refactoring: graph state

frontend/docs/IMPROVEMENTS.md

@@ -48,6 +48,20 @@ This doc summarizes recent improvements and suggested next steps for readability
 - **config/renderingLogic**: uses context nodes/edges directly (no casts); `setVarInContext(src: NodeLike)`.
 - **useRenderingNodeState**: casts to `NodeLike[]` / `EdgeLike[]` when calling `buildSourceSignatures` (types from renderingSignatures).
 
+### 9. Graph state, connection state, and node display state
+
+- **lib/graph/state.ts**: Central state contracts and flow doc.
+  - **GraphState** – in-memory nodes + edges (useGraphStateWithHistory, persisted by useCanvasGraph).
+  - **ConnectionPathState** – type describing the slice that drives edge status and path animation (trigger/updating/paused/error sets).
+  - **NodeDisplayStatus** – `'initial' | 'loading' | 'success' | 'error'` for node UI; **getNodeDisplayStatus({ loading, error, hasContent })**.
+  - **StoredGraphState** – shape for save/load (version + nodes + edges).
+- **FlowContext**: Module doc splits value into (1) Graph state, (2) Connection path state, (3) UI state. Same flat props, clearer sections.
+- **useGraphStateWithHistory**: JSDoc explains history (past/future), setNodes vs setNodesSilent, setStateImmediate.
+- **projectGraphStorage**: Uses **StoredGraphState** from state.ts; re-exports type. Doc references state flow.
+- **useRenderingNodeState**: Returns **displayStatus** (for NodeStatusIndicator/empty/error UI) and **lifecycle** (updating/error/paused for useSyncConnectionStatus). Hook calls useSyncConnectionStatus(id, state.lifecycle). Type includes RenderingNodeLifecycle.
+- **RenderingNode**: Uses **state.displayStatus** for NodeStatusIndicator instead of computing status locally.
+- **nodeLifecycle** and **connectionStatus**: Docs reference state.ts for overall state flow.
+
 ## Design patterns in use
 
 | Pattern        | Where                                      |