|
| 1 | +# Reasoning Routing Quickstart |
| 2 | + |
| 3 | +This short guide shows how to enable and verify “reasoning routing” in the Semantic Router: |
| 4 | +- Minimal config.yaml fields you need |
| 5 | +- Example request/response (OpenAI-compatible) |
| 6 | +- A comprehensive evaluation command you can run |
| 7 | + |
| 8 | +Prerequisites |
| 9 | +- A running OpenAI-compatible backend for your models (e.g., vLLM or any OpenAI-compatible server). It must be reachable at the addresses you configure under vllm_endpoints (address:port). |
| 10 | +- Envoy + the router (see Start the router section) |
| 11 | + |
| 12 | +1) Minimal configuration |
| 13 | +Put this in config/config.yaml (or merge into your existing config). It defines: |
| 14 | +- Categories that require reasoning (e.g., math) |
| 15 | +- Reasoning families for model syntax differences (DeepSeek/Qwen3 use chat_template_kwargs; GPT-OSS/GPT use reasoning_effort) |
| 16 | +- Which concrete models use which reasoning family |
| 17 | +- The classifier (required for category detection; without it, reasoning will not be enabled) |
| 18 | + |
| 19 | +```yaml |
| 20 | +# Category classifier (required for reasoning to trigger) |
| 21 | +classifier: |
| 22 | + category_model: |
| 23 | + model_id: "models/category_classifier_modernbert-base_model" |
| 24 | + use_modernbert: true |
| 25 | + threshold: 0.6 |
| 26 | + use_cpu: true |
| 27 | + category_mapping_path: "models/category_classifier_modernbert-base_model/category_mapping.json" |
| 28 | + |
| 29 | +# vLLM endpoints that host your models |
| 30 | +vllm_endpoints: |
| 31 | + - name: "endpoint1" |
| 32 | + address: "127.0.0.1" |
| 33 | + port: 8000 |
| 34 | + models: ["deepseek-v31", "qwen3-30b", "openai/gpt-oss-20b"] |
| 35 | + weight: 1 |
| 36 | + |
| 37 | +# Reasoning family configurations (how to express reasoning for a family) |
| 38 | +reasoning_families: |
| 39 | + deepseek: |
| 40 | + type: "chat_template_kwargs" |
| 41 | + parameter: "thinking" |
| 42 | + qwen3: |
| 43 | + type: "chat_template_kwargs" |
| 44 | + parameter: "enable_thinking" |
| 45 | + gpt-oss: |
| 46 | + type: "reasoning_effort" |
| 47 | + parameter: "reasoning_effort" |
| 48 | + gpt: |
| 49 | + type: "reasoning_effort" |
| 50 | + parameter: "reasoning_effort" |
| 51 | + |
| 52 | +# Default effort used when a category doesn’t specify one |
| 53 | +default_reasoning_effort: medium # low | medium | high |
| 54 | + |
| 55 | +# Map concrete model names to a reasoning family |
| 56 | +model_config: |
| 57 | + "deepseek-v31": |
| 58 | + reasoning_family: "deepseek" |
| 59 | + preferred_endpoints: ["endpoint1"] |
| 60 | + "qwen3-30b": |
| 61 | + reasoning_family: "qwen3" |
| 62 | + preferred_endpoints: ["endpoint1"] |
| 63 | + "openai/gpt-oss-20b": |
| 64 | + reasoning_family: "gpt-oss" |
| 65 | + preferred_endpoints: ["endpoint1"] |
| 66 | + |
| 67 | +# Categories: which kinds of queries require reasoning and at what effort |
| 68 | +categories: |
| 69 | +- name: math |
| 70 | + use_reasoning: true |
| 71 | + reasoning_effort: high # overrides default_reasoning_effort |
| 72 | + reasoning_description: "Mathematical problems require step-by-step reasoning" |
| 73 | + model_scores: |
| 74 | + - model: openai/gpt-oss-20b |
| 75 | + score: 1.0 |
| 76 | + - model: deepseek-v31 |
| 77 | + score: 0.8 |
| 78 | + - model: qwen3-30b |
| 79 | + score: 0.8 |
| 80 | + |
| 81 | + |
| 82 | +# A safe default when no category is confidently selected |
| 83 | +default_model: qwen3-30b |
| 84 | +``` |
| 85 | +
|
| 86 | +Notes |
| 87 | +- Reasoning is controlled by categories.use_reasoning and optionally categories.reasoning_effort. |
| 88 | +- A model only gets reasoning fields if it has a model_config.<MODEL>.reasoning_family that maps to a reasoning_families entry. |
| 89 | +- DeepSeek/Qwen3 (chat_template_kwargs): the router injects chat_template_kwargs only when reasoning is enabled. When disabled, no chat_template_kwargs are added. |
| 90 | +- GPT/GPT-OSS (reasoning_effort): when reasoning is enabled, the router sets reasoning_effort based on the category (fallback to default_reasoning_effort). When reasoning is disabled, if the request already contains reasoning_effort and the model’s family type is reasoning_effort, the router preserves the original value; otherwise it is absent. |
| 91 | +- Category descriptions (for example, description and reasoning_description) are informational only today; they do not affect routing or classification. |
| 92 | +- Categories must be from MMLU-Pro at the moment; avoid free-form categories like "general". If you want generic categories, consider opening an issue to map them to MMLU-Pro. |
| 93 | +
|
| 94 | +2) Start the router |
| 95 | +Option A: Local build + Envoy |
