Qwen3.5-35B-A3B Intent Router

A general intent router: it reads a user turn plus an intent catalog supplied in the prompt and returns exactly one intent id from that catalog. The catalog is an input, not a trained-in label set, so the same checkpoint routes for a catalog it has never seen -- which is what the held-out BANKING77 column below measures.

Fine-tuned from Qwen/Qwen3.5-35B-A3B.

Read this before you load it

Three things about this checkpoint will produce wrong results silently if you do not know them.

1. It is text-only. The base is a multimodal qwen3_5_moe checkpoint. What is published here is the text tower alone -- model_type is qwen3_5_moe_text, and the vision config and the MTP speculative-decoding head are not present. 34,660,610,688 parameters against the base checkpoint's 35,951,822,704. If you need vision or MTP, use the base model.

2. Load it as a normal transformers model.

from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

model = AutoModelForCausalLM.from_pretrained(
    "VikramPal/Qwen3.5-35B-A3B-bf16", dtype=torch.bfloat16, device_map="auto",
    trust_remote_code=True,
    experts_implementation="eager",   # grouped_mm needs sm_90; drop this on Hopper+
)
tok = AutoTokenizer.from_pretrained("VikramPal/Qwen3.5-35B-A3B-bf16")

3. vLLM cannot serve this checkpoint. vLLM refuses fused MoE weights at layer 0. Use transformers.

How to prompt it

The system prompt carries the catalog; the user turn carries the utterance. The model was trained on a fixed system template (published in this repo as system_template.txt) and renders through the chat template with enable_thinking=False. Scoring at eval time used add_special_tokens=False because the template already emits them -- passing both prepends a second BOS and measures a different model.

messages = [
    {"role": "system",  "content": SYSTEM_TEMPLATE.format(catalog="\n".join(intent_ids))},
    {"role": "user",    "content": "my card hasn't turned up yet"},
]
text = tok.apply_chat_template(messages, tokenize=False,
                               add_generation_prompt=True, enable_thinking=False)
enc = tok(text, return_tensors="pt", add_special_tokens=False).to(model.device)
out = model.generate(**enc, max_new_tokens=24, do_sample=False)
print(tok.decode(out[0, enc.input_ids.shape[1]:], skip_special_tokens=True))
# -> card_arrival

Greedy decoding, and 24 new tokens is enough for every label in these catalogs. The router answers with a bare intent id, or out_of_scope when the catalog does not cover the turn, or a clarifying question when the turn conjoins two intents.

Results

1,500 held-out items, 150 per (split, catalog) group, greedy decoding, strict exact match against the gold intent id.

Invented ids are answers that are not in the catalog the model was given -- the failure mode that makes a router unusable downstream, because the caller has no branch for them.

Strict requires the reply to be exactly the intent id and nothing else; right id present also accepts the id surrounded by other text. The two are identical for Qwen3.5-35B-A3B (no fine-tune), this router, bf16, this router, DynQuant 4-bit, so those strict numbers are accuracy outright. They separate on this router, DynQuant 3-bit (22 of 1500 items), which reached the correct id and then kept writing -- a note, a caveat, or a markdown table. Whether that counts as a loss is the caller's choice: a router that reads the first line of the reply recovers those items, one that requires a bare label does not. Both numbers are given so neither reading has to be taken on trust.

Paired McNemar against the un-fine-tuned base model on the same 1,500 items (18 items where only that arm was right, 447 where only this one was): +28.60 points, exact binomial p = 2.53e-108. The test is paired because both arms answer the identical items; the ~1035 items they agree on carry no information about which is better.

By catalog

banking77 is never seen in training -- neither its utterances nor its 77 intent ids. It is the column that says whether this is a router or a 77-way classifier wearing one.

By item kind

By language

Training

LoRA (r=32, alpha=64, dropout=0.05) on bf16 base weights -- not QLoRA; the base is not quantized during training, so the harvested gradient signal describes the tensors that are actually quantized afterwards. Adapters on every attention and MLP projection including the linear-attention in_proj_* family, merged into the base before quantization.

Training data is assembled from five public intent datasets, each turned into catalog-in-prompt form and augmented with the rule behaviours the router has to get right (refusing to guess when the intent was removed from the catalog, asking when two intents are conjoined, staying silent about intents that are not offered).

BANKING77 appears only in the test split -- it is the generalization measurement, and training on it would destroy the only evidence that the catalog is really an input.

Limitations

• Text only. No vision tower, no MTP head (see the top of this card).
• Not servable by vLLM. vLLM's fused-MoE guard rejects this architecture at layer 0.
• Six languages. en/de/es/fr/hi/th. Other languages are untested and the catalog ids are English regardless of the utterance language.
• Catalog size. Tested at 60-151 intents. Much larger catalogs will not fit the context the same way and are unmeasured here.
• One intent per turn. Conjoined intents are trained to produce a clarifying question, not two labels.
• experts_implementation="eager" is needed below sm_90. The default grouped-MoE path requires Hopper or newer.

Citation

The quantization method:

@misc{dynquant2026,
  title  = {DynQuant: Dynamic-Signal Quantization for Extreme LLM Compression},
  author = {Pal, Vikram and Kour, Manpreet},
  year   = {2026}
}

The base model is Qwen/Qwen3.5-35B-A3B; please cite Qwen as well, and the five source datasets listed above.