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

The no-subscriber flush interval is inert at its default of 0

Not switched on
Useful1 Signal2
Remote Control

Subscriber-aware flush buffering is disabled by its default of zero.

tengu_ccr_no_subscriber_flush_ms defaults to 0, which disables the path.

Feature flag
tengu_ccr_no_subscriber_flush_ms Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.248: not a boolean we can read

Read once, for one account on one subscription tier, against v2.1.248. It isn't a statement about your account. What a flag value here can and cannot tell you

What

The subscriber-aware buffering above is switched off in this build. The interval comes from tengu_ccr_no_subscriber_flush_ms with a fallback of 0, and 0 disables the path entirely, so only a server value can turn it on.

Details
  • The server's events response carries a has_subscribers field, but the response body is only parsed at all when the interval is greater than 0.
  • The value is re-read on every remote-config refresh, so it can start applying mid-session without a restart.
  • With it enabled, ephemeral events wait for the longer of the two intervals instead of the normal one, meaning a cloud session nobody is watching streams less eagerly.
Evidence

tengu_ccr_no_subscriber_flush_ms

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 →