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Intelligence beyond any one model.

An open, programmable decision layer for models and compute.

Industry voices

The shift is already underway

System-level optimizationMark PapermasterAMD CTO & EVP
We’ve become system optimizers, still optimizing every component, but then equally looking at how you optimize how each of the pieces come together.SourcetheCUBE at RAISE Summit · 2026
Trending highlights
Hugging Face models143K+ downloads across open router models
143K+Downloads
96Models
6Collections

As of October 10, 2026, vLLM Semantic Router models on Hugging Face total about 143,000 downloads across 96 models in 6 collections—Decision, Vela, and MoM families.

SourceHugging Face · vllm-sr collections
#1 trending collectionDecision 2.0 tops Hugging Face trending

Decision 2.0 reached #1 on Hugging Face trending collections, leading selected open decision models across every size range on the Jev Decision Index 0.3.

SourceHugging Face collection · Decision 2.0
Community upvoteJev Decision Index author upvotes Decision 2.0

multimodalart, author of the Jev Decision Index Space, upvoted the Decision 2.0 collection on Hugging Face—community recognition from the benchmark that tracks open decision models.

SourceHugging Face collection · Decision 2.0
Vela 2.0 launchOpen foundation routing models

Vela 2.0 ships four open routing models that answer safety, domain, PII, and hallucination questions in one call—with span-level answers.

SourceLaunch post · Vela 2.0
AlphaSignal coverageVela 2.0 covered by AlphaSignal

AlphaSignal reported on Vela 2.0: four open routing models that fold nine LLM router checks into a single call.

SourceAlphaSignal · Vela 2.0
Hugging Face SpaceJev Decision Index on Hugging Face

The community Jev Decision Index Space tracks open decision-model benchmarks and news, with Decision 2.0 models listed among them.

SourceHugging Face Space · Jev Decision Index
v0.4 Hermes releaseDecision and classification models in Hermes

v0.4 Hermes shipped open Decision models and Vela classification models inside one improving Mixture-of-Models system.

SourceRelease post · v0.4 Hermes
Installation

Get started in one line

curl -fsSL https://vllm-sr.ai/install.sh | bash -s -- --channel dev

Development channelMatches the latest docs, including the built-in model runtime.

See it in action

Watch it work.

Demos, deployments, and ideas from the community.

FeaturedAMD

Enterprise AI Inference at Scale with AMD

1 / 7
Architecture

Your models. Your rules.

Choose models and compute for each request.

Models

Closed models
ClaudeOpenAI
Open models
DeepSeekMistral

Different strengths. One model fleet.

Compute

GPU nodes
Local runtime
Model APIs
vLLMSGLangOpenAI API

Route to the backends you configure.

Location

CloudPrivateEdge

You configure where inference runs.

Preference

Quality
Latency
Cost

Set priorities for each task.

Programmable decision layer
ContextPolicy
vLLM Semantic RoutervLLM Semantic Router

Bring the right intelligence to every request.

Per-request choice
ModelBackend
Signals20

Context, intent, safety, preferences, and system state.

Algorithms16

11 selection algorithms and 5 loopers.

Papers19

19 papers on routing, safety, and inference.

Where it fits

One frontend. Compose what you need.

Route chat through a Decision Engine, or call model intelligence directly. Both paths share the frontend and scalable Serving Engine.

vLLM Semantic RoutervLLM Semantic Router
Direct native path · bypasses routing
Shared entry

Frontend

Listeners, authentication, and API contracts.

Chat & Responses/v1/chat/completions/v1/responses
System One · native decisions/v1/systemoneAlias: /v1/decisions
Optional routing layer

Decision Engine

Each entrypoint resolves to an isolated recipe.

  1. 01Signals
  2. 02Projections
  3. 03Decisions
  4. 04Algorithms
Recipe plugins · request & response hooks
Chat backendsLocal, private, or cloud generation
Model tasks
Model execution

Serving Engine

Choose a model deployment, then a ready replica.

