1. Side effects inside setState updaters
main.tsx enables <StrictMode>, and useProject.ts performs side effects inside state updaters:
useProject.ts:189-203 — setUndoStack/setRedoStack calls and timer scheduling inside the setProject updaterundo/redo (useProject.ts:205-233) — nested setProject inside setUndoStack/setRedoStack updatersselectPiece (:393-399) — setActiveSheetId inside a setProject updater; addPieceFromBox (:674,684) — setSelectedPieceIds inside the updater
React double-invokes updaters in dev StrictMode, so every edit pushes onto the undo stack twice — in dev, each Ctrl+Z must be pressed twice and canUndo is wrong. Beyond dev mode, this pattern is explicitly unsupported and breaks under concurrent rendering.
Fix: move history into a single reducer — { past, present, future } — so one dispatch atomically updates project + history. This also gives selection/undo consistency for free.
2. loadProjectData doesn't reset history — and can overwrite the previous project's file
useProject.ts:849-856 — unlike switchProject/createNewProject (which reset both stacks), loadProjectData (used by JSON import, drag-drop import, and the tutorial at App.tsx:387) leaves the old project's states in undoStack. Import project B while editing project A, press Ctrl+Z → the canvas snaps to A's old state and the scheduled persist(prev, prev.name) (useProject.ts:213) writes that stale state over A's file in OPFS. Two projects desynced by one keystroke.
3. No schema version or validation on imported/loaded JSON
Project (types.ts:80-93) has no version field; loadProjectFromOPFS blind-casts JSON.parse (opfs.ts:21); loadProjectData accepts raw user JSON from file-open/drag-drop with zero validation (App.tsx:719, 984). A truncated or hand-edited file doesn't fail at load — it crashes later deep in render (e.g. prev.patternCrop spread at useProject.ts:372), and the broken object can get autosaved over the OPFS copy. The schema has clearly evolved (lampConfig, curvePoints); add version: number + a small migration ladder + structural validation at the import boundary, and reset undo/redo there.
4. Minor: sheet IDs from Date.now()
useProject.ts:34,922,959 — pieces use crypto.randomUUID() but sheets use sheet-${Date.now()}; two sheets in the same millisecond (or import + tutorial defaults sheet-1..n) can collide, breaking piece→sheet references and React keys. Use randomUUID() everywhere.
1. Side effects inside setState updaters
main.tsxenables<StrictMode>, anduseProject.tsperforms side effects inside state updaters:useProject.ts:189-203—setUndoStack/setRedoStackcalls and timer scheduling inside thesetProjectupdaterundo/redo(useProject.ts:205-233) — nestedsetProjectinsidesetUndoStack/setRedoStackupdatersselectPiece(:393-399) —setActiveSheetIdinside asetProjectupdater;addPieceFromBox(:674,684) —setSelectedPieceIdsinside the updaterReact double-invokes updaters in dev StrictMode, so every edit pushes onto the undo stack twice — in dev, each Ctrl+Z must be pressed twice and
canUndois wrong. Beyond dev mode, this pattern is explicitly unsupported and breaks under concurrent rendering.Fix: move history into a single reducer —
{ past, present, future }— so one dispatch atomically updates project + history. This also gives selection/undo consistency for free.2.
loadProjectDatadoesn't reset history — and can overwrite the previous project's fileuseProject.ts:849-856— unlikeswitchProject/createNewProject(which reset both stacks),loadProjectData(used by JSON import, drag-drop import, and the tutorial atApp.tsx:387) leaves the old project's states inundoStack. Import project B while editing project A, press Ctrl+Z → the canvas snaps to A's old state and the scheduledpersist(prev, prev.name)(useProject.ts:213) writes that stale state over A's file in OPFS. Two projects desynced by one keystroke.3. No schema version or validation on imported/loaded JSON
Project(types.ts:80-93) has noversionfield;loadProjectFromOPFSblind-castsJSON.parse(opfs.ts:21);loadProjectDataaccepts raw user JSON from file-open/drag-drop with zero validation (App.tsx:719, 984). A truncated or hand-edited file doesn't fail at load — it crashes later deep in render (e.g.prev.patternCropspread atuseProject.ts:372), and the broken object can get autosaved over the OPFS copy. The schema has clearly evolved (lampConfig,curvePoints); addversion: number+ a small migration ladder + structural validation at the import boundary, and reset undo/redo there.4. Minor: sheet IDs from
Date.now()useProject.ts:34,922,959— pieces usecrypto.randomUUID()but sheets usesheet-${Date.now()}; two sheets in the same millisecond (or import + tutorial defaultssheet-1..n) can collide, breaking piece→sheet references and React keys. UserandomUUID()everywhere.