# Models Reference

Complete reference for all data models, DTOs, and records in OpenQuery.

## 📋 Table of Contents

1. [Core Data Models](#core-data-models)
2. [OpenRouter API Models](#openrouter-api-models)
3. [SearxNG API Models](#searxng-api-models)
4. [JSON Serialization](#json-serialization)
5. [Model Relationships](#model-relationships)

## Core Data Models

### OpenQueryOptions

**Location**: `Models/OpenQueryOptions.cs`  
**Type**: `record`  
**Purpose**: Immutable options object for a single query execution

```csharp
public record OpenQueryOptions(
    int Chunks,      // Number of top chunks to include in context
    int Results,     // Search results per generated query
    int Queries,     // Number of search queries to generate (if >1)
    bool Short,      // Request concise answer
    bool Long,       // Request detailed answer
    bool Verbose,    // Enable verbose logging
    string Question  // Original user question (required)
);
```

**Lifecycle**:
- Created in `Program.cs` by combining CLI options, config defaults, and environment variables
- Passed to `OpenQueryApp.RunAsync(options)`

**Validation**: None (assumes valid values from CLI parser/config)

**Example**:
```csharp
var options = new OpenQueryOptions(
    Chunks: 3,
    Results: 5,
    Queries: 3,
    Short: false,
    Long: false,
    Verbose: true,
    Question: "What is quantum entanglement?"
);
```

---

### Chunk

**Location**: `Models/Chunk.cs`  
**Type**: `record`  
**Purpose**: Content chunk with metadata, embedding, and relevance score

```csharp
public record Chunk(
    string Content,      // Text content (typically ~500 chars)
    string SourceUrl,    // Original article URL
    string? Title = null // Article title (optional, may be null)
)
{
    public float[]? Embedding { get; set; }  // Vector embedding (1536-dim for text-embedding-3-small)
    public float Score { get; set; }         // Relevance score (0-1, higher = more relevant)
}
```

**Lifecycle**:
1. **Created** in `SearchTool.ExecuteParallelArticleFetchingAsync`:
   ```csharp
   chunks.Add(new Chunk(chunkText, result.Url, article.Title));
   ```
   At this point: `Embedding = null`, `Score = 0`

2. **Embedded** in `SearchTool.ExecuteParallelEmbeddingsAsync`:
   ```csharp
   validChunks[i].Embedding = validEmbeddings[i];
   ```

3. **Scored** in `SearchTool.RankAndSelectTopChunks`:
   ```csharp
   chunk.Score = EmbeddingService.CosineSimilarity(queryEmbedding, chunk.Embedding!);
   ```

4. **Formatted** into context string:
   ```csharp
   $"[Source {i+1}: {c.Title ?? "Unknown"}]({c.SourceUrl})\n{c.Content}"
   ```

**Properties**:
- `Content`: Never null/empty (filters empty chunks in `ChunkingService`)
- `SourceUrl`: Always provided (from `SearxngResult.Url`)
- `Title`: May be null if article extraction failed to get title
- `Embedding`: Null until phase 3; may remain null if embedding failed
- `Score`: 0 until phase 4; irrelevant for non-embedded chunks

**Equality**: Records use value equality (all properties compared). Two chunks with same content/url/title are equal; embeddings and scores ignored for equality (as they're mutable).

---

### ParallelProcessingOptions

**Location**: `Models/ParallelOptions.cs`  
**Type**: `class`  
**Purpose**: Configuration for parallel/concurrent operations

```csharp
public class ParallelProcessingOptions
{
    public int MaxConcurrentArticleFetches { get; set; } = 10;
    public int MaxConcurrentEmbeddingRequests { get; set; } = 4;
    public int EmbeddingBatchSize { get; set; } = 300;
}
```

**Usage**:
- Instantiated in `SearchTool` constructor (hardcoded new)
- Passed to `EmbeddingService` constructor
- Read by `SearchTool` for article fetching semaphore

**Default Values**:
| Property | Default | Effect |
|----------|---------|--------|
| `MaxConcurrentArticleFetches` | 10 | Up to 10 articles fetched simultaneously |
| `MaxConcurrentEmbeddingRequests` | 4 | Up to 4 embedding batches in parallel |
| `EmbeddingBatchSize` | 300 | Each embedding API call handles up to 300 texts |

