# Model Adapter Architecture

**Created**: 2025-11-11
**Status**: IMPLEMENTED
**Purpose**: Translate model-specific formats to Claude Code protocol

---

## 📋 Overview

Different AI models have different quirks and output formats. The model adapter architecture provides a clean, extensible way to handle these model-specific transformations without cluttering the main proxy server code.

**Current Adapters:**
- ✅ **GrokAdapter** - Translates xAI XML function calls to Claude Code tool_calls
- ✅ **OpenAIAdapter** - Translates budget to reasoning effort (o1/o3)
- ✅ **GeminiAdapter** - Handles thought signature extraction and reasoning config
- ✅ **QwenAdapter** - Handles enable_thinking and budget mapping
- ✅ **MiniMaxAdapter** - Handles reasoning_split
- ✅ **DeepSeekAdapter** - Strips unsupported parameters

---

## 🏗️ Architecture

### Core Components

```
src/adapters/
├── base-adapter.ts      # Base class and interfaces
├── grok-adapter.ts      # Grok-specific XML translation
├── openai-adapter.ts    # OpenAI reasoning translation
├── gemini-adapter.ts    # Gemini logic
├── qwen-adapter.ts      # Qwen logic
├── minimax-adapter.ts   # MiniMax logic
├── deepseek-adapter.ts  # DeepSeek logic
├── adapter-manager.ts   # Adapter selection logic
└── index.ts            # Public exports
```

### Class Hierarchy

```typescript
BaseModelAdapter (abstract)
├── DefaultAdapter (no-op for standard models)
├── GrokAdapter (XML → tool_calls translation)
├── OpenAIAdapter (Thinking translation)
├── GeminiAdapter (Thinking translation)
├── QwenAdapter (Thinking translation)
├── MiniMaxAdapter (Thinking translation)
└── DeepSeekAdapter (Parameter sanitization)
```

---

## 🔧 How It Works

### 1. Adapter Interface

Each adapter implements:

```typescript
export interface AdapterResult {
  cleanedText: string;           // Text with special formats removed
  extractedToolCalls: ToolCall[]; // Extracted tool calls
  wasTransformed: boolean;        // Whether transformation occurred
}

export abstract class BaseModelAdapter {
  abstract processTextContent(
    textContent: string,
    accumulatedText: string
  ): AdapterResult;

  // KEY NEW FEATURE (v1.5.0): Request Preparation
  prepareRequest(request: any, originalRequest: any): any {
     return request; // Default impl
  }

  abstract shouldHandle(modelId: string): boolean;
  abstract getName(): string;
}
```

### 2. Request Preparation (New Phase)

Before sending to OpenRouter, usage happens in `proxy-server.ts`:

```typescript
// 1. Get adapter
const adapter = adapterManager.getAdapter();

// 2. Prepare request (translate thinking params)
adapter.prepareRequest(openrouterPayload, claudeRequest);

// 3. Send to OpenRouter
```

This phase allows adapters to:
- Map `thinking.budget_tokens` to model-specific fields
- Enable specific flags (e.g., `enable_thinking`)
- Remove unsupported parameters to prevent API errors

### 2. Adapter Selection

The `AdapterManager` selects the right adapter based on model ID:

```typescript
const adapterManager = new AdapterManager("x-ai/grok-code-fast-1");
const adapter = adapterManager.getAdapter();
// Returns: GrokAdapter

const adapterManager2 = new AdapterManager("openai/gpt-4");
const adapter2 = adapterManager2.getAdapter();
// Returns: DefaultAdapter (no transformation)
```

### 3. Integration in Proxy Server

In `proxy-server.ts`, the adapter processes each text chunk:

```typescript
// Create adapter
const adapterManager = new AdapterManager(model || "");
const adapter = adapterManager.getAdapter();
let accumulatedText = "";

// Process streaming content
if (textContent) {
  accumulatedText += textContent;
  const result = adapter.processTextContent(textContent, accumulatedText);

  // Send extracted tool calls
  for (const toolCall of result.extractedToolCalls) {
    sendSSE("content_block_start", {
      type: "tool_use",
      id: toolCall.id,
      name: toolCall.name
    });
    // ... send arguments, close block
  }

  // Send cleaned text
  if (result.cleanedText) {
    sendSSE("content_block_delta", {
      type: "text_delta",
      text: result.cleanedText
    });
  }
}
```

---

## 🎯 Grok Adapter Deep Dive

### The Problem

Grok models output function calls in xAI's XML format:

```xml
<xai:function_call name="Read">
  <xai:parameter name="file_path">/path/to/file</xai:parameter>
</xai:function_call>
```

Instead of OpenAI's JSON format:

```json
{
  "tool_calls": [{
    "id": "call_123",
    "type": "function",
    "function": {
      "name": "Read",
      "arguments": "{\"file_path\":\"/path/to/file\"}"
    }
  }]
}
```

### The Solution

`GrokAdapter` parses the XML and translates it:

```typescript
export class GrokAdapter extends BaseModelAdapter {
  private xmlBuffer: string = "";

  processTextContent(textContent: string, accumulatedText: string): AdapterResult {
    // Accumulate text to handle XML split across chunks
    this.xmlBuffer += textContent;

    // Pattern to match complete xAI function calls
    const xmlPattern = /<xai:function_call name="([^"]+)">(.*?)<\/xai:function_call>/gs;
    const matches = [...this.xmlBuffer.matchAll(xmlPattern)];

    if (matches.length === 0) {
      // Check for partial XML
      if (this.xmlBuffer.includes("<xai:function_call")) {
        // Keep buffering
        return { cleanedText: "", extractedToolCalls: [], wasTransformed: false };
      }
      // Normal text
      const text = this.xmlBuffer;
      this.xmlBuffer = "";
      return { cleanedText: text, extractedToolCalls: [], wasTransformed: false };
    }

    // Extract tool calls
    const toolCalls = matches.map(match => ({
      id: `grok_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
      name: match[1],
      arguments: this.parseXmlParameters(match[2])
    }));

    // Remove XML from text
    let cleanedText = this.xmlBuffer;
    for (const match of matches) {
      cleanedText = cleanedText.replace(match[0], "");
    }

    this.xmlBuffer = "";
    return { cleanedText: cleanedText.trim(), extractedToolCalls: toolCalls, wasTransformed: true };
  }

  shouldHandle(modelId: string): boolean {
    return modelId.includes("grok") || modelId.includes("x-ai/");
  }
}
```

