CLAUDE_CODE_NONBLOCKING_STDOUT makes Claude Code write terminal output through a second, non-blocking channel so a stalled terminal (like a paused tmux pane or a frozen SSH connection) can't freeze the session. Previously this only applied when the environment variable was explicitly set. Now, if the environment variable isn't set, Claude Code also checks a remote server-controlled setting, tengu_event_loop_stall, as well as an internal first-party check, to decide whether to enable it.
This lets Anthropic roll out the non-blocking stdout behavior to more users gradually via a remote setting, without requiring everyone to manually set the environment variable themselves.
tengu_event_loop_stall Off in both readingsThe flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.
This account: off · anonymous baseline: off · compiled default in v2.1.267: off
Read once, for one account on one subscription tier, against v2.1.267. It isn't a statement about your account. What a flag value here can and cannot tell you
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
New in this build: tengu_event_loop_stall