Add collected for-loop nodes

README.md

@@ -10,6 +10,9 @@ The node is registered as:
 - `prompt_builder / SxCP Seed Locker`
 - `prompt_builder / SxCP Camera Control`
 - `prompt_builder / SxCP Camera Orbit Control`
+- `prompt_builder / SxCP For Loop Start`
+- `prompt_builder / SxCP For Loop End`
+- `prompt_builder / SxCP Loop Append`
 - `prompt_builder / SxCP Category Preset`
 - `prompt_builder / SxCP Cast Control`
 - `prompt_builder / SxCP Generation Profile`
@@ -71,6 +74,35 @@ as one long chain:
    manually into either generation lane, but they are not part of the default
    main path.
 
+## Loop Nodes
+
+`SxCP For Loop Start` and `SxCP For Loop End` provide a lightweight replacement
+for the easy-use for-loop dependency. They use the same recursive ComfyUI loop
+pattern, but add a dedicated collector output for building a result sequence.
+
+Basic loop wiring:
+
+1. Connect `For Loop Start.flow` to `For Loop End.flow`.
+2. Use `For Loop Start.index` inside the loop for seed/index changes.
+3. Connect the per-iteration output you want to keep, such as an image, latent,
+   prompt, or metadata string, to `For Loop End.collect_value`.
+4. Optionally connect `For Loop Start.collected` to `For Loop End.collected`.
+   If omitted, the end node uses the start collector internally.
+5. After the loop finishes, use `For Loop End.collected` as the combined output.
+
+`collection_mode` controls how values are stored:
+
+- `auto_batch`: concatenates image tensors or latent samples when possible,
+  otherwise falls back to a Python list.
+- `image_batch`: prefers image tensor batching.
+- `latent_batch`: prefers latent `samples` batching.
+- `list`: always appends each iteration result to a list.
+- `string_lines`: joins each collected value with newlines.
+
+`value1`, `value2`, and later slots are normal carry-through channels for state
+you want to update each iteration. They are separate from the collector and grow
+dynamically in the UI as you connect them.
+
 ## Character Profiles
 
 `SxCP Woman Slot` and `SxCP Man Slot` are the scalable per-participant control