feat: support encrypted seen-video syncing

[D3SOX]

Marked-as-seen subscription videos currently stay on one device even when history sync is enabled. Add the optional seen_videos capability and accept the encrypted seenVideos collection so clients can sync those marks separately from watch history.

Existing endpoints, encryption formats, and migration requirements are unchanged. Older clients ignore the new capability and collection. The collection uses the existing encrypted storage and a 16 MiB per-collection limit.

Client implementation: OpenTubeX/OpenTubeX#1209.

Related to OpenTubeX/OpenTubeX#1208.

Validation: all 57 server tests pass; cargo fmt --check passes.

Implemented with GPT-6 in Codex.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 9599758c-a468-446d-8cda-32dcbd7aad6f

📥 Commits

Reviewing files that changed from the base of the PR and between 94f41df and 44621c4.

📒 Files selected for processing (2)

• src/dto.rs
• src/handlers/encrypted_sync.rs

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

---

📝 Walkthrough

Walkthrough

The sync API now exposes a seen_videos capability and accepts the seenVideos encrypted collection with a 16 MiB limit. Tests cover both changes.

Changes

Seen videos synchronization

Layer / File(s)	Summary
Advertise and limit seen videos support src/dto.rs, src/handlers/encrypted_sync.rs	SyncCapabilities adds seen_videos. The handler sets the capability to 1 and accepts seenVideos with a 16 MiB limit. Tests verify both values.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 44621

This adds optional encrypted syncing for seen videos, advertising support to clients and allowing a 16 MiB encrypted collection. The implementation and its stated coverage are consistent, with no identified merge-blocking risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely summarizes the main change: support for encrypted synchronization of seen videos.
Description check	✅ Passed	The description directly explains the new capability, collection, compatibility behavior, storage limit, and validation results.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch sync-seen-videos

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}