Model deployment
Replica 1Replica 2+ replicas
Scale each model independently
ChoiceNoulScoreSetSpan
Specialist workers: classify · embed · rerank
Composable capabilities; not fixed process boundaries.
Chat backendsLocal, private, or cloud generation
CPU / GPUManaged or attached workersWorker APIs are separate from the public frontend.
Chat follows recipe policy to a generation backend. The Decision Engine calls model workers when signals or plugins need them.
Add routing policy

Router mode

Route Chat, Messages, and Responses to your model backends. Keep native decisions available alongside routing.

vllm-sr serve vllm-sr/Decision-2.0-Kai-0.6B

Call /v1/chat/completions or /v1/messages.

Use model intelligence directly

Engine mode

Start the same frontend and model workers with routing disabled. Your application owns the next step.

vllm-sr serve -e vllm-sr/Decision-2.0-Kai-0.6B

Call /v1/systemone with an explicit published model.

Development channelChoose the composition at CLI startup.

Sovereignty AI

Your knowledge. Your control.

Keep private domain knowledge on premises with open models running on your GPUs. Use external frontier models for requests your routing policy allows.

  • Privacy-aware request routing
  • On-prem GPUs. Open models.
  • Frontier models, under your policy.
Explore routing policies
Privacy-aware routingPolicy in control
Incoming requestInternal domain knowledge
Keep on-prem
Policy gateKeep on-prem
PrivacyLocalityAccess
On-prem GPU
Open models
DeepSeekQwenLlama
Domain knowledge stays on-premSelected for private context
External provider
Frontier closed models
ClaudeGPTGemini
Only policy-eligible requestsExcluded for private context
Eligibility firstModel selectionQuality · latency · cost

This animation illustrates a configured privacy policy: internal domain knowledge is routed to open models on on-prem GPUs, while public requests can use external frontier closed models when eligible. Privacy, locality, and access constraints apply before model selection.

Research

Papers behind the router

The ideas that move inference forward.

2026 / PaperPOSITION PAPER

vLLM Semantic Router: Signal Driven Decision Routing for Mixture-of-Modality Models

vLLM Semantic Router Team

arXiv Technical Report

We introduce vLLM Semantic Router, a signal-driven decision routing framework for Mixture-of-Modality deployments that composes heterogeneous signals into deployment-specific routing policies across cost, privacy, latency, and safety constraints.

2026 / PaperVISION PAPER

The Workload-Router-Pool Architecture for LLM Inference Optimization: A Vision Paper from the vLLM Semantic Router Project

Huamin Chen, Xunzhuo Liu, Bowei He, Fuyuan Lyu, Yankai Chen, Xue Liu, Yuhan Liu, Junchen Jiang

arXiv Technical Report

We synthesize the project’s recent routing, fleet, multimodal, and governance results into the Workload-Router-Pool (WRP) architecture, connecting signal-driven routing to a full-stack inference optimization framework and outlining future research directions across workload, router, and pool design.

2026 / Paper

Visual Confused Deputy: Exploiting and Defending Perception Failures in Computer-Using Agents

Xunzhuo Liu, Bowei He, Xue Liu, Andy Luo, Haichen Zhang, Huamin Chen

arXiv Technical Report

We formalize the visual confused deputy as a security failure mode in computer-using agents and introduce a dual-channel guardrail that independently checks click targets and action reasoning before execution.

2026 / Paper

Outcome-Aware Tool Selection for Semantic Routers: Latency-Constrained Learning Without LLM Inference

Huamin Chen, Xunzhuo Liu, Junchen Jiang, Bowei He, Xue Liu

arXiv Technical Report

We introduce Outcome-Aware Tool Selection (OATS), an offline embedding refinement method that improves semantic-router tool ranking under single-digit millisecond CPU budgets without adding serving-time model inference.

2026 / Paper

Adaptive Vision-Language Model Routing for Computer Use Agents

Xunzhuo Liu, Bowei He, Xue Liu, Andy Luo, Haichen Zhang, Huamin Chen

arXiv Technical Report

We propose Adaptive VLM Routing (AVR), which estimates action difficulty and routes computer-use agent steps to the cheapest model that still satisfies a target reliability threshold.

2026 / Paper

98× Faster LLM Routing Without a Dedicated GPU: Flash Attention, Prompt Compression, and Near-Streaming for the vLLM Semantic Router

Xunzhuo Liu, Bowei He, Xue Liu, Andy Luo, Haichen Zhang, Huamin Chen

arXiv Technical Report

We combine Flash Attention, prompt compression, and near-streaming body processing to cut routing latency from seconds to tens of milliseconds while keeping the router lightweight enough to share hardware with serving.