**Current Limitation**: These are **compile-time defaults** (hardcoded in `SearchTool.cs`). To make them configurable:
1. Add to `AppConfig`
2. Read in `ConfigManager`
3. Pass through `SearchTool` constructor

---

## OpenRouter API Models

**Location**: `Models/OpenRouter.cs`  
**Purpose**: DTOs for OpenRouter's REST API (JSON serialization)

### Chat Completion

#### `ChatCompletionRequest`
```csharp
public record ChatCompletionRequest(
    [property: JsonPropertyName("model")] string Model,
    [property: JsonPropertyName("messages")] List<Message> Messages,
    [property: JsonPropertyName("tools")] List<ToolDefinition>? Tools = null,
    [property: JsonPropertyName("stream")] bool Stream = false
);
```

**Example**:
```json
{
  "model": "qwen/qwen3.5-flash-02-23",
  "messages": [
    { "role": "system", "content": "You are a helpful assistant." },
    { "role": "user", "content": "What is 2+2?" }
  ],
  "stream": true
}
```

#### `Message`
```csharp
public record Message(
    [property: JsonPropertyName("role")] string Role,
    [property: JsonPropertyName("content")] string? Content = null,
    [property: JsonPropertyName("tool_calls")] List<ToolCall>? ToolCalls = null,
    [property: JsonPropertyName("tool_call_id")] string? ToolCallId = null
)
{
    // Factory method for tool responses
    public static Message FromTool(string content, string toolCallId) =>
        new Message("tool", content, null, toolCallId);
}
```

**Roles**: `"system"`, `"user"`, `"assistant"`, `"tool"`

**Usage**:
- `Content` for text messages
- `ToolCalls` when assistant requests tool use
- `ToolCallId` when responding to tool call

#### `ChatCompletionResponse`
```csharp
public record ChatCompletionResponse(
    [property: JsonPropertyName("choices")] List<Choice> Choices,
    [property: JsonPropertyName("usage")] Usage? Usage = null
);

public record Choice(
    [property: JsonPropertyName("message")] Message Message,
    [property: JsonPropertyName("finish_reason")] string? FinishReason = null
);
```

**Response Example**:
```json
{
  "choices": [
    {
      "message": {
        "role": "assistant",
        "content": "Answer text..."
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 100,
    "completion_tokens": 50,
    "total_tokens": 150
  }
}
```

#### `Usage`
```csharp
public record Usage(
    [property: JsonPropertyName("prompt_tokens")] int PromptTokens,
    [property: JsonPropertyName("completion_tokens")] int CompletionTokens,
    [property: JsonPropertyName("total_tokens")] int TotalTokens
);
```

### Tool Calling (Not Currently Used)

#### `ToolDefinition` / `ToolFunction`
```csharp
public record ToolDefinition(
    [property: JsonPropertyName("type")] string Type,  // e.g., "function"
    [property: JsonPropertyName("function")] ToolFunction Function
);

public record ToolFunction(
    [property: JsonPropertyName("name")] string Name,
    [property: JsonPropertyName("description")] string Description,
    [property: JsonPropertyName("parameters")] JsonElement Parameters  // JSON Schema
);
```

#### `ToolCall` / `FunctionCall`
```csharp
public record ToolCall(
    [property: JsonPropertyName("id")] string Id,
    [property: JsonPropertyName("type")] string Type,
    [property: JsonPropertyName("function")] FunctionCall Function
);

public record FunctionCall(
    [property: JsonPropertyName("name")] string Name,
    [property: JsonPropertyName("arguments")] string Arguments  // JSON string
);
```

**Note**: OpenQuery doesn't use tools currently, but models are defined for future tool-calling capability.

### Streaming

#### `StreamChunk`
```csharp
public record StreamChunk(
    string? TextDelta = null,
    ClientToolCall? Tool = null
);
```

Yielded by `OpenRouterClient.StreamAsync()` for each SSE event.

