Document required Unreal plugins

AGRARIAN_DEVELOPMENT_ROADMAP.md

@@ -176,7 +176,7 @@ Remaining version 0.01 cleanup before moving deeper into new gameplay:
 - [x] Implement Linastorage incremental project backup job.
 - [x] Implement quiesced VM backup job for Windows-Builder and Ubuntu-Codex.
 - [x] Create repeatable dedicated server build instructions.
-- [~] Finish required plugin documentation.
+- [x] Finish required plugin documentation.
 - [ ] Confirm the project opens cleanly from a fresh checkout, not just the current working share.
 - [ ] Organize `Content/Agrarian/` folders and move starter/prototype assets into clearly named locations.
 - [ ] Launch near-term MVP map-tile serving cloud VM.
@@ -214,7 +214,7 @@ Goal: Prepare the project so all future development is controlled, recoverable,
 - [x] Create repeatable local build instructions.
 - [x] Create repeatable packaged build instructions.
 - [x] Create repeatable dedicated server build instructions.
-- [~] Document required plugins.
+- [x] Document required plugins.
 - [x] Disable unneeded plugins.
 - [x] Confirm project compiles from a clean checkout.
 - [ ] Confirm project opens from a clean checkout.
@@ -1418,7 +1418,7 @@ Earliest incomplete foundation items:
 - [x] Implement Linastorage incremental project backup job.
 - [x] Implement quiesced VM backup job for Windows-Builder and Ubuntu-Codex.
 - [x] Create repeatable dedicated server build instructions.
-- [~] Finish required plugin documentation.
+- [x] Finish required plugin documentation.
 - [ ] Confirm project opens cleanly from a fresh checkout.
 - [ ] Create the core design document.
 - [ ] Create the technical design document.
@@ -1434,4 +1434,4 @@ Earliest incomplete foundation items:
 
 Immediate next item:
 
-- [~] Finish required plugin documentation.
+- [ ] Confirm project opens cleanly from a fresh checkout.

Docs/RequiredPlugins.md

@@ -0,0 +1,82 @@
+# Required Unreal Plugins
+
+Agrarian should keep plugins boring and intentional. Every enabled plugin must
+either be required by compiled code, required by checked-in content, or clearly
+limited to editor workflow.
+
+## Current Enabled Plugins
+
+These are the only plugins intentionally enabled in `AgrarianGame.uproject`.
+
+| Plugin | Required For | Runtime Needed | Notes |
+| --- | --- | --- | --- |
+| `StateTree` | Template AI code that still compiles under `Variant_Combat` and `Variant_SideScrolling` | Yes, until those template variants are removed or rewritten | Required by `StateTreeModule` includes and dependencies. |
+| `GameplayStateTree` | StateTree AI component support used by the template AI controllers | Yes, until those template variants are removed or rewritten | Required by `GameplayStateTreeModule` and `UStateTreeAIComponent`. |
+| `ModelingToolsEditorMode` | Editor-side terrain, mesh, and prototype world-building workflow | No | Keep enabled for developer/editor use. Revisit before shipping if it adds unnecessary packaging overhead. |
+
+## Module Dependencies Tied To Plugins
+
+`Source/AgrarianGame/AgrarianGame.Build.cs` currently depends on:
+
+- `StateTreeModule`
+- `GameplayStateTreeModule`
+
+Do not disable `StateTree` or `GameplayStateTree` until the template AI source
+under these folders is removed or refactored:
+
+- `Source/AgrarianGame/Variant_Combat/`
+- `Source/AgrarianGame/Variant_SideScrolling/`
+
+The roadmap already tracks a decision on whether to keep or remove current
+Unreal template variants. If those variants are removed, revisit this document
+and remove the StateTree plugin/module dependencies if no Agrarian-specific AI
+code needs them.
+
+## Explicitly Not Enabled Yet
+
+These plugins are intentionally not part of the baseline yet:
+
+- `OnlineSubsystemSteam`: enable only when Steam account/session integration is
+  ready to implement and test.
+- `GameplayAbilities`: decide after the core survival/crafting/combat model is
+  better defined. Do not add it just because it may be useful later.
+- Marketplace content plugins: add only when the asset is actively used by the
+  current build and the repository storage policy has been checked.
+- Visual Studio tooling plugins: avoid committing machine-specific editor helper
+  plugin references.
+
+## Add Or Remove Plugin Checklist
+
+Before enabling a plugin:
+
+1. Confirm whether it is needed at runtime, editor-only, or only for one-time
+   asset authoring.
+2. Check the license, redistribution terms, and whether it can be used in
+   packaged builds.
+3. Run `Scripts/audit_repo_storage.sh` if the plugin brings assets into the
+   repository.
+4. Update `AgrarianGame.uproject`.
+5. Update `Source/AgrarianGame/AgrarianGame.Build.cs` only when code needs the
+   plugin's modules.
+6. Build `AgrarianGameEditor` after the change.
+7. If runtime code or packaged content depends on it, build a packaged client
+   and eventually the dedicated server target.
+8. Update this document and the roadmap note for the plugin decision.
+
+Before disabling a plugin:
+
+1. Search source, config, Blueprints, maps, and data assets for references.
+2. Remove unused module dependencies from `AgrarianGame.Build.cs`.
+3. Open the project and fix missing asset/class references.
+4. Run the editor build and relevant automation checks.
+5. Package a client if runtime content was affected.
+
+## Current Decision
+
+Keep `StateTree`, `GameplayStateTree`, and `ModelingToolsEditorMode` enabled for
+version `0.01`.
+
+Do not add additional plugins until a roadmap item requires them. The next
+likely plugin review is the template-variant cleanup item, because that may
+allow the project to remove StateTree dependencies if the template AI code is
+deleted.