CHANGES.md.txt

# Data Analyst Workbench — Change Log

## 10-05-2026 — Phase 0: App Shell
- Built complete app shell with tab navigation (5 tabs)
- Tabs 2–5 locked until CSV file is uploaded
- Dark mode / Light mode toggle with localStorage save
- Settings gear icon modal (top right)
- Toast notification system (bottom right, 3s auto dismiss)
- Footer: "Built by Sanjay Polamarasetti | Data Analyst"
- Welcome toast on page load

## 10-05-2026 — Phase 1: Upload & Preview
- Drag and drop CSV upload zone
- PapaParse chunked streaming for large files
- Upload progress bar with percentage
- Stats bar: Rows, Columns, File Size, Parse Time
- Automatic column type detection (NUMBER, TEXT, DATE, BOOLEAN)
- Virtualized data table with sort and filter
- Global search box above table
- Pagination controls (50, 100, 250, 500 rows per page)
- Column summary sidebar (click column header)
- Export Preview CSV button
- Filename chip shown in top nav after upload

## 10-05-2026 — Phase 2: Clean & Transform
- Remove empty rows button
- Remove duplicate rows button
- Remove a column (dropdown select)
- Rename column
- Change data type conversion
- Text formatting (UPPERCASE, lowercase, Title Case, Trim)
- Find & Replace
- Fill null values (Fixed, Mean, Median, Mode)
- Create calculated column with formula (e.g. {Sales} - {Cost})
- Live action log with timestamps
- Undo last action button
- Export Cleaned CSV button
- Export Action Log as PDF button

## 10-05-2026 — Phase 3: SQL Query
- sql.js in-browser SQLite engine (no server needed)
- SQL editor with Run Query button
- Ctrl + Enter keyboard shortcut to run query
- Query execution time shown after each run
- Query result table with Export CSV and Export PDF
- Query template chips (SELECT *, COUNT(*), GROUP BY, AVG/MAX)
- Natural Language search bar with Generate SQL button
- Small clear/refresh button (↺) inside NL search bar

## 10-05-2026 — Bug Fixes & Changes
- Fixed: Start Over confirmation button showing blank red rectangle
  → Added explicit white color and "Yes, Start Over" text
- Fixed: Settings modal opening when Generate SQL was clicked
  → Removed openSettings() call from NL query handler
- Changed: Replaced Anthropic paid API with free browser-based
  keyword SQL engine (no API key needed for anyone)
- Added: Session restore on page refresh using sessionStorage
  → Data, columns, action log, active tab all preserved on refresh
- Added: "New File" button in top nav (refresh icon + text)
  → Shows confirmation dialog before clearing everything
- Added: Clear button (↺) inside NL search bar
  → Clears search input, SQL editor, and results only