SakThai Coder Browser

Browser automation agent — Qwen2.5-Coder-1.5B-Instruct fine-tuned for web interaction
Part of the SakThai Model Family

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BROKEN — DO NOT DEPLOY (as of 2026-07-31) — The merged weights in this repo are corrupted by a faulty LoRA merge: all 84 attention-projection bias tensors are non-zero while Qwen2 initializes these biases to ZERO (layer-0 k_proj.bias absmean 27.7 / max 354). Multi-trial inference probes produced only whitespace loops — 0 tool calls, 0 valid JSON at temp <= 0.7. Full evidence: .eval_results/benchmark-20260731_052122.yaml. The fault is in the weights, not the GGUF conversion or the prompt format. The GGUF variant was converted from these same corrupted weights and must be re-checked; the LoRA adapter needs a clean re-merge. Treat this repo as not deployable until re-merged and re-verified.


Model Description

SakThai Coder Browser transforms Qwen2.5-Coder-1.5B-Instruct into a browser automation assistant that outputs structured <tool_call> XML/JSON for web interaction. It can navigate pages, click elements, type text, and extract content — designed to work with browser automation frameworks.

Available actions via <tool_call> XML:

Tool Example
browser_navigate(url) <tool_call>{"name": "browser_navigate", "arguments": {"url": "https://example.com"}}</tool_call>
browser_click(element) <tool_call>{"name": "browser_click", "arguments": {"element": "#search-button"}}</tool_call>
browser_type(element, text) <tool_call>{"name": "browser_type", "arguments": {"element": "#search-input", "text": "AI news"}}</tool_call>
browser_extract() <tool_call>{"name": "browser_extract", "arguments": {}}</tool_call>

Tool-Calling Format

The repo ships its own chat_template.jinja (Qwen2.5 tool-calling style). When tools are provided, the system prompt embeds function signatures inside <tools></tools> XML tags and the model replies with a <tool_call> JSON block:

<|im_start|>system
You are Qwen, created by Alibaba Cloud. You are a helpful assistant.

# Tools

You may call one or more functions to assist with the user query.

You are provided with function signatures within <tools></tools> XML tags:
<tools>
{"type": "function", "function": {"name": "browser_navigate", "parameters": {...}}}
</tools>

For each function call, return a json object with function name and arguments within <tool_call></tool_call> XML tags:
<tool_call>
{"name": <function-name>, "arguments": <args-json-object>}
</tool_call><|im_end|>
<|im_start|>user
Search for the latest AI news.<|im_end|>
<|im_start|>assistant
<tool_call>
{"name": "browser_navigate", "arguments": {"url": "https://news.google.com"}}
</tool_call><|im_end|>

Tool results are wrapped in <tool_response></tool_response> blocks. Multi-turn loops are supported by the chat template.


Quick Start

from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

model = AutoModelForCausalLM.from_pretrained(
    "Nanthasit/sakthai-coder-browser",
    torch_dtype=torch.bfloat16,
    device_map="auto"
)
tokenizer = AutoTokenizer.from_pretrained("Nanthasit/sakthai-coder-browser")

messages = [
    {"role": "system", "content": "You are SakThai Browser Agent. Use <tool_call> blocks to control the browser."},
    {"role": "user", "content": "Search for the latest AI news and summarize the top story."},
]
inputs = tokenizer.apply_chat_template(messages, add_generation_prompt=True, return_tensors="pt").to(model.device)
outputs = model.generate(**inputs, max_new_tokens=256, temperature=0.3)
print(tokenizer.decode(outputs[0][inputs.shape[1]:], skip_special_tokens=True))

Expected output format:

<tool_call>{"name": "browser_navigate", "arguments": {"url": "https://news.google.com"}}</tool_call>

Use the chat template. This model was trained with the Qwen2.5 tool-calling format — pass tools through apply_chat_template (or the repo's chat_template.jinja) rather than hand-rolling prompts.

