Explanation

Background and design rationale behind scinexus.

• Why composable apps? -- the problem scinexus solves and how it compares to alternatives
• The app lifecycle -- base classes and define_app
• Type system -- how composition-time type checking works
• Execution flow -- step-by-step data flow through a composed pipeline
• NotCompleted design -- why a sentinel pattern instead of exceptions
• Source tracking -- how source_proxy tracks data provenance through pipelines
• Customisation hooks -- set_summary_display and set_id_from_source registry functions
• Data store model -- unique IDs, checkpointing, and backend choices