docs: add design doc for TUI enhancements

Issues: #204, #205, #206, #207, #208, #234
Branch: feature/tui-enhancements

Author: joshsmithxrm

.claude/design.md

@@ -0,0 +1,128 @@
+# Design: TUI Enhancements
+
+## Issues
+
+| # | Title | Type | Priority | Size |
+|---|-------|------|----------|------|
+| 204 | TUI: Add search/filter within loaded results | feature | P2-Medium | M |
+| 205 | TUI: Add multi-cell selection with Shift+Arrow | feature | P2-Medium | M |
+| 206 | TUI: Export selection as CSV/TSV | feature | P2-Medium | S |
+| 207 | TUI: Add mouse support for table navigation | feature | P3-Low | S |
+| 208 | TUI: Query history as selectable list | feature | P2-Medium | M |
+| 234 | refactor(tui): Abstract SQL table pattern for reuse across all data tables | refactor | P2-Medium | L |
+
+## Context
+
+The TUI (Terminal User Interface) provides an interactive SQL query experience for Dataverse. Current implementation works but lacks ergonomic features that would improve daily workflow.
+
+### Current TUI Location
+```
+src/PPDS.Cli/Tui/
+├── SqlQueryScreen.cs      # Main query interface
+├── DataTableView.cs       # Table display component
+├── QueryInputView.cs      # SQL input component
+└── ...
+```
+
+## Feature Dependencies
+
+```
+#234 (Abstract table pattern) ─┬─► #204 (Search/filter)
+                               ├─► #205 (Multi-cell selection)
+                               ├─► #206 (Export CSV)
+                               └─► #207 (Mouse support)
+
+#208 (Query history) ──► Independent
+```
+
+**Recommendation:** Do #234 first to establish the abstraction, then others can build on it.
+
+## Suggested Implementation Order
+
+1. **#234** - Abstract SQL table pattern (foundation for others)
+2. **#208** - Query history (independent, can be parallel)
+3. **#204** - Search/filter within results
+4. **#205** - Multi-cell selection
+5. **#206** - Export CSV (needs #205 for selection)
+6. **#207** - Mouse support (nice-to-have)
+
+## Key Files
+
+```
+src/PPDS.Cli/Tui/SqlQueryScreen.cs
+src/PPDS.Cli/Tui/DataTableView.cs
+src/PPDS.Cli/Tui/QueryInputView.cs
+src/PPDS.Cli/Services/QueryHistoryService.cs (new)
+```
+
+## Technical Notes
+
+### #234 - Table Abstraction
+- Extract generic `DataTableView<T>` from current SQL-specific implementation
+- Should support: column definitions, row data, selection, scrolling
+- Reusable for: query results, metadata listings, import previews
+
+### #204 - Search/Filter
+- `/` key to enter search mode (vim-style)
+- Filter rows by text match across all visible columns
+- `n`/`N` to navigate between matches
+- `Esc` to clear filter
+
+### #205 - Multi-Cell Selection
+- `Shift+Arrow` to extend selection
+- `Ctrl+A` to select all
+- Visual highlight for selected cells
+- Store selection state for export
+
+### #206 - Export CSV
+- `Ctrl+E` or command to export
+- Export current selection or all if no selection
+- Prompt for file path or use clipboard
+- Support both CSV and TSV formats
+
+### #207 - Mouse Support
+- Terminal.Gui supports mouse events
+- Click to select cell
+- Drag to select range
+- Scroll wheel for navigation
+
+### #208 - Query History
+- Store last N queries (configurable, default 100)
+- `Ctrl+R` for reverse search (like bash)
+- Arrow up/down in query input to cycle history
+- Persist to `~/.ppds/query-history.json`
+
+## Acceptance Criteria
+
+### #234
+- [ ] Generic `DataTableView<T>` component extracted
+- [ ] Current SqlQueryScreen uses the abstraction
+- [ ] No regression in existing TUI functionality
+
+### #204
+- [ ] `/` enters filter mode
+- [ ] Filter text shown in status bar
+- [ ] Rows filtered in real-time
+- [ ] `Esc` clears filter
+
+### #205
+- [ ] Shift+Arrow extends selection
+- [ ] Selection visually highlighted
+- [ ] Selection state accessible programmatically
+
+### #206
+- [ ] Export hotkey works
+- [ ] CSV format correct (quoted strings, escaped commas)
+- [ ] TSV option available
+- [ ] Clipboard support if no file specified
+
+### #207
+- [ ] Click selects cell
+- [ ] Drag selects range
+- [ ] Scroll wheel scrolls table
+
+### #208
+- [ ] History persisted across sessions
+- [ ] Arrow keys cycle through history
+- [ ] Ctrl+R reverse search works
+- [ ] Duplicate queries collapsed