ComfyUI Node
Feature Probe
Inject a single SAE/transcoder feature direction into conditioning to visualize what it encodes. Each feature's decoder column is a direction in the hidden space — this node adds that direction to your conditioning so the generated image reveals the concept. Use 'sweep' mode to batch-test multiple features at once.
Feature Probe
- conditioning
- CONDITIONING
- PROBE_INFO
◄sae_path►
◄feature_indices0►
◄probe_strength1.0►
◄inject_modeadd►
◄replace_blend0.00►
◄sae_expansion8►
◄transcoder_repo►
CategoryConcept Steer/Features
Inputs (8)
| Name | Type | Default | Description |
|---|---|---|---|
| conditioning | CONDITIONING | — | |
| sae_path | STRING | Absolute path to SAE weights (.pt file). Must match the SAE used in Feature Map. | |
| feature_indices | STRING | 0 | Feature index or comma-separated list of indices. Single index → one output conditioning. Multiple indices → batch output (one per feature). Get indices from the Feature Map node. |
| probe_strength | FLOAT | 1.00–10 | How strongly to inject the feature direction. 1.0 = moderate effect (~30% of conditioning norm). 2.0-5.0 = strong effect, dominates the image. Start at 1.0 and increase until the concept is visible. |
| inject_mode | COMBO | add | 'add' = adds feature direction to existing conditioning. The prompt still matters, feature concept is layered on. 'replace' = replaces conditioning with pure feature direction. Shows the raw concept with no prompt influence. |
| replace_blend | FLOAT | 0.000–1 | Only used in 'replace' mode. Blend between pure feature direction (0.0) and original conditioning (1.0). 0.0 = pure feature, 0.5 = half-and-half, 1.0 = no change. |
| sae_expansion | INT | 82–128 | SAE expansion factor (auto-detected for transcoders). 8x for trained SAEs, 64x for pretrained transcoders. |
| transcoder_repo | STRING | HuggingFace repo for pretrained transcoders (e.g. 'mwhanna/qwen3-4b-transcoders'). Auto-downloads on first use. Leave empty to use sae_path instead. |
Outputs (2)
| Name | Type | Description |
|---|---|---|
| CONDITIONING | CONDITIONING | — |
| PROBE_INFO | STRING | — |