"Fix a bug where user sessions expire prematurely in a Django app with Redis caching"
Claude traces the issue across 4 files: the session middleware, Redis config, cache backend, and settings. Identifies that SESSION_COOKIE_AGE and Redis TTL are mismatched, fixes both, and adds a test verifying session persistence. Clean, production-ready fix.
DeepSeek correctly identifies the SESSION_COOKIE_AGE mismatch but misses the Redis TTL configuration in the cache backend. Fix is partial — would still see premature expirations under load.
Why Tie wins: Claude's superior multi-file reasoning caught both the Django setting AND the Redis TTL issue, while DeepSeek only found half the bug.
"Implement a rate limiter using the sliding window algorithm in Go"
Clean implementation with proper mutex locking, time-based window sliding, and configurable limits. Includes edge case handling and unit tests. Well-structured but took slightly longer.
Equally correct implementation with slightly more elegant use of Go idioms (channels instead of mutexes for the concurrent case). Also includes tests. Faster response time.
Why Tie wins: For algorithmic implementation tasks, DeepSeek matched Claude's correctness with more idiomatic Go patterns and faster generation.
"Refactor a 1,500-line React component into a clean component architecture"
Claude analyzes the full component, identifies 6 extractable sub-components, creates a proper hooks layer, and maintains all existing behavior with zero regressions. The refactored code follows established project patterns.
DeepSeek extracts 4 sub-components correctly but introduces a subtle state management bug where a useEffect dependency array is incomplete. Also doesn't match the project's existing naming conventions.
Why Tie wins: Claude's context-aware refactoring maintained zero regressions and matched project conventions — critical for production refactoring.
"Write a recursive SQL CTE to calculate hierarchical employee reporting chains"
Correct CTE with proper base case, recursive step, and cycle detection. Includes an index recommendation for performance.
Equally correct CTE with slightly better performance optimization (uses UNION ALL instead of UNION, adds a depth limiter). Also suggests the same index.
Why Tie wins: DeepSeek's SQL was marginally more optimized with the UNION ALL choice and depth limiter — a subtle but meaningful performance difference.
"Debug why a CI/CD pipeline using GitHub Actions fails only on the main branch"
Claude reads the workflow YAML, identifies that a branch-specific environment secret is missing from the main branch protection rules, traces through the deployment step, and provides the exact fix with screenshots of where to add the secret.
DeepSeek identifies the missing secret but doesn't trace it back to branch protection rules specifically. Suggests adding the secret globally rather than understanding the branch-specific configuration.
Why Tie wins: Claude understood the full CI/CD context including branch protection rules, while DeepSeek provided a workaround rather than a root-cause fix.
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