Comfy Flow Control

---
created: 2026-07-07
modified: 2026-07-31
reviewed: 2026-07-07
name: comfy-flow-control
description: >-
  ComfyUI routing nodes: typed switches, index switches, broadcast (Anything Everywhere), pipe/context bundles, for/while loops, ExecutionBlocker gates. Use when wiring where a signal routes in a workflow.
allowed-tools: Read, Grep, Glob
---

# ComfyUI flow control

Routing, switching, broadcast, bundling, looping, gating. *Where does
the signal go* once the decision is made.

Six packs on this install contribute flow-control primitives. Each has
overlapping options and pack-specific quirks — the goal of this skill
is to pick the right one in one decision, not browse a dropdown.

## When to Use This Skill

| Use this skill when... | Use instead when... |
|---|---|
| Wiring how a signal routes, switches, broadcasts, loops, or is gated | Forming the predicate that drives the route -> `comfy-conditionals` |
| Picking a switch / index-switch / broadcast node | Debugging or inspecting a routed value -> `comfy-debug-preview` |

## Sources of truth

- `custom_nodes/rgthree-comfy/__init__.py` — context bundles, Any Switch, Power Lora Loader, fast groups muter (frontend-only)
- `custom_nodes/cg-use-everywhere/__init__.py` — broadcast "Anything Everywhere" sentinels
- `custom_nodes/ComfyUI-Crystools/crystools/nodes_switch.py` — type-typed CSwitchBoolean* family
- `custom_nodes/comfyui-impact-pack/modules/impact/special_samplers.py` and `core.py` — ImpactSwitch (`GeneralSwitch`/`GeneralInversedSwitch`), ImpactConditionalBranch, ExecutionOrderController
- `custom_nodes/comfyui-easy-use/py/nodes/logic.py` and `flow.py` — easy switches, pipes, forLoop, whileLoop, blocker
- ComfyUI core — built-in `ComfySwitchNode` (boolean toggle between two same-type inputs)

## Pick-a-switch decision

| You have… | Selector | Best node | Why |
|---|---|---|---|
| 2 IMAGE inputs, BOOLEAN selector | bool | `easy imageSwitch` or Crystools `CSwitchBooleanImage` | Lazy: only the chosen branch runs |
| 2 ANY inputs, BOOLEAN selector | bool | Crystools `CSwitchBooleanAny` | Lazy; cleanest signature |
| 2 STRING inputs, BOOLEAN selector | bool | `easy textSwitch` or Crystools `CSwitchBooleanString` | Both lazy |
| 2 CONDITIONING inputs, BOOLEAN | bool | Crystools `CSwitchBooleanConditioning` | Lazy; native CONDITIONING type |
| 2 LATENT / MASK inputs, BOOLEAN | bool | Crystools `CSwitchBooleanLatent` / `CSwitchBooleanMask` | Lazy; typed |
| N ANY inputs, INT selector (3-20) | index | `easy anythingIndexSwitch` (up to 20) | Only easy-use scales past 2 inputs |
| N IMAGE / TEXT / CONDITIONING, INT | index | `easy imageIndexSwitch` / `easy textIndexSwitch` / `easy conditioningIndexSwitch` | Typed N-way |
| K ANY inputs, "first non-None wins" | any | rgthree `Any Switch` | Pick the first connected/non-empty input |
| 1 ANY input → 2 ANY outputs (demux) | bool | Crystools `CSwitchFromAny` | Unique: output-side mux. Bool routes the *one* input to one of two outputs |
| 2 BOOLEAN inputs that disagree | logic | `easy compare` or `ImpactCompare` then a switch above | Predicate formation lives in `comfy-conditionals` |
| Toggle entire LoRA stack on/off | bool | rgthree `Power Lora Loader` with toggles per row | Single node holds the stack + per-LoRA enable/strength |
| Mute/bypass a whole group of nodes | mouse | rgthree fast groups muter (frontend) | Right-click group → Mute / Bypass. No node needed |

### Input-side vs output-side mux

- **Input-side mux** (the standard pattern): N inputs → 1 output. The
  switch decides which input to forward. The bool/index selector reads
  *before* the upstream graph evaluates, so unselected branches can
  often be skipped (see lazy-vs-eager below).
- **Output-side mux** (Crystools `CSwitchFromAny` only): 1 input → 2
  outputs. The bool picks which output port receives the value; the
  other port emits None / a default. Use this when *one upstream*
  feeds two divergent downstream paths and you want to send it to only
  one at a time.

