feat: Add DuckDuckGo search fallback.

- Refactor web tool to use Provider pattern (Brave/DuckDuckGo)
- Add robust HTML scraping for keyless DuckDuckGo search
- Update README with search provider guidelines

README.md

@@ -52,7 +52,7 @@
 🤖 **AI-Bootstrapped**: Autonomous Go-native implementation — 95% Agent-generated core with human-in-the-loop refinement.
 
 |                               | OpenClaw      | NanoBot                  | **PicoClaw**                              |
-| --- | --- | --- |--- |
+| ----------------------------- | ------------- | ------------------------ | ----------------------------------------- |
 | **Language**                  | TypeScript    | Python                   | **Go**                                    |
 | **RAM**                       | >1GB          | >100MB                   | **< 10MB**                                |
 | **Startup**</br>(0.8GHz core) | >500s         | >30s                     | **<1s**                                   |
@@ -123,7 +123,7 @@ make install
 > [!TIP]
 > Set your API key in `~/.picoclaw/config.json`.
 > Get API keys: [OpenRouter](https://openrouter.ai/keys) (LLM) · [Zhipu](https://open.bigmodel.cn/usercenter/proj-mgmt/apikeys) (LLM)
-> Web search is **optional** - get free [Brave Search API](https://brave.com/search/api) (2000 free queries/month)
+> Web search is **optional** - get free [Brave Search API](https://brave.com/search/api) (2000 free queries/month) or use built-in auto fallback.
 
 **1. Initialize**
 
@@ -183,7 +183,7 @@ That's it! You have a working AI assistant in 2 minutes.
 Talk to your picoclaw through Telegram, Discord, or DingTalk
 
 | Channel      | Setup                      |
-|---------|-------|
+| ------------ | -------------------------- |
 | **Telegram** | Easy (just a token)        |
 | **Discord**  | Easy (bot token + intents) |
 | **QQ**       | Easy (AppID + AppSecret)   |
@@ -343,8 +343,6 @@ Connect Picoclaw to the Agent Social Network simply by sending a single message
 
 **Read `https://clawdchat.ai/skill.md` and follow the instructions to join [ClawdChat.ai](https://clawdchat.ai)**
 
-
-
 ## ⚙️ Configuration
 
 Config file: `~/.picoclaw/config.json`
@@ -372,7 +370,7 @@ PicoClaw stores data in your configured workspace (default: `~/.picoclaw/workspa
 > Groq provides free voice transcription via Whisper. If configured, Telegram voice messages will be automatically transcribed.
 
 | Provider                   | Purpose                                 | Get API Key                                            |
-|----------|---------|-------------|
+| -------------------------- | --------------------------------------- | ------------------------------------------------------ |
 | `gemini`                   | LLM (Gemini direct)                     | [aistudio.google.com](https://aistudio.google.com)     |
 | `zhipu`                    | LLM (Zhipu direct)                      | [bigmodel.cn](bigmodel.cn)                             |
 | `openrouter(To be tested)` | LLM (recommended, access to all models) | [openrouter.ai](https://openrouter.ai)                 |
@@ -405,8 +403,8 @@ PicoClaw stores data in your configured workspace (default: `~/.picoclaw/workspa
     "zhipu": {
       "api_key": "Your API Key",
       "api_base": "https://open.bigmodel.cn/api/paas/v4"
-    },
+    }
-  },
+  }
 }
 ```
 
@@ -480,7 +478,7 @@ picoclaw agent -m "Hello"
 ## CLI Reference
 
 | Command                   | Description                   |
-|---------|-------------|
+| ------------------------- | ----------------------------- |
 | `picoclaw onboard`        | Initialize config & workspace |
 | `picoclaw agent -m "..."` | Chat with the agent           |
 | `picoclaw agent`          | Interactive chat mode         |
@@ -515,8 +513,10 @@ This is normal if you haven't configured a search API key yet. PicoClaw will pro
 
 To enable web search:
 
-1. Get a free API key at [https://brave.com/search/api](https://brave.com/search/api) (2000 free queries/month)
+1. **Option 1 (Recommended)**: Get a free API key at [https://brave.com/search/api](https://brave.com/search/api) (2000 free queries/month) for the best results.
-2. Add to `~/.picoclaw/config.json`:
+2. **Option 2 (No Credit Card)**: If you don't have a key, we automatically fall back to **DuckDuckGo** (no key required).
+
+Add the key to `~/.picoclaw/config.json` if using Brave:
 
