## Codebase Patterns
- Project uses Next.js 16 with App Router, TypeScript, and TailwindCSS 4
- Source files are in `src/` directory (app, components, lib, types)
- Supabase is configured with @supabase/supabase-js and @supabase/ssr packages
- Environment variables follow NEXT_PUBLIC_* convention for client-side access
- Use `npm run typecheck` to run TypeScript type checking (tsc --noEmit)
- Flowchart types exported from `src/types/flowchart.ts`
- Supabase migrations go in `supabase/migrations/` with timestamp prefix (YYYYMMDDHHMMSS_*.sql)
- Database has profiles table (linked to auth.users) and projects table (with flowchart_data JSONB)
- RLS policies enforce user_id = auth.uid() for project access
- Supabase client utilities in `src/lib/supabase/`: client.ts (browser), server.ts (App Router), middleware.ts (route protection)
- Next.js middleware.ts at project root handles route protection using updateSession helper
- Public auth routes: /login, /signup, /forgot-password, /reset-password
- Protected routes: /dashboard, /editor/* (redirect to /login if unauthenticated)
- Auth pages use 'use client' with useState, createClient() from lib/supabase/client.ts, and useRouter for redirects
- For lists with client-side updates (delete/add), use wrapper client component that receives initialData from server component
- Toast component in `src/components/Toast.tsx` for success/error notifications (auto-dismiss after 3s)
- Admin operations use SUPABASE_SERVICE_ROLE_KEY (server-side only via server actions)
- Admin users have is_admin=true in profiles table; check via .select('is_admin').eq('id', user.id).single()
- React Flow editor is in `src/app/editor/[projectId]/` with page.tsx (server) and FlowchartEditor.tsx (client)
- React Flow requires 'use client' and importing 'reactflow/dist/style.css'
- Use toReactFlowNodes/toReactFlowEdges helpers to convert app types to React Flow types
- Custom node components go in `src/components/editor/nodes/` with NodeProps<T> typing and useReactFlow() for updates
- Register custom node types in nodeTypes object (memoized with useMemo) and pass to ReactFlow component
- FlowchartEditor uses ReactFlowProvider wrapper + inner component pattern for useReactFlow() hook access
- Use nanoid for generating unique node IDs (import from 'nanoid')
- Reusable LoadingSpinner component in `src/components/LoadingSpinner.tsx` with size ('sm'|'md'|'lg') and optional message
- Toast component supports an optional `action` prop: `{ label: string; onClick: () => void }` for retry/undo buttons
- Settings page at `/dashboard/settings` reuses dashboard layout; re-auth via signInWithPassword before updateUser
- Character/Variable types (`Character`, `Variable`) and extracted node data types (`DialogueNodeData`, `VariableNodeData`) are in `src/types/flowchart.ts`
- `EditorContext` at `src/components/editor/EditorContext.tsx` provides shared state (characters, onAddCharacter) to all custom node components via React context
- Use `useEditorContext()` in node components to access project-level characters and variables without prop drilling through React Flow node data
- New JSONB fields (characters, variables) must be defaulted to `[]` when reading from DB in page.tsx to handle pre-existing data
- Reusable `Combobox` component at `src/components/editor/Combobox.tsx` - use for all character/variable dropdowns. Props: items (ComboboxItem[]), value, onChange, placeholder, onAddNew
- `ProjectSettingsModal` at `src/components/editor/ProjectSettingsModal.tsx` manages characters/variables. Receives state + callbacks from FlowchartEditor
- Characters and variables state is managed in `FlowchartEditorInner` with `useState` hooks, passed down to the modal
- For settings-style modals, use `max-w-2xl h-[80vh]` with overflow-y-auto content area and fixed header/tabs
- `EditorContext` provides both characters (onAddCharacter) and variables (onAddVariable) to node components. Use `useEditorContext()` to access them.
- In FlowchartEditor, `handleAddVariable` adds a variable *node* to the canvas; `handleAddVariableDefinition` creates a variable *definition* in project data. Avoid naming collisions between "add node" and "add definition" callbacks.
- Edge interactions use `onEdgeClick` on ReactFlow component. ConditionEditor opens as a modal overlay since React Flow edges don't support inline panels.
- `Condition.value` supports `number | string | boolean` — always check variable type before rendering value inputs for edge conditions.
- `OptionConditionEditor` at `src/components/editor/OptionConditionEditor.tsx` handles choice option conditions. Same pattern as `ConditionEditor` but with simpler props (no edgeId).
- `ChoiceOption` type includes optional `condition?: Condition`. When counting variable usage, check variable nodes + edge conditions + choice option conditions.
- React Compiler lint forbids `setState` in effects and reading `useRef().current` during render. Use `useState(() => computeValue())` lazy initializer pattern for one-time initialization logic.
- For detecting legacy data shape (pre-migration), pass a flag from the server component (page.tsx) to the client component, since only the server reads raw DB data.
- Collaboration tables: `project_collaborators` (roles), `collaboration_sessions` (presence), `audit_trail` (history) — all with RLS scoped by project ownership or collaborator membership
- RLS pattern for shared resources: check `projects.user_id = auth.uid()` OR `project_collaborators.user_id = auth.uid()` to cover both owners and collaborators
- `RealtimeConnection` class at `src/lib/collaboration/realtime.ts` manages Supabase Realtime channel lifecycle (connect, heartbeat, reconnect, disconnect). Instantiate with (projectId, userId, callbacks).
- FlowchartEditor receives `userId` prop from page.tsx server component for collaboration features
- Toolbar accepts optional `connectionState` prop to show green/yellow/red connection indicator
- `collaboration_sessions` table has UNIQUE(project_id, user_id) constraint to support upsert-based session management
- Server actions for project-specific operations go in `src/app/editor/[projectId]/actions.ts` — use `'use server'` directive and return `{ success: boolean; error?: string }` pattern
- Editor page.tsx supports both owner and collaborator access: first checks ownership, then falls back to `project_collaborators` lookup. Pass `isOwner` prop to client component.
- `ShareModal` at `src/components/editor/ShareModal.tsx` manages collaborator invites/roles/removal via server actions. Only owners see invite form.
- Dashboard shared projects use Supabase join query: `project_collaborators.select('role, projects(id, name, updated_at)')` to fetch projects shared with the user
- `ProjectCard` supports optional `shared` and `sharedRole` props — when `shared=true`, hide edit/delete buttons and show role badge instead
- `PresenceAvatars` at `src/components/editor/PresenceAvatars.tsx` renders connected collaborator avatars. Receives `PresenceUser[]` from `RealtimeConnection.onPresenceSync`.
- `RealtimeConnection` constructor takes `(projectId, userId, displayName, callbacks)` — `displayName` is broadcast via Supabase Realtime presence tracking
- User color for presence is derived from a hash of their userId, ensuring consistency across sessions. Use `getUserColor(userId)` pattern from PresenceAvatars.
- `CRDTManager` at `src/lib/collaboration/crdt.ts` wraps a Yjs Y.Doc with Y.Map<string> for nodes and edges. Connects to Supabase Realtime channel for broadcasting updates.
- CRDT sync pattern: local React Flow changes → `updateNodes`/`updateEdges` on CRDTManager → Yjs broadcasts to channel; remote broadcasts → Yjs applies update → callbacks set React Flow state. Use `isRemoteUpdateRef` to prevent echo loops.
- For Supabase Realtime broadcast of binary data (Yjs updates), convert `Uint8Array` → `Array.from()` for JSON payload, and `new Uint8Array()` on receive.
- For ephemeral real-time data (cursors, typing indicators), use Supabase Realtime broadcast (`channel.send({ type: 'broadcast', event, payload })`) + `.on('broadcast', { event }, callback)` — not persistence-backed
- `RemoteCursors` at `src/components/editor/RemoteCursors.tsx` renders collaborator cursors on canvas. Uses `useViewport()` to transform flow→screen coordinates. Throttle broadcasts to 50ms via timestamp ref.

