fix(drive): accept MMR-aligned shielded note proof ranges

[llbartekll]

Summary

• validate shielded encrypted-note proof resume offsets against the on-chain MMR chunk size instead of the multi-chunk request limit
• add a proof-based regression test for start index 2048 with an 8192-element request cap

Context

Wallet sync rewinds its encrypted-note watermark to a 2048-note MMR chunk boundary, while one request may fetch four chunks. The verifier previously treated the 8192-element request limit as the alignment unit and rejected the valid 2048 resume point, leaving shielded sync and balance recovery stuck.

Validation

• cargo fmt --package drive -- --check
• cargo test -p drive accepts_mmr_aligned_start_inside_multi_chunk_query_boundary --lib
• ./packages/swift-sdk/build_ios.sh --target ios --target sim
• xcodebuild dashwallet-dashpay Debug for arm64 iOS Simulator

Summary by CodeRabbit

• Bug Fixes
  • Improved shielded notes verification when resuming from multi-chunk queries.
  • Resume points are now validated against the correct MMR chunk boundaries (not element-count alignment).
  • Added safety to prevent index overflow during range calculations, returning a clear corruption error when invalid.
• Tests
  • Added coverage for aligned resume points inside multi-chunk requests.
  • Added coverage for rejecting chunk-aligned start points near the maximum index with the expected error.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: d5909da3-b642-4d9e-88b3-ea00392924d2

📥 Commits

Reviewing files that changed from the base of the PR and between 8e680ab and 1fd481e.

📒 Files selected for processing (1)

• packages/rs-drive/src/verify/shielded/verify_shielded_encrypted_notes/v0/mod.rs

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📝 Walkthrough

Walkthrough

The shielded encrypted notes verifier now aligns start_index to MMR chunk boundaries and uses checked arithmetic for inclusive range ends. Tests cover aligned resumes within multi-chunk requests and overflow rejection near u64::MAX.

Changes

Shielded notes verification

Layer / File(s)	Summary
MMR-aligned resume validation packages/rs-drive/src/verify/shielded/verify_shielded_encrypted_notes/v0/mod.rs	Resume validation uses the MMR chunk size, with coverage for aligned positions inside multi-chunk requests and correct total_count extraction.
Query range overflow protection packages/rs-drive/src/verify/shielded/verify_shielded_encrypted_notes/v0/mod.rs	Inclusive end-index calculation now fails with a corruption error when the range exceeds u64::MAX, covered by a boundary test.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• dashpay/platform#3756: Updates related shielded encrypted notes v0 alignment validation and tests.

Suggested reviewers: shumkov, quantumexplorer

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: accepting MMR-aligned shielded note proof ranges.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/fix-shielded-proof-chunk-alignment

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[thepastaclaw]

🕓 Ready for review — 2 ahead in queue (commit 8e680ab)
Queue position: 3/25 · 2 reviews active
ETA: start ~03:16 UTC · complete ~03:38 UTC (median 21m across 30 recent reviews; 2 slots)
Queued 13h 23m ago · Last checked: 2026-07-23 02:50 UTC

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In
`@packages/rs-drive/src/verify/shielded/verify_shielded_encrypted_notes/v0/mod.rs`:
- Around line 47-54: In the shielded notes verification flow around the
start_index alignment check and PathQuery construction, validate the inclusive
end index with checked arithmetic using start_index and limit - 1. If the
addition overflows, return the existing Drive corruption error before
constructing the PathQuery; otherwise use the checked result for the query
range.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 45f7a606-a0fa-4a43-b1b8-dea16c66b770

📥 Commits

Reviewing files that changed from the base of the PR and between 267e1cb and 8e680ab.

📒 Files selected for processing (1)

• packages/rs-drive/src/verify/shielded/verify_shielded_encrypted_notes/v0/mod.rs