Contributing to ComfyUI-fal-API

Thanks for helping! Before you write anything, read this — it will probably save you the PR entirely.

A new fal model does NOT need code

Historically, adding a model to this pack meant hand-writing a node class. That is no longer how it works. Every live public model on fal gets a node automatically, generated at ComfyUI startup from the committed snapshot at data/fal_registry.json. No node class, no mapping entry, no code.

The snapshot stays fresh three ways:

A daily GitHub Action (.github/workflows/registry-refresh.yml) builds a candidate, validates it against the committed baseline, and commits safe changes automatically.
Anyone can run it locally: python scripts/build_registry.py --out data/fal_registry.json (then python scripts/build_readme.py to regenerate MODELS.md).
The fal sidebar can rebuild the local registry; restart ComfyUI afterward so new node classes register.

The automated validator rejects malformed records, duplicate or unsorted endpoint IDs, suspiciously small catalogs, and unexpectedly large additions or removals. A maintainer can explicitly override only the change-size thresholds when manually dispatching the workflow; all structural checks still apply.

Missing endpoints are preserved by default with deprecated: true, which keeps their node keys available under FAL/Compatibility for old workflows. Use --prune-missing only for an intentional breaking cleanup. A fresh endpoint record automatically replaces its deprecated copy if it returns to the live catalog.

To check whether a model is already covered:

grep '"endpoint_id": "fal-ai/your/endpoint"' data/fal_registry.json
# or browse MODELS.md, or search the node browser in ComfyUI

If a model is live on fal.ai/models but missing from the snapshot, rerun scripts/build_registry.py — if it's still missing, open an issue with the endpoint id. And if you need a model right now, the Fal Any Endpoint (fal) node calls any endpoint by id without any registry entry at all.

So: please don't open a PR that adds a node class for a new model. It will be redundant the moment the registry refreshes.

Want a model promoted or renamed? Edit `data/featured_models.json`

When a model deserves curation — a spot in the FAL/Featured menu tier or a friendlier display name — add its endpoint to data/featured_models.json (featured tier + display-name override). That's the whole change: one JSON entry, not a new node class.

When a hand-written node IS justified

A curated node earns its place only when the generated node genuinely can't express the UX:

Multi-endpoint orchestration — one node fanning out to several endpoints (e.g. Combined Video Generation).
Special input ergonomics — first/last-frame image pairing, unified T2V/I2V dispatch, LoRA slots with per-slot scales.

If you're writing one, the rules are non-negotiable:

Import only from the .fal_utils facade (from .fal_utils import ApiHandler, FalConfig, ImageUtils, ResultProcessor, ...) — never reach into nodes/utils/ internals or call fal_client directly. The facade gives you the result cache, spend guard, session ledger, and error handling for free.
Raise errors — no silent fallbacks. Never return blank images or "Error: ..." strings; let ApiHandler surface fal's actual error message.
Tooltips on every input. Users should never have to guess a parameter.
Never change existing node keys, input names, or output signatures. Existing user workflows reference them forever. tests/legacy_node_keys.json is the snapshot of keys that must never be removed or renamed, and tests/test_mappings.py fails the suite if one disappears. New inputs must be optional with backward-compatible defaults.
Add tests alongside the existing ones in tests/.

Dev setup

pip install -r requirements.txt
python -m pytest tests     # the suite MUST pass
ruff check .               # lint, same as CI

CI runs both on every PR (Python 3.10 and 3.12). The most important test to understand is the compatibility snapshot: tests/test_mappings.py asserts that every node key recorded in tests/legacy_node_keys.json still registers. If your change makes it fail, the fix is to restore the key — not to edit the snapshot.

Architecture map

scripts/build_registry.py     queries fal's platform APIs → writes the snapshot
scripts/validate_registry.py  safety gate for generated registry candidates
data/fal_registry.json        committed model catalog (~1,400 models)
data/featured_models.json     curation: featured tier + display-name overrides
scripts/build_readme.py       renders MODELS.md from the snapshot

nodes/dynamic/                the auto-generated node machinery
  registry_loader.py          reads the snapshot, applies [dynamic_nodes] config;
                              never raises — failures degrade to curated-only
  factory.py                  builds one node class per model, in memory
  schema_to_inputs.py         registry input specs → ComfyUI INPUT_TYPES (+ tooltips)
  arguments.py                widget/socket values → API arguments (uploads media)
  outputs.py                  API result → IMAGE / VIDEO / AUDIO / result_json
  any_endpoint.py             the generic "call any endpoint by id" node

nodes/*.py                    curated hand-written nodes (image, video, llm, vlm,
                              trainer, upscaler, util_*)
nodes/fal_utils.py            import facade — node modules import ONLY from here
nodes/utils/                  the implementations behind the facade: api, config,
                              pricing, result_cache, ledger, billing (spend guard),
                              job_store, media, archive, errors, logger
nodes/platform_node.py        platform nodes (Submit/Collect, costs, request ids)
nodes/inbox_node.py           durable job inbox
nodes/billing_node.py         account balance
nodes/server_routes.py        HTTP endpoints backing the frontend extension
web/                          ComfyUI frontend: cost badges, fal sidebar,
                              endpoint autocomplete
tests/                        pytest suite, incl. the legacy_node_keys.json snapshot

PR checklist

Not a hand-written node for a single new model (registry covers it — see above)
python -m pytest tests passes locally
ruff check . is clean
No existing node keys, inputs, or outputs changed
New curated node (if truly justified): uses .fal_utils, raises errors, has tooltips and tests
No secrets, no config.ini, no generated artifacts in the diff

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