Sweep 19 Sep 2026 · 02:36Z Build v2.1.278 500 read Stable v2.1.267 Latest v2.1.278 Next v2.1.278 Feeds RSS JSON llms.txt Unofficial
Claude Code v2.1.269 ·

New mime types recognized for text/code files

File-type detection now recognizes .ts, .css, .js, .mjs, and .cjs files by MIME type

TierYou'll noticehow much it should matter to you
Useful2my rating, 1 to 5
Signal0worth watching, 1 to 5
AreaElsewherewhat it touches
KindImprovementsin v2.1.269,
You'll notice

File-type detection now recognizes .ts, .css, .js, .mjs, and .cjs files by MIME type

What

Claude Code's internal map of file extensions to MIME types (labels describing a file's content type) gained entries for .ts and .js/.mjs/.cjs files (mapped to text/plain) and .css files (mapped to text/css), alongside a JavaScript mapping to text/javascript.

Why

This likely improves how these common code file types are handled when attached or used as artifacts, since they can now be correctly identified by type instead of falling back to a generic or missing classification.

How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhich specific feature (artifact handling, attachments, or something else) consumes this map is not stated.

See this entry in the whole of v2.1.269 →