Long-running hooks keep remote sessions alive, with CLAUDE_CODE_HOOK_HEARTBEAT_INTERVAL_MS

What

Hooks are your own commands that Claude Code runs at set moments, such as before a tool runs. Environment variables are named values set outside Claude Code that change how it works.

• While a hook runs for UserPromptSubmit, PreToolUse, PostToolUse, PostToolUseFailure, Stop, PreCompact or PostCompact, Claude Code now sends a regular progress signal (a tool_progress heartbeat) so a slow hook does not let a remote session time out.
• The new CLAUDE_CODE_HOOK_HEARTBEAT_INTERVAL_MS sets how often that signal is sent. It is on the list of variables passed through to hosted or remote sessions, next to the other hook variables.
• The signals are skipped when CLAUDE_CODE_REMOTE_SEND_KEEPALIVES is set.
• The feature is controlled by a server-side switch, tengu_mellow_pulse, that falls back to on when the server sends no value. Nothing has been read about this switch yet.
• DISABLE_ERROR_REPORTING was added to two more lists of variables passed through to those sessions, one of which also holds CLAUDE_CODE_DISABLE_AGENT_PROGRESS_SUMMARIES and CLAUDE_CODE_DISABLE_MCP_TASKS.

Internal markers added in the same release also point to a fix in how stopping is handled when Claude Code runs without its interactive screen.

Why

If you use hooks that take a while, a remote or hosted session should no longer drop while it waits for them. Opting out of error reporting now carries through to those sessions.