---

## 2026-01-23 - US-054
- What was implemented: Character and Variable TypeScript types added to `src/types/flowchart.ts`
- Files changed:
  - `src/types/flowchart.ts` - Added `Character`, `Variable`, `DialogueNodeData`, `VariableNodeData` types; updated `FlowchartData`, `DialogueNode`, `VariableNode`, `Condition` types
  - `src/app/editor/[projectId]/page.tsx` - Updated FlowchartData initialization to include `characters: []` and `variables: []` defaults
- **Learnings for future iterations:**
  - The node components (`DialogueNode.tsx`, `VariableNode.tsx`, `ChoiceNode.tsx`) define their own local data types that mirror the global types. When adding fields, both the global type and local component type may need updating in later stories.
  - `flowchart_data` is a JSONB column in Supabase, so it comes as `any` type. Always provide defaults for new fields when reading from DB to handle existing data without those fields.
  - The new `characterId` and `variableId` fields are optional alongside existing `speaker`/`variableName` fields to support migration from free-text to referenced-entity pattern.
---

## 2026-01-23 - US-055
- What was implemented: Database migration to update flowchart_data JSONB default to include `characters: []` and `variables: []`
- Files changed:
  - `supabase/migrations/20260123000000_add_characters_variables_to_flowchart_data.sql` - New migration that alters the default value for the flowchart_data column and documents the expected JSONB structure
- **Learnings for future iterations:**
  - Since characters and variables are stored within the existing flowchart_data JSONB column (not as separate tables), schema changes are minimal - just updating the column default. The real data integrity is handled at the application layer.
  - The app-side defaults in page.tsx (from US-054) already handle existing projects gracefully, so no data migration of existing rows is needed.
  - For JSONB-embedded arrays, the pattern is: update the DB default for new rows + handle missing fields in app code for old rows.
---

## 2026-01-23 - US-065
- What was implemented: Reusable searchable combobox component at `src/components/editor/Combobox.tsx`
- Files changed:
  - `src/components/editor/Combobox.tsx` - New component with searchable dropdown, keyboard navigation, color swatches, badges, "Add new..." option, and auto-positioning
- **Learnings for future iterations:**
  - The Combobox exports both the default component and the `ComboboxItem` type for consumers to use
  - Props: `items` (ComboboxItem[]), `value` (string | undefined), `onChange` (id: string) => void, `placeholder` (string), `onAddNew` (() => void, optional)
  - ComboboxItem shape: `{ id: string, label: string, color?: string, badge?: string }`
  - The component uses neutral zinc colors for borders/backgrounds (not blue/green/orange) so it can be reused across different node types
  - Dropdown auto-positions above or below based on available viewport space (200px threshold)
  - Keyboard: ArrowDown/Up navigate, Enter selects, Escape closes
  - The component is designed to be a drop-in replacement for text inputs in node components (same `w-full` and `text-sm` sizing)
---