2026 / Paper

inference-fleet-sim: A Queueing-Theory-Grounded Fleet Capacity Planner for LLM Inference

Huamin Chen, Xunzhuo Liu, Yuhan Liu, Junchen Jiang, Bowei He, Xue Liu

arXiv Technical Report

We present a queueing-theory-grounded fleet planner and discrete-event simulator for sizing multi-pool LLM GPU fleets against P99 TTFT targets, without requiring hardware profiling runs up front.

2026 / Paper

FleetOpt: Analytical Fleet Provisioning for LLM Inference with Compress-and-Route as Implementation Mechanism

Huamin Chen, Xunzhuo Liu, Yuhan Liu, Junchen Jiang, Bowei He, Xue Liu

arXiv Technical Report

We derive the minimum-cost two-pool LLM fleet directly from the workload CDF and P99 TTFT target, then use Compress-and-Route to make the optimal boundary deployable in practice.

2026 / Paper

The 1/W Law: An Analytical Study of Context-Length Routing Topology and GPU Generation Gains for LLM Inference Energy Efficiency

Huamin Chen, Xunzhuo Liu, Yuhan Liu, Junchen Jiang, Bowei He, Xue Liu

arXiv Technical Report

We derive the 1/W law showing that tokens per watt roughly halve whenever the serving context window doubles, making context-length routing topology a larger energy-efficiency lever than a pure GPU generation upgrade.

2026 / PaperRAG VERIFICATION

Beyond Document Grounding: Span-Level Hallucination Detection over Code, Tool Output, and Documents

Ádám Kovács, Bowei He, Xue Liu, István Boros, Szilveszter Tóth, Gábor Recski

EMNLP 2026 - GroundLM Workshop

We introduce a unified benchmark for span-level hallucination detection over code, tool output, structured documents, and existing natural-language RAG datasets, built by injecting localized hallucinations with exact character labels into grounded correct answers. Our fine-tuned Qwen3.5-2B detector reaches 0.689 span-F1 on the unified test set and 0.60 on the code-agent source, substantially outperforming LettuceDetect-large and the strongest zero-shot LLM judges evaluated.

2026 / Paper

Conflict-Free Policy Languages for Probabilistic ML Predicates: A Framework and Case Study with the Semantic Router DSL

Xunzhuo Liu, Hao Wu, Huamin Chen, Bowei He, Xue Liu

arXiv Technical Report

We show how probabilistic ML predicates in policy languages can silently co-fire on the same query, and implement conflict detection plus a softmax-based prevention mechanism in the Semantic Router DSL.

2026 / Paper

From Inference Routing to Agent Orchestration: Declarative Policy Compilation with Cross-Layer Verification

Huamin Chen, Xunzhuo Liu, Bowei He, Xue Liu

arXiv Technical Report

We extend the Semantic Router DSL from stateless, per-request routing to multi-step agent workflows, emitting verified decision nodes for orchestration frameworks, Kubernetes artifacts, YANG/NETCONF payloads, and protocol-boundary gates from a single declarative source file.

2026 / Paper

Knowledge Access Beats Model Size: Memory Augmented Routing for Persistent AI Agents

Xunzhuo Liu, Bowei He, Xue Liu, Andy Luo, Haichen Zhang, Huamin Chen

arXiv Technical Report

We show that conversational memory and retrieval-grounded routing let a lightweight 8B model recover most of a 235B model’s performance on persistent user-specific queries while cutting effective inference cost by 96%.

2026 / PaperRAG VERIFICATION

Fast and Faithful: Real-Time Verification for Long-Document Retrieval-Augmented Generation Systems

Xunzhuo Liu, Bowei He, Xue Liu, Haichen Zhang, Huamin Chen

SIGIR 2026 Industry Track

We present a real-time verification component for long-document RAG that processes contexts up to 32K tokens, balancing latency and grounding coverage so interactive systems can detect unsupported answers without falling back to truncated checks.

