# SQ-014: SDK Producer

**Status:** `[ ] TODO`
**Blocked by:** SQ-010
**Priority:** Medium

## Description

Ergonomic Rust producer client in sq-sdk. Handles connection management, batching, and retry logic.

## Files to Create/Modify

- `crates/sq-sdk/src/lib.rs` - re-exports
- `crates/sq-sdk/src/connection.rs` - gRPC channel management
- `crates/sq-sdk/src/producer.rs` - Producer with batching, linger timer, retry
- `crates/sq-sdk/src/error.rs` - SqError type

## Producer API

```rust
pub struct ProducerConfig {
    pub server_addresses: Vec<String>,
    pub default_ack_mode: AckMode,
    pub max_retries: u32,
    pub retry_backoff_ms: u64,
}

pub struct Producer { /* ... */ }

impl Producer {
    pub async fn connect(config: ProducerConfig) -> Result<Self, SqError>;
    pub async fn send(&self, topic: &str, key: Option<&[u8]>, value: &[u8]) -> Result<SendResult, SqError>;
    pub async fn send_batch(&self, messages: Vec<ProducerMessage>) -> Result<Vec<SendResult>, SqError>;
}
```

## Acceptance Criteria

- [ ] Producer connects to running server, sends message, gets offset back
- [ ] Send batch: all messages get sequential offsets
- [ ] Connection failure: returns appropriate error
- [ ] Multiple server addresses: round-robin or failover