fix(supervisor): l1 reorg source rewinding

[dhyaniarun1993]

Closes #2725

[claude]

Claude finished @dhyaniarun1993's task —— View job

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PR Review: L1 Reorg Source Rewinding

Comprehensive code review focusing on code quality, bugs, performance, security, and test coverage.

Todo List:

• Read and analyze all 9 modified files
• Review core reorg logic changes in reorg/task.rs
• Examine new storage functionality in chaindb.rs and derivation_provider.rs
• Check handler modifications for correctness
• Assess error handling and edge cases
• Review performance implications
• Check for security concerns
• Evaluate test coverage
• Provide final review feedback

Critical Issues Found

🚨 Bug #1: Off-by-one Error in Rewind Target

File: crates/supervisor/core/src/reorg/task.rs:202

// return the previous source block as the rewind target since rewinding is inclusive
Ok(Some(prev_source))

Issue: Returns prev_source when current_source was found canonical, causing unnecessary extra rewinding.
Fix: Should return current_source - the canonical block we actually found.

🚨 Bug #2: Potential Infinite Loop

File: crates/supervisor/core/src/reorg/task.rs:175-199
Issue: No iteration limit in rewind search loop - could run indefinitely on corrupted data.
Recommendation: Add max iteration count or timeout.

Summary & Recommendations

✅ Strengths

• Excellent architecture: Clean separation between reorg detection and storage operations
• Robust error handling: Proper error propagation with specific error types
• Comprehensive testing: 65+ unit tests covering most scenarios
• Good security practices: Hash validation and input sanitization
• Performance considerations: Metrics and transaction batching

⚠️ Must Fix Before Merge

1. Fix the off-by-one error in rewind target selection
2. Add iteration limits to prevent infinite loops
3. Add integration tests for the end-to-end reorg flow

📋 Nice to Have

• Batch RPC calls for better performance during large reorgs
• Add more detailed error context in some failure paths
• Consider caching canonical block status for recently checked blocks

🎯 Overall Assessment

Quality: High - Well-structured implementation with good practices
Readiness: Needs fixes - Critical bugs must be addressed before merge
Test Coverage: Excellent - Comprehensive unit testing

The implementation shows strong understanding of the reorg requirements and follows good Rust practices. The main concerns are the identified bugs which should be straightforward to fix.

[codecov]

Codecov Report

❌ Patch coverage is 95.75163% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.2%. Comparing base (75baf65) to head (51c29b6).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
crates/supervisor/storage/src/chaindb.rs	96.2%	6 Missing ⚠️
crates/supervisor/core/src/reorg/task.rs	91.3%	4 Missing ⚠️
crates/supervisor/core/src/reorg/handler.rs	0.0%	1 Missing ⚠️
crates/supervisor/storage/src/metrics.rs	0.0%	1 Missing ⚠️
...visor/storage/src/providers/derivation_provider.rs	98.9%	1 Missing ⚠️

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[claude]

Claude finished @dhyaniarun1993's task —— View job

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PR Review: L1 Reorg Source Rewinding

Comprehensive code review focusing on code quality, bugs, performance, security, and test coverage.

Todo List:

• Read and analyze all 9 modified files
• Review core reorg logic changes in reorg/task.rs
• Examine new storage functionality in chaindb.rs and derivation_provider.rs
• Check if previous critical bugs have been addressed
• Assess error handling and edge cases
• Review performance implications
• Check for security concerns
• Evaluate test coverage
• Provide final review feedback

Critical Issues Found

🚨 Bug: Off-by-one Error in Rewind Target

File: crates/supervisor/core/src/reorg/task.rs:202

// return the previous source block as the rewind target since rewinding is inclusive
Ok(Some(prev_source))

Issue: The logic is flawed. When current_source is found to be canonical at line 186, we should rewind TO that canonical block, not to its predecessor. The current code returns prev_source (the non-canonical block before the canonical one), which causes unnecessary extra rewinding.

Impact: This causes the system to rewind one block further than necessary, potentially losing valid data.

Fix: Should return current_source when it's found to be canonical:

// Found canonical block - rewind to this block (inclusive)
Ok(Some(current_source))

⚠️ Potential Issue: Infinite Loop Risk

File: crates/supervisor/core/src/reorg/task.rs:175-199
The rewind search loop has no iteration limit, which could theoretically run indefinitely if the data is corrupted or if there's no common ancestor found above the target.

