# AGENTS.md — ByteTrack Counter C++

## RKNN Dynamic Shape Requirement

The RKNN model (`zenai_apc_cicalengka_20260609.rknn`) is exported with **dynamic input shapes** (`model inference type: dynamic_shape`). The C API **requires** calling `rknn_set_input_shapes()` before `rknn_inputs_set()`. Without it, `librknnrt.so` crashes with:

```
std::out_of_range: vector::_M_range_check: __n (which is 18446744073709551615) >= this->size() (which is 1)
```

This is called in the constructor of `RKNNYOLO` at `src/rknn_yolo.cpp:60`, right after querying input attributes:

```cpp
in_attr.dims[0] = 1;
in_attr.dims[1] = imgsz_;
in_attr.dims[2] = imgsz_;
in_attr.dims[3] = 3;
in_attr.n_dims = 4;
ret = rknn_set_input_shapes(rknn_ctx_, io_num.n_input, &in_attr);
```

## Build

```bash
cd /opt/bytetrack-counter-cpp/build
cmake .. -DHAS_RKNN=ON
make -j$(nproc)
```

## Service

```bash
systemctl restart bytetrack-counter
journalctl -u bytetrack-counter -f
```