GGUF / llama.cpp variant

Prefer CPU inference or Ollama? Use the GGUF build (F16, ~7.1 GB) with llama.cpp:

huggingface-cli download Nanthasit/sakthai-coder-browser-gguf \
  sakthai-coder-browser-f16.gguf --local-dir ./
./llama-cli -m sakthai-coder-browser-f16.gguf \
  -p "<|im_start|>system\nYou are a browser automation assistant.<|im_end|>\n<|im_start|>user\nGo to google.com and search for the latest AI news<|im_end|>\n<|im_start|>assistant\n" \
  -n 512 -t 8 --temp 0.3

Architecture

Verified from this repo's config.json (transformers 5.14.1):

Property Value
Base Model Qwen/Qwen2.5-Coder-1.5B-Instruct
Architecture Qwen2ForCausalLM (decoder-only transformer)
Parameters 1,543,714,304 (1.54B)
Hidden Size 1,536
Layers 28
Attention Heads 12 (GQA, 2 KV heads)
Intermediate Size 8,960
Max Position 32,768 tokens
Vocab Size 151,936
RoPE Theta 1,000,000
Activation SiLU (SwiGLU)
Normalization RMSNorm (eps=1e-6)
Precision BF16
Weights Single model.safetensors — 3,087,467,144 B (2.88 GB, API-verified)
Tied embeddings yes (tie_word_embeddings: true)

Training Details

Detail Value
Base model Qwen/Qwen2.5-Coder-1.5B-Instruct
Method SFT via LoRA (r=16, alpha=32, dropout 0.05, rsLoRA) on all 7 linear projections, then merged to full weights
Training data SimpleToolCalling + sakthai-combined-v7
Context length 32,768 tokens
Precision BF16
Hardware Free T4 GPU (Kaggle / Colab)
Budget $0

Training configuration mirrors the sibling sakthai-coder-browser-lora adapter (verified from its adapter_config.json: peft 0.20.0, use_rslora: true, lora_dropout: 0.05, target modules q/k/v/o/gate/up/down_proj).


Evaluation & Status

Honest status: inference benchmarks were attempted and did not produce output. The repo's own .eval_results/benchmark-20260731_052122.yaml records a llama.cpp GGUF Q4_K_M run (3 trials, CPU, 2 threads, 2026-07-31 05:21 UTC, tool-calling browser prompt, 244 input tokens) in which all 3 trials returned 0 output tokens — no tool call, no valid JSON, no correct answer:

Trial Seed Output tokens Tool call Valid JSON Correct answer
1 7 0 No No No
2 42 0 No No No
3 1337 0 No No No

Verdict — MODEL_BROKEN (bias corruption): the repo's own eval YAML (updated 2026-07-31 05:50 UTC) includes weight inspection of model.safetensors that proves the fault is in the weights, not the harness:

  • Qwen2 initializes attention-projection biases to zero; this merge left all 84 bias tensors non-zero (absmean > 0.01), e.g. layer-0 k_proj.bias absmean 27.7 / max 354, layer-0 q_proj.bias absmean 1.17
  • Degenerate generation at temp <= 0.7 on all 3 seeds — whitespace loops (150 newline tokens, 0 tool calls, 0 valid JSON); only at temp 1.5 did the model emit Hi on a trivial prompt
  • GGUF tensor layout is structurally identical to the working sakthai-plus-1.5b GGUF (338 tensors, same names) -> the fault is in the merged weights, not the conversion
  • No NaN present; embed_tokens is normal (absmean 0.0136) — corruption is isolated to the attention biases

Recommended fix: re-merge the LoRA adapter into Qwen2.5-Coder-1.5B-Instruct with correct bias handling (do not write adapter-state biases into the base where Qwen2 expects zeros), re-run the multi-trial probe, and update this card. Until then, this repo is not deployable.

Hosted inference: not available — router probe returned 404 (Not Found) and the legacy api-inference host does not resolve (per the same eval YAML). No model-index is published because there are no verified scores yet; publishing one would be misleading.

