geny-harness

Rust-core Python library — A drop-in replacement for geny-executor, providing the same 16-stage dual-abstraction agent pipeline architecture.

pip install geny-harness

geny-executor vs geny-harness: What's Different?

Both libraries provide identical Python APIs — the same classes, same methods, same import paths. You can switch between them by changing a single import. The difference is where the code runs.

Architecture Comparison

geny-executor (v0.3.0)                    geny-harness (v0.3.0)
┌─────────────────────────┐               ┌─────────────────────────┐
│     Python Application  │               │     Python Application  │
├─────────────────────────┤               ├─────────────────────────┤
│  Pipeline Orchestration │  Python       │  Pipeline Orchestration │  Python
│  16 Stage Execution     │               │  16 Stage Execution     │
│  EventBus / Session     │               │  EventBus / Session     │
├─────────────────────────┤               ├─────────────────────────┤
│  PipelineState (40+fld) │  Python       │  PipelineState (40+fld) │  Rust (PyO3)
│  TokenUsage / Metrics   │  dataclass    │  TokenUsage / Metrics   │  Rust struct
│  PipelineConfig         │               │  PipelineConfig         │
│  PipelineResult         │               │  PipelineResult         │
│  PipelineEvent          │               │  PipelineEvent          │
│  Error Hierarchy        │               │  Error Hierarchy        │  Rust enum
├─────────────────────────┤               ├─────────────────────────┤
│          N/A            │               │  Full Rust Core Engine  │  148 .rs files
│                         │               │  (16 stages, 60+ strat.)│  Pure Rust
│                         │               │  reqwest HTTP client    │
│                         │               │  tokio async runtime    │
└─────────────────────────┘               └─────────────────────────┘
   176 Python files                          144 Rust + 34 Python files
   deps: anthropic, pydantic, mcp           deps: Rust (compiled), anthropic

What's Actually in Rust

The data layer is implemented in Rust and exposed to Python via PyO3:

Additionally, geny-harness contains a complete Rust implementation of the entire pipeline engine (148 .rs files), including all 16 stages and 60+ strategy implementations. This Rust core is designed for:

• Future native execution — bypassing Python entirely for maximum throughput
• Embedding in Rust applications — use the pipeline engine directly from Rust/C/C++
• WebAssembly compilation — run the pipeline in browsers or edge environments

What's Still in Python (Same as executor)

The pipeline orchestration layer remains in Python for both libraries:

• Pipeline class (3-phase execution engine)
• EventBus (pub/sub with pattern matching)
• Session / SessionManager
• PipelineBuilder / PipelinePresets
• All 16 stage implementations (using anthropic SDK for API calls)

This means the actual pipeline execution flow is identical. The Anthropic API calls, streaming, tool execution, and agent loops work exactly the same way.

Performance Characteristics

Key insight: For the current Python-orchestrated usage pattern, there is no significant performance difference. The real performance advantage of geny-harness will emerge when:

1. The Rust pipeline engine is used natively (without Python)
2. Multiple pipelines run concurrently via tokio
3. State serialization/deserialization is done in Rust (JSON, MessagePack)

When to Use Which

Quick Start

# Identical to geny-executor — just change the import
from geny_harness import PipelinePresets

pipeline = PipelinePresets.agent(
    api_key="sk-ant-...",
    model="claude-sonnet-4-20250514",
    system_prompt="You are a helpful assistant.",
)

result = await pipeline.run("Hello!")
print(result.text)

Drop-in Replacement

# Before (geny-executor)
from geny_executor import Pipeline, PipelineConfig, PipelinePresets
from geny_executor.session.manager import SessionManager

# After (geny-harness) — just change the package name
from geny_harness import Pipeline, PipelineConfig, PipelinePresets
from geny_harness.session.manager import SessionManager

Project Structure

geny-harness/
├── crates/
│   ├── geny-harness-core/    # Pure Rust library (148 .rs files)
│   │   └── src/
│   │       ├── core/          # Pipeline, State, Config, Errors, Builder
│   │       ├── events/        # EventBus, PipelineEvent
│   │       ├── session/       # Session, Manager, Freshness
│   │       ├── tools/         # Tool, Registry, MCP
│   │       └── stages/        # 16 stages × (interface + types + artifact)
│   └── geny-harness-py/      # PyO3 bindings (cdylib)
├── python/
│   └── geny_harness/          # Python package
│       ├── core/              # Pipeline, Builder, Presets, Stage
│       ├── events/            # EventBus
│       ├── session/           # Session, Manager
│       ├── stages/            # 16 stage implementations
│       └── tools/             # Tool, Registry
└── tests/

Supported Platforms

• Python: 3.10 — 3.14
• OS: Linux (x86_64), Windows (x64), macOS (arm64)
• Rust: 2021 edition (for building from source)

License

MIT