To simplify our system, I asked Opus to port the file indexer to native TypeScript. Here's the prompt I used: > compile our rust+napi file index to native ts. compile the code over, and make sure the code perfectly passes the ORIGINAL test suite from the package. then profile
@bcherny
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Claude Code introduces fileSuggestion setting for large codebases
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But in big codebases, it would fall over. So we introduced a new fileSuggestion setting in Claude Code, so customers with large codebases could plug in their custom code index (using SourceGraph, an in-house index, etc.). https://
code.claude.com/docs/en/settin
gs#file-suggestion-settings
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Claude Code @-mentions Performance Tripled for Enterprise Codebases
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Just got a nice DM from a big enterprise customer using Claude Code in one of the world's biggest codebases Here's how we made @-mentions 3x faster in large enterprise codebases
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Custom Rust File Indexer for Claude Code @-mentions via NAPI
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To power file @-mentions in Claude Code, we used to use a custom Rust-based file indexer that we invoked from Claude Code via NAPI. It was pretty fast.
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Claude Cowork Now Generally Available
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Claude Cowork, now generally available! https://t.co/y0gDkmyYRg
— Boris Cherny (@bcherny) 9 avril 2026Claude Cowork, now generally available!
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Mythos Model: Powerful AI Preview with Cyber Defenders
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Mythos is very powerful, and should feel terrifying. I am proud of our approach to responsibly preview it with cyber defenders, rather than generally releasing it into the wild. Model card here: https://
www-cdn.anthropic.com/53566bf5440a10
affd749724787c8913a2ae0841.pdf
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Claude Code Drives Exponential Growth in Engineering Velocity at Anthropic
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Appreciate the feedback. Since we introduced Claude Code at Anthropic, engineering velocity has increased hundreds of %, and the rate at which it is increasing is itself accelerating. The velocity is very much not performative — we're actively trying to figure out how to
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Invalid API Key in Environment Variable Precedence Mode
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It is also possible you have an invalid api key set in an env var, and in -p mode that takes precedence
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Refining Abuse Detection Systems and Technical Terminology
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We think this is an overactive abuse-detection system, digging in. Also working on making the terms for -p crystal clear.
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Token efficiency improvements enable extended AI sessions
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We've been landing token-efficiency improvements so you can do more in your sessions. If you have a session where usage felt particularly high, can you run /bug and post the feedback id? Feel free to tag me directly