# Codebase simplification and design patterns

This doc summarizes recent improvements and suggested next steps for readability, extension, and consistency.

## Done

### 1. Single place for template/reachability (DRY)

- **Added** `lib/graph/templateRefs.ts`: `isReachable`, `resolveExtendsRef`, `getTemplateRefs`.
- **Refactored** `config/renderingLogic.ts` and `useRenderingNodeState.ts` to use these helpers instead of duplicating the same logic.
- **Pattern:** Extract shared pure helpers into a small lib module; keep call sites thin and consistent.

### 2. Naming and comments

- **Renamed** `outputMenuRegistry.tsx` → `outputMenuHandlers.tsx` (no registry, only helpers).
- **Updated** `rendering.ts` and `sourceRenderingLogic.ts`: output menu is described as coming from the node descriptor (`getOutputMenuContent`), not a separate registry.
- **Documented** `NodeMenubar`: extra content can come from props or from the descriptor (`getNodeMenuExtraContent`).
- **Documented** `nodeTypes.ts`: clarifies React Flow types vs node type id (nodeRegistry).

### 3. Central pipeline entry

- **rendering.ts** documents the 3-step pipeline, how to add a source/output type, and points to `templateRefs.ts` for shared helpers.

### 4. Rendering signatures (pure module)

- **Added** `lib/graph/renderingSignatures.ts`: `buildConnectedNodeIds`, `buildSourceSignatures` (connectedNodeIds + all five signatures + sourceSignature).
- **Refactored** `useRenderingNodeState` to call `buildSourceSignatures` in a single useMemo; hook is shorter and signature logic is testable in isolation.

### 5. Canvas split

- **CanvasContextMenuContent** (`app/canvas/CanvasContextMenuContent.tsx`): context menu content (Create Node grouped by classification, Paste). CanvasPage passes `onCreateNode` and `onPaste`.
- **useCanvasConnectionPath** (`app/canvas/useCanvasConnectionPath.ts`): all connection-path state and callbacks (updating/trigger/paused/error node ids, path node ids, start/end update, add/remove paused/error). CanvasPage calls the hook with `edges` and passes the result into FlowContext.

## Design patterns in use

| Pattern        | Where                                      |
|----------------|--------------------------------------------|
| **Registry**   | nodeRegistry, sourceRenderingLogic         |
| **Builder**    | nodeTypeBuilder (descriptor per node type) |
| **Pipeline**   | Resolve → Render → Display (rendering.ts)   |
| **Strategy**   | Source logic per node type; output menu per descriptor |
| **Shared helpers** | templateRefs, outputMenuHandlers, renderingUtils |

## Suggested next steps

1. **CanvasPage**: Further split optional: e.g. `useCanvasGraph()` for graph state + persistence + connection rules, so the page is mostly composition and layout.

2. **Config types**: If you add more output types (e.g. Mermaid), consider a small registry API (`registerConfigType`, `getConfigType`) instead of a single large `CONFIG_TYPES` array.

3. **Consistent node shape in lib**: `templateRefs` and `renderingSignatures` use `EdgeLike` / `NodeLike`; standardize where appropriate to reduce casts.