---
license: apache-2.0
language:
  - en
base_model: Qwen/Qwen3.6-27B
base_model_relation: adapter
library_name: peft
pipeline_tag: image-text-to-text
tags:
  - code
  - code-generation
  - coding-agent
  - agent
  - agentic
  - software-engineering
  - swe-bench
  - lora
  - peft
  - qwen
  - qwen3
  - multimodal
  - vision
  - visual-coding
  - image-to-code
  - chart-to-code
  - image-text-to-text
  - render-verified
  - execution-verified
  - best-of-n
  - self-hostable
  - open-source
  - australia
---

# SwarmDo-A2 — one model, both skills (code **and** vision)

**SwarmDo-A2 is an open, self-hostable, multimodal coding agent that fixes real software bugs *and* writes code from images — in a single model.** It combines SwarmDo-A1's execution-verified **coding** delta with a teacher-free, render-verified **visual-coding** delta, folded together into one LoRA adapter on `Qwen/Qwen3.6-27B`. Built in Australia; measured, not marketing — we publish the negatives and the confidence intervals.

> Public model hub & full results: **https://github.com/SwarmDo/models**

**Keywords:** open-source coding agent · agentic software engineering · SWE-bench-style patch generation · execution-verified best-of-N selection · image-to-code / chart-to-code / visual coding · render-verified self-improvement · multimodal vision LLM · Qwen3.6-27B LoRA / PEFT adapter · self-hostable on vLLM · Apache-2.0.

## What A2 is (and how it differs from A1)

[SwarmDo-A1](https://huggingface.co/SwarmDo/SwarmDo-A1) is the **coding** tier — a re-based open base plus a hardened agentic harness that verifies patches by **running the project's tests**. SwarmDo-**A2** takes that same coding delta and **combines it, on the same 27B base, with a separately trained visual-coding delta** — a *render-verified flywheel* that turns a chart / plot / UI screenshot into the code that reproduces it and checks itself by **rendering the output and comparing to the target image** (an objective, hard-to-hack reward). The two deltas are fused into one rank-48 adapter, so A2 is a **single checkpoint that carries both skills** rather than two models you swap between.

The adapter reaches the architecture's **gated-DeltaNet sequence-mixing layers** (`in_proj_*`, `out_proj`), not just the standard attention projections — which is why A2 must be **served merged** (see Usage).

## What's decision-grade (paired, held-out, execution-verified)

The headline claim for A2 is the **churn gate**: folding two independently trained skills into one model must not degrade *either* skill. We measured both, paired and held-out.

| Result | Number | Significance |
|---|---|---|
| **Visual moat preserved** — combined A2 vs the pure visual model (held-out chart render-reward) | Δ −0.006, CI [−0.016, +0.004] | p = 0.63 (**not** worse) |
| Combined A2 still beats the raw base on visual coding | 14 wins : 5 | directional |
| **Coding preserved** — A2 vs A1 on held-out SWE tasks (**execution-grounded**, real `FAIL_TO_PASS`) | 18/40 vs 19/40 solved, Δ −1 | McNemar p = 1.0 (39/40 agreement) |
| Visual flywheel **compounds** (teacher-free self-fuel → held-out lift) | +0.0192 render-reward | sign-test p = 0.0063 |

Inherited from the SwarmDo line (see A1): re-basing to Qwen3.6-27B ≈ **+25 pp** (p = 0.013); base **+ execution-verified selection** solves **36 vs 24** (p = 0.0005); visual coding is image-driven (image-on 15 vs image-off 0, p = 6e-05).

These are **relative, held-out, execution-verified** comparisons on our own task sets — **not** an absolute public-leaderboard number we can't stand behind under paired testing.

> **Methodology note we're proud of:** our harness can *self-judge* a patch (an LLM reading its own diff). We found that signal is ~2× optimistic, so **every SWE number above is re-derived by actually executing the project's tests** against the generated patch — never by self-grading.

## Honest limitations (published, not buried)

- **As a single model, A2 is ~neutral vs the base on raw coding** — the same "churn wall" trade-off A1 documents. A2's value is (1) **carrying both skills in one model** with *no measured degradation of either*, and (2) the **system** around it (execution-verified best-of-N selection + render-verified visual coding).
- The **SWE churn arm is deliberately small** (40 paired tasks, 1 discordant pair): it rules out *gross* coding regression (39/40 verdict agreement, 40% byte-identical patches) but is underpowered for a *subtle* difference. The evidence for "coding preserved" is the near-identity, not the p-value.
- Python-centric agentic SWE + chart/plot/UI visual coding. Like all coding agents it can produce plausible-but-wrong patches — **always run the project's tests against its output.** Not a general chat assistant.