## 2026-01-23 - US-056
- What was implemented: Character management UI in the project settings modal
- Files changed:
  - `src/components/editor/ProjectSettingsModal.tsx` - New modal component with Characters and Variables tabs; Characters tab has full CRUD (add, edit, delete with usage warnings), name uniqueness validation, color picker, inline forms
  - `src/components/editor/Toolbar.tsx` - Added `onProjectSettings` prop and "Project Settings" button to the right side of the toolbar
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Added `characters` and `variables` state management, `showSettings` modal state, usage count helpers (`getCharacterUsageCount`, `getVariableUsageCount`), and ProjectSettingsModal rendering
- **Learnings for future iterations:**
  - The ProjectSettingsModal receives `onCharactersChange` and `onVariablesChange` callbacks that directly set state in FlowchartEditor. When save is implemented, it should read from this state.
  - The Variables tab is a read-only placeholder in US-056; US-057 will implement the full CRUD for variables using the same patterns (inline forms, validation, delete warnings).
  - Modal pattern: fixed inset-0 z-50 with backdrop click to close, max-w-2xl for settings modals (larger than max-w-md used for simple dialogs).
  - Character usage count checks dialogue nodes for `data.characterId`; variable usage count checks both variable nodes and edge conditions.
  - The `randomHexColor()` utility picks from a curated list of 12 vibrant colors for character defaults.
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-23 - US-057
- What was implemented: Variable management UI with full CRUD in the project settings modal Variables tab
- Files changed:
  - `src/components/editor/ProjectSettingsModal.tsx` - Replaced placeholder VariablesTab with full implementation: add/edit/delete with inline forms, type dropdown (numeric/string/boolean), type-adaptive initial value input (number input for numeric, text for string, select for boolean), name uniqueness validation, delete warnings with usage count, colored type badges
- **Learnings for future iterations:**
  - The VariableForm uses a `handleTypeChange` helper that resets the initial value to the type's default when the type changes, preventing invalid state (e.g., "hello" as a numeric value)
  - Initial values are stored as strings in form state and parsed to the correct type (number/string/boolean) on save via `parseInitialValue()`
  - Type badges use distinct colors: blue for numeric, green for string, purple for boolean - making variable types instantly recognizable in the list
  - The same form patterns from CharactersTab apply: inline form within the list for editing, appended form below the list for adding
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-23 - US-059
- What was implemented: Variable node variable dropdown using Combobox component, replacing the free-text input
- Files changed:
  - `src/components/editor/nodes/VariableNode.tsx` - Replaced text input with Combobox for variable selection, added inline "Add new variable" form with name + type, added orange warning border for invalid references, filtered operation options (add/subtract only for numeric type)
  - `src/components/editor/EditorContext.tsx` - Extended context to include `variables: Variable[]` and `onAddVariable` callback
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Added `handleAddVariableDefinition` callback and passed variables + onAddVariable through EditorContext
- **Learnings for future iterations:**
  - The existing `handleAddVariable` in FlowchartEditor adds a variable *node* to the canvas (toolbar action). The new `handleAddVariableDefinition` creates a variable *definition* in the project's data. Name carefully to avoid collisions.
  - EditorContext is the shared context for node components to access project-level characters and variables. Extend it when new entity types need to be accessible from custom node components.
  - The VariableNode follows the same pattern as DialogueNode for Combobox integration: items derived via useMemo, handleSelect sets both variableId and variableName, inline add form for quick creation, hasInvalidReference for warning state.
  - Operations filtering uses `isNumeric` flag: if no variable is selected (undefined) or type is 'numeric', all operations are shown; otherwise only 'set' is available. When selecting a non-numeric variable, operation is auto-reset to 'set' if it was 'add' or 'subtract'.
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-23 - US-060
- What was implemented: Edge condition variable dropdown using Combobox component, replacing free-text input with a type-aware condition editor modal
- Files changed:
  - `src/types/flowchart.ts` - Updated `Condition.value` type from `number` to `number | string | boolean` to support all variable types
  - `src/components/editor/ConditionEditor.tsx` - New component: modal-based condition editor with Combobox for variable selection, type-aware operator filtering, type-adaptive value inputs, inline "Add new variable" form, orange warning for invalid references, and "Remove condition" action
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Added `onEdgeClick` handler to open ConditionEditor, `handleConditionChange` to update edge condition data, `selectedEdgeId` state, and ConditionEditor rendering
- **Learnings for future iterations:**
  - Edge interactions in React Flow use `onEdgeClick` prop on the ReactFlow component (not on individual edges). The handler receives `(event: React.MouseEvent, edge: Edge)`.
  - The ConditionEditor is rendered as a modal overlay (fixed z-50), not as part of the edge itself — since edges don't have built-in panel/popover support in React Flow.
  - `Condition.value` was originally typed as just `number` but needed broadening to `number | string | boolean` to support string/boolean variables in conditions. This change didn't break existing code since the VariableNode's `value` field is a separate type.
