ComfyUI V3 Custom Nodes (Server-Side)

ComfyUI baseline: v0.12.0 (Comfy API v0_0_2). Update this line when revising the skill.

Scope

Focus on server-side V3 nodes (Python).

Exclude client-server extension patterns and frontend-only extensions.

Quick Workflow

Choose API adapter:

comfy_api.v0_0_2

for stability or

comfy_api.latest

for newest features.

(Optional) Scaffold a nodepack using

comfy node scaffold

.

Implement a V3 node with

io.ComfyNode.define_schema()

and

execute()

.

Return

io.NodeOutput

(or tuple/dict) from

execute()

.

Register nodes via

ComfyExtension.get_node_list()

and

comfy_entrypoint()

.

Restart ComfyUI and validate in UI/API.

Do / Don’t

Do use classmethods

define_schema()

and

execute()

.

Do return

io.NodeOutput

(or tuple/dict) from

execute()

.

Do use

ui.Preview*

helpers for UI previews.

Don’t store mutable instance state in nodes.

Don’t use client-server extension patterns (out of scope for this skill).

Reference Map

Use these references as needed (progressive disclosure):

references/v3-core.md

API versions, ComfyExtension, progress reporting.

references/io-types.md

IO types, widget inputs, custom types.

references/schema-nodeoutput.md

Schema fields, flags, hidden inputs, NodeOutput patterns.

references/ui-helpers.md

Preview and save helpers for UI outputs.

references/scaffold.md

Scaffold workflow and V3 defaults.

references/lazy-evaluation.md

Lazy inputs, check_lazy_status, execution blocking.

references/validation-and-caching.md

validate_inputs and fingerprint_inputs patterns.

references/folder-paths-and-files.md

folder_paths helpers and save/load patterns.

references/image-mask-performance.md

Tensor shapes, resizing, batching, device tips.

Official docs:

Comfy-Org/docs custom-nodes

Template

assets/v3_extension_template.py

Minimal V3 node + extension + entrypoint.