
+    return Response.json(
+      { error: "Maximum 10 items allowed per comparison" },
+      { status: 400 }
+    );
+  }
+
+  if (items.some((item) => item.trim().length === 0)) {
+    return Response.json(
+      { error: "Item names cannot be empty" },
       { status: 400 }
     );
   }
@@ -70,6 +88,20 @@ export async function POST(request: Request) {
             );
           }
 
+          if (progress.stage === "searching") {
+            controller.enqueue(
+              encoder.encode(
+                serializeSSE("progress", {
+                  status: "researching",
+                  message: `Searching the web for ${progress.item}... (${progress.results} results found)`,
+                  itemsCompleted,
+                  totalItems: items.length,
+                  currentStep: `Searching ${progress.item}`,
+                })
+              )
+            );
+          }
+
           if (progress.stage === "researching") {
             itemsCompleted++;
             controller.enqueue(
@@ -102,7 +134,17 @@ export async function POST(request: Request) {
           if (progress.stage === "complete") {
             const result = progress.result;
 
-            const comparisonData: Omit<ComparisonData, "id" | "userId" | "slug" | "tags" | "isPublic" | "viewCount" | "createdAt" | "updatedAt"> = {
+            const comparisonData: Omit<
+              ComparisonData,
+              | "id"
+              | "userId"
+              | "slug"
+              | "tags"
+              | "isPublic"
+              | "viewCount"
+              | "createdAt"
+              | "updatedAt"
+            > = {
               title,
               query: query || "",
               status: "completed",
@@ -177,7 +219,7 @@ export async function POST(request: Request) {
               encoder.encode(
                 serializeSSE("progress", {
                   status: "failed",
-                  message: progress.error,
+                  message: `Comparison failed: ${progress.error}`,
                   itemsCompleted,
                   totalItems: items.length,
                   currentStep: "Failed",
@@ -192,11 +234,16 @@ export async function POST(request: Request) {
           .set({ status: "failed", updatedAt: new Date() })
           .where(eq(comparisons.id, id));
 
+        const message =
+          error instanceof Error
+            ? error.message
+            : "An unexpected error occurred during research";
+
         controller.enqueue(
           encoder.encode(
             serializeSSE("progress", {
               status: "failed",
-              message: error instanceof Error ? error.message : "Unknown error",
+              message: `Comparison failed: ${message}`,
               itemsCompleted,
               totalItems: items.length,
               currentStep: "Failed",

src/app/page.tsx

@@ -1,65 +1,186 @@
-import Image from "next/image";
+import Link from "next/link"
+import { Sparkles, BarChart3, Search, Share2, ArrowRight, CheckCircle2 } from "lucide-react"
+import { Button } from "@/components/ui/button"
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card"
 
