A session is the runtime-native conversation identity aggregated from canonical events. The stable key is (runtime, session_id); project is best-effort metadata, not identity.
The sessions view summarizes first/last timestamps, user and assistant counts, tool calls, and reported token counters. interrupted_sessions diagnoses a last unanswered user turn or a tool call cut off before another assistant turn. These are query views, not additional stored records.
show <session-id> reconstructs selected event types oldest-first. Its default is user,assistant; --include all adds thinking, tool, meta, and hook records. The footer states rendered versus matched counts so limits never look complete by accident.
The Oko export hashes runtime + "\n" + session_id to choose a per-session filename. Oko may index that projection, but ownership of the canonical masked session remains with Transcript Lake and ownership of the raw conversation remains with its vendor runtime.
See event, export, and CLI read commands.