  - Operator filtering for non-numeric types: only `==` and `!=` are available for string/boolean variables. When switching from a numeric variable to a string/boolean, the operator auto-resets to `==` if it was a comparison operator.
  - Value input adapts to type: number input for numeric, text input for string, boolean dropdown for boolean.
  - The `selectedEdge` is derived via `useMemo` from `edges` state and `selectedEdgeId`, so it always reflects the latest condition data.
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-23 - US-061
- What was implemented: Choice option condition variable dropdown using OptionConditionEditor component with Combobox
- Files changed:
  - `src/types/flowchart.ts` - Added `condition?: Condition` to `ChoiceOption` type; moved `Condition` type definition before `ChoiceOption` for correct reference order
  - `src/components/editor/OptionConditionEditor.tsx` - New component: modal-based condition editor for choice options with Combobox variable selection, type-aware operators, type-adaptive value inputs, inline "Add new variable" form, orange warning for invalid references
  - `src/components/editor/nodes/ChoiceNode.tsx` - Added condition button per option (clipboard icon), condition summary text below options, OptionConditionEditor integration, EditorContext usage for variables, invalid reference detection with orange warning styling
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Extended `getVariableUsageCount` to also count variable references in choice option conditions
- **Learnings for future iterations:**
  - The `OptionConditionEditor` follows the same pattern as `ConditionEditor` but with a simpler API: it doesn't need an edgeId since it works with a single option's condition via `onChange(condition | undefined)` callback
  - The `ChoiceOption` type in `flowchart.ts` now references `Condition`, which required reordering type definitions (Condition must be defined before ChoiceOption)
  - Each choice option shows a small clipboard icon button that turns blue when a condition is set, or orange when the referenced variable is invalid/deleted
  - A condition summary line (e.g., "if score > 10") appears below each option label when a condition is active
  - The `getVariableUsageCount` in FlowchartEditor now counts three sources: variable nodes, edge conditions, and choice option conditions
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-23 - US-062
- What was implemented: Auto-migration of existing free-text speaker/variable values to character/variable definitions on project load
- Files changed:
  - `src/app/editor/[projectId]/page.tsx` - Added `needsMigration` flag that detects whether raw DB data has characters/variables arrays
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Added `computeMigration()` helper function and `needsMigration` prop; migration result initializes state directly via lazy `useState` to avoid React Compiler lint issues
  - `src/components/editor/nodes/DialogueNode.tsx` - Included pre-existing US-058 changes (speaker dropdown with Combobox) that were not previously committed
- **Learnings for future iterations:**
  - React Compiler lint (`react-hooks/set-state-in-effect`) forbids calling `setState` synchronously within `useEffect`. For one-time initialization logic, compute the result and use it directly in state initializers instead.
  - React Compiler lint (`react-hooks/refs`) forbids reading `useRef().current` during render. Use `useState(() => ...)` lazy initializer pattern instead of `useRef` for values computed once at mount.
  - The migration detection relies on `rawData.characters` being `undefined` (old projects) vs `[]` (migrated projects). The `page.tsx` server component passes `needsMigration` flag to the client component since only the server has access to the raw DB shape.
  - `computeMigration` is a pure function called outside the component render cycle (via lazy useState). It uses `nanoid()` for IDs, so it must only be called once — lazy `useState` ensures this.
  - The toast message for migration is set as initial state, so it shows immediately on first render without needing an effect.
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-23 - US-063
- What was implemented: Import characters/variables from another project via modal in project settings
- Files changed:
  - `src/components/editor/ImportFromProjectModal.tsx` - New component: project list modal with checkbox selection for characters or variables, duplicate-by-name skipping with warnings, select all/none controls
  - `src/components/editor/ProjectSettingsModal.tsx` - Added `projectId` prop, `ImportFromProjectModal` integration, and "Import from project" buttons in both Characters and Variables tabs
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Passed `projectId` through to `ProjectSettingsModal`
- **Learnings for future iterations:**
  - The `ImportFromProjectModal` uses `z-[60]` to layer above the `ProjectSettingsModal` (which uses `z-50`), since it's rendered as a child of that modal
  - Imported characters/variables get new IDs via `nanoid()` to avoid ID collisions between projects. The original colors, types, and initial values are preserved.
  - Duplicate detection is case-insensitive by name. Duplicates are skipped (not overwritten) with a warning message shown to the user.
  - The `LoadingSpinner` component mentioned in Codebase Patterns doesn't exist; used inline text loading indicators instead.
  - Supabase client-side fetching from `createClient()` (browser) automatically scopes by the logged-in user's RLS policies, so fetching other projects just uses `.neq('id', currentProjectId)` and RLS handles ownership filtering.
  - No browser testing tools are available; manual verification is needed.
---