-export default function Home() {
+const exampleComparisons = [
+  {
+    title: "React vs Vue vs Svelte",
+    description: "Frontend framework comparison for modern web development",
+    tags: ["Tech", "JavaScript"],
+    items: ["React", "Vue", "Svelte"],
+    scores: [8.5, 7.8, 8.2],
+  },
+  {
+    title: "GPT-4 vs Claude vs Gemini",
+    description: "Comparing top AI language models for reasoning tasks",
+    tags: ["AI", "Products"],
+    items: ["GPT-4", "Claude 3", "Gemini Pro"],
+    scores: [8.8, 9.0, 8.4],
+  },
+  {
+    title: "Notion vs Obsidian vs Roam",
+    description: "Knowledge management tools for productivity",
+    tags: ["Products", "Productivity"],
+    items: ["Notion", "Obsidian", "Roam Research"],
+    scores: [7.5, 8.3, 7.2],
+  },
+  {
+    title: "AWS vs GCP vs Azure",
+    description: "Cloud platform comparison for enterprise infrastructure",
+    tags: ["Tech", "Cloud"],
+    items: ["AWS", "Google Cloud", "Microsoft Azure"],
+    scores: [9.0, 8.2, 8.5],
+  },
+]
+
+const features = [
+  {
+    icon: BarChart3,
+    title: "Rich Visualizations",
+    description: "Interactive radar charts, bar graphs, and comparison tables to understand your results at a glance.",
+  },
+  {
+    icon: Search,
+    title: "Deep Research",
+    description: "AI-powered research that gathers comprehensive data from multiple sources for each item.",
+  },
+  {
+    icon: Share2,
+    title: "Save & Share",
+    description: "Keep your comparisons private or share them with the world. Build a library of research.",
+  },
+]
+
+export default function HomePage() {
   return (
-    <div className="flex flex-col flex-1 items-center justify-center bg-zinc-50 font-sans dark:bg-black">
+    <div className="flex flex-col min-h-screen">
-      <main className="flex flex-1 w-full max-w-3xl flex-col items-center justify-between py-32 px-16 bg-white dark:bg-black sm:items-start">
+      <section className="flex-1 flex flex-col items-center justify-center py-20 px-4 bg-gradient-to-b from-background to-muted/30">
-        <Image
+        <div className="max-w-3xl mx-auto text-center space-y-8">
-          className="dark:invert"
+          <div className="inline-flex items-center gap-2 px-4 py-2 rounded-full bg-primary/10 text-primary text-sm font-medium mb-4">
-          src="/next.svg"
+            <Sparkles className="size-4" />
-          alt="Next.js logo"
+            AI-Powered Research
-          width={100}
+          </div>
-          height={20}
+
-          priority
+          <h1 className="text-4xl sm:text-5xl lg:text-6xl font-bold tracking-tight leading-tight">
-        />
+            Compare Anything with{" "}
-        <div className="flex flex-col items-center gap-6 text-center sm:items-start sm:text-left">
+            <span className="text-primary">AI-Powered</span> Deep Research
-          <h1 className="max-w-xs text-3xl font-semibold leading-10 tracking-tight text-black dark:text-zinc-50">
-            To get started, edit the page.tsx file.
           </h1>
-          <p className="max-w-md text-lg leading-8 text-zinc-600 dark:text-zinc-400">
+
-            Looking for a starting point or more instructions? Head over to{" "}
+          <p className="text-lg sm:text-xl text-muted-foreground max-w-2xl mx-auto">
-            <a
+            Stop spending hours researching. Let AI do the work for you with comprehensive,
-              href="https://vercel.com/templates?framework=next.js&utm_source=create-next-app&utm_medium=appdir-template-tw&utm_campaign=create-next-app"
+            multi-dimensional comparisons on anything you can think of.
-              className="font-medium text-zinc-950 dark:text-zinc-50"
-            >
-              Templates
-            </a>{" "}
-            or the{" "}
-            <a
-              href="https://nextjs.org/learn?utm_source=create-next-app&utm_medium=appdir-template-tw&utm_campaign=create-next-app"
-              className="font-medium text-zinc-950 dark:text-zinc-50"
-            >
-              Learning
-            </a>{" "}
-            center.
           </p>
+
+          <div className="flex flex-col sm:flex-row gap-4 justify-center pt-4">
+            <Link href="/compare">
+              <Button size="lg" className="gap-2 text-lg px-8">
+                <Sparkles className="size-5" />
+                Start Comparing
+                <ArrowRight className="size-4" />
+              </Button>
+            </Link>
+            <Link href="/explore">
+              <Button size="lg" variant="outline" className="text-lg px-8">
+                Explore Examples
+              </Button>
+            </Link>
+          </div>
         </div>
-        <div className="flex flex-col gap-4 text-base font-medium sm:flex-row">
+      </section>
-          <a
+
-            className="flex h-12 w-full items-center justify-center gap-2 rounded-full bg-foreground px-5 text-background transition-colors hover:bg-[#383838] dark:hover:bg-[#ccc] md:w-[158px]"
+      <section className="py-16 px-4 bg-muted/20">
-            href="https://vercel.com/new?utm_source=create-next-app&utm_medium=appdir-template-tw&utm_campaign=create-next-app"