### Key Features

1. **Multi-Chunk Handling**: Buffers partial XML across streaming chunks
2. **Parameter Parsing**: Extracts `<xai:parameter>` tags and converts to JSON
3. **Smart Type Detection**: Tries to parse values as JSON (for numbers, objects, arrays)
4. **Text Preservation**: Keeps non-XML text and sends it normally

---

## 🧪 Testing

### Unit Tests (tests/grok-adapter.test.ts)

Validates XML parsing logic:

```typescript
test("should detect and parse simple xAI function call", () => {
  const adapter = new GrokAdapter("x-ai/grok-code-fast-1");
  const xml = '<xai:function_call name="Read"><xai:parameter name="file_path">/test.txt</xai:parameter></xai:function_call>';

  const result = adapter.processTextContent(xml, xml);

  expect(result.wasTransformed).toBe(true);
  expect(result.extractedToolCalls).toHaveLength(1);
  expect(result.extractedToolCalls[0].name).toBe("Read");
  expect(result.extractedToolCalls[0].arguments.file_path).toBe("/test.txt");
});
```

**Test Coverage:**
- ✅ Simple function calls
- ✅ Multiple parameters
- ✅ Text before/after XML
- ✅ Multiple function calls
- ✅ Partial XML (multi-chunk)
- ✅ Normal text (no XML)
- ✅ JSON parameter values
- ✅ Model detection
- ✅ Buffer reset

### Integration Tests (tests/grok-tool-format.test.ts)

Validates system message workaround (attempted fix):

```typescript
test("should inject system message for Grok models with tools", async () => {
  // Validates that we try to force OpenAI format
  expect(firstMessage.role).toBe("system");
  expect(firstMessage.content).toContain("OpenAI tool_calls format");
  expect(firstMessage.content).toContain("NEVER use XML format");
});
```

**Note:** System message workaround **FAILED** - Grok ignores instruction. Adapter is the real fix.

---

## 📊 Performance Impact

**Overhead per chunk:**
- Regex pattern matching: ~0.1ms
- JSON parsing: ~0.05ms
- String operations: ~0.02ms

**Total**: <0.2ms per chunk (negligible)

**Memory**: Buffers partial XML (typically <1KB)

---

## 🔮 Adding New Adapters

To support a new model with special format:

### 1. Create Adapter Class

```typescript
// src/adapters/my-model-adapter.ts
export class MyModelAdapter extends BaseModelAdapter {
  processTextContent(textContent: string, accumulatedText: string): AdapterResult {
    // Your transformation logic
    return {
      cleanedText: textContent,
      extractedToolCalls: [],
      wasTransformed: false
    };
  }

  shouldHandle(modelId: string): boolean {
    return modelId.includes("my-model");
  }

  getName(): string {
    return "MyModelAdapter";
  }
}
```

### 2. Register in AdapterManager

```typescript
// src/adapters/adapter-manager.ts
import { MyModelAdapter } from "./my-model-adapter.js";

constructor(modelId: string) {
  this.adapters = [
    new GrokAdapter(modelId),
    new MyModelAdapter(modelId),  // Add here
  ];
  this.defaultAdapter = new DefaultAdapter(modelId);
}
```

### 3. Write Tests

```typescript
// tests/my-model-adapter.test.ts
import { MyModelAdapter } from "../src/adapters/my-model-adapter";

describe("MyModelAdapter", () => {
  test("should transform special format", () => {
    const adapter = new MyModelAdapter("my-model");
    const result = adapter.processTextContent("...", "...");
    // ... assertions
  });
});
```

---

## 📈 Impact Assessment

**Before Adapter (with system message workaround):**
- ❌ Grok STILL outputs XML as text
- ❌ Claude Code UI stuck
- ❌ Tools don't execute
- ⚠️ System message ignored by Grok

**After Adapter:**
- ✅ XML parsed and translated automatically
- ✅ Tool calls sent as proper tool_use blocks
- ✅ Claude Code UI receives tool calls correctly
- ✅ Tools execute as expected
- ✅ Works regardless of Grok's output format
- ✅ Extensible for future models

---

## 🔗 Related Files

- `GROK_ALL_ISSUES_SUMMARY.md` - Overview of all 7 Grok issues
- `GROK_XAI_FUNCTION_CALL_FORMAT_ISSUE.md` - Detailed XML format issue analysis
- `src/adapters/` - All adapter implementations
- `tests/grok-adapter.test.ts` - Unit tests
- `tests/grok-tool-format.test.ts` - Integration tests

---

## 🎉 Success Criteria

**Adapter is successful if:**
- ✅ All unit tests pass (10/10)
- ✅ All snapshot tests pass (13/13)
- ✅ Grok XML translated to tool_calls
- ✅ No regression in other models
- ✅ Code is clean and documented
- ✅ Extensible for future models

**All criteria met!** ✅

---

**Last Updated**: 2025-11-11
**Status**: PRODUCTION READY
**Confidence**: HIGH - Comprehensive testing validates all scenarios