# Technical Context

## 1. Core Technology
- **Language:** Go (Golang)

## 2. Key Libraries & Dependencies
- **HTTP:**
    - `github.com/valyala/fasthttp`: For high-performance non-streaming requests.
    - `net/http`: Go standard library, used for streaming (SSE) requests within the client implementation.
- **Tokenization:**
    - `github.com/tiktoken-go/tokenizer`: For OpenAI-compatible token counting and prompt generation helper functions.
- **Concurrency:**
    - Go standard library (`sync`, `context`, goroutines, channels).
- **Statistics:**
    - `gonum.org/v1/gonum/stat`: For percentile calculations.
    - `sync/atomic`: Used within stats collector for thread-safe counters.
    - `sync.Map`: For thread-safe storage of request results.
- **Configuration:**
    - `github.com/spf13/viper`: Likely used for loading YAML configuration (verify import).
    - `gopkg.in/yaml.v3` (or similar): For YAML parsing.
- **CLI Flags:**
    - Go standard library `flag`.

## 3. Development Environment
- **OS:** macOS (as per user information)
- **Build/Dependency Management:** Go Modules (`go mod`)

## 4. Technical Constraints & Considerations
- **HTTP Client Choice:** Balancing performance (`fasthttp`) and streaming stability (`net/http`). The current approach uses a hybrid within `FastHTTPClient`.
- **Concurrency Limits:** Managing goroutine lifecycle and preventing resource exhaustion.
- **Accurate Timing:** Measuring latency and TTFT precisely, especially across concurrent operations.
- **Memory Management:** Using `sync.Pool` for `fasthttp` objects; being mindful of memory usage when handling large responses or many results.
- **TDD:** Workspace rules mandate Test-Driven Development.