+        <div className="max-w-5xl mx-auto">
-            target="_blank"
+          <h2 className="text-2xl font-bold text-center mb-10">Example Comparisons</h2>
-            rel="noopener noreferrer"
+
-          >
+          <div className="grid gap-6 sm:grid-cols-2 lg:grid-cols-4">
-            <Image
+            {exampleComparisons.map((example) => (
-              className="dark:invert"
+              <Link key={example.title} href="/compare" className="group">
-              src="/vercel.svg"
+                <Card className="h-full transition-all group-hover:border-primary group-hover:shadow-md">
-              alt="Vercel logomark"
+                  <CardHeader className="pb-3">
-              width={16}
+                    <div className="flex items-center gap-2 mb-2">
-              height={16}
+                      <span className="text-lg font-bold">{example.title}</span>
-            />
+                    </div>
-            Deploy Now
+                    <CardDescription className="text-sm line-clamp-2">
-          </a>
+                      {example.description}
-          <a
+                    </CardDescription>
-            className="flex h-12 w-full items-center justify-center rounded-full border border-solid border-black/[.08] px-5 transition-colors hover:border-transparent hover:bg-black/[.04] dark:border-white/[.145] dark:hover:bg-[#1a1a1a] md:w-[158px]"
+                  </CardHeader>
-            href="https://nextjs.org/docs?utm_source=create-next-app&utm_medium=appdir-template-tw&utm_campaign=create-next-app"
+                  <CardContent className="space-y-3">
-            target="_blank"
+                    <div className="flex flex-wrap gap-1.5">
-            rel="noopener noreferrer"
+                      {example.tags.map((tag) => (
-          >
+                        <span
-            Documentation
+                          key={tag}
-          </a>
+                          className="px-2 py-0.5 rounded-full bg-muted text-xs font-medium"
+                        >
+                          {tag}
+                        </span>
+                      ))}
+                    </div>
+                    <div className="flex items-center justify-between text-sm">
+                      <span className="text-muted-foreground">
+                        {example.items.slice(0, 2).join(" vs ")}
+                        {example.items.length > 2 && ` vs ${example.items.length - 2}+`}
+                      </span>
+                    </div>
+                    <div className="flex items-center gap-1">
+                      {example.scores.slice(0, 3).map((score, i) => (
+                        <div
+                          key={i}
+                          className="h-1 flex-1 rounded-full bg-primary/30"
+                          style={{ width: `${score * 10}%` }}
+                        />
+                      ))}
+                    </div>
+                  </CardContent>
+                </Card>
+              </Link>
+            ))}
+          </div>
         </div>
-      </main>
+      </section>
+
+      <section className="py-20 px-4">
+        <div className="max-w-4xl mx-auto">
+          <h2 className="text-2xl font-bold text-center mb-12">Why ComparAIson?</h2>
+
+          <div className="grid gap-8 sm:grid-cols-3">
+            {features.map((feature) => (
+              <div key={feature.title} className="flex flex-col items-center text-center space-y-3">
+                <div className="size-12 rounded-xl bg-primary/10 flex items-center justify-center">
+                  <feature.icon className="size-6 text-primary" />
+                </div>
+                <h3 className="font-semibold text-lg">{feature.title}</h3>
+                <p className="text-muted-foreground text-sm">{feature.description}</p>
+              </div>
+            ))}
+          </div>
+        </div>
+      </section>
+
+      <section className="py-16 px-4 bg-primary text-primary-foreground">
+        <div className="max-w-2xl mx-auto text-center space-y-6">
+          <h2 className="text-2xl sm:text-3xl font-bold">Ready to compare?</h2>
+          <p className="text-primary-foreground/80">
+            Start your first comparison in seconds. It&apos;s free to get started.
+          </p>
+          <Link href="/compare">
+            <Button size="lg" variant="secondary" className="gap-2 text-lg px-8">
+              <Sparkles className="size-5" />
+              Start Comparing
+            </Button>
+          </Link>
+        </div>
+      </section>
+
+      <footer className="border-t py-8 px-4">
+        <div className="max-w-4xl mx-auto flex flex-col sm:flex-row items-center justify-between gap-4 text-sm text-muted-foreground">
+          <div className="flex items-center gap-2">
+            <Sparkles className="size-4 text-primary" />
+            <span className="font-semibold">ComparAIson</span>
+          </div>
+          <p>AI-powered deep research comparisons</p>
+        </div>
+      </footer>
     </div>
-  );
+  )
-}
+}

