Cloud sessions can hold a writing tool until its call is on record

What

In cloud (CCR) sessions, Claude Code uploads a record of each event, including every tool call, which is a single action Claude takes such as editing a file. The server sends a policy saying when those uploads are flushed. That policy now accepts three more fields.

• flush_before_tools_wait_ms: before a tool that may write runs, Claude Code releases held events and waits until the tool-call row is recorded as stored (on the client events lane, and the transcript lane when in use). The wait is capped at 30000 ms, with a separate grace limit for the row first reaching the queue.
• flush_after_tools: "none", "write" or "all" (default "none"). A tool result then forces a flush; with "write", results from the gated writing calls do.
• live_twin_types: rows of the listed types are held while a viewer is present.
• The worker gains gatesToolCalls and toolCallRowGraceMs options and tracks whether uploaded tool-call rows were stored or dropped. gatesToolCalls is on for every session type except bridge.
• These apply only when the hold rule is the server-sent policy, which also depends on tengu_ccr_event_hold_enabled (fallback true; nothing has been read about it for this release). If the policy leaves the fields out, the wait is 0 and nothing waits.

Why

A file change in a cloud session can be on record before it takes effect, so a crash cannot leave files changed with no trace of the edit in the transcript. The cost is that a writing tool may pause for up to 30 seconds, and only once the server sends a policy asking for it.