[t-kalinowski]

Add an optional session argument so clients and agents can run independent Console sessions concurrently. New names start with their first code cell; ordinary calls default to default. Empty calls collect all active sessions and report names and statuses in text and structured output. Restarting a named session without code or nonempty input leaves it stopped until reuse; default recovery stays unchanged.

Internally, each session owns startup, requirements, worker generations, input, and output. The connection retains shared configuration and recording. Aggregate polls share response limits and a deadline and recover output after cancellation. Connection closure retires all sessions. Python clients, R tool discovery, documentation, and public regressions cover the new interface. Existing tests that observe only the default session now select it explicitly.

Warmup selects the default session when the discovered interface exposes session; hidden or older interfaces keep their supported arguments. The installed-wheel smoke check also selects the default session before checking readiness. The shutdown fixture associates each named worker with its Linux PID namespace before checking that all nine worker, relay, and child identities retire at connection closure. Startup-cancellation fixtures wait for response delivery before probing a long poll, with a native write gate exercising the ordering. Completion collectors retain [done] when a controlled evaluation returns its output and completion in separate replies, while preserving session selection.

Focused macOS validation passed 15 session, startup, cancellation, restart, native R, and writable-root cases (19 executions). The response-write gate reproduced the exact aggregate-poll failure before the fixture repair. The Linux writable-roots transcript was regenerated successfully through the repository runner on hosted Ubuntu, preserving its R/Python writes and sandbox assertions; the temporary capture step is removed. All 23 client self-tests passed. scripts/check passed for the fixture and collector repair; the final shared-deadline adjustment passed its owning regression. Formatting and whitespace checks passed. Full current-head CI remains pending.