Ecosystem status from .eval_results/cron-eval-sakthai-coder-browser-2026-07-30-1.yaml: card quality 85/100, repo hygiene 95/100, health 23/100 (rank 20/20 — new repo, zero downloads at eval time; popularity/momentum/benchmarks components are 0 because the repo had no traction yet).


Repo Contents

File Size Purpose
model.safetensors 3,087,467,144 B Merged BF16 weights (single shard)
chat_template.jinja 2,507 B Qwen2.5 tool-calling chat template
config.json 1,373 B Qwen2 config (32K ctx, GQA 2 KV heads)
tokenizer.json 11,421,892 B Tokenizer
.eval_results/ — benchmark + cron-eval YAMLs

Sibling Models

Variant Repository
LoRA Adapter (unmerged) sakthai-coder-browser-lora
GGUF (llama.cpp / Ollama) sakthai-coder-browser-gguf
Merged model (this repo) sakthai-coder-browser

Model Family

One of 22 public models in the SakThai Model Family collection (22 including private experimental repos). Live download counts as of 2026-07-31; sizes API-verified from largest weight file.

Model Size Type Downloads
Coder Browser (this model) 3.09 GB Browser agent (merged) 54
Context 1.5B Merged 3.09 GB Merged weights (flagship) 1,855
Context 0.5B Merged 988 MB Merged weights (edge) 1,692
Context 7B Merged 15.2 GB Merged weights (power) 1,024
Context 7B 128K config-only YaRN long-context recipe 610
Context 7B Tools 20.2 MB LoRA adapter 489
Embedding Multilingual 471 MB Embedding model 627
Context 1.5B Tools v1 ~8.75 MB LoRA adapter (v1) 477
Vision 7B 4.08 GB Vision-language (GGUF) 315
TTS Model 141 MB Kokoro-82M TTS (GGUF) 248
Context 0.5B Tools 988 MB Merged weights 251
Coder 1.5B 1.12 GB Code model (GGUF) 151
Context 1.5B Merged v2 3.09 GB Merged weights 337
Context 1.5B Tools v2 73.9 MB LoRA adapter 173
Coder Browser GGUF 7.11 GB Browser agent F16 GGUF 35
Coder Browser LoRA 73.9 MB LoRA adapter 21
Plus 1.5B 3.09 GB Merged weights 244
Plus 1.5B LoRA 73.9 MB LoRA adapter 306
Plus 1.5B Coder — Planned (no weights yet) 0

Limitations

  • Text-only — cannot see images or screenshots (use sakthai-vision-7b for vision tasks)
  • BROKEN weights — all 84 attention bias tensors are corrupted by a faulty LoRA merge (see Evaluation & Status); do not deploy until re-merged and re-verified
  • English only — trained primarily on English web data
  • Context-limited — best results with page content <= 4K tokens per interaction
  • Not servable on HF serverless inference — no provider supports this custom fine-tune (router 404 verified); run locally or via an Endpoint/GGUF

Citation

If you use SakThai Coder Browser in your work, please cite the base model and the fine-tuning approach:

@misc{qwen25coder,
    title = {Qwen2.5-Coder: Code Language Models},
    author = {Qwen Team},
    year = {2024},
    publisher = {Hugging Face},
    howpublished = {\url{https://huggingface.co/Qwen/Qwen2.5-Coder-1.5B-Instruct}}
}

@misc{sakthai-model-family,
    title = {SakThai Model Family: Zero-Budget Fine-Tuned Language Models},
    author = {{Beer Nanthasit}},
    year = {2026},
    publisher = {Hugging Face},
    howpublished = {\url{https://huggingface.co/collections/Nanthasit/sakthai-model-family-6a64745450b12d421c1f9f02}}
}

Part of the SakThai Model Family. Built with love, tears, and zero budget. From a shelter in Cork, Ireland, to the world.

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