Auto-target for read-only slideshow sources

[mateicanavra]

TL;DR

When saving a slideshow with no writable targetId (e.g., pasted/imported content), auto-generate a writable file in the default data directory instead of blocking.

Context

Depends on PER-38 (basic save infrastructure + provenance). This is Phase 3 of the persistence feature.

Scope

• Slug generation utility (slideshow title → my-slideshow.json)
• Server auto-creates file when targetId is null
• Collision avoidance (suffix if file exists)
• Response includes resolved targetId so client can update provenance

Implementation

// In FS adapter save()
if (!targetId) {
  const slug = slugify(slideshow.title || 'untitled');
  const targetPath = await findAvailablePath(dataDir, slug);
  // ... save to targetPath
  // Return resolved targetId in response
}

Acceptance Criteria

• Pasted/imported slideshows can be saved without manual target selection
• Generated filename is human-readable (slugified title)
• Collisions handled gracefully (e.g., my-deck-1.json, my-deck-2.json)
• Client provenance updated with resolved targetId after save
• Subsequent saves go to the same file

References

• Parent feature: PER-38
• Issue spec

[linear]

PER-39