These terms describe the local reader consistently.
Session — one continuous user/Codex exchange, and the unit chosen in the picker.
Session name — the name Codex stores for a session. It is the primary identifier shown to the user; utterlog does not generate a replacement name.
Session log — the complete local record left by a session, including conversation and tool activity. It is not the same thing as a transcript.
Transcript — the read-only conversation extracted for viewing: user-authored text and user-facing assistant messages in their original order, with other activity excluded.
Message boundary — the role, source time, and ordinal marker separating one transcript message from the next without changing the message body.
Source timestamp — the timestamp stored on the source log record. It is displayed in local YYYY-MM-DD HH:mm form; a missing or invalid value is unknown time, not a reader or export timestamp.
Reading position — the visible scroll location in the message list. Browsing and refresh preserve the nearby message and offset when the selected log changes; there is no persisted last-read position.
Follow — the reader state enabled at the bottom of the log. While follow is on, a new visible message moves the viewport to the latest content. Moving upward or starting a search pauses it; G or returning to the bottom resumes it.
Refresh — a reread of the selected session log. File notifications are coalesced and serialized; r requests one immediately. A partial or failed refresh leaves the last good transcript visible and reports status until a valid refresh succeeds.