fix(spiders): persist seen fingerprints in checkpoints

[Liohtml]

Summary

Upstream sync (2/4). Checkpoints saved on pause wrote seen_fingerprints: Vec::new(), so a resumed crawl lost the dedup set and re-visited every URL crawled before the pause.

• Scheduler::snapshot() returns pending URLs plus a copy of the seen fingerprint set; Scheduler::restore_seen() restores it.
• The engine persists the seen set on pause and restores it before re-enqueuing pending URLs on resume (pending URLs bypass the dedup via dont_filter since their fingerprints are part of the restored set).
• Mirrors upstream Scrapling d1082bd/95687a5, where the scheduler owns checkpoint state including the seen set. In-flight requests remain covered by the existing drain-before-checkpoint on pause (fix: drain tasks before checkpoint and enforce per-domain limit (#9 #10) #22).

Tests

• Scheduler: snapshot captures pending + seen (including dequeued URLs), restored seen set rejects already-crawled URLs, restored pending re-enqueues with dont_filter.
• Engine (end-to-end via dev cache): resume skips a follow link whose fingerprint is in the checkpoint; checkpoint written on pause contains non-empty seen fingerprints.

Full suite green locally: 222 passed (cargo test, cargo clippy --all-targets -- -D warnings, cargo fmt --check).

🤖 Generated with Claude Code

https://claude.ai/code/session_01KDFsMaKk764vogjUW3nqpk

---

Generated by Claude Code

[coderabbitai]

Warning

Review limit reached

@Liohtml, you've reached your PR review limit, so we couldn't start this review.

Next review available in: 13 minutes

Enable usage-based reviews in Billing to review now. Otherwise, wait until the next included review is available.
You're only billed for reviews past your plan's rate limits ($0.25/file).

How can I continue?

After more reviews become available, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

To avoid repeated limits, reduce automatic review volume by pausing incremental auto-reviews earlier, using label-based review opt-in, excluding WIP or generated PR titles, or requesting reviews manually when the PR is ready. If your team needs uninterrupted high-volume reviews, an organization admin can enable usage-based reviews.

How do review limits work?

CodeRabbit enforces per-developer PR review limits for each organization. Most developers receive the normal plan review availability.

For paid Pro and Pro+ PR reviews, CodeRabbit uses adaptive limits for sustained high-volume activity. When a developer's recent PR review activity reaches the 95th percentile or higher among CodeRabbit users, additional reviews become available more gradually as earlier reviews age out of the rolling window.

Please refer docs for additional details.

Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 6bd12739-72fa-4585-ae0c-ae060cf1431d

📥 Commits

Reviewing files that changed from the base of the PR and between df09f89 and a5ca9cf.

📒 Files selected for processing (5)

• src/spiders/checkpoint.rs
• src/spiders/engine.rs
• src/spiders/scheduler.rs
• tests/engine_crawl.rs
• tests/spiders_scheduler.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/upstream-scrapling-changes-1sub94-pr2

---

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.}