### Lazy vs eager evaluation

Lazy switches mark unselected branches as "do not evaluate", so the
upstream chain feeding the discarded branch is skipped entirely. Saves
GPU and time. Eager switches force every upstream branch to compute
even if its output gets thrown away.

| Lazy (skip unselected upstream) | Eager (run all branches always) |
|---|---|
| `easy ifElse`, `easy imageSwitch`, `easy textSwitch`, `easy anythingIndexSwitch` (and the typed `*IndexSwitch` siblings), `easy blocker` (downstream blocker) | `ImpactSwitch` / `GeneralSwitch` (data routing only) |
| All `CSwitchBoolean*` (Crystools) | `CSwitchFromAny` (must compute input before routing) |
| `ImpactConditionalBranch`, `ImpactConditionalBranchSelMode` | rgthree `Any Switch` (selects after upstream resolves) |

When the unselected branch is cheap (a constant or a small VAEDecode),
the difference is invisible. When it's a sampler chain, lazy switches
save tens of seconds per queue.

## Broadcast routing — `cg-use-everywhere`

The `Anything Everywhere` family doesn't have output ports. You wire a
value (model / clip / vae / seed / conditioning / anything) *into* the
node, and it acts as an invisible producer: any *unconnected* input
slot of the matching type elsewhere in the graph receives the value
automatically.

| Node | Use when |
|---|---|
| `Anything Everywhere` | One MODEL or VAE is reused by 6 nodes scattered across the graph — declare once, skip 6 reroute wires |
| `Anything Somewhere` | Regex-filtered: broadcasts only to inputs whose *socket name* matches the regex you set on the broadcaster |
| `Anything Everywhere Triplet` | Positive + negative + latent triplet bundle (the SDXL/Flux conditioning trio) |
| `Seed Everywhere` | Deprecated; the frontend auto-rewrites to a regular `Anything Everywhere` connected to INT |

**Silent-failure mode**: if two broadcasters carry compatible types
and both could match an empty socket, *one of them wins* (depends on
node id ordering) and the other is silently ignored. Color the broadcasters
in the UI so the routing is visible — they're invisible by design and
hard to debug otherwise. When debugging, replace with explicit reroutes
to see exactly where each value lands.

Use broadcast for **scalars and constants** (seed, model, vae, a
shared prompt). Avoid for transient intermediate values whose meaning
shifts as the graph runs — explicit wires there make the workflow
more legible.

## Context vs pipe bundles

Both rgthree's `Context` and easy-use's `pipeIn`/`pipeOut` carry a
multi-typed bundle on a single wire. They are not interchangeable.

| | rgthree Context | easy-use pipe |
|---|---|---|
| Wire type | `RGTHREE_CONTEXT` (custom) | `PIPE_LINE` (custom) |
| Field access | Named (model / clip / vae / positive / negative / latent / image / seed) | Positional (model, pos, neg, latent, vae, clip, image, seed) |
| Override / edit mid-graph | `Context Merge` / `Context Merge Big` | `pipeEdit` |
| Unpack | `Context Switch` selects between multiple full contexts; individual fields auto-emerge from the Context node's right side | `pipeOut` emits all 8 slots; or downstream nodes consume `PIPE_LINE` directly |
| Bridge between | Convert manually: unpack with `Context` outputs → repack with `pipeIn` (and vice-versa) | Same, reverse |
| Best for | Sharing a stable model/clip/vae across many subgraphs | easy-use's own ecosystem (its samplers and pre-samplers expect PIPE_LINE) |

Mixing the two in one workflow is allowed but every cross-bridge is a
manual repack. Pick one bundle convention per workflow.

## Loops

Easy-use ships the only general-purpose loop primitives in this
install. Use sparingly — ComfyUI's execution model wasn't designed for
iteration, and loops expand at prompt-queue time to a sequence of
copied subgraph nodes (so an N=50 loop is N=50 sampler instances in
the graph, not one node looping).

| Loop | Setup |
|---|---|
| `easy forLoopStart` → body → `easy forLoopEnd` | `total` count (INT), `values_1..N` carry state through iterations |
| `easy whileLoopStart` → body → `easy whileLoopEnd` | `condition` (BOOLEAN) checked after each iteration; emits FLOW_CONTROL token + state |

Best practice:

- Keep loop bodies short. Each iteration replicates the entire subgraph
  in the queue, so 30 iterations × 50 nodes ≈ 1500-node queue.
- Always have an exit predicate. `whileLoopEnd` with no terminating
  condition will hang the queue forever.
- The state-carry slots (`values_*`) are how you accumulate — write to
  them at the end, read at the start.
- For per-image batch iteration, prefer ComfyUI's native batch
  semantics (let the sampler process a batch) over a loop. Loops are
  for iteration where each round depends on the previous round's
  output.

## Execution gating

| Primitive | What it does |
|---|---|
| `easy blocker` | Pass-through; if `continue=False` returns an `ExecutionBlocker` sentinel. Any downstream node touching the sentinel is silently skipped. |
| `ImpactConditionalStopIteration` | Inside an Impact iterator (detector → detailer loop), halts the loop when its BOOLEAN input is True. |
| `ImpactExecutionOrderController` | Pins a side-effect node (SaveImage, log, webhook) to run before / after a designated other node. Used when ComfyUI's free reordering picks the wrong sequence. |

`ExecutionBlocker` is the canonical "kill this path" primitive in
ComfyUI — see `comfy-conditionals` for predicate formation and
detailed semantics (Preview Bridge consumes the sentinel silently;
SaveImage downstream is the abort target).

