# Data flow — Comfy-Org/ComfyUI

> Canonical page: https://codevetter.com/unpack/comfyui/data-flow

# Data flow — Comfy-Org/ComfyUI

Scanned commit b33e2b55cae074eca5aec96283cceac19aa249ba (2026-09-22). Generated by codevetter codevetter 1.12.0 on 2026-09-22.

A prompt enters as JSON at POST /prompt, is validated into an executable output list, and becomes a heapq item on PromptQueue. The worker thread wraps it in DynamicPrompt (original + ephemeral + override layers) and builds an ExecutionList — a topological dissolve where nodes become ready when their link dependencies resolve. Each node call resolves inputs from cached upstream outputs, invokes the node's FUNCTION (mapped over input lists, async-aware), and stores outputs in signature-keyed caches; UI outputs and progress flow back over WebSocket via send_sync. Model weights flow through folder_paths resolvers into comfy.sd loaders that detect the architecture and wrap it in a ModelPatcher managed by model_management for VRAM offload. Results persist to the output dir (SaveImage) and the run record lands in the in-memory history dict (capped at 10000) plus the assets DB when enabled.
- Input boundary: POST /prompt -> trigger_on_prompt(on_prompt_handlers) -> number assignment -> node_replace_manager.apply_replacements -> execution.validate_prompt -> PromptQueue.put((number, prompt_id, prompt, extra_data, outputs_to_execute, sensitive)). — [server.py#L1075-1136](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/server.py#L1075-L1136) [server.py#L1459-1470](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/server.py#L1459-L1470) [execution.py#L1128-1282](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L1128-L1282)
- validate_prompt collects OUTPUT_NODE classes (optionally filtered by partial_execution_targets), recursively validates inputs (type matching via validate_node_input, min/max, combo membership, custom VALIDATE_INPUTS/validate_inputs hooks), detects dependency cycles, and validates loop boundaries via validate_loops. — [execution.py#L846-1120](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L846-L1120) [execution.py#L1163-1282](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L1163-L1282) [comfy_execution/validation.py](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy_execution/validation.py)
- Execution loop: PromptExecutor.execute_async wraps everything in torch.inference_mode, builds DynamicPrompt + ExecutionList, seeds it with output node ids, then repeatedly calls stage_node_execution -> module-level execute() -> complete/unstage until the list empties. — [execution.py#L727-843](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L727-L843) [comfy_execution/graph.py#L212-387](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy_execution/graph.py#L212-L387)
- Per-node execution order inside execute(): check output cache -> get_input_data resolves each input link through execution_list.get_cache (missing -> mark_missing and lazy evaluation via check_lazy_status returns PENDING) -> instantiate/cache the node object in caches.objects -> get_output_data -> _async_map_node_over_list -> node FUNCTION. — [execution.py#L438-565](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L438-L565) [execution.py#L163-235](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L163-L235) [execution.py#L251-327](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L251-L327)
- Intermediate results are cached by CacheSet: outputs cache uses CacheKeySetInputSignature (class_type + IS_CHANGED value + ancestor input signatures, folded via to_hashable) while objects cache uses CacheKeySetID (node_id, class_type); modes are CLASSIC/LRU/NONE/RAM_PRESSURE chosen by --cache-* flags. — [execution.py#L113-159](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L113-L159) [comfy_execution/caching.py#L68-120](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy_execution/caching.py#L68-L120) [main.py#L319-339](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/main.py#L319-L339)
- Node functions can return plain tuples, dicts with 'result'/'ui'/'expand', or V3 NodeOutput objects; 'expand' produces an ephemeral subgraph injected into DynamicPrompt.ephemeral_prompt and re-scheduled, with the node's final outputs resolved later from pending_subgraph_results. — [execution.py#L359-422](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L359-L422) [execution.py#L578-612](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L578-L612) [comfy_execution/graph.py#L21-71](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy_execution/graph.py#L21-L71) [comfy_api/latest/_io.py#L2344](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy_api/latest/_io.py#L2344)
- Streaming output: nodes emit UI data via 'ui' dicts -> register_executed_outputs enriches them into asset references -> send_sync('executed', ...) to the client; sampler progress goes through comfy.utils.ProgressBar global hook -> send_sync('progress') + binary preview frames. — [execution.py#L565-577](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L565-L577) [comfy_execution/asset_enrichment.py](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy_execution/asset_enrichment.py) [main.py#L420-449](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/main.py#L420-L449) [comfy/utils.py#L1292-1306](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy/utils.py#L1292-L1306)
- Model loading path: folder_paths.get_full_path_or_raise resolves a filename inside a category's search dirs -> comfy.utils.load_torch_file reads safetensors/ckpt -> model_detection.model_config_from_unet fingerprints the state dict -> comfy.supported_models builds the model -> ModelPatcher wraps it -> load_models_gpu places it per VRAM policy. — [folder_paths.py#L441-468](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/folder_paths.py#L441-L468) [comfy/sd.py#L2132-2215](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy/sd.py#L2132-L2215) [comfy/model_detection.py#L44-120](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy/model_detection.py#L44-L120) [comfy/model_management.py#L939-1044](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy/model_management.py#L939-L1044)
- Sampling path inside a node: KSampler.sample -> common_ksampler -> comfy.sample.prepare_noise (seeded) -> latent_preview.prepare_callback -> comfy.sample.sample -> comfy.samplers.KSampler.sample drives the denoise loop calling model.apply_model per sigma step. — [nodes.py#L1572-1624](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/nodes.py#L1572-L1624) [comfy/sample.py#L79-86](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy/sample.py#L79-L86) [comfy/samplers.py#L1276-1443](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/comfy/samplers.py#L1276-L1443)
- History persistence: task_done() pops currently_running, strips the sensitive tuple element via process_item=remove_sensitive, and stores {prompt, outputs, status} in self.history keyed by prompt_id, evicting FIFO beyond MAXIMUM_HISTORY_SIZE=10000. — [execution.py#L1284-1341](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L1284-L1341) [main.py#L366-372](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/main.py#L366-L372)
- Auth-sensitive extra_data keys (auth_token_comfy_org, api_key_comfy_org) are popped into a separate `sensitive` dict at enqueue time, reattached only inside the worker, and injected into node inputs via hidden input plumbing (Hidden.auth_token_comfy_org / hidden AUTH_TOKEN_COMFY_ORG). — [server.py#L1129-1134](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/server.py#L1129-L1134) [execution.py#L161](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L161) [execution.py#L206-211](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/execution.py#L206-L211) [main.py#L356-359](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/main.py#L356-L359)
- File output boundary: SaveImage writes PNGs (with embedded prompt/workflow metadata unless --disable-metadata) into folder_paths.get_output_directory() with counter-suffixed filenames; LoadImage reads from the input directory through annotated_filepath/get_annotated_filepath resolvers. — [nodes.py#L1660-1679](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/nodes.py#L1660-L1679) [folder_paths.py#L255-270](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/folder_paths.py#L255-L270) [folder_paths.py#L343-357](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/folder_paths.py#L343-L357)
- Asset enrichment: when enabled, AssetManager pauses its background scan during execution, registers uploaded/executed files into the DB catalog, and /view resolves blake3:<hash> filenames to asset paths via resolve_hash_to_path. — [main.py#L361-362](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/main.py#L361-L362) [server.py#L524-531](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/server.py#L524-L531) [app/assets/manager.py](https://github.com/Comfy-Org/ComfyUI/blob/b33e2b55cae074eca5aec96283cceac19aa249ba/app/assets/manager.py)

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