 ```json
 {
@@ -544,7 +544,7 @@ This happens when another instance of the bot is running. Make sure only one `pi
 ## 📝 API Key Comparison
 
 | Service          | Free Tier           | Use Case                              |
-|---------|-----------|-----------|
+| ---------------- | ------------------- | ------------------------------------- |
 | **OpenRouter**   | 200K tokens/month   | Multiple models (Claude, GPT-4, etc.) |
 | **Zhipu**        | 200K tokens/month   | Best for Chinese users                |
 | **Brave Search** | 2000 queries/month  | Web search functionality              |

pkg/tools/web.go

@@ -13,11 +13,178 @@ import (
 )
 
 const (
-	userAgent = "Mozilla/5.0 (compatible; picoclaw/1.0)"
+	userAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36"
 )
 
-type WebSearchTool struct {
+type SearchProvider interface {
+	Search(ctx context.Context, query string, count int) (string, error)
+}
+
+type BraveSearchProvider struct {
 	apiKey string
+}
+
+func (p *BraveSearchProvider) Search(ctx context.Context, query string, count int) (string, error) {
+	searchURL := fmt.Sprintf("https://api.search.brave.com/res/v1/web/search?q=%s&count=%d",
+		url.QueryEscape(query), count)
+
+	req, err := http.NewRequestWithContext(ctx, "GET", searchURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("Accept", "application/json")
+	req.Header.Set("X-Subscription-Token", p.apiKey)
+
+	client := &http.Client{Timeout: 10 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("failed to read response: %w", err)
+	}
+
+	var searchResp struct {
+		Web struct {
+			Results []struct {
+				Title       string `json:"title"`
+				URL         string `json:"url"`
+				Description string `json:"description"`
+			} `json:"results"`
+		} `json:"web"`
+	}
+
+	if err := json.Unmarshal(body, &searchResp); err != nil {
+		// Log error body for debugging
+		fmt.Printf("Brave API Error Body: %s\n", string(body))
+		return "", fmt.Errorf("failed to parse response: %w", err)
+	}
+
+	results := searchResp.Web.Results
+	if len(results) == 0 {
+		return fmt.Sprintf("No results for: %s", query), nil
+	}
+
+	var lines []string
+	lines = append(lines, fmt.Sprintf("Results for: %s", query))
+	for i, item := range results {
+		if i >= count {
+			break
+		}
+		lines = append(lines, fmt.Sprintf("%d. %s\n   %s", i+1, item.Title, item.URL))
+		if item.Description != "" {
+			lines = append(lines, fmt.Sprintf("   %s", item.Description))
+		}
+	}
+
+	return strings.Join(lines, "\n"), nil
+}
+
+type DuckDuckGoSearchProvider struct{}
+
+func (p *DuckDuckGoSearchProvider) Search(ctx context.Context, query string, count int) (string, error) {
+	searchURL := fmt.Sprintf("https://html.duckduckgo.com/html/?q=%s", url.QueryEscape(query))
+
+	req, err := http.NewRequestWithContext(ctx, "GET", searchURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to create request: %w", err)
+	}
+
+	req.Header.Set("User-Agent", userAgent)
+
+	client := &http.Client{Timeout: 10 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("failed to read response: %w", err)
+	}
+
+	return p.extractResults(string(body), count, query)
+}
+
+func (p *DuckDuckGoSearchProvider) extractResults(html string, count int, query string) (string, error) {
+	// Simple regex based extraction for DDG HTML
+	// Strategy: Find all result containers or key anchors directly
+	
+	// Try finding the result links directly first, as they are the most critical
+	// Pattern: <a class="result__a" href="...">Title</a>
+	// The previous regex was a bit strict. Let's make it more flexible for attributes order/content
+	reLink := regexp.MustCompile(`<a[^>]*class="[^"]*result__a[^"]*"[^>]*href="([^"]+)"[^>]*>([\s\S]*?)</a>`)
+	matches := reLink.FindAllStringSubmatch(html, count+5)
+
+	if len(matches) == 0 {
+		return fmt.Sprintf("No results found or extraction failed. Query: %s", query), nil
+	}
+
+	var lines []string
+	lines = append(lines, fmt.Sprintf("Results for: %s (via DuckDuckGo)", query))
+
+	// Pre-compile snippet regex to run inside the loop
+	// We'll search for snippets relative to the link position or just globally if needed
+	// But simple global search for snippets might mismatch order.
+	// Since we only have the raw HTML string, let's just extract snippets globally and assume order matches (risky but simple for regex)
+	// Or better: Let's assume the snippet follows the link in the HTML
+	
+	// A better regex approach: iterate through text and find matches in order
+	// But for now, let's grab all snippets too
+	reSnippet := regexp.MustCompile(`<a class="result__snippet[^"]*".*?>([\s\S]*?)</a>`)
+	snippetMatches := reSnippet.FindAllStringSubmatch(html, count+5)
+
+	maxItems := min(len(matches), count)
+	
+	for i := 0; i < maxItems; i++ {
+		urlStr := matches[i][1]
+		title := stripTags(matches[i][2])
+		title = strings.TrimSpace(title)
+
+		// URL decoding if needed
+		if strings.Contains(urlStr, "uddg=") {
+			if u, err := url.QueryUnescape(urlStr); err == nil {
+				idx := strings.Index(u, "uddg=")
+				if idx != -1 {
+					urlStr = u[idx+5:]
+				}
+			}
+		}
+
+		lines = append(lines, fmt.Sprintf("%d. %s\n   %s", i+1, title, urlStr))
+		
+		// Attempt to attach snippet if available and index aligns
+		if i < len(snippetMatches) {
+			snippet := stripTags(snippetMatches[i][1])
+			snippet = strings.TrimSpace(snippet)
+			if snippet != "" {
+				lines = append(lines, fmt.Sprintf("   %s", snippet))
+			}
+		}
+	}
+
+	return strings.Join(lines, "\n"), nil
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func stripTags(content string) string {
+	re := regexp.MustCompile(`<[^>]+>`)
+	return re.ReplaceAllString(content, "")
+}
+
+type WebSearchTool struct {
+	provider   SearchProvider
 	maxResults int
 }
 