| 96 | +- Download classifier models and mappings (required) |
| 97 | + - make download-models |
| 98 | +- Build and run the router |
| 99 | + - make build |
| 100 | + - make run-router |
| 101 | +- Start Envoy (install func-e once with make prepare-envoy if needed) |
| 102 | + - func-e run --config-path config/envoy.yaml --component-log-level "ext_proc:trace,router:trace,http:trace" |
| 103 | +
|
| 104 | +Option B: Docker Compose |
| 105 | +- docker compose up -d |
| 106 | + - Exposes Envoy at http://localhost:8801 (proxying /v1/* to backends via the router) |
| 107 | +
|
| 108 | +Note: Ensure your OpenAI-compatible backend is running and reachable (e.g., http://127.0.0.1:8000) so that vllm_endpoints address:port matches a live server. Without a running backend, routing will fail at the Envoy hop. |
| 109 | +
|
| 110 | +3) Send example requests |
| 111 | +Math (reasoning should be ON and effort high) |
| 112 | +```bash |
| 113 | +curl -sS http://localhost:8801/v1/chat/completions \ |
| 114 | + -H "Content-Type: application/json" \ |
| 115 | + -d '{ |
| 116 | + "model": "auto", |
| 117 | + "messages": [ |
| 118 | + {"role": "system", "content": "You are a math teacher."}, |
| 119 | + {"role": "user", "content": "What is the derivative of f(x) = x^3 + 2x^2 - 5x + 7?"} |
| 120 | + ] |
| 121 | + }' | jq |
| 122 | +``` |
| 123 | + |
| 124 | +General (reasoning should be OFF) |
| 125 | +```bash |
| 126 | +curl -sS http://localhost:8801/v1/chat/completions \ |
| 127 | + -H "Content-Type: application/json" \ |
| 128 | + -d '{ |
| 129 | + "model": "auto", |
| 130 | + "messages": [ |
| 131 | + {"role": "system", "content": "You are a helpful assistant."}, |
| 132 | + {"role": "user", "content": "Who are you?"} |
| 133 | + ] |
| 134 | + }' | jq |
| 135 | +``` |
| 136 | + |
| 137 | +Verify routing via response headers |
| 138 | +The router does not inject routing metadata into the JSON body. Instead, inspect the response headers added by the router: |
| 139 | +- X-Selected-Model |
| 140 | +- X-Semantic-Destination-Endpoint |
| 141 | + |
| 142 | +Example: |
| 143 | +```bash |
| 144 | +curl -i http://localhost:8801/v1/chat/completions \ |
| 145 | + -H "Content-Type: application/json" \ |
| 146 | + -d '{ |
| 147 | + "model": "auto", |
| 148 | + "messages": [ |
| 149 | + {"role": "system", "content": "You are a math teacher."}, |
| 150 | + {"role": "user", "content": "What is the derivative of f(x) = x^3 + 2x^2 - 5x + 7?"} |
| 151 | + ] |
| 152 | + }' |
| 153 | +# In the response headers, look for: |
| 154 | +# X-Selected-Model: <your-selected-model> |
| 155 | +# X-Semantic-Destination-Endpoint: <address:port> |
| 156 | +``` |
| 157 | + |
| 158 | +4) Run a comprehensive evaluation |
| 159 | +You can benchmark the router vs a direct vLLM endpoint across categories using the included script. This runs a ReasoningBench based on MMLU-Pro and produces summaries and plots. |
| 160 | + |
| 161 | +Quick start (router + vLLM): |
| 162 | +```bash |
| 163 | +SAMPLES_PER_CATEGORY=25 \ |
| 164 | +CONCURRENT_REQUESTS=4 \ |
| 165 | +ROUTER_MODELS="auto" \ |
| 166 | +VLLM_MODELS="openai/gpt-oss-20b" \ |
| 167 | +./bench/run_bench.sh |
| 168 | +``` |
| 169 | + |
| 170 | +Router-only benchmark: |
| 171 | +```bash |
| 172 | +BENCHMARK_ROUTER_ONLY=true \ |
| 173 | +SAMPLES_PER_CATEGORY=25 \ |
| 174 | +CONCURRENT_REQUESTS=4 \ |
| 175 | +ROUTER_MODELS="auto" \ |
| 176 | +./bench/run_bench.sh |
| 177 | +``` |
| 178 | + |
| 179 | +Direct invocation (advanced): |
| 180 | +```bash |
| 181 | +python bench/router_reason_bench.py \ |
| 182 | + --run-router \ |
| 183 | + --router-endpoint http://localhost:8801/v1 \ |
| 184 | + --router-models auto \ |
| 185 | + --run-vllm \ |
| 186 | + --vllm-endpoint http://localhost:8000/v1 \ |
| 187 | + --vllm-models openai/gpt-oss-20b \ |
| 188 | + --samples-per-category 25 \ |
| 189 | + --concurrent-requests 4 \ |
| 190 | + --output-dir results/reasonbench |
| 191 | +``` |
| 192 | + |
| 193 | +Tips |
| 194 | +- If your math request doesn’t enable reasoning, confirm the classifier assigns the "math" category with sufficient confidence (see classifier.category_model.threshold) and that the target model has a reasoning_family. |
| 195 | +- For models without a reasoning_family, the router will not inject reasoning fields even when the category requires reasoning (this is by design to avoid invalid requests). |
| 196 | +- You can override the effort per category via categories.reasoning_effort or set a global default via default_reasoning_effort. |
| 197 | +- Ensure your OpenAI-compatible backend is reachable at the configured vllm_endpoints (address:port). If it’s not running, routing will fail even though the router and Envoy are up. |
| 198 | + |
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