2026 / Paper

Token-Budget-Aware Pool Routing for Cost-Efficient LLM Inference

Huamin Chen, Xunzhuo Liu, Junchen Jiang, Bowei He, Xue Liu

arXiv Technical Report

We propose token-budget-aware pool routing, which estimates each request’s total token budget using a self-calibrating bytes-per-token ratio and dispatches it to short or long vLLM pools to cut fleet cost while avoiding KV-cache failures.

2025 / Paper

When to Reason: Semantic Router for vLLM

Chen Wang, Xunzhuo Liu, Yuhan Liu, Yue Zhu, Xiangxi Mo, Junchen Jiang, Huamin Chen

NeurIPS - MLForSys

We present a semantic router that classifies queries based on their reasoning requirements and selectively applies reasoning only when beneficial.

2025 / Paper

Category-Aware Semantic Caching for Heterogeneous LLM Workloads

Chen Wang, Xunzhuo Liu, Yue Zhu, Alaa Youssef, Priya Nagpurkar, Huamin Chen

We present a category-aware semantic caching where similarity thresholds, TTLs, and quotas vary by query category, with a hybrid architecture separating in-memory HNSW search from external document storage.

2025 / Paper

Semantic Inference Routing Protocol (SIRP)

Huamin Chen, Luay Jalil

Internet Engineering Task Force (IETF)

This document specifies the Semantic Inference Routing Protocol (SIRP), a framework for content-level classification and semantic routing in AI inference systems.

2025 / Paper

Multi-Provider Extensions for Agentic AI Inference APIs

H. Chen, L. Jalil, N. Cocker

Internet Engineering Task Force (IETF) - Network Management Research Group

This document specifies multi-provider extensions for agentic AI inference APIs. Published: 20 October 2025. Intended Status: Informational. Expires: 23 April 2026.

Community

Researchers and builders, working together.

Maintainer

Xunzhuo Liu

@AMD

Maintainer

Huamin Chen

@Microsoft

Maintainer

Kun-Tai Wu

Software Engineer @Delta Electronics

Maintainer

Aayush Saini

Senior Software Engineer, Data and AI @Red Hat

Maintainer

FAUST

Cloud-native Open Source Contributor

Committer

Guan-Ming Chiu

Software Engineering Intern @Quid

Committer

Abhinav Mahajan

Software Engineer @Barclays

Committer

Park Soobin

Forward Deployed Engineer @Rebellions

Committer

Anup Sharma

Member of Technical Staff @Nutanix

Committer

Alex Jia

Software & Data Engineer

Committer

Ádám Kovács

Co-founder & CTO @KR Labs

Committer

David Shrader

GTM Tech Lead @Google

Committer

yangw

Cloud-native Engineer @DaoCloud

Committer

Ramakrishnan Sathyavageeswaran

Computer Science Engineer @Intuit

Committer

Akshay Viswanathan

PMTS, Silo AI @AMD

Committer

Theo Hsiung

Junior Software Engineer (Research Scientist) @Delta Electronics

Committer

Wilson Wu

Cloud-Native / AI Engineer

Committer

Yincheng Ren

Software Engineer @Meta

Committer

Stefan Wang

AI Infrastructure @LinkedIn

Committer

Binbin Zhang

Container R&D Engineer @Telecom Cloud

Committer

Hao Wu

Individual Contributor

Help shape what comes next.

Meet the team

Ecosystem & partnerships

An open, programmable decision layer for models and compute.

  • AMDAMD
  • Hugging FaceHugging Face
  • MicrosoftMicrosoft
  • IntelIntel
  • NVIDIANVIDIA
  • Red HatRed Hat
  • IBMIBM
  • LiquidLiquid
  • DaoCloudDaoCloud
  • DeltaDelta
  • MBZUAIMBZUAI
  • McGill UniversityMcGill University
  • [KR] Labs[KR] Labs
  • University of ChicagoUniversity of Chicago
  • UC BerkeleyUC Berkeley
  • UMass BostonUMass Boston
  • University of Illinois ChicagoUniversity of Illinois Chicago
  • National Taiwan UniversityNational Taiwan University
  • New York UniversityNew York University
  • UBSUBS
  • AI21AI21
  • BayerBayer
  • DellDell
  • NutanixNutanix
Make it yours

Make every request count.

Explore intelligent routing in the Playground. Bring it to your own stack when you're ready.