---
phase: 02-media-library-grid
plan: 01
subsystem: media
tags: [wordpress, media-grid, drag-drop, taxonomy-filter, backbone-js]

requires:
  - phase: 01-media-folders-plugin
    provides: media_folder taxonomy, AJAX CRUD, folder tree UI
provides:
  - Media grid filtering by folder via WP backbone props
  - mfp_assign_media AJAX endpoint
  - HTML5 drag & drop media to folders
affects: [03-media-modal, 04-polish-ux]

tech-stack:
  added: []
  patterns: [ajax_query_attachments_args filter, wp.media.props integration, HTML5 drag&drop, MutationObserver for dynamic content]

key-files:
  created:
    - wp-content/plugins/media-folder-pro/includes/class-media-query.php
    - wp-content/plugins/media-folder-pro/assets/js/media-filter.js
  modified:
    - wp-content/plugins/media-folder-pro/includes/class-ajax-handler.php
    - wp-content/plugins/media-folder-pro/assets/js/folder-tree.js
    - wp-content/plugins/media-folder-pro/assets/css/admin.css
    - wp-content/plugins/media-folder-pro/media-folder-pro.php

key-decisions:
  - "Filter via ajax_query_attachments_args — no core WP modifications"
  - "wp.media library.props.set() triggers grid reload natively"
  - "HTML5 Drag & Drop API — no jQuery UI dependency"
  - "MutationObserver to catch dynamically loaded attachments (infinite scroll)"
  - "Drop on 'All Media' unassigns from folder (folder_id=0)"

patterns-established:
  - "window.mfpRefreshTree() exposed for cross-module communication"
  - "media-filter.js depends on media-views + media-folder-pro-tree"
  - "Delegated drag events on #mfp-folder-root for drop targets"

duration: ~10min
started: 2026-03-28
completed: 2026-03-28
---

# Phase 2 Plan 01: Media Library Grid Integration Summary

**Media grid filtering by folder click + drag & drop media assignment with live counter updates, integrated via WP backbone props and HTML5 Drag & Drop API.**

## Performance

| Metric | Value |
|--------|-------|
| Duration | ~10min |
| Tasks | 2 completed |
| Files created | 2 |
| Files modified | 4 |

## Acceptance Criteria Results

| Criterion | Status | Notes |
|-----------|--------|-------|
| AC-1: Filtrowanie mediow po kliknieciu folderu | Pass | ajax_query_attachments_args + library.props.set |
| AC-2: Przypisywanie mediow przez AJAX | Pass | mfp_assign_media with folder_counts response |
| AC-3: Drag & drop mediow na foldery | Pass | HTML5 D&D + MutationObserver + counter refresh |

## Accomplishments

- Server-side filter via `ajax_query_attachments_args` hook — supports folder filtering and "uncategorized" (id=-1)
- `mfp_assign_media` endpoint assigns media to exactly 1 folder (or removes) and returns updated folder counts
- HTML5 drag & drop from media grid thumbnails to folder tree with visual feedback
- Drop on "All Media" removes folder assignment
- MutationObserver catches dynamically loaded attachments for draggable setup

## Files Created/Modified

| File | Change | Purpose |
|------|--------|---------|
| `includes/class-media-query.php` | Created | WP attachment query filter by media_folder taxonomy |
| `assets/js/media-filter.js` | Created | Grid filter via wp.media props + drag & drop logic |
| `includes/class-ajax-handler.php` | Modified | Added mfp_assign_media endpoint |
| `assets/js/folder-tree.js` | Modified | Exposed window.mfpRefreshTree() |
| `assets/css/admin.css` | Modified | Drag & drop visual styles (drop target, cursors) |
| `media-folder-pro.php` | Modified | MFP_Media_Query init, media-filter.js enqueue, i18n strings |

## Decisions Made

| Decision | Rationale | Impact |
|----------|-----------|--------|
| Use ajax_query_attachments_args | Native WP filter, no core mods | Clean integration |
| library.props.set for grid reload | Backbone native, triggers AJAX automatically | No manual DOM manipulation |
| MutationObserver for infinite scroll | Attachments load dynamically, need draggable on each | Robust for any load pattern |

## Deviations from Plan

None — plan executed exactly as written.

## Issues Encountered

None

## Next Phase Readiness

**Ready:**
- Full folder filtering + assignment pipeline operational
- media-filter.js pattern reusable for modal integration (Phase 3)
- mfp_assign_media endpoint ready for bulk use (Phase 4)

**Concerns:**
- Media modal uses different wp.media frame — will need separate integration path
- List view (table) not yet handled (deferred to Phase 4)

**Blockers:**
- None

---
*Phase: 02-media-library-grid, Plan: 01*
*Completed: 2026-03-28*