Status Updates From Nucleation

Post-mortem -- and a slip reveals the truth behind the comforting euphemistic account of her Navigator's situation.

It's construction in the far future, done by telepresence across a quantum link that allows instantaneous communication across tens or hundreds of lightyears. An "orphan star" with no family of planets, just asteroids there for the mining -- and something has gone wrong, The nanobots failed to complete the structure -- and then things really go pear shaped.