Dynamic Workflows

Dynamic workflows have no fixed workflow.json. Instead, they define reusable block templates that the backend assembles at runtime based on user input.

Why Dynamic?

Static workflows have a fixed graph — every user gets the same node structure. Dynamic workflows solve three problems that static can't:

1. Variable repetition — a multi-scene video needs N scene blocks, where N is chosen by the user
2. Conditional sections — hires fix and face fix should only run if the user enables them
3. Reusable composition — the same "setup" block (checkpoint + CLIP + prompt encoding) can be shared across many workflows

File Structure

workflows/t2i-batch/
├── manifest.yaml
└── blocks/
    ├── setup.json          # Loads checkpoint, encodes prompts
    └── generate.json       # Creates latent, samples, decodes, saves

Pipeline

The manifest defines the assembly order:

pipeline:
  - block: setup
    file: "setup.json"
  - block: generate
    file: "generate.json"

The backend processes blocks in order:

1. Load setup.json, instantiate its nodes, prefix all node IDs with setup_
2. Load generate.json, instantiate its nodes, prefix with generate_
3. Connect generate's imports to setup's exports
4. Substitute all {{variables}} with user values
5. Merge all nodes into one flat workflow dict and send to ComfyUI

Block Connections

Blocks communicate through imports and exports:

setup block                     generate block
┌─────────────────┐            ┌─────────────────┐
│ CheckpointLoader ─── model ──→ KSampler         │
│ CLIPTextEncode   ── positive ──→                 │
│ CLIPTextEncode   ── negative ──→                 │
│ CheckpointLoader ─── vae ────→ VAEDecode         │
└─────────────────┘            └─────────────────┘
     exports:                       imports:
     model, positive,              model, positive,
     negative, vae                 negative, vae

The setup block exports model, positive, negative, vae. The generate block imports the same names. The assembler wires them together.

Repetition

Fixed Repeat

A block can be instantiated a fixed number of times:

pipeline:
  - block: scene_first
    file: "scene_first.json"
    repeat: 1

Each instance gets a unique prefix: scene_first_0_, scene_first_1_, etc.

Variable Repeat

A block can repeat based on a runtime value:

pipeline:
  - block: scene_extend
    file: "scene_extend.json"
    repeat_variable: "extra_scenes"

If the user creates 5 scenes, extra_scenes = 4 (first scene uses scene_first, the remaining 4 use scene_extend). The assembler creates 4 instances: scene_extend_0_, scene_extend_1_, scene_extend_2_, scene_extend_3_.

Each instance's imports connect to the previous instance's exports (or to the previous block if it's the first instance). This creates a chain:

scene_first → scene_extend_0 → scene_extend_1 → scene_extend_2 → scene_extend_3 → output

Node ID Prefixing

To prevent collisions when the same block is instantiated multiple times, the assembler prefixes all node IDs with {block_name}_{instance_index}_:

Block definition:

{"nodes": {"sampler": {...}, "vae_decode": {...}}}

After assembly (instance 0 of "generate" block):

{"generate_0_sampler": {...}, "generate_0_vae_decode": {...}}

References within the block are also updated: ["sampler", 0] becomes ["generate_0_sampler", 0].

Variable Substitution in Repeated Blocks

When a block repeats, each instance can receive different variables. For the scene system:

• Instance 0 gets scene_2_prompt, scene_2_duration, scene_2_seed (scene 2 because scene 1 is scene_first)
• Instance 1 gets scene_3_prompt, scene_3_duration, scene_3_seed
• And so on

The assembler maps per-scene values from the scene_list input to per-instance variables.

Conditional Blocks

The Text to Image dynamic workflow uses booleans to conditionally enable blocks:

inputs:
  - id: hires_enabled
    type: boolean
    default: false
  - id: facefix_enabled
    type: boolean
    default: false

The assembler checks these booleans and skips the corresponding blocks if disabled. The pipeline still lists them, but they're only instantiated if the condition is true.

Current Dynamic Workflows

ID	Blocks	Pipeline
wan22-svi-dynamic	setup, scene_first, scene_extend, output	setup → scene_first(1) → scene_extend(N) → output
t2i-dynamic	setup, generate, hires, face_fix, output	setup → generate → [hires] → [face_fix] → output
t2i-batch	setup, generate	setup → generate
i2i-batch	setup, generate	setup → generate(N)
ipa-batch	setup, generate	setup → generate
faceid-batch	setup, generate	setup → generate

Brackets [...] indicate conditional blocks. (N) indicates repeated blocks.