#### `ChatCompletionChunk` (Server Response)
```csharp
public record ChatCompletionChunk(
    [property: JsonPropertyName("choices")] List<ChunkChoice> Choices
);

public record ChunkChoice(
    [property: JsonPropertyName("delta")] ChunkDelta Delta
);

public record ChunkDelta(
    [property: JsonPropertyName("content")] string? Content = null,
    [property: JsonPropertyName("tool_calls")] List<ToolCall>? ToolCalls = null
);
```

**Streaming Response Example** (SSE):
```
data: {"choices":[{"delta":{"content":"Hello"}}]}
data: {"choices":[{"delta":{"content":" world"}}]}
data: [DONE]
```

`OpenRouterClient.StreamAsync` parses and yields `StreamChunk` with non-null `TextDelta` for content.

### Embeddings

#### `EmbeddingRequest`
```csharp
public record EmbeddingRequest(
    [property: JsonPropertyName("model")] string Model,
    [property: JsonPropertyName("input")] List<string> Input
);
```

**Example**:
```json
{
  "model": "openai/text-embedding-3-small",
  "input": ["text 1", "text 2", ...]
}
```

#### `EmbeddingResponse`
```csharp
public record EmbeddingResponse(
    [property: JsonPropertyName("data")] List<EmbeddingData> Data,
    [property: JsonPropertyName("usage")] Usage Usage
);

public record EmbeddingData(
    [property: JsonPropertyName("embedding")] float[] Embedding,
    [property: JsonPropertyName("index")] int Index
);
```

**Response Example**:
```json
{
  "data": [
    { "embedding": [0.1, 0.2, ...], "index": 0 },
    { "embedding": [0.3, 0.4, ...], "index": 1 }
  ],
  "usage": {
    "prompt_tokens": 100,
    "total_tokens": 100
  }
}
```

**Note**: `_client.EmbedAsync` orders by `index` to match input order.

---

## SearxNG API Models

**Location**: `Models/Searxng.cs`  
**Purpose**: DTOs for SearxNG's JSON response format

### `SearxngRoot`
```csharp
public record SearxngRoot(
    [property: JsonPropertyName("results")] List<SearxngResult> Results
);
```

Top-level response object.

### `SearxngResult`
```csharp
public record SearxngResult(
    [property: JsonPropertyName("title")] string Title,
    [property: JsonPropertyName("url")] string Url,
    [property: JsonPropertyName("content")] string Content  // Snippet/description
);
```

**Fields**:
- `Title`: Result title (from page `<title>` or OpenGraph)
- `Url`: Absolute URL to article
- `Content`: Short snippet (~200 chars) from search engine

**Usage**:
- `Url` passed to `ArticleService.FetchArticleAsync`
- `Title` used as fallback if article extraction fails
- `Content` currently unused (could be for quick answer without fetching)

**Example Response**:
```json
{
  "results": [
    {
      "title": "Quantum Entanglement - Wikipedia",
      "url": "https://en.wikipedia.org/wiki/Quantum_entanglement",
      "content": "Quantum entanglement is a physical phenomenon..."
    }
  ]
}
```

---

## JSON Serialization

### JsonContext (Source Generation)

**Location**: `Models/JsonContexts.cs`  
**Purpose**: Provide source-generated JSON serializer context for AOT compatibility

#### Declaration
```csharp
[JsonSerializable(typeof(ChatCompletionRequest))]
[JsonSerializable(typeof(ChatCompletionResponse))]
[JsonSerializable(typeof(ChatCompletionChunk))]
[JsonSerializable(typeof(EmbeddingRequest))]
[JsonSerializable(typeof(EmbeddingResponse))]
[JsonSerializable(typeof(SearxngRoot))]
[JsonJsonSerializer(typeof(List<string>))]
internal partial class AppJsonContext : JsonSerializerContext
{
}
```

**Usage**:
```csharp
var json = JsonSerializer.Serialize(request, AppJsonContext.Default.ChatCompletionRequest);
var response = JsonSerializer.Deserialize(json, AppJsonContext.Default.ChatCompletionResponse);
```

**Benefits**:
- **AOT-compatible**: No reflection, works with PublishAot=true
- **Performance**: Pre-compiled serializers are faster
- **Trimming safe**: Unused serializers trimmed automatically

**Generated**: Partial class compiled by source generator (no manual implementation)

**Important**: Must include ALL types that will be serialized/deserialized in `[JsonSerializable]` attributes, otherwise runtime exception in AOT.

