Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.248 Home All releases olderv2.1.247 v2.1.250newer
Claude Code v2.1.248

Very large transcripts are reassembled by paging instead of failing

You'll notice
Useful4 Signal2
Sessions

Very large transcripts now load by paging instead of erroring, on the newer storage backend.

What

When a session transcript is too big to read in one go, Claude Code now walks it forward record by record and stitches the pieces back together, so a large history loads instead of erroring. This applies only when the newer storage backend (storage v5) is in use.

Details
  • A failed whole-file read, or a backend refusal reporting telemetryCode "EFBIG", triggers the paged read, which itself has a byte cap; exceeding it throws an error carrying { code: "EFBIG" }.
  • A cursor that fails to advance throws loadTranscriptFile: the record cursor did not advance; a successful paged read logs record and byte counts.
  • Tail reads of a session file fall back to a backward record page when the tail read is unsupported, and the tail result gains a cut flag meaning the content was truncated.
  • Which flag selects the storage v5 backend is not settled by this build's code.
Evidence

loadTranscriptFile: the paged transcript is too large

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.248 →