## 2026-01-22 - US-030
- What was implemented: Right-click context menu for canvas, nodes, and edges
- Files changed:
  - src/components/editor/ContextMenu.tsx - new component with menu items for different contexts (canvas/node/edge)
  - src/app/editor/[projectId]/FlowchartEditor.tsx - integrated context menu with handlers for all actions
- **Learnings for future iterations:**
  - Use `onPaneContextMenu`, `onNodeContextMenu`, and `onEdgeContextMenu` React Flow callbacks for context menus
  - `screenToFlowPosition()` converts screen coordinates to flow coordinates for placing nodes at click position
  - Context menu state includes type ('canvas'|'node'|'edge') and optional nodeId/edgeId for targeted actions
  - Use `document.addEventListener('click', handler)` and `e.stopPropagation()` on menu to close on outside click
  - Escape key listener via `document.addEventListener('keydown', handler)` for menu close
  - NodeMouseHandler and EdgeMouseHandler types from reactflow provide proper typing for context menu callbacks
---

## 2026-01-22 - US-031
- What was implemented: Condition editor modal for adding/editing/removing conditions on edges
- Files changed:
  - src/components/editor/ConditionEditor.tsx - new modal component with form for variable name, operator, and value
  - src/app/editor/[projectId]/FlowchartEditor.tsx - integrated condition editor with double-click and context menu triggers
- **Learnings for future iterations:**
  - Use `onEdgeDoubleClick` React Flow callback for double-click on edges
  - Store condition editor state separately from context menu state (`conditionEditor` vs `contextMenu`)
  - Use `edge.data.condition` to access condition object on edges
  - When removing properties from edge data, use `delete` operator instead of destructuring to avoid lint warnings about unused variables
  - Condition type has operators: '>' | '<' | '==' | '>=' | '<=' | '!='
  - Preview condition in modal using template string: `${variableName} ${operator} ${value}`
---

