What probably matters to youSection of the release
Unclear How held updates are joined, and whether a joined line keeps the same event format as a single one, is not stated.
What
Two new environment variables (settings read from your shell when Claude Code starts) control how Claude Code prints its stream-json output, the line-by-line machine-readable format used when other programs drive Claude Code:
CLAUDE_CODE_STREAM_EVENT_HOLD_MS: when set, the lines carrying pieces of a reply as it is written (stream_event deltas) are held for that many milliseconds and joined together before being printed. When it is not set, nothing is held and output works as before.
CLAUDE_CODE_STREAM_EVENT_MAX_LINE_BYTES: sets a size limit for these lines. If it is set to anything other than a whole number of at least 1, the hold is ignored and lines are printed as they arrive.
Both names were added to the lists of environment variables Claude Code passes on to the processes it runs, next to the other CLAUDE_CODE_* tuning variables.
Why
If you run Claude Code from your own program or through the SDK, you can choose to receive fewer, larger output lines instead of one line per small piece of text. Nothing changes unless you set the variables.
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 doubtHow held updates are joined, and whether a joined line keeps the same event format as a single one, is not stated.
