<!-- REVIEW: Status claims "Specification (VAPORA v1.0)" — verify against vapora-llm-router/src/ which is production-ready at v1.2.0+ with rig-core 0.30 (doc may reference 0.15) -->
# 🧠 Multi-IA Router
## Routing Inteligente entre Múltiples Proveedores de LLM

**Version**: 0.1.0
**Status**: Specification (VAPORA v1.0 - Multi-Agent Multi-IA)
**Purpose**: Sistema de routing dinámico que selecciona el LLM óptimo por contexto

---

## 🎯 Objetivo

**Problema**:
- Cada tarea necesita un LLM diferente (code ≠ embeddings ≠ review)
- Costos varían enormemente (Ollama gratis vs Claude Opus $$$)
- Disponibilidad varía (rate limits, latencia)
- Necesidad de fallback automático

**Solución**: Sistema inteligente de routing que decide qué LLM usar según:
1. **Contexto de la tarea** (type, domain, complexity)
2. **Reglas predefinidas** (mappings estáticos)
3. **Decisión dinámica** (disponibilidad, costo, carga)
4. **Override manual** (usuario especifica LLM requerido)

---

## 🏗️ Arquitectura

### Layer 1: LLM Providers (Trait Pattern)

```rust
pub enum LLMProvider {
    Claude {
        api_key: String,
        model: String,  // "opus-4", "sonnet-4", "haiku-3"
        max_tokens: usize,
    },
    OpenAI {
        api_key: String,
        model: String,  // "gpt-4", "gpt-4-turbo", "gpt-3.5-turbo"
        max_tokens: usize,
    },
    Gemini {
        api_key: String,
        model: String,  // "gemini-2.0-pro", "gemini-pro", "gemini-flash"
        max_tokens: usize,
    },
    Ollama {
        endpoint: String,  // "http://localhost:11434"
        model: String,     // "llama3.2", "mistral", "neural-chat"
        max_tokens: usize,
    },
}

pub trait LLMClient: Send + Sync {
    async fn complete(
        &self,
        prompt: String,
        context: Option<String>,
    ) -> anyhow::Result<String>;

    async fn stream(
        &self,
        prompt: String,
    ) -> anyhow::Result<tokio::sync::mpsc::Receiver<String>>;

    fn cost_per_1k_tokens(&self) -> f64;
    fn latency_ms(&self) -> u32;
    fn available(&self) -> bool;
}
```

### Layer 2: Task Context Classifier

```rust
#[derive(Debug, Clone, PartialEq)]
pub enum TaskType {
    // Code tasks
    CodeGeneration,
    CodeReview,
    CodeRefactor,
    UnitTest,
    Integration Test,

    // Analysis tasks
    ArchitectureDesign,
    SecurityAnalysis,
    PerformanceAnalysis,

    // Documentation
    DocumentGeneration,
    CodeDocumentation,
    APIDocumentation,

    // Search/RAG
    Embeddings,
    SemanticSearch,
    ContextRetrieval,

    // General
    GeneralQuery,
    Summarization,
    Translation,
}

#[derive(Debug, Clone)]
pub struct TaskContext {
    pub task_type: TaskType,
    pub domain: String,              // "backend", "frontend", "infra"
    pub complexity: Complexity,       // Low, Medium, High, Critical
    pub quality_requirement: Quality, // Low, Medium, High, Critical
    pub latency_required_ms: u32,     // 500 = <500ms required
    pub budget_cents: Option<u32>,    // Cost limit in cents for 1k tokens
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
pub enum Complexity {
    Low,
    Medium,
    High,
    Critical,
}

#[derive(Debug, Clone, PartialEq, PartialOrd)]
pub enum Quality {
    Low,     // Quick & cheap
    Medium,  // Balanced
    High,    // Good quality
    Critical // Best possible
}
```

