MiniMax H3 Scene LoRA Scheduler

Swap LoRA'd models per scene without ever loading one

By ethanfel·Created about a month ago·Updated a day ago· 415

state
base_model
lora_a
lora_b
lora_c
lora_d
lora_e
lora_f
lora_g
lora_h
lora_i
lora_j
lora_k
lora_l
lora_m
lora_n
lora_o
lora_p
lora_q
lora_r
lora_s
lora_t
lora_u
lora_v
lora_w
lora_x
lora_y
lora_z

model
status

MiniMax H3 Scene LoRA Scheduler is the node that says "scene 1 gets the base model, scenes 2–3 get LoRA A, scene 4 gets LoRA B" - and it doesn't load or apply a single LoRA itself. That's the whole trick, and it's a good one. It routes pre-patched MODELs.

The insight: instead of re-implementing LoRA loading, the scheduler takes the ordinary ComfyUI model and LoRA loaders you already know and just switches between their outputs per scene. You build a Base model branch and up to four LoRA branches with normal loaders, then choose which one the active scene gets. The base_model input is required and is meant to be the exact unpatched MODEL that already feeds your workflow - so the scheduler slots in without changing how you load anything.

The inputs and the lazy bit

state - from Current Shot. The active scene's lora_route (set per scene in the Plan) selects the MODEL branch.
base_model - the unpatched/base route.
lora_a through lora_d (optional) - each a MODEL from an existing ComfyUI LoRA loader, or a stack of LoRA loaders.

The genuinely clever part is the laziness. The tooltip spells it out: inputs are lazy, so an unused branch is not evaluated merely because it's connected. ComfyUI's lazy-evaluation machinery means a LoRA branch for a scene that never uses it doesn't get loaded into VRAM, doesn't get computed, doesn't exist for that pass. That's what makes per-scene model routing practical instead of a VRAM catastrophe.

The output is just model - only the active scene's selected pre-patched MODEL - plus a status STRING reporting the chosen Base/LoRA route and scene number. You wire the output to the sampler, or to Chain Context when Drift-Control owns the MODEL path.

Where you'd use it

Any production where scenes want different stylistic or character models. A two-minute piece with an establishing shot and a close-up interior could run the base model on the establishing wide and a stylistic LoRA on the close-ups. The main maintained use case, though, is combining this with between_scene_cleanup on Loop End: the fresh_scene memory policy exists exactly for model-switching chains - it unloads the previous scene's weights before the next scene's branch is loaded, which keeps a per-scene LoRA chain from accumulating VRAM.

Installing it

Part of ComfyUI-MiniMaxH3-Contex-Loop (ComfyUI Manager: "MiniMax H3 Contex Loop"), or:

cd ComfyUI/custom_nodes && git clone https://github.com/ethanfel/ComfyUI-MiniMaxH3-Contex-Loop.git

Restart ComfyUI. It adds no LoRA machinery of its own - you still need your LoRA files and the ordinary ComfyUI LoRA loader. Standing requirements: H3 weights, current ComfyUI with native Add Guide (PR #15439).

Common issues

The main trap is expecting the scheduler to load LoRAs for you - it won't, and if a branch is just a bare base_model dangling in, that's on the graph, not the node. Also, the selection is per-scene via the Plan's lora_route, so if every scene is coming out with the same model, check you actually set the route per scene rather than relying on a default. And when switching models leaves you OOM mid-run, add between_scene_cleanup (see Loop End) rather than shrinking your LoRA - the scheduler was built to be paired with it.

Categoryconditioning/minimax/context_loop

Inputs (28)

Name	Type	Description
state	H3_CHAIN_STATE	Current Shot state. The active scene's lora_route selects one MODEL branch.
base_model	MODEL	Unpatched/base MODEL route. Keep using the ordinary ComfyUI model loader that already feeds your workflow.
lora_aopt	MODEL	Route A MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_bopt	MODEL	Route B MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_copt	MODEL	Route C MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_dopt	MODEL	Route D MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_eopt	MODEL	Route E MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_fopt	MODEL	Route F MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_gopt	MODEL	Route G MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_hopt	MODEL	Route H MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_iopt	MODEL	Route I MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_jopt	MODEL	Route J MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_kopt	MODEL	Route K MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_lopt	MODEL	Route L MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_mopt	MODEL	Route M MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_nopt	MODEL	Route N MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_oopt	MODEL	Route O MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_popt	MODEL	Route P MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_qopt	MODEL	Route Q MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_ropt	MODEL	Route R MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_sopt	MODEL	Route S MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_topt	MODEL	Route T MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_uopt	MODEL	Route U MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_vopt	MODEL	Route V MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_wopt	MODEL	Route W MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_xopt	MODEL	Route X MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_yopt	MODEL	Route Y MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.
lora_zopt	MODEL	Route Z MODEL from an existing ComfyUI LoRA loader or a stack of LoRA loaders.

Outputs (2)

Name	Type	Description
model	MODEL	Only the active scene's selected pre-patched MODEL. Connect this to the sampler or to Chain Context when Drift-Control owns the MODEL path.
status	STRING	Selected Base/LoRA route and scene number.