## Recipes

### Toggleable LoRA stack with bypass

You have 3–8 LoRAs stacked into a chain. You want each one individually
toggleable, with a master "all off" too.

```
UNETLoader ─┐
            │
            ▼
rgthree Power Lora Loader  ← per-row: enabled (bool), name, strength
            │
            ▼
ModelSamplingAuraFlow (or whatever)
```

- One node holds the stack. UI per-row toggle + strength.
- Group the loader + downstream sampler nodes; right-click → Mute
  Group to bypass the whole branch when prototyping.
- To make a *single* LoRA toggleable as a separate node, wrap with
  Crystools `CSwitchBooleanAny`: bool=on → goes through `LoraLoaderModelOnly`,
  bool=off → bypasses straight to the next stage.

### Optional upscale pass with lazy switch

User sometimes wants a 2× upscale, sometimes doesn't. Without lazy
evaluation, the upscale chain (model loader + KSampler + VAEDecode)
runs even when discarded.

```
                              ┌── on_true: UpscaleModelLoader → Sampler → VAEDecode ──┐
SaveImage upstream ────────── ┤                                                       ├── SaveImage
                              └── on_false: passthrough ─────────────────────────────┘
                                 ▲
                                 │
                              Crystools CSwitchBooleanImage (lazy)
```

- The Crystools switch is lazy → when bool=False, the entire upscale
  chain is skipped, not just discarded.
- Bool can come from a `PrimitiveBoolean`, a `RgthreeContext` field, or
  an `easy compare` predicate.

### Migrating a workflow off broadcast wires for review

When sharing a workflow that uses `Anything Everywhere`, the rest of
the graph has unconnected input sockets that "look" wrong but work
fine because of the broadcaster. For readability when sending the
workflow to someone:

1. Right-click `Anything Everywhere` → "Show connections" (frontend
   flag in the rgthree side panel) — renders dashed lines.
2. Manually wire what the broadcaster was implicitly doing.
3. Delete the broadcaster node.

Reverse the process when receiving a wired workflow you want to
clean up.

## Gotchas

- **`ComfySwitchNode` (core)** is widget-overridden by an input.
  When you wire a BOOLEAN into the `switch` slot of `ComfySwitchNode`,
  the node's own widget value is ignored — the connected input wins.
  This bites you when the widget shows False but a connected
  PrimitiveBoolean(True) is in effect.
- **`Any Switch` (rgthree)** is eager — it evaluates *all* upstream
  inputs before picking the first non-None. Don't use it as a
  performance optimizer; use a typed `CSwitchBoolean*` for laziness.
- **`Preview Bridge` swallows `ExecutionBlocker`**: if you tee a path
  through Preview Bridge to inspect it, and the path is blocked, the
  Preview shows nothing and the downstream abort doesn't propagate
  through the bridge. Use `FastPreview` (`comfyui-kjnodes`) downstream
  of a Preview Bridge when blockers may appear, or wire previews off
  branches that can't be blocked.
- **`ImpactConditionalBranch.cond` is BOOLEAN, not INT/FLOAT**.
  `SimpleMathCondition` (essentials) returns FLOAT — convert with a
  comparator before feeding the branch.
- **Context Big silently drops mismatched slots**. If you wire an
  `IMAGE` to a `Context Big.latent` slot the wire is ignored at
  evaluation. Hover the Context outputs to check what's actually
  populated.
- **Easy-use loops expand at queue-time, not runtime**. A loop of 50
  iterations becomes 50 copies of the body inside the queue's prompt
  graph. Very large loops can OOM the *frontend* (browser) before
  even reaching the backend.

## Cross-refs

- `comfy-conditionals` — forming the boolean / index that feeds these
  switches. Predicates, comparisons, null checks, ExecutionBlocker
  patterns.
- `comfy-prompting` — `Power Lora Loader` plays nicely with LoRA
  trigger-word autoload nodes; see the cross-ref there for the full
  recipe.
- `comfy-debug-preview` — Preview Bridge details, FastPreview as the
  blocker-aware alternative.
- `comfy-math-strings` — primitive sources (PrimitiveBoolean, INT/FLOAT
  constants, sliders) that drive these switches.

## Things this skill does NOT cover

- **Predicate formation** — how to build the boolean that feeds a
  switch. → `comfy-conditionals`.
- **Reroute nodes for visual cleanup** — those are frontend-only and
  don't affect execution; covered by `comfy-workflow-layout` and
  rgthree's UI affordances.
- **Sampler / model routing** (KSampler vs DPMPP vs Euler, model
  loader switching) — that's model-family work; see `wan`, `z-image`,
  `hidream-o1` skills.
- **Subgraph composition** — packaging part of a workflow into a
  reusable subgraph. That's a project `CLAUDE.md` topic under
  "Editing workflow JSON".