### Layer 3: Mapping Engine (Reglas Predefinidas)

```rust
pub struct IAMapping {
    pub task_type: TaskType,
    pub primary: LLMProvider,
    pub fallback_order: Vec<LLMProvider>,
    pub reasoning: String,
    pub cost_estimate_per_task: f64,
}

pub static DEFAULT_MAPPINGS: &[IAMapping] = &[
    // Embeddings → Ollama (local, free)
    IAMapping {
        task_type: TaskType::Embeddings,
        primary: LLMProvider::Ollama {
            endpoint: "http://localhost:11434".to_string(),
            model: "nomic-embed-text".to_string(),
            max_tokens: 8192,
        },
        fallback_order: vec![
            LLMProvider::OpenAI {
                api_key: "".to_string(),
                model: "text-embedding-3-small".to_string(),
                max_tokens: 8192,
            },
        ],
        reasoning: "Ollama local es gratis y rápido para embeddings. Fallback a OpenAI si Ollama no disponible".to_string(),
        cost_estimate_per_task: 0.0,  // Gratis localmente
    },

    // Code Generation → Claude Opus (máxima calidad)
    IAMapping {
        task_type: TaskType::CodeGeneration,
        primary: LLMProvider::Claude {
            api_key: "".to_string(),
            model: "opus-4".to_string(),
            max_tokens: 8000,
        },
        fallback_order: vec![
            LLMProvider::OpenAI {
                api_key: "".to_string(),
                model: "gpt-4".to_string(),
                max_tokens: 8000,
            },
        ],
        reasoning: "Claude Opus mejor para código complejo. GPT-4 como fallback".to_string(),
        cost_estimate_per_task: 0.06,  // ~6 cents per 1k tokens
    },

    // Code Review → Claude Sonnet (balance calidad/costo)
    IAMapping {
        task_type: TaskType::CodeReview,
        primary: LLMProvider::Claude {
            api_key: "".to_string(),
            model: "sonnet-4".to_string(),
            max_tokens: 4000,
        },
        fallback_order: vec![
            LLMProvider::Gemini {
                api_key: "".to_string(),
                model: "gemini-pro".to_string(),
                max_tokens: 4000,
            },
        ],
        reasoning: "Sonnet balance perfecto. Gemini como fallback".to_string(),
        cost_estimate_per_task: 0.015,
    },

    // Documentation → GPT-4 (mejor formato)
    IAMapping {
        task_type: TaskType::DocumentGeneration,
        primary: LLMProvider::OpenAI {
            api_key: "".to_string(),
            model: "gpt-4".to_string(),
            max_tokens: 4000,
        },
        fallback_order: vec![
            LLMProvider::Claude {
                api_key: "".to_string(),
                model: "sonnet-4".to_string(),
                max_tokens: 4000,
            },
        ],
        reasoning: "GPT-4 mejor formato para docs. Claude como fallback".to_string(),
        cost_estimate_per_task: 0.03,
    },

    // Quick Queries → Gemini Flash (velocidad)
    IAMapping {
        task_type: TaskType::GeneralQuery,
        primary: LLMProvider::Gemini {
            api_key: "".to_string(),
            model: "gemini-flash-2.0".to_string(),
            max_tokens: 1000,
        },
        fallback_order: vec![
            LLMProvider::Ollama {
                endpoint: "http://localhost:11434".to_string(),
                model: "llama3.2".to_string(),
                max_tokens: 1000,
            },
        ],
        reasoning: "Gemini Flash muy rápido. Ollama como fallback".to_string(),
        cost_estimate_per_task: 0.002,
    },
];
```

