Add global seed node

README.md

@@ -6,6 +6,7 @@ generator without writing image batches.
 The node is registered as:
 
 - `prompt_builder / SxCP Prompt Builder`
+- `prompt_builder / SxCP Global Seed`
 - `prompt_builder / SxCP Seed Control`
 - `prompt_builder / SxCP Seed Locker`
 - `prompt_builder / SxCP Camera Control`
@@ -231,6 +232,13 @@ like an auto-labeled slot and can participate in couple/group casts. The outfit,
 scene, pose, expression, and composition can still change while the saved
 character appearance remains stable.
 
+`SxCP Global Seed` is the simplest reproducibility node. Set `global_seed`,
+connect its `seed` output to the prompt node's `seed` input, and connect its
+`seed_config` output to the prompt node's `seed_config` input. With the same
+row number, settings, category files, and sampler seed, this recreates the same
+prompt result. Manual fields and explicitly fixed per-axis or character-slot
+seeds still override the global seed for those parts.
+
 `SxCP Seed Control` outputs `seed_config`, which can be connected to the prompt
 builder's optional `seed_config` input. When an axis is set to `random`, the
 visible seed value is materialized before the workflow queues, and that exact
@@ -716,6 +724,14 @@ axis has its own mode plus seed value:
 The `Lock Random Seeds Now` button turns every current `random` axis into a
 visible concrete seed and switches those axes to `fixed`.
 
+For exact prompt reproduction, `SxCP Global Seed` is the shortest path:
+
+- Connect `seed` to the generator `seed` input.
+- Connect `seed_config` to the generator `seed_config` input.
+- Keep character `slot_seed=-1` when that character should follow the global
+  person seed; set `slot_seed` only when that character should be independently
+  pinned.
+
 For normal prompt iteration, `SxCP Seed Locker` is usually simpler:
 
 - `base_seed`: the seed whose character/location/etc. you want to keep.