---
id: ML-169.5
title: "Fix: Display toggle (grid/list) triggers full DB reload"
status: Done
assignee: []
created_date: "2026-05-19 11:45"
updated_date: "2026-05-19 15:13"
labels:
  - perf
  - fix
dependencies: []
references:
  - >-
    backlog/documents/doc-27 -
    Phase-4-Performance-Audit-Low-Hanging-Fruit-Findings.md
modified_files:
  - lib/music_library_web/live_helpers/index_actions.ex
  - lib/music_library_web/live/collection_live/index.ex
  - lib/music_library_web/live/wishlist_live/index.ex
parent_task_id: ML-169
priority: high
ordinal: 26000
---

## Description

<!-- SECTION:DESCRIPTION:BEGIN -->

Fix performance issue where toggling between grid and list display views triggers a full FTS database reload.

## Problem

`handle_set_display` in `index_actions.ex` calls `load_and_assign_records/2` which re-executes the full FTS search query (`search_records_count` + `search_records`). The toggle only changes a CSS layout class (`@display == :grid` vs `@display == :list`) — no data changes.

## Impact

Every grid/list toggle wastes 2 FTS queries. This is a common user interaction (clicking the view switcher button).

## Files

- `lib/music_library_web/live_helpers/index_actions.ex:136-143` — `handle_set_display/2` calls `load_and_assign_records`
- `lib/music_library_web/live/collection_live/index.ex:336` — `handle_event("set_display")`
- `lib/music_library_web/live/wishlist_live/index.ex:259` — `handle_event("set_display")`

## Fix

Remove the `load_and_assign_records` call from `handle_set_display`. Only `assign(:display, mode)` is needed. The existing `:if={@display == :grid}` / `:if={@display == :list}` conditionals already handle showing/hiding the appropriate view.

<!-- SECTION:DESCRIPTION:END -->

## Acceptance Criteria

<!-- AC:BEGIN -->

- [ ] #1 Grid/list toggle no longer triggers DB queries (verified via QueryReporter)
- [ ] #2 Grid view renders correctly after toggle
- [ ] #3 List view renders correctly after toggle
- [ ] #4 No regression in search/filter functionality after toggle
<!-- AC:END -->

## Archive Reason

<!-- SECTION:ARCHIVE_REASON:BEGIN -->

Archived after validation showed the proposed optimization is not correct with the current
LiveView stream rendering structure.

Collection and wishlist render either `<.record_grid>` or `<.record_list>` behind
mutually exclusive `:if` branches, and both components consume the same `@streams.records`
stream. LiveView stream entries are consumed after render and the existing DOM holds the
streamed children. When the display mode changes, the previously mounted stream container
is removed and a different stream container is mounted. Without re-running
`stream(:records, records, reset: true)`, the newly mounted container has no queued stream
entries to insert, so only its static empty-state node remains and `only:block` displays
“No records yet”.

The DB reload avoided by this task is therefore also the step that rehydrates the stream
for the newly mounted container. A future optimization would need a different rendering
shape, such as keeping both containers mounted or avoiding conditional stream container
replacement, before removing the reload.

<!-- SECTION:ARCHIVE_REASON:END -->

## Final Summary

<!-- SECTION:FINAL_SUMMARY:BEGIN -->

Reverted the proposed `handle_set_display/2` change and archived this task as not
actionable in the current UI structure. The reload is required because grid/list toggling
replaces the mounted stream container.

<!-- SECTION:FINAL_SUMMARY:END -->
