What
An environment variable is a named value you set outside Claude Code, for example in your shell. A new one, CLAUDE_CODE_POLL_EVENT_DECLARATIONS, now appears in Claude Code alongside CLAUDE_CODE_SYNC_SESSION_REFS and other variables in the same group.
Why
Nothing says what setting it does, so there is no known reason to set it yet.
Names in the bundleCLAUDE_CODE_POLL_EVENT_DECLARATIONSCLAUDE_CODE_SYNC_SESSION_REFS
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear what this variable controls or what the list it belongs to is for.
The name it cites is new in this build
New in this build: CLAUDE_CODE_POLL_EVENT_DECLARATIONS