src/lib/llm/index.ts

@@ -3,7 +3,9 @@ import type {
   ComparisonResult,
   ResearchProgress,
 } from "./types";
-import { generateComparison } from "./providers/openai";
+import { searchItem, type SearchResult } from "./providers/tavily";
+import { generateComparisonWithResearch } from "./providers/openai";
+import { getActiveProvider } from "./providers";
 
 export type {
   ComparisonRequest,
@@ -24,21 +26,44 @@ export async function* runResearch(
     return;
   }
 
-  for (let i = 0; i < request.items.length; i++) {
+  const provider = getActiveProvider();
-    yield {
+  const searchResults: Record<string, SearchResult[]> = {};
-      stage: "researching",
+
-      item: request.items[i],
+  if (provider.hasSearch) {
-      progress: Math.round(((i + 0.5) / request.items.length) * 80),
+    for (let i = 0; i < request.items.length; i++) {
-    };
+      const item = request.items[i];
+      const results = await searchItem(item, request.query);
+      searchResults[item] = results;
+
+      yield {
+        stage: "searching",
+        item,
+        results: results.length,
+      };
+
+      yield {
+        stage: "researching",
+        item,
+        progress: Math.round(((i + 1) / request.items.length) * 50),
+      };
+    }
+  } else {
+    for (let i = 0; i < request.items.length; i++) {
+      yield {
+        stage: "researching",
+        item: request.items[i],
+        progress: Math.round(((i + 0.5) / request.items.length) * 80),
+      };
+    }
   }
 
   yield {
     stage: "synthesizing",
-    message: "Synthesizing research into structured comparison...",
+    message: `Synthesizing research into structured comparison using ${provider.name}...`,
   };
 
   try {
-    const result = await generateComparison(request);
+    const result = await provider.synthesize(request, searchResults);
     yield { stage: "complete", result };
   } catch (error) {
     yield {

src/lib/llm/providers/index.ts

@@ -0,0 +1,63 @@
+import type { ComparisonRequest, ComparisonResult } from "../types";
+import type { SearchResult } from "./tavily";
+import { generateComparisonWithResearch, generateComparison } from "./openai";
+import { synthesizeResearch } from "./perplexity";
+
+export interface Provider {
+  name: string;
+  hasSearch: boolean;
+  synthesize: (
+    request: ComparisonRequest,
+    searchResults: Record<string, SearchResult[]>
+  ) => Promise<ComparisonResult>;
+}
+
+export function getActiveProvider(): Provider {
+  const hasTavily = !!process.env.TAVILY_API_KEY;
+  const hasPerplexity = !!process.env.PERPLEXITY_API_KEY;
+  const hasOpenAI = !!process.env.OPENAI_API_KEY;
+
+  if (hasTavily && hasPerplexity) {
+    console.log("[llm] Using provider: Tavily search + Perplexity synthesis");
+    return {
+      name: "Tavily + Perplexity",
+      hasSearch: true,
+      synthesize: synthesizeResearch,
+    };
+  }
+
+  if (hasTavily && hasOpenAI) {
+    console.log("[llm] Using provider: Tavily search + OpenAI synthesis");
+    return {
+      name: "Tavily + OpenAI",
+      hasSearch: true,
+      synthesize: generateComparisonWithResearch,
+    };
+  }
+
+  if (hasOpenAI) {
+    console.log("[llm] Using provider: OpenAI only (no web search)");
+    return {
+      name: "OpenAI",
+      hasSearch: false,
+      synthesize: async (request) => generateComparison(request),
+    };
+  }
+
+  console.warn(
+    "[llm] No API keys configured. Research will fail at synthesis."
+  );
+  return {
+    name: "None",
+    hasSearch: false,
+    synthesize: async () => {
+      throw new Error(
+        "No LLM provider configured. Set OPENAI_API_KEY, TAVILY_API_KEY, or PERPLEXITY_API_KEY."
+      );
+    },
+  };
+}
+
+export { searchItem, type SearchResult } from "./tavily";
+export { generateComparison, generateComparisonWithResearch } from "./openai";
+export { synthesizeResearch } from "./perplexity";

src/lib/llm/providers/openai.ts

@@ -5,6 +5,7 @@ import type {
   DimensionResult,
   ItemResearch,
 } from "../types";
+import type { SearchResult } from "./tavily";
 
 let _client: OpenAI | null = null;
 
