docs: API key is optional, fix layer cross-references

- REST API, demo, and skill docs: mark API key as optional
- Demo api.ts: only send X-Api-Key header when configured
- Fix layer1-product links to match current doc structure

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Blackman99

docs/api/rest-api.md

@@ -4,14 +4,14 @@ TxGraph components are designed to work with the **TrustIn graph_explore API**.
 
 ## Authentication
 
-Contact [info@trustin.info](mailto:info@trustin.info) to obtain an API key.
-
-Include the key in all requests:
+The TrustIn API works without an API key. You can optionally include one for higher rate limits:
 
 ```
 X-Api-Key: your_api_key_here
 ```
 
+Contact [info@trustin.info](mailto:info@trustin.info) to obtain an API key for production use.
+
 ## Endpoints
 
 ### `POST /api/v1/graph_explore`
@@ -25,7 +25,6 @@ Explore transaction graph starting from a given address.
 ```http
 POST /api/v1/graph_explore
 Content-Type: application/json
-X-Api-Key: your_api_key_here
 ```
 
 ```json
@@ -98,8 +97,8 @@ X-Api-Key: your_api_key_here
 ```json
 {
   "success": false,
-  "error": "Invalid API key",
-  "code": 401
+  "error": "Rate limit exceeded",
+  "code": 429
 }
 ```
 

docs/guide/claude-code-skill.md

@@ -10,7 +10,6 @@ The `/trace-graph` skill guides you through specifying parameters, starts the lo
 
 - [Claude Code](https://claude.com/claude-code) installed
 - Node.js >= 18, pnpm >= 8
-- A TrustIn API key (contact [info@trustin.info](mailto:info@trustin.info))
 
 ## Usage
 
@@ -41,7 +40,6 @@ You'll be prompted for:
 ### 2. Environment Setup
 
 Claude checks that everything is ready:
-- Creates `examples/local-demo/.env` with your API key if missing
 - Installs dependencies if needed
 - Builds the core `@trustin/txgraph` package
 

docs/guide/layer1-product.md

@@ -51,4 +51,4 @@ Switch between two renderers:
 ✅ Full feature set including AI risk scoring  
 ✅ Regular compliance checks
 
-→ For programmatic access or embedding in your own app, see [Layer 2: Run Demo Locally](/guide/layer2-demo) or [Layer 3: Build Your Own](/guide/layer3-component).
+→ For programmatic access, see [Layer 2: AI Agent API](/guide/layer2-agent). To run locally, see [Layer 3: Local Demo](/guide/layer3-demo). To embed in your own app, see [Layer 4: Build Your Own](/guide/layer4-component).

docs/guide/layer3-demo.md

@@ -6,7 +6,6 @@ Run TxGraph as a local Vite app connected to the TrustIn API. Ideal for evaluati
 
 - **Node.js** ≥ 18
 - **pnpm** ≥ 8 (`npm i -g pnpm`)
-- A **TrustIn API key** (contact [info@trustin.info](mailto:info@trustin.info))
 
 ## Quick Start
 
@@ -18,19 +17,15 @@ cd txgraph
 # 2. Install dependencies
 pnpm install
 
-# 3. Configure your API key
-cp examples/local-demo/.env.example examples/local-demo/.env
-# Edit .env and set VITE_TRUSTIN_API_KEY=your_key_here
-
-# 4. Start the demo
+# 3. Start the demo
 pnpm dev:demo
 ```
 
 Open [http://localhost:5173](http://localhost:5173)
 
-## Configuration
+## Configuration (Optional)
 
-Edit `examples/local-demo/.env`:
+The demo works out of the box without any API key. For higher rate limits, create `examples/local-demo/.env`:
 
 ```env
 VITE_TRUSTIN_API_URL=https://api.trustin.info
@@ -40,7 +35,7 @@ VITE_TRUSTIN_API_KEY=your_api_key_here
 | Variable | Default | Description |
 |----------|---------|-------------|
 | `VITE_TRUSTIN_API_URL` | `https://api.trustin.info` | API base URL |
-| `VITE_TRUSTIN_API_KEY` | — | Your API key (required) |
+| `VITE_TRUSTIN_API_KEY` | — | Optional API key for higher rate limits |
 
 ## Using the Demo
 

examples/local-demo/src/App.tsx

@@ -321,7 +321,7 @@ export default function App() {
           <div style={{ height: '100%', display: 'flex', flexDirection: 'column', alignItems: 'center', justifyContent: 'center', gap: 12, color: c.dimmed }}>
             <div style={{ fontSize: 48 }}>🔍</div>
             <div style={{ fontSize: 15 }}>Enter an address and click <strong>Explore</strong></div>
-            <div style={{ fontSize: 12, color: c.dimmed }}>Requires a TrustIn API key in <code>.env</code></div>
+            <div style={{ fontSize: 12, color: c.dimmed }}>Powered by TrustIn API</div>
           </div>
         )}
         {(graph || loading) && (

examples/local-demo/src/api.ts

@@ -12,14 +12,16 @@ export interface GraphExploreParams {
 
 export async function exploreGraph(params: GraphExploreParams): Promise<TxGraph> {
   const apiUrl = import.meta.env.VITE_TRUSTIN_API_URL || 'https://api.trustin.info'
-  const apiKey = import.meta.env.VITE_TRUSTIN_API_KEY as string
+  const apiKey = import.meta.env.VITE_TRUSTIN_API_KEY as string | undefined
+
+  const headers: Record<string, string> = {
+    'Content-Type': 'application/json',
+  }
+  if (apiKey) headers['X-Api-Key'] = apiKey
 
   const res = await fetch(`${apiUrl}/api/v1/graph_explore`, {
     method: 'POST',
-    headers: {
-      'Content-Type': 'application/json',
-      'X-Api-Key': apiKey,
-    },
+    headers,
     body: JSON.stringify({
       address: params.address,
       chain_name: params.chain,