arkennemasis System Instructions

Every LLM node in your graph needs a system prompt, and if you're wiring the same "you are a professional storyboard writer who always returns valid JSON" text into five different nodes, you're maintaining five copies. System Instructions is the pack's answer: one node that holds the text and outputs it as a plain STRING. It's deliberately boring - no model calls, no API, no key - and that's the whole point. Wire the output into any LLM node that accepts a system prompt and you've got one authoritative source for instructions you can edit in one place.

One input, system_instructions (default "You are a helpful assistant."), one output, system_instructions. That's the entire node. It's provider-neutral by design - the source docstring says it explicitly: it works with any LLM node, Replicate, Ollama, Fal, whatever accepts a system prompt or text input. The pack's own Replicate GPT-5 LLM node has a system_prompt input with a tooltip that says "Type here, or wire in a 'System Instructions' node" - this is that node.

Why a dedicated node for this is worth it

The "value node" pattern (one source fanned out to many consumers) is core ComfyUI plumbing, and this is a textbook instance. Beyond the copy-paste relief, a separate node keeps the system prompt visible and versionable - it's a widget on the canvas, not buried inside an LLM node's settings, and it survives workflow export as part of the graph. If you keep a long, careful system prompt, it's also the thing you'll thank yourself for when a workflow update resets the LLM node's widget values and your instructions weren't inside it.

There's a legitimate mild take here: for a single LLM node, this adds a node for no benefit - just type the system prompt into the node. It pays off the moment you have several LLM nodes sharing a persona (the pack's story-agent pipeline runs a planning LLM and then downstream calls, all wanting the same voice), or when you want to switch system prompts per run without touching each node.

Install

SystemInstructions is one of the 61 nodes in the comfyui-arkennemasis pack, under arkennemasis/Utility:

cd ComfyUI/custom_nodes
git clone https://github.com/Hishamahmer/comfyui-arkennemasis
pip install -r comfyui-arkennemasis/requirements.txt   # then restart ComfyUI

Or ComfyUI Manager → Install via Git URL with the repo URL. Nothing to configure afterwards - it's pure text, and it loads with the pack even if you never use the Replicate or Codex providers.

If you're building an LLM-in-the-graph workflow, a shared system-prompt node is one of those quiet habits that keeps a graph maintainable, and this is the pack's no-frills version. If you want richer reusable-prompt tooling - conditionals, slots, per-input overrides - you're looking for a bigger text-template pack; this node is the simple version that does exactly one thing.