### Layer 4: Routing Engine (Decisiones Dinámicas)

```rust
pub struct LLMRouter {
    pub mappings: HashMap<TaskType, Vec<LLMProvider>>,
    pub providers: HashMap<String, Box<dyn LLMClient>>,
    pub cost_tracker: CostTracker,
    pub rate_limiter: RateLimiter,
}

impl LLMRouter {
    /// Routing decision: hybrid (rules + dynamic + override)
    pub async fn route(
        &mut self,
        context: TaskContext,
        override_llm: Option<LLMProvider>,
    ) -> anyhow::Result<LLMProvider> {
        // 1. Si hay override manual, usar ese
        if let Some(llm) = override_llm {
            self.cost_tracker.log_usage(&llm, &context);
            return Ok(llm);
        }

        // 2. Obtener mappings predefinidos
        let mut candidates = self.get_mapping(&context.task_type)?;

        // 3. Filtrar por disponibilidad (rate limits, latencia)
        candidates = self.filter_by_availability(candidates).await?;

        // 4. Filtrar por presupuesto si existe
        if let Some(budget) = context.budget_cents {
            candidates = candidates.into_iter()
                .filter(|llm| llm.cost_per_1k_tokens() * 10.0 < budget as f64)
                .collect();
        }

        // 5. Seleccionar por balance calidad/costo/latencia
        let selected = self.select_optimal(candidates, &context)?;

        self.cost_tracker.log_usage(&selected, &context);
        Ok(selected)
    }

    async fn filter_by_availability(
        &self,
        candidates: Vec<LLMProvider>,
    ) -> anyhow::Result<Vec<LLMProvider>> {
        let mut available = Vec::new();
        for llm in candidates {
            if self.rate_limiter.can_use(&llm).await? {
                available.push(llm);
            }
        }
        Ok(available.is_empty() ? candidates : available)
    }

    fn select_optimal(
        &self,
        candidates: Vec<LLMProvider>,
        context: &TaskContext,
    ) -> anyhow::Result<LLMProvider> {
        // Scoring: quality * 0.4 + cost * 0.3 + latency * 0.3
        let best = candidates.iter().max_by(|a, b| {
            let score_a = self.score_llm(a, context);
            let score_b = self.score_llm(b, context);
            score_a.partial_cmp(&score_b).unwrap()
        });

        Ok(best.ok_or(anyhow::anyhow!("No LLM available"))?.clone())
    }

    fn score_llm(&self, llm: &LLMProvider, context: &TaskContext) -> f64 {
        let quality_score = match context.quality_requirement {
            Quality::Critical => 1.0,
            Quality::High => 0.9,
            Quality::Medium => 0.7,
            Quality::Low => 0.5,
        };

        let cost = llm.cost_per_1k_tokens();
        let cost_score = 1.0 / (1.0 + cost);  // Inverse: lower cost = higher score

        let latency = llm.latency_ms();
        let latency_score = 1.0 / (1.0 + latency as f64);

        quality_score * 0.4 + cost_score * 0.3 + latency_score * 0.3
    }
}
```

### Layer 5: Cost Tracking & Monitoring

```rust
pub struct CostTracker {
    pub tasks_completed: HashMap<TaskType, u32>,
    pub total_tokens_used: u64,
    pub total_cost_cents: u32,
    pub cost_by_provider: HashMap<String, u32>,
    pub cost_by_task_type: HashMap<TaskType, u32>,
}

impl CostTracker {
    pub fn log_usage(&mut self, llm: &LLMProvider, context: &TaskContext) {
        let provider_name = llm.provider_name();
        let cost = (llm.cost_per_1k_tokens() * 10.0) as u32;  // Estimate per task

        *self.cost_by_provider.entry(provider_name).or_insert(0) += cost;
        *self.cost_by_task_type.entry(context.task_type.clone()).or_insert(0) += cost;
        self.total_cost_cents += cost;
        *self.tasks_completed.entry(context.task_type.clone()).or_insert(0) += 1;
    }

    pub fn monthly_cost_estimate(&self) -> f64 {
        self.total_cost_cents as f64 / 100.0  // Convert to dollars
    }

    pub fn generate_report(&self) -> String {
        format!(
            "Cost Report:\n  Total: ${:.2}\n  By Provider: {:?}\n  By Task: {:?}",
            self.monthly_cost_estimate(),
            self.cost_by_provider,
            self.cost_by_task_type
        )
    }
}
```