---

## Model Relationships

### Object Graph (Typical Execution)

```
OpenQueryOptions
    ↓
OpenQueryApp.RunAsync()
    │
    ├─ queryGenerationMessages (List<Message>)
    │   ├─ system: "You are an expert researcher..."
    │   └─ user: "Generate N queries for: {question}"
    │       ↓
    │   ChatCompletionRequest → OpenRouter → ChatCompletionResponse
    │       ↓
    │   List<string> generatedQueries
    │
    ├─ SearchTool.ExecuteAsync()
    │       ↓
    │   ┌─────────────────────────────────────┐
    │   │ Phase 1: Parallel Searches         │
    │   │ SearxngClient.SearchAsync(query) × N
    │   │ → List<SearxngResult>              │
    │   │   (Title, Url, Content)            │
    │   └─────────────────────────────────────┘
    │       ↓
    │   ┌─────────────────────────────────────┐
    │   │ Phase 2: Article Fetch & Chunking  │
    │   │ ArticleService.FetchAsync(Url) × M
    │   │ → Article (TextContent, Title)
    │   │ → ChunkingService.ChunkText → List<string> chunks
    │   │ → Chunk(content, url, title) × K  │
    │   └─────────────────────────────────────┘
    │       ↓
    │   ┌─────────────────────────────────────┐
    │   │ Phase 3: Embeddings                │
    │   │ EmbeddingService.GetEmbeddingsAsync(chunkContents)
    │   │ → float[][] chunkEmbeddings        │
    │   │ → Set chunk.Embedding for each     │
    │   │ Also: GetEmbeddingAsync(question) → float[] queryEmbedding
    │   └─────────────────────────────────────┘
    │       ↓
    │   ┌─────────────────────────────────────┐
    │   │ Phase 4: Ranking                   │
    │   │ For each chunk: Score = CosineSimilarity(queryEmbedding, chunk.Embedding)
    │   │ → Set chunk.Score                 │
    │   │ → OrderByDescending(Score)        │
    │   │ → Take(topChunksLimit) → topChunks (List<Chunk>)
    │   └─────────────────────────────────────┘
    │       ↓
    │   Context string: formatted topChunks
    │       ↓
    └─ OpenQueryApp → final ChatCompletionRequest
        System: "Answer based on context..."
        User: "Context:\n{context}\n\nQuestion: {question}"
            ↓
        StreamAsync() → StreamChunk.TextDelta → Console
```

### Record Immutability

Most DTOs are `record` types:
- **Immutable**: Properties are init-only (`{ get; init; }`)
- **Value semantics**: Equality based on content
- **Thread-safe**: Can be shared across threads

**Exception**:
- `Chunk`: Has mutable properties `Embedding` and `Score` (set during pipeline)
- `ParallelProcessingOptions`: Class with mutable setters
- `AppConfig`: Class with mutable setters

---

## Next Steps

- **[API Reference](../../api/cli.md)** - How these models are used in CLI commands
- **[OpenRouterClient](../../services/OpenRouterClient.md)** - Uses OpenRouter models
- **[SearxngClient](../../services/SearxngClient.md)** - Uses Searxng models
- **[SearchTool](../../components/search-tool.md)** - Orchestrates all models

---

**Quick Reference Table**

| Model | Category | Purpose | Mutable? |
|-------|----------|---------|----------|
| `OpenQueryOptions` | Core | CLI options | No (record) |
| `Chunk` | Core | Content + metadata + ranking | Partially (Embedding, Score) |
| `ParallelProcessingOptions` | Config | Concurrency settings | Yes (class) |
| `ChatCompletionRequest/Response` | OpenRouter | LLM API | No |
| `EmbeddingRequest/Response` | OpenRouter | Embeddings API | No |
| `SearxngRoot/Result` | SearxNG | Search results | No |
| `AppJsonContext` | Internal | JSON serialization | No (generated partial) |