@@ -145,3 +146,75 @@ Provide a comprehensive comparison with scores, pros/cons, and a recommendation.
     `Failed to generate comparison after ${MAX_RETRIES} attempts: ${lastError?.message}`
   );
 }
+
+export async function generateComparisonWithResearch(
+  request: ComparisonRequest,
+  searchResults: Record<string, SearchResult[]>
+): Promise<ComparisonResult> {
+  const allResults = Object.values(searchResults).flat();
+  if (allResults.length === 0) {
+    return generateComparison(request);
+  }
+
+  let researchContext = "Web research data:\n\n";
+  for (const [itemName, results] of Object.entries(searchResults)) {
+    if (results.length === 0) continue;
+    researchContext += `=== ${itemName} ===\n`;
+    for (const r of results) {
+      researchContext += `- ${r.title}: ${r.content}\n  Source: ${r.url}\n`;
+    }
+    researchContext += "\n";
+  }
+
+  const userPrompt = `Compare the following items: ${request.items.join(", ")}
+${request.query ? `Focus: ${request.query}` : ""}
+${request.dimensions?.length ? `Specific dimensions to include: ${request.dimensions.join(", ")}` : ""}
+
+${researchContext}
+
+Use the web research data above to provide factual, data-driven insights. Reference specific data points in your analysis. Provide a comprehensive comparison with scores, pros/cons, and a recommendation.`;
+
+  let lastError: Error | null = null;
+
+  for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+    try {
+      const response = await client.chat.completions.create({
+        model: "gpt-4o-mini",
+        messages: [
+          { role: "system", content: SYSTEM_PROMPT },
+          {
+            role: "system",
+            content:
+              "You have access to real web search results. Use them to ground your comparison in factual data. Cite specific findings from the research when scoring and analyzing items.",
+          },
+          { role: "user", content: userPrompt },
+        ],
+        response_format: { type: "json_object" },
+        temperature: 0.3,
+      });
+
+      const content = response.choices[0]?.message?.content;
+      if (!content) {
+        throw new Error("Empty response from OpenAI");
+      }
+
+      const parsed: unknown = JSON.parse(content);
+
+      if (!validateComparisonResult(parsed)) {
+        throw new Error("Invalid comparison result structure from OpenAI");
+      }
+
+      return parsed;
+    } catch (error) {
+      lastError = error instanceof Error ? error : new Error(String(error));
+
+      if (attempt < MAX_RETRIES) {
+        await sleep(RETRY_DELAY_MS * attempt);
+      }
+    }
+  }
+
+  throw new Error(
+    `Failed to generate comparison with research after ${MAX_RETRIES} attempts: ${lastError?.message}`
+  );
+}

