Selective Confluence: Coverage-Conditioned Recovery for Agent-Memory Handoffs

Cross-session agents use compact memories to continue work without replaying their full histories. A later decision may nevertheless require an exact identifier, status, or prior outcome that was unknown when the memory was written. Better retention and retrieval do not by themselves specify which evidence may authorize that decision. We introduce SELECTIVE CONFLUENCE, a handoff contract that keeps semantic memory advisory and recovers a claim-selected canonical record from an external archive. A local membership check controls release before model exposure; failed lookup or verification returns Defer. Under explicit selection and decision assumptions, the authoritative evidence and the decision grounded in it are independent of the memory-update order. In offline reconstruction over 24 recorded-session tasks and five high-load writer states, with frozen exact selection, verified recovery increases correct decisions from 21/120 to 109/120, with no wrong action and positive mean gains on 23/24 tasks. Matched controls separate the information supplied by episode evidence from the integrity enforced by verification. Structured memory and a released memory-system control show that recovery gains depend on missing coverage, while an open-weight full stack exposes record addressing as a separate bottleneck. These results support a verifiable evidence path for exact commitments when compact memory cannot guarantee coverage.