Benchmark

Terminal-Bench 4.0

Sources

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Welcome to September 29, 2026 (theinnermostloop.substack.com)
Source linked by the September 29 issue (www.anthropic.com)

Terminal-task evaluation comparing Sonnet 5, Sonnet 5.5 and Opus 5.5.

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Development timeline

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2026-09-29: Sonnet 5.5 improves on Terminal-Bench 4.0

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Related to

Terminal Bench 2.0

Referenced by

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Terminal-Bench 4.0
Innermost Loop KB — secondary record
Reporting date: unknown
KB permalink: https://nicholsn.github.io/innermost-loop-kb/benchmarks/terminal-bench-4
Attributed sources:
- Welcome to September 29, 2026 — https://theinnermostloop.substack.com/p/welcome-to-september-29-2026
- Source linked by the September 29 issue — https://www.anthropic.com/claude-sonnet-5-5
This citation does not imply independent verification of linked-source claims.

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