src/lib/llm/providers/perplexity.ts

@@ -0,0 +1,117 @@
+import type { ComparisonRequest, ComparisonResult } from "../types";
+import type { SearchResult } from "./tavily";
+import { generateComparisonWithResearch } from "./openai";
+
+const PERPLEXITY_API_URL = "https://api.perplexity.ai/chat/completions";
+
+const SYSTEM_PROMPT = `You are a research synthesis engine. Given web search results for multiple items, produce a structured JSON comparison.
+
+You MUST respond with valid JSON matching this exact structure:
+{
+  "items": [
+    {
+      "name": "item name",
+      "description": "brief overview",
+      "overallScore": 7.5,
+      "dimensions": {
+        "Dimension Name": {
+          "score": 8,
+          "summary": "brief assessment",
+          "details": "detailed analysis",
+          "pros": ["pro 1"],
+          "cons": ["con 1"]
+        }
+      },
+      "pros": ["overall pro 1"],
+      "cons": ["overall con 1"],
+      "sources": [{ "title": "source", "url": "https://...", "snippet": "excerpt" }]
+    }
+  ],
+  "dimensions": ["Dimension 1", "Dimension 2"],
+  "summary": "comparison summary",
+  "recommendation": "clear recommendation"
+}`;
+
+export async function synthesizeResearch(
+  request: ComparisonRequest,
+  searchResults: Record<string, SearchResult[]>
+): Promise<ComparisonResult> {
+  const apiKey = process.env.PERPLEXITY_API_KEY;
+  if (!apiKey) {
+    return generateComparisonWithResearch(request, searchResults);
+  }
+
+  const allResults = Object.values(searchResults).flat();
+  if (allResults.length === 0) {
+    return generateComparisonWithResearch(request, searchResults);
+  }
+
+  let researchContext = "Search results for each item:\n\n";
+  for (const [itemName, results] of Object.entries(searchResults)) {
+    if (results.length === 0) continue;
+    researchContext += `=== ${itemName} ===\n`;
+    for (const r of results) {
+      researchContext += `- ${r.title}: ${r.content}\n  Source: ${r.url}\n`;
+    }
+    researchContext += "\n";
+  }
+
+  const userPrompt = `Compare: ${request.items.join(", ")}
+${request.query ? `Focus: ${request.query}` : ""}
+${request.dimensions?.length ? `Dimensions: ${request.dimensions.join(", ")}` : ""}
+
+${researchContext}`;
+
+  try {
+    const response = await fetch(PERPLEXITY_API_URL, {
+      method: "POST",
+      headers: {
+        Authorization: `Bearer ${apiKey}`,
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({
+        model: "sonar",
+        messages: [
+          { role: "system", content: SYSTEM_PROMPT },
+          { role: "user", content: userPrompt },
+        ],
+        temperature: 0.3,
+      }),
+    });
+
+    if (!response.ok) {
+      console.error(
+        `Perplexity API error: ${response.status} ${response.statusText}`
+      );
+      return generateComparisonWithResearch(request, searchResults);
+    }
+
+    const data = await response.json();
+    const content = data.choices?.[0]?.message?.content;
+
+    if (!content) {
+      console.error("Empty response from Perplexity");
+      return generateComparisonWithResearch(request, searchResults);
+    }
+
+    const parsed: unknown = JSON.parse(content);
+
+    if (
+      !parsed ||
+      typeof parsed !== "object" ||
+      !Array.isArray((parsed as Record<string, unknown>).items) ||
+      !Array.isArray((parsed as Record<string, unknown>).dimensions)
+    ) {
+      console.error("Invalid structure from Perplexity, falling back to OpenAI");
+      return generateComparisonWithResearch(request, searchResults);
+    }
+
+    return parsed as ComparisonResult;
+  } catch (error) {
+    console.error(
+      "Perplexity synthesis failed, falling back to OpenAI:",
+      error instanceof Error ? error.message : error
+    );
+    return generateComparisonWithResearch(request, searchResults);
+  }
+}

src/lib/llm/providers/tavily.ts

@@ -0,0 +1,69 @@
+export interface SearchResult {
+  title: string;
+  url: string;
+  content: string;
+  score: number;
+}
+
+const TAVILY_API_URL = "https://api.tavily.com/search";
+
+export async function searchItem(
+  itemName: string,
+  context: string
+): Promise<SearchResult[]> {
+  const apiKey = process.env.TAVILY_API_KEY;
+  if (!apiKey) {
+    return [];
+  }
+
+  try {
+    const query = `${itemName} ${context}`.trim();
+
+    const response = await fetch(TAVILY_API_URL, {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({
+        api_key: apiKey,
+        query,
+        max_results: 5,
+        include_answer: false,
+        search_depth: "advanced",
+      }),
+    });
+
+    if (!response.ok) {
+      console.error(
+        `Tavily API error: ${response.status} ${response.statusText}`
+      );
+      return [];
+    }
+
+    const data = await response.json();
+
+    if (!data.results || !Array.isArray(data.results)) {
+      return [];
+    }
+
+    return data.results.map(
+      (result: {
+        title?: string;
+        url?: string;
+        content?: string;
+        score?: number;
+      }) => ({
+        title: result.title ?? "",
+        url: result.url ?? "",
+        content: result.content ?? "",
+        score: result.score ?? 0,
+      })
+    );
+  } catch (error) {
+    console.error(
+      `Tavily search failed for "${itemName}":`,
+      error instanceof Error ? error.message : error
+    );
+    return [];
+  }
+}

src/lib/llm/types.ts

@@ -31,6 +31,7 @@ export interface ComparisonResult {
 
 export type ResearchProgress =
   | { stage: "parsing"; message: string }
+  | { stage: "searching"; item: string; results: number }
   | { stage: "researching"; item: string; progress: number }
   | { stage: "synthesizing"; message: string }
   | { stage: "complete"; result: ComparisonResult }