## 2026-01-22 - US-032
- What was implemented: Display conditions on edges with dashed styling and labels
- Files changed:
  - src/components/editor/edges/ConditionalEdge.tsx - new custom edge component with condition display
  - src/app/editor/[projectId]/FlowchartEditor.tsx - integrated custom edge type, added EdgeTypes import and edgeTypes definition
- **Learnings for future iterations:**
  - Custom React Flow edges use EdgeProps<T> typing where T is the data shape
  - Use `BaseEdge` component for rendering the edge path, and `EdgeLabelRenderer` for positioning labels
  - `getSmoothStepPath` returns [edgePath, labelX, labelY] - labelX/labelY are center coordinates for labels
  - Custom edge types are registered in edgeTypes object (similar to nodeTypes) and passed to ReactFlow
  - Style edges with conditions using strokeDasharray: '5 5' for dashed lines
  - Custom edges go in `src/components/editor/edges/` directory
  - Use amber color scheme for conditional edges to distinguish from regular edges
---

## 2026-01-22 - US-033
- What was implemented: Auto-save to LocalStorage with debounced saves and draft restoration prompt
- Files changed:
  - src/app/editor/[projectId]/FlowchartEditor.tsx - added LocalStorage auto-save functionality, draft check on load, and restoration prompt UI
- **Learnings for future iterations:**
  - Use lazy useState initializer for draft check to avoid ESLint "setState in effect" warning
  - LocalStorage key format: `vnwrite-draft-{projectId}` for project-specific drafts
  - Debounce saves with 1 second delay using useRef for timer tracking
  - Convert React Flow Node/Edge types back to app types using helper functions (fromReactFlowNodes, fromReactFlowEdges)
  - React Flow Edge has `sourceHandle: string | null | undefined` but app types use `string | undefined` - use nullish coalescing (`?? undefined`)
  - Check `typeof window === 'undefined'` in lazy initializer for SSR safety
  - clearDraft is exported for use in save functionality (US-034) to clear draft after successful database save
  - JSON.stringify comparison works for flowchart data equality check
---

## 2026-01-22 - US-034
- What was implemented: Save project to database functionality
- Files changed:
  - src/app/editor/[projectId]/FlowchartEditor.tsx - implemented handleSave with Supabase update, added isSaving state and Toast notifications
  - src/components/editor/Toolbar.tsx - added isSaving prop with loading spinner indicator
- **Learnings for future iterations:**
  - Use createClient() from lib/supabase/client.ts for browser-side database operations
  - Supabase update returns { error } object for error handling
  - Use async/await with try/catch for async save operations
  - Set updated_at manually with new Date().toISOString() for Supabase JSONB updates
  - Clear LocalStorage draft after successful save to avoid stale drafts
  - Toast state uses object with message and type for flexibility
  - Loading spinner SVG with animate-spin class for visual feedback during save
---

## 2026-01-22 - US-035
- What was implemented: Export project as .vnflow file functionality
- Files changed:
  - src/app/editor/[projectId]/FlowchartEditor.tsx - implemented handleExport with blob creation and download trigger, added projectName prop
  - src/app/editor/[projectId]/page.tsx - passed projectName prop to FlowchartEditor
- **Learnings for future iterations:**
  - Use Blob with type 'application/json' for JSON file downloads
  - JSON.stringify(data, null, 2) creates pretty-printed JSON with 2-space indentation
  - URL.createObjectURL creates a temporary URL for the blob
  - Create temporary anchor element with download attribute to trigger file download
  - Remember to cleanup: remove the anchor from DOM and revoke the object URL
  - Props needed for export: pass data down from server components (e.g., projectName) to client components that need them
---

## 2026-01-22 - US-036
- What was implemented: Import project from .vnflow file functionality
- Files changed:
  - src/app/editor/[projectId]/FlowchartEditor.tsx - implemented handleImport, handleFileSelect, validation, and confirmation dialog for unsaved changes
- **Learnings for future iterations:**
  - Use hidden `<input type="file">` element with ref to trigger file picker programmatically via `ref.current?.click()`
  - Accept multiple file extensions using comma-separated values in `accept` attribute: `accept=".vnflow,.json"`
  - Reset file input value after selection (`event.target.value = ''`) to allow re-selecting the same file
  - Use FileReader API with `readAsText()` for reading file contents, handle onload and onerror callbacks
  - Type guard function `isValidFlowchartData()` validates imported JSON structure before loading
  - Track unsaved changes by comparing current state to initialData using JSON.stringify comparison
  - Show confirmation dialog before import if there are unsaved changes to prevent accidental data loss
---