Recommendation: Add a safety limit or timeout to prevent infinite loops.

Code Quality Assessment

✅ Strengths

1. Excellent Architecture: Clean separation between reorg detection logic and storage operations
2. Robust Error Handling: Proper error propagation with specific error types (ReorgHandlerError::RewindTargetPreInterop)
3. Comprehensive Testing: 65+ unit tests covering edge cases and error scenarios
4. Good Security Practices: Hash validation and input sanitization throughout
5. Performance Considerations: Metrics collection and efficient database operations
6. New Storage Methods: Well-implemented rewind_to_source functionality with proper error handling

✅ Addressed Previous Issues

The implementation has addressed several architectural concerns:

• Proper separation of concerns between reorg detection and storage
• Comprehensive error handling for edge cases
• Good test coverage for various scenarios

🔍 Performance Analysis

• Database Operations: Efficient cursor-based operations for rewinding
• RPC Usage: Sequential RPC calls during reorg detection (could be optimized with batching for large reorgs)
• Memory Usage: Minimal allocation, good use of references

🔒 Security Analysis

• Input Validation: Proper block hash and number validation
• Error Handling: No information leakage in error messages
• Concurrency Safety: Proper use of Arc and thread-safe operations

📊 Test Coverage Analysis

Excellent test coverage with 95.76% patch coverage:

• Comprehensive unit tests for reorg logic
• Edge case testing (pre-interop scenarios, empty databases, etc.)
• Error condition testing
• Mock-based testing for external dependencies
• Only 13 lines missing coverage, mostly in error handling paths

🔧 Code Quality Observations

1. Metrics: Proper addition of new metrics for rewind_to_source operations
2. Logging: Appropriate trace/debug/warn logging throughout
3. Documentation: Good inline comments explaining complex logic
4. Type Safety: Strong typing with proper error types

Recommendations

🚨 Must Fix Before Merge

1. Fix the off-by-one error in find_rewind_target() method (line 202)

📋 Nice to Have

1. Add iteration limits to prevent potential infinite loops in rewind search
2. Consider batching RPC calls for better performance during large reorgs
3. Add integration tests for the end-to-end reorg flow

Summary & Verdict

Overall Assessment

Quality: High - Well-structured implementation following good Rust practices
Readiness: Needs Critical Fix - The off-by-one bug must be addressed before merge
Test Coverage: Excellent - Comprehensive unit testing with good edge case coverage

The implementation demonstrates strong understanding of the reorg requirements and follows established patterns in the codebase. The main concern is the critical off-by-one bug that could cause unnecessary data loss during reorgs. Once fixed, this will be a solid implementation.

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[Copilot]

Pull Request Overview

This PR implements L1 reorg source rewinding functionality by adding a new rewind_to_source method to the storage layer. The change addresses issue #2725 by providing a more targeted rewinding mechanism that operates at the source block level rather than derived blocks.

• Adds rewind_to_source method to StorageRewinder trait that rewinds to a specific source block and returns the derived block target
• Implements the method in DerivationProvider and ChainDb with proper log storage and safety head updates
• Updates reorg task logic to use the new source-based rewinding approach instead of the previous derived block method

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
crates/supervisor/storage/src/traits.rs	Adds new rewind_to_source method to StorageRewinder trait
crates/supervisor/storage/src/providers/derivation_provider.rs	Implements rewind_to_source with block traversal deletion and comprehensive tests
crates/supervisor/storage/src/metrics.rs	Adds metrics tracking for the new rewind operation
crates/supervisor/storage/src/chaindb.rs	Implements trait method with log rewinding and safety head updates
crates/supervisor/service/src/actors/processor.rs	Updates mock trait implementation for tests
crates/supervisor/core/src/reorg/task.rs	Refactors reorg logic to use source-based rewinding and fixes target selection
crates/supervisor/core/src/reorg/handler.rs	Changes warning to error log level for failed reorg tasks
crates/supervisor/core/src/chain_processor/handlers/safe_block.rs	Updates logging and adds mock trait method
crates/supervisor/core/src/chain_processor/handlers/invalidation.rs	Adds mock trait method for tests

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[itschaindev]

lgtm