add probe usage doc

PROBE_USAGE.md

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+# Probe
+
+[![npm version](https://img.shields.io/npm/v/@buger/probe)](https://www.npmjs.com/package/@buger/probe)
+
+Probe is a powerful, AI-augmented code search and extraction tool. It combines fast, tree-sitter–powered queries with optional LLM integration to help you find, extract, and understand code across any codebase.
+
+---
+
+## 📦 Installation
+
+The easiest way to install Probe is via npm:
+
+```bash
+npm install -g @buger/probe@latest
+```
+
+Or using curl (for macOS and Linux):
+
+```bash
+curl -fsSL https://raw.githubusercontent.com/buger/probe/main/install.sh | bash
+```
+
+## 🔍 Basic Search Example
+
+Search for code containing specific phrases in the current directory:
+
+```bash
+probe search "parser" ./
+```
+
+This will search for the terms "parser" in your codebase and return the most relevant code blocks.
+
+## 🔄 Advanced Search (with Token Limiting)
+
+Limit the total tokens for AI tools with context window constraints:
+
+```bash
+probe search "prompt injection" ./ --max-tokens 10000
+```
+
+## 💾 Session-Based Caching
+
+Use session IDs to avoid seeing the same code blocks multiple times in related searches:
+
+```bash
+# First search - generates a session ID
+probe search "authentication" --session ""
+# Session: a1b2 (example output)
+
+# Subsequent searches - reuse the session ID
+probe search "login" --session "a1b2"
+# Will skip code blocks already shown in the previous search
+```
+
+## 🔎 Elastic Search Queries
+
+Use advanced query syntax for more powerful searches:
+
+```bash
+# Use AND operator for terms that must appear together
+probe search "error AND handling" ./
+
+# Use OR operator for alternative terms
+probe search "login OR authentication OR auth" ./src
+
+# Group terms with parentheses for complex queries
+probe search "(error OR exception) AND (handle OR process)" ./
+
+# Use wildcards for partial matching
+probe search "auth* connect*" ./
+
+# Exclude terms with NOT operator
+probe search "database NOT sqlite" ./
+```
+
+## 📋 Extract Code Blocks
+
+Extract a specific function or code block containing a specific line:
+
+```bash
+probe extract src/main.rs:42
+```
+
+This uses tree-sitter to find the closest suitable parent node (function, struct, class, etc.) for that line.
+
+You can even pipe failing test output:
+
+```bash
+go test | probe extract
+```
+
+Extract code with LLM prompt and instructions for AI integration:
+
+```bash
+# Extract with engineer prompt template
+probe extract src/auth.rs#authenticate --prompt engineer --instructions "Explain this authentication function"
+
+# Extract with architect prompt template
+probe extract src/api.js --prompt architect --instructions "Analyze this API module"
+```
+
+## 🔍 Query Code Structures
+
+Find specific code structures using tree-sitter patterns:
+
+```bash
+# Find JavaScript functions
+probe query "function $NAME($$$PARAMS) $$$BODY" ./src --language javascript
+
+# Find Python functions
+probe query "def $NAME($$$PARAMS): $$$BODY" ./src --language python
+
+# Find Go structs
+probe query "type $NAME struct { $$$FIELDS }" ./src --language go
+```
+
+## 💬 Interactive AI Chat
+
+Use the built-in AI assistant with web interface:
+
+```bash
+# Run directly with npx (no installation needed)
+npx -y @buger/probe-chat@latest --web
+npx -y @buger/probe-chat@latest
+
+# Set your API key first
+export ANTHROPIC_API_KEY=your_api_key
+# Or for OpenAI
+# export OPENAI_API_KEY=your_api_key
+# Or for Gemini
+# export GOOGLE_API_KEY=your_api_key
+
+# Specify a directory to search (optional)
+npx -y @buger/probe-chat@latest /path/to/your/project
+```
+
+Example questions you might ask:
+
+- "How does the workers pick up jobs?"
+- "How does the mcp functionality work?"
+- "What are the main components of the windmill backend?"
+
+## 🔌 MCP Server Integration
+
+Integrate with any AI editor by adding this to your MCP configuration:
+
+```json
+{
+  "mcpServers": {
+    "memory": {
+      "command": "npx",
+      "args": ["-y", "@buger/probe-mcp"]
+    }
+  }
+}
+```
+
+## 📖 Official Documentation
+
+https://probeai.dev/features