## 2026-01-22 - US-037
- What was implemented: Export to Ren'Py JSON format functionality
- Files changed:
  - src/components/editor/Toolbar.tsx - added 'Export to Ren'Py' button with purple styling
  - src/app/editor/[projectId]/FlowchartEditor.tsx - implemented Ren'Py export types, conversion functions, and handleExportRenpy callback
- **Learnings for future iterations:**
  - Ren'Py export uses typed interfaces for different node types: RenpyDialogueNode, RenpyMenuNode, RenpyVariableNode
  - Find first node by identifying nodes with no incoming edges (not in any edge's target set)
  - Use graph traversal (DFS) to organize nodes into labeled sections based on flow
  - Choice nodes create branching sections - save current section before processing each branch
  - Track visited nodes to detect cycles and create proper labels for jump references
  - Labels are generated based on speaker name or incremental counter for uniqueness
  - Replace node IDs with proper labels in a second pass after traversal completes
  - Include metadata (projectName, exportedAt) at the top level of the export
  - Validate JSON output with JSON.parse before download to ensure validity
  - Use purple color scheme for Ren'Py-specific button to distinguish from generic export
---

## 2026-01-22 - US-038
- What was implemented: Unsaved changes warning with dirty state tracking, beforeunload, and navigation confirmation modal
- Files changed:
  - src/app/editor/[projectId]/FlowchartEditor.tsx - added isDirty tracking via useMemo comparing current state to lastSavedDataRef, beforeunload event handler, navigation warning modal, back button with handleBackClick, moved header from page.tsx into this component
  - src/app/editor/[projectId]/page.tsx - simplified to only render FlowchartEditor (header moved to client component for dirty state access)
- **Learnings for future iterations:**
  - Dirty state tracking uses useMemo comparing JSON.stringify of current flowchart data to a lastSavedDataRef
  - lastSavedDataRef is a useRef initialized with initialData and updated after successful save
  - Browser beforeunload requires both event.preventDefault() and setting event.returnValue = '' for modern browsers
  - Header with back navigation was moved from server component (page.tsx) to client component (FlowchartEditor.tsx) so it can access isDirty state
  - Back button uses handleBackClick which checks isDirty before navigating or showing confirmation modal
  - Navigation warning modal shows "Leave Page" (red) and "Stay" buttons for clear user action
  - "(unsaved changes)" indicator shown next to project name when isDirty is true
---

## 2026-01-22 - US-039
- What was implemented: Loading and error states with reusable spinner, error page, and toast retry
- Files changed:
  - src/components/LoadingSpinner.tsx - new reusable loading spinner component with size variants and optional message
  - src/app/editor/[projectId]/loading.tsx - updated to use LoadingSpinner component
  - src/app/editor/[projectId]/page.tsx - replaced notFound() with custom error UI showing "Project Not Found" with back to dashboard link
  - src/components/Toast.tsx - added optional action prop for action buttons (e.g., retry)
  - src/app/editor/[projectId]/FlowchartEditor.tsx - updated toast state type to include action, save error now shows retry button via handleSaveRef pattern
- **Learnings for future iterations:**
  - Use a ref (handleSaveRef) to break circular dependency when a useCallback needs to reference itself for retry logic
  - Toast action prop uses `{ label: string; onClick: () => void }` for flexible action buttons
  - Don't auto-dismiss toasts that have action buttons (users need time to click them)
  - Replace `notFound()` with inline error UI when you need custom styling and navigation links
  - LoadingSpinner uses size prop ('sm' | 'md' | 'lg') for flexibility across different contexts
  - Link component from next/link is needed in server components for navigation (no useRouter in server components)
---

