Remove slideshow support #6353

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Overview

Slideshow content can no longer be created: the Studio editor never supported it, and ricecooker removed SlideshowNode, so only Studio's ricecooker endpoint still accepts slides, and no current ricecooker sends them. Production holds 81 slideshow nodes, all in test or QA channels, with 85 SlideshowSlide rows created between 2019 and 2021. File.slideshow_slide's index costs 6.6 GB to cover those 85 rows. Slideshow support and the existing slideshow nodes should be removed from Studio.

Complexity: Medium
Target branch: hotfixes

Context

• Slideshow nodes on production, all in test channels:

  Channel	Tree	Slideshow nodes
  Prueba (deleted)	staging, main	67
  Studio Test Channel 1, Studio Test Channel 4	main, trash	4
  Test QA Channel 66	main, trash	2
  Kolibri QA Channel, Kolibri QAv2, Regression fixture, Shared resources, Slides Slides Slides! (×2), Velox testing channel	main	7
  (no channel)	—	1

• The 85 slide Files are attached only through slideshow_slide, never to a node.

• Slideshow code in Studio:

  • SlideshowSlide and File.slideshow_slide
  • the ricecooker endpoint: views/internal.py:811-824, create_slides, map_files_to_slideshow_slide_item
  • publish: utils/publish.py:408-409 calls create_slideshow_manifest
  • garbage collection: utils/garbage_collect.py:208

• Ricecooker removed SlideshowNode (docs/migration.md:17-18).

• Kolibri still ships kolibri.plugins.slideshow_viewer, so channels already published with slideshows keep rendering.

The Change

• The existing slideshow nodes should be deleted, along with their slides and slide Files.
• SlideshowSlide and File.slideshow_slide should be removed. The column drop takes a brief ACCESS EXCLUSIVE lock on contentcuration_file, so the migration should set a lock_timeout and fail rather than retry.
• The ricecooker endpoint should reject a slideshow node with a 400 rather than create it.
• Publish should no longer build slideshow manifests.

Out of Scope

• The slideshow kind in le-utils, and Kolibri's slideshow_viewer.

Acceptance Criteria

General

• After deploy to hotfixes, no contentnode row has kind_id = 'slideshow'
• contentcuration_slideshowslide no longer exists, and contentcuration_file has no slideshow_slide_id column or index
• The migration aborts with a non-zero exit when it can't acquire its lock within lock_timeout
• Uploading a slideshow node through the ricecooker endpoint returns a 400
• makemigrations --check reports no changes

Testing

• A test covers the ricecooker endpoint rejecting a slideshow node

AI usage

Drafted with Claude Code, which measured slideshow usage on production through read-only queries in the disposable debugging job and traced the slideshow code paths. I chose to remove the feature and delete the existing nodes.