roskosmos19/Rhea-4B-fast-0409-high

TEXT GENERATIONPricing:Input $0.4 / Cached $0.08 / Output $0.8Concurrent Unit Cost:1Model Size:4BQuant:BF16Context Size:32kTool Calling:SupportedPublished:Sep 6, 2026License:apache-2.0Architecture:Transformer0.0K Open Weights Featherless Exclusive Cold

Rhea-4B-fast-0409-high is a 4 billion parameter Qwen3ForCausalLM-based model developed by roskosmos19, optimized for agentic and coding tasks. This iteration focuses on faster, cheaper inference by adopting a single-pass reasoning style and a 32,768 token context window. It features a clean tool-calling format and optional tags for chain-of-thought, making it highly efficient for real-world agentic workflows.

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Rhea-4B-fast-0409-high: Optimized for Agentic & Coding Tasks

This model, developed by roskosmos19, is an optimized successor in the Rhea-4B-Coding / Athenea lineage, built on the Qwen3ForCausalLM architecture with 4 billion parameters. It is specifically engineered for enhanced performance in agentic and coding applications, prioritizing speed and cost-efficiency over its predecessors.

Key Optimizations & Capabilities

  • Single-Pass Reasoning: Moves away from forced multi-pass generation, utilizing a single-pass approach with optional <think>...</think> tags for chain-of-thought, significantly reducing latency and inference costs.
  • Efficient Context Handling: Features a 32,768 token context window, designed to cover typical real-world agentic workloads effectively.
  • Clean Tool-Calling: Provides a reliable and streamlined tool-calling format, improving agentic readiness.
  • Optimized Generation Defaults: Tuned with temperature=0.4 and top_p=0.9 for a balance of quality and speed, removing forced long outputs.
  • Lower Inference Cost: Achieves significantly lower VRAM and time consumption compared to previous versions due to its architectural changes.
  • Strong Coding & Reasoning: Retains a core focus on robust coding and reasoning capabilities.

Ideal Use Cases

  • AI Agents: Excellent for developing AI agents that require efficient tool use and flexible reasoning without unnecessary overhead.
  • Code Generation & Analysis: Suited for tasks involving secure and efficient Python function generation, code validation, and general programming assistance.
  • Cost-Sensitive Applications: Recommended for scenarios where inference cost and speed are critical factors, especially in production environments.

For optimal deployment, Q4_K_M or AWQ quantization is suggested, and keeping context within 16k–24k tokens in production is advised for peak performance.