## Usage — serve **merged** (important)

A2's adapter targets the base's gated-DeltaNet modules, which **JIT-hang when served as a vLLM LoRA**. Serve A2 as **merged weights** (native fast path). Merge with the VL-aware helper (it preserves the vision tower and emits the image-processor config so vLLM can serve it):

```bash
# 1) merge the A2 adapter into the base, keeping the vision tower
python merge_lora_vl.py --base Qwen/Qwen3.6-27B --lora ./ --out ./swarmdo-a2-merged

# 2) serve the merged model (multimodal + tool-calling)
vllm serve ./swarmdo-a2-merged --served-model-name swarmdo-a2 \
  --enable-auto-tool-choice --tool-call-parser qwen3_xml --reasoning-parser qwen3 \
  --enforce-eager --trust-remote-code
```

`merge_lora_vl.py` is included in this repo. **For one-step serving with no merge, use the pre-merged weights → [SwarmDo/SwarmDo-A2-merged](https://huggingface.co/SwarmDo/SwarmDo-A2-merged)**:

```bash
vllm serve SwarmDo/SwarmDo-A2-merged --served-model-name swarmdo-a2 \
  --enable-auto-tool-choice --tool-call-parser qwen3_xml --reasoning-parser qwen3 \
  --enforce-eager --trust-remote-code
```

Or load with PEFT for local experimentation:

```python
from transformers import AutoModelForImageTextToText, AutoProcessor
from peft import PeftModel
base = AutoModelForImageTextToText.from_pretrained("Qwen/Qwen3.6-27B", torch_dtype="bfloat16", device_map="auto", trust_remote_code=True)
model = PeftModel.from_pretrained(base, "SwarmDo/SwarmDo-A2").merge_and_unload()
processor = AutoProcessor.from_pretrained("Qwen/Qwen3.6-27B", trust_remote_code=True)
```

**Serving notes:** use `--tool-call-parser qwen3_xml` (not `hermes` — it silently drops tool calls) *with* `--enable-auto-tool-choice`; serve in eager mode if you hit hybrid-attention graph-capture issues; the linear-attention base keeps a fixed-size recurrent state, so long contexts cost prefill tokens, not growing KV cache. A **text-only GGUF is not offered for A2** — quantizing to GGUF drops the vision tower, which would make the visual half inert. For code-only local runs, use [SwarmDo-A1-GGUF](https://huggingface.co/SwarmDo/SwarmDo-A1-GGUF).

## Use cases

- **One model for both** automated bug-fixing *and* image-to-code — no adapter swapping.
- **Automated bug fixing** in Python repositories — generate a patch, verify it against the project's tests.
- **Image-to-code / chart-to-code / screenshot-to-code** — reproduce a chart, plot, or UI as working code, checked by rendering and comparing.
- **Agentic software engineering** — a coding agent that edits files, runs commands, and self-checks patches.
- **Self-hosted / private multimodal coding assistant** — runs entirely on your own hardware via vLLM; no data leaves your machine.
- **Best-of-N patch generation** — sample multiple candidate fixes and select the one that passes execution.

## License

Apache-2.0, consistent with the base model family.

## Citation

```bibtex
@software{swarmdo_a2_2026,
  title  = {SwarmDo-A2: One open model for execution-verified coding and render-verified visual coding},
  author = {SwarmDo},
  year   = {2026},
  url    = {https://github.com/SwarmDo/models}
}
```

## FAQ

**What is SwarmDo-A2?** An open, self-hostable multimodal coding agent that both **fixes software bugs** and **writes code from images**, in a single model — the coding (A1) delta and a render-verified visual-coding delta fused into one LoRA on `Qwen/Qwen3.6-27B`.

**How is A2 different from A1?** A1 is the coding tier (adapter + execution-verified harness, with a text GGUF for easy local runs). A2 folds a *separately trained visual-coding skill* into the same model, so one checkpoint does code **and** vision — with measured proof that combining them degrades neither skill.

**Is it open source?** Yes — Apache-2.0, commercial use permitted. Weights, recipe, and full (including negative) results are public.

**Can I run it on my own hardware?** Yes — self-host with vLLM on the **merged** weights (see Usage: a one-line merge, then `vllm serve`). Full multimodal serving needs a GPU sized for a 27B; a driver new enough for the base's CUDA build is required.

**Why must it be served merged, not as a LoRA?** The adapter reaches the base's gated-DeltaNet layers, which JIT-hang under vLLM's LoRA path. Merged weights use the native fast path.

**Is there a GGUF?** Not for A2 — GGUF conversion drops the vision tower, making the visual half inert. Use A2 merged (vLLM) for code+vision, or the [A1 GGUF](https://huggingface.co/SwarmDo/SwarmDo-A1-GGUF) for code-only local runs.

**Does it really do image-to-code?** Yes — it writes code from images and we verify it by *rendering the output and comparing to the target image*, an objective signal, not eyeballing. The visual skill is a teacher-free flywheel that measurably compounds as we scale its self-generated fuel.

**Is it good at SWE-bench?** We report *relative, paired, held-out, execution-verified* results (and re-derive every SWE number by running real tests, not self-grading), not a single absolute leaderboard number we can't stand behind.

**What languages?** Python-centric agentic software engineering, plus Python visual coding (charts/plots/UI). It is a coding agent, not a general chat assistant.

**Where are the full results?** Public hub: https://github.com/SwarmDo/models

---

*Topics: open source multimodal coding model · one model for code and vision · self-hosted AI coding assistant · agentic SWE-bench model · image to code / chart to code / screenshot to code · render-verified visual coding · execution-verified code generation · Qwen3.6-27B LoRA · run a coding LLM locally · Apache-2.0 code model.*