@@ -25,8 +192,16 @@ func NewWebSearchTool(apiKey string, maxResults int) *WebSearchTool {
 	if maxResults <= 0 || maxResults > 10 {
 		maxResults = 5
 	}
+
+	var provider SearchProvider
+	if apiKey != "" {
+		provider = &BraveSearchProvider{apiKey: apiKey}
+	} else {
+		provider = &DuckDuckGoSearchProvider{}
+	}
+
 	return &WebSearchTool{
-		apiKey:     apiKey,
+		provider:   provider,
 		maxResults: maxResults,
 	}
 }
@@ -59,10 +234,6 @@ func (t *WebSearchTool) Parameters() map[string]interface{} {
 }
 
 func (t *WebSearchTool) Execute(ctx context.Context, args map[string]interface{}) (string, error) {
-	if t.apiKey == "" {
-		return "Error: BRAVE_API_KEY not configured", nil
-	}
-
 	query, ok := args["query"].(string)
 	if !ok {
 		return "", fmt.Errorf("query is required")
@@ -75,61 +246,7 @@ func (t *WebSearchTool) Execute(ctx context.Context, args map[string]interface{}
 		}
 	}
 
-	searchURL := fmt.Sprintf("https://api.search.brave.com/res/v1/web/search?q=%s&count=%d",
+	return t.provider.Search(ctx, query, count)
-		url.QueryEscape(query), count)
-
-	req, err := http.NewRequestWithContext(ctx, "GET", searchURL, nil)
-	if err != nil {
-		return "", fmt.Errorf("failed to create request: %w", err)
-	}
-
-	req.Header.Set("Accept", "application/json")
-	req.Header.Set("X-Subscription-Token", t.apiKey)
-
-	client := &http.Client{Timeout: 10 * time.Second}
-	resp, err := client.Do(req)
-	if err != nil {
-		return "", fmt.Errorf("request failed: %w", err)
-	}
-	defer resp.Body.Close()
-
-	body, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return "", fmt.Errorf("failed to read response: %w", err)
-	}
-
-	var searchResp struct {
-		Web struct {
-			Results []struct {
-				Title       string `json:"title"`
-				URL         string `json:"url"`
-				Description string `json:"description"`
-			} `json:"results"`
-		} `json:"web"`
-	}
-
-	if err := json.Unmarshal(body, &searchResp); err != nil {
-		return "", fmt.Errorf("failed to parse response: %w", err)
-	}
-
-	results := searchResp.Web.Results
-	if len(results) == 0 {
-		return fmt.Sprintf("No results for: %s", query), nil
-	}
-
-	var lines []string
-	lines = append(lines, fmt.Sprintf("Results for: %s", query))
-	for i, item := range results {
-		if i >= count {
-			break
-		}
-		lines = append(lines, fmt.Sprintf("%d. %s\n   %s", i+1, item.Title, item.URL))
-		if item.Description != "" {
-			lines = append(lines, fmt.Sprintf("   %s", item.Description))
-		}
-	}
-
-	return strings.Join(lines, "\n"), nil
 }
 
 type WebFetchTool struct {