// Package sources defines feedkit's input-source abstraction.
//
// A source ingests upstream input and emits one or more event.Event values.
//
// feedkit supports two source modes:
//   - PollSource: scheduler invokes Poll on a cadence.
//   - StreamSource: source runs continuously and pushes events as input arrives.
//
// Source drivers are domain-specific and registered into Registry by driver name.
// Registry can then build configured sources from config.SourceConfig.
//
// A single source may emit 0..N events per poll or stream iteration, and those
// events may span multiple event kinds.
package sources