---
phase: 02-browse
plan: 02
subsystem: ui
tags: [textual, datatable, drill-down, filter, breadcrumb, navigation]

# Dependency graph
requires:
  - phase: 02-01
    provides: MainScreen with DataTable, VIM keybindings, PossessionApp with db_path
  - phase: 01-02
    provides: list_rooms, list_containers, list_items CRUD API functions

provides:
  - Live filter bar (/ to open, Escape to clear) that narrows DataTable rows in real time
  - Drill-down state machine (rooms -> containers -> items) with Enter/q navigation
  - Breadcrumb widget (Breadcrumb(Static)) showing current navigation path
  - possession/tui/widgets package with Breadcrumb export

affects: [02-03, future-phases]

# Tech tracking
tech-stack:
  added: []
  patterns:
    - "Deferred widget import inside compose()/methods to avoid circular import risk"
    - "try/except TypeError for DataTable.clear(columns=True) compatibility across Textual versions"
    - "View mode state machine with _view_mode string ('rooms'|'containers'|'items')"
    - "_load_view() as single source of truth for DataTable column+row population"

key-files:
  created:
    - possession/tui/widgets/__init__.py
    - possession/tui/widgets/breadcrumb.py
  modified:
    - possession/tui/screens/main.py

key-decisions:
  - "Breadcrumb imported inside compose() and _update_breadcrumb() to keep import clean and avoid potential circular imports"
  - "table.clear(columns=True) wrapped in try/except TypeError for Textual version compatibility"
  - "Initial view on mount is 'rooms' (not flat items) so users navigate the physical hierarchy from start"
  - "_apply_filter guarded by _view_mode == 'items' check so filter only applies in item-list mode"
  - "q at rooms level exits the app (self.app.exit()) rather than popping screen"

patterns-established:
  - "State machine pattern: _view_mode drives _load_view() which populates DataTable differently per mode"
  - "Breadcrumb updates called at every view transition point (on_mount, on_data_table_row_selected, action_go_back)"

requirements-completed: [NAV-02, NAV-03, NAV-04]

# Metrics
duration: 4min
completed: 2026-02-24
---

# Phase 2 Plan 02: Filter Bar, Drill-Down, and Breadcrumb Summary

**Live filter bar with / keybinding, three-level drill-down state machine (rooms->containers->items), and Breadcrumb(Static) widget with real-time path display**

## Performance

- **Duration:** 4 min
- **Started:** 2026-02-24T07:16:19Z
- **Completed:** 2026-02-24T07:20:30Z
- **Tasks:** 3
- **Files modified:** 3 (1 modified, 2 created)

## Accomplishments
- Live filter bar activated with / key, clears with Escape, filters name/description/room/container/category in real time
- Three-level drill-down navigation (rooms -> containers -> items) with Enter to go deeper and q to go back
- Breadcrumb widget shows current path (e.g. "All Rooms", "Garage", "Garage > Tool Cabinet") and updates on every transition
- New possession/tui/widgets package created with Breadcrumb(Static) class

## Task Commits

Each task was committed atomically:

1. **Task 1+2: Live filter bar and drill-down state machine (NAV-02, NAV-03)** - `41d338a` (feat)
2. **Task 3: Breadcrumb widget (NAV-04)** - `4d90ff6` (feat)

_Note: Tasks 1 and 2 were implemented in one atomic write to main.py since the filter bar guard (_view_mode) required the drill-down state established in Task 2. Both verified before commit._

## Files Created/Modified
- `possession/tui/screens/main.py` - Extended with filter bar, drill-down state machine, breadcrumb integration (276 lines, up from 91)
- `possession/tui/widgets/__init__.py` - New package marker for widgets subpackage
- `possession/tui/widgets/breadcrumb.py` - Breadcrumb(Static) widget with set_path() method and DEFAULT_CSS

## Decisions Made
- Breadcrumb imported inside `compose()` and `_update_breadcrumb()` rather than at module top, keeping the import chain clean
- `table.clear(columns=True)` wrapped in `try/except TypeError` for Textual version compatibility (Textual >= 0.47 supports this, older does not)
- Initial view mode on mount is "rooms" so users see the spatial hierarchy immediately rather than a flat item dump
- `_apply_filter` exits early when `_view_mode != "items"` so filter does not interfere with rooms/containers views

## Deviations from Plan

None - plan executed exactly as written. Tasks 1 and 2 were implemented in one write (since both modify main.py and the filter guard depends on _view_mode from Task 2), but all plan specifications were followed precisely.

## Issues Encountered
None.

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- Full browse hierarchy is navigable: rooms -> containers -> items with back-navigation
- Filter bar ready for use in items view
- Breadcrumb gives spatial context at all levels
- Phase 3 (quick-add) can use on_data_table_row_selected in items mode (currently returns early) for edit/detail view
- No blockers for 02-03

---
*Phase: 02-browse*
*Completed: 2026-02-24*
