2.4.4 — Session Idle-Timeout Sweeper

Goal

Automatically mark sessions as abandoned after a configurable idle period so Phase 3 extraction can process them. Without this, sessions stay active forever and never enter the extraction pipeline.

Acceptance criteria

Background sweeper runs periodically (configurable interval, default 1 minute)
Sessions with status = 'active' and updated_at older than idle timeout (default 45 minutes) are marked abandoned
Sweeper is org-scoped (RLS-aware / service-account privileged job; rows retain org_id)
Metric: ibex_proxy_session_sweeper_marked_total{status="abandoned"}
Config: IBEX_SESSION_IDLE_TIMEOUT (default 45m), IBEX_SESSION_SWEEP_INTERVAL (default 1m)
Documented: X-IBEX-Session-End may still mark completed when wired; idle path marks abandoned
Phase 3.4.2 already documents status IN ('completed', 'abandoned') for the extraction query

Design notes

Idle means no checkpoint activity: checkpoints bump sessions.updated_at, so never-checkpointed sessions age from create time. Multi-replica proxies coordinate with pg_try_advisory_xact_lock. Batch limit + SKIP LOCKED drain backlogs safely. Redis session cache keys are invalidated on abandon.