---

## 🔧 Routing: Tres Modos

### Modo 1: Reglas Estáticas (Default)

```rust
// Automático, usa DEFAULT_MAPPINGS
let router = LLMRouter::new();
let llm = router.route(
    TaskContext {
        task_type: TaskType::CodeGeneration,
        domain: "backend".to_string(),
        complexity: Complexity::High,
        quality_requirement: Quality::High,
        latency_required_ms: 5000,
        budget_cents: None,
    },
    None,  // Sin override
).await?;
// Resultado: Claude Opus (regla predefinida)
```

### Modo 2: Decisión Dinámica (Smart)

```rust
// Router evalúa disponibilidad, latencia, costo
let router = LLMRouter::with_tracking();
let llm = router.route(
    TaskContext {
        task_type: TaskType::CodeReview,
        domain: "frontend".to_string(),
        complexity: Complexity::Medium,
        quality_requirement: Quality::Medium,
        latency_required_ms: 2000,
        budget_cents: Some(20),  // Max 2 cents por task
    },
    None,
).await?;
// Router elige entre Sonnet vs Gemini según disponibilidad y presupuesto
```

### Modo 3: Override Manual (Control Total)

```rust
// Usuario especifica exactamente qué LLM usar
let llm = router.route(
    context,
    Some(LLMProvider::Claude {
        api_key: "sk-...".to_string(),
        model: "opus-4".to_string(),
        max_tokens: 8000,
    }),
).await?;
// Usa exactamente lo especificado, registra en cost tracker
```

---

## 📊 Configuración (vapora.toml)

```toml
[llm_router]
# Mapeos personalizados (override DEFAULT_MAPPINGS)
[[llm_router.custom_mapping]]
task_type = "CodeGeneration"
primary_provider = "claude"
primary_model = "opus-4"
fallback_providers = ["openai:gpt-4"]

# Proveedores disponibles
[[llm_router.providers]]
name = "claude"
api_key = "${ANTHROPIC_API_KEY}"
model_variants = ["opus-4", "sonnet-4", "haiku-3"]
rate_limit = { tokens_per_minute = 1000000 }

[[llm_router.providers]]
name = "openai"
api_key = "${OPENAI_API_KEY}"
model_variants = ["gpt-4", "gpt-4-turbo"]
rate_limit = { tokens_per_minute = 500000 }

[[llm_router.providers]]
name = "gemini"
api_key = "${GEMINI_API_KEY}"
model_variants = ["gemini-pro", "gemini-flash-2.0"]

[[llm_router.providers]]
name = "ollama"
endpoint = "http://localhost:11434"
model_variants = ["llama3.2", "mistral", "neural-chat"]
rate_limit = { tokens_per_minute = 10000000 }  # Local, sin límites reales

# Cost tracking
[llm_router.cost_tracking]
enabled = true
warn_when_exceeds_cents = 1000  # Warn if daily cost > $10
```

---

## 🎯 Implementation Checklist

- [ ] Trait `LLMClient` + implementaciones (Claude, OpenAI, Gemini, Ollama)
- [ ] `TaskContext` y clasificación de tareas
- [ ] `IAMapping` y DEFAULT_MAPPINGS
- [ ] `LLMRouter` con routing híbrido
- [ ] Fallback automático + error handling
- [ ] `CostTracker` para monitoreo
- [ ] Config loading desde vapora.toml
- [ ] CLI: `vapora llm-router status` (ver providers, costos)
- [ ] Tests unitarios (routing logic)
- [ ] Integration tests (real providers)

---

## 📈 Success Metrics

✅ Routing decision < 100ms
✅ Fallback automático funciona
✅ Cost tracking preciso
✅ Documentación de costos por tarea
✅ Override manual siempre funciona
✅ Rate limiting respetado

---

**Version**: 0.1.0
**Status**: ✅ Specification Complete (VAPORA v1.0)
**Purpose**: Multi-IA routing system para orquestación de agentes
