// Package watch notices that a site root changed and says so.
//
// Contributes: a polling loop `cmd` runs in the background (no request-path behaviour).
// Cascade keys: none.
// Contract fields: none.
// Not doing: filesystem notifications — polling needs no dependency and no per-platform code, and a site this
// size is cheap to stat (ADR-0022). Fetching changes: the engine notices, it never pulls.
package watch