fix(recording): write segment start times off the async runtime

[richiemcilroy]

#2642 persists each Studio segment's track start times while recording. The persister ran the write, a file fsync and a directory fsync inside its tokio task, which blocks one runtime worker for the duration of the syncs. The capture pipelines run on the same runtime.

let dir = segment_dir.clone();
let result = tokio::task::spawn_blocking(move || write_segment_start_times(&dir, &times))
    .await
    .unwrap_or_else(|error| Err(std::io::Error::other(error)));

• crates/recording/src/studio_recording.rs: the write runs on a blocking thread; retries, the 5-attempt limit and the written-state check are unchanged.
• The persister writes once per track's first frame, so this affects only the first moments of a recording.

Confidence Score: 5/5

The PR appears safe to merge.

Summary

Moves segment start-time writes and file syncs onto a blocking thread.

• Segment start-time writes no longer occupy capture runtime workers.

_{Reviews (1) · Last reviewed commit: "fix(recording): write segment start time..." · Reviewed by Greptile}

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Project	Deployment	Actions	Updated
cap-status	Ready	Preview	Oct 16, 2026 2:19pm UTC

[capy-ai]

Capy found no issues.