fn append_tsidx_entry(
fs: &Arc<FileStore>,
zone: &str,
batch_start: u64,
now_ms: i64,
)Expand description
Append one receive-time record to a zone’s output.tsidx sidecar:
NDJSON {"off":<byte offset the batch starts at in output>,"ms":<unix ms>}.
Batch granularity is deliberate — one flush of one turn’s output; sub-batch
precision has no UI meaning
(SPEC_AGENT_PANE_SESSION_SCOPED_SCROLLBACK_AND_AGENT_HISTORY_VIEW_2026_08_09.md §4.4).
Fire-and-forget like every other write on this path: any failure logs at
debug and the transcript append is unaffected. Only called for agent
transcript streams (never PTY term data).