## 2026-01-22 - US-040
- What was implemented: Conditionals on choice options - per-option visibility conditions
- Files changed:
  - src/types/flowchart.ts - moved Condition type before ChoiceOption, added optional condition field to ChoiceOption
  - src/components/editor/nodes/ChoiceNode.tsx - added condition button per option, condition badge display, condition editing state management
  - src/components/editor/OptionConditionEditor.tsx - new modal component for editing per-option conditions (variable name, operator, value)
  - src/app/editor/[projectId]/FlowchartEditor.tsx - updated Ren'Py export to include per-option conditions (option condition takes priority over edge condition)
- **Learnings for future iterations:**
  - Per-option conditions use the same Condition type as edge conditions
  - Condition type needed to be moved above ChoiceOption in types file since ChoiceOption now references it
  - Use `delete obj.property` pattern instead of destructuring with unused variable to avoid lint warnings
  - OptionConditionEditor is separate from ConditionEditor because it operates on option IDs vs edge IDs
  - In Ren'Py export, option-level condition takes priority over edge condition since it represents visibility
  - Condition button uses amber color scheme (bg-amber-100) when condition is set, neutral when not
  - Condition badge below option shows "if variableName operator value" text in compact format
---

## 2026-01-22 - US-041
- What was implemented: Change password for logged-in user from settings page
- Files changed:
  - src/app/dashboard/settings/page.tsx - new client component with password change form (current, new, confirm fields)
  - src/components/Navbar.tsx - added "Settings" link to navbar
- **Learnings for future iterations:**
  - Settings page lives under /dashboard/settings to reuse the dashboard layout (navbar, auth check)
  - Re-authentication uses signInWithPassword with current password before allowing updateUser
  - Supabase getUser() returns current user email needed for re-auth signInWithPassword call
  - Password validation: check match and minimum length (6 chars) before making API calls
  - Clear form fields after successful password update for security
  - Settings link in navbar uses neutral zinc colors to distinguish from admin/action links
---

## 2026-01-22 - US-042
- What was implemented: Password reset modal that automatically appears when a recovery token is detected in the URL
- Files changed:
  - src/components/PasswordResetModal.tsx - new client component with modal that detects recovery tokens from URL hash, sets session, and provides password reset form
  - src/app/login/page.tsx - integrated PasswordResetModal component on the login page
- **Learnings for future iterations:**
  - PasswordResetModal is a standalone component that can be placed on any page to detect recovery tokens
  - Use window.history.replaceState to clean the URL hash after extracting the token (prevents re-triggering on refresh)
  - Separate tokenError state from form error state to show different UI (expired link vs. form validation)
  - Modal uses fixed positioning with z-50 to overlay above page content
  - After successful password update, sign out the user and redirect to login with success message (same as reset-password page)
  - The modal coexists with the existing /reset-password page - both handle recovery tokens but in different UX patterns
---

## 2026-01-23 - US-047
- What was implemented: Live cursor positions on canvas showing collaborators' mouse positions in real-time
- Files changed:
  - `src/lib/collaboration/realtime.ts` - Added `CursorPosition`, `RemoteCursor` types, `onCursorUpdate` callback to `RealtimeCallbacks`, broadcast listener for 'cursor' events, and `broadcastCursor()` method
  - `src/components/editor/RemoteCursors.tsx` - New component: renders colored arrow cursors with user name labels, smooth position interpolation via CSS transition, 5-second fade-out for inactive cursors, flow-to-screen coordinate transformation using React Flow viewport
  - `src/app/editor/[projectId]/FlowchartEditor.tsx` - Added `remoteCursors` state, `cursorThrottleRef` for 50ms throttling, `handleMouseMove` that converts screen→flow coordinates and broadcasts via RealtimeConnection, cleanup of cursors for disconnected users, rendering of RemoteCursors overlay
  - `src/app/editor/[projectId]/page.tsx` - Fixed broken JSX structure (malformed HTML nesting and dead code after return)
- **Learnings for future iterations:**
  - `screenToFlowPosition` from `useReactFlow()` converts screen-relative mouse coordinates to flow coordinates; for the reverse (rendering cursors), multiply by viewport.zoom and add viewport offset
  - Cursor broadcast uses Supabase Realtime broadcast (not presence) for efficiency: `channel.send({ type: 'broadcast', event: 'cursor', payload })`. Broadcast is fire-and-forget (no persistence).
  - React Compiler lint treats `Date.now()` as an impure function call — use `useState(() => Date.now())` lazy initializer pattern instead of `useState(Date.now())`
  - Throttling mouse events uses a ref storing the last broadcast timestamp (`cursorThrottleRef`), checked at the start of the handler before computing flow position
  - Remote cursors are removed when their user disconnects (filtered by `presenceUsers` list changes)
  - CSS `transition: transform 80ms linear` provides smooth interpolation between position updates without needing requestAnimationFrame
  - The `page.tsx` had a corrupted structure with unclosed tags and dead code — likely from a failed merge. Fixed by restructuring the error/not-found case into a proper early return
  - No browser testing tools are available; manual verification is needed.
---