LTX Attn — QKV Store Inspect

The QKV store is the pack's most expensive artifact - raw per-head Q/K/V tensors from a generation, captured only when you flip capture_qkv=True in Setup Capture. When a QKV Transfer silently transfers nothing, or targets="all" resolves to an empty list, the cause is almost always "the QKV store doesn't contain what you think it does." QKV Store Inspect is the audit tool: it prints the QKVStore contents and, critically, the memory footprint, so you can see exactly what you paid for and whether it matches your qkv_targets.

Raw Q/K/V is a different beast from attention maps, and this node's report is built around that difference. The attention store is about patterns (maps and metrics); the QKV store is about components (the tensors you can recombine in QKV Transfer). Inspecting one doesn't tell you about the other - they're populated by different capture flags, and a run with capture_qkv=False produces an empty QKV store while the attention store looks perfectly healthy. That asymmetry is the number-one reason people get confused, and it's exactly what this node exists to surface.

How it works

Like its attention-store sibling, it inspects the currently active QKV store (creating default if none exists), walks each attention type in the store, and prints what was recorded for each block: which steps, which heads, tensor shapes, and a running total of the memory those raw tensors occupy. That total-MB number is the practical headline - it's your "did this capture break my RAM budget" readout, and it tells you whether the qkv_targets you set in Setup Capture actually matched the reality of what got stored.

The only input is trigger (type *) - it's an output/debug terminal, so wire anything in to force it to run at the right point in the queue. It's an OUTPUT_NODE returning a single store_summary STRING.

Install

cd ComfyUI/custom_nodes
git clone https://github.com/g-raw/ComfyUI-LTX-Attention-Toolkit.git

Restart ComfyUI. No extra dependencies, no model files. Work-in-progress pack - the QKV store format is exactly the kind of thing that changes between versions, so don't trust an old dump without a fresh inspect.

Common issues

If the report comes back empty or tiny, first check that the source capture actually had capture_qkv=True - not the attention-map store_mode, the separate QKV flag. Then check qkv_targets: a narrow list means few blocks/heads recorded, which is fine for a targeted transfer but will make targets="all" resolve to almost nothing. And as always, run the inspect after the capture generation in a later queue pass - inspecting mid-